Antennas

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Electronics electronics	2.6	5.3	2012	16.8 Days	CHF 2400
Future Internet futureinternet	2.8	7.1	2009	13.1 Days	CHF 1600
Sensors sensors	3.4	7.3	2001	16.8 Days	CHF 2600
Telecom telecom	2.1	4.8	2020	22.7 Days	CHF 1200

11 pages, 242 KiB

Open AccessEditorial

Editorial on Antennas

by Naser Ojaroudi Parchin, Chan Hwang See and Raed A. Abd-Alhameed

Sensors 2023, 23(24), 9643; https://doi.org/10.3390/s23249643 - 6 Dec 2023

Viewed by 1132

In the ever-evolving landscape of modern wireless communication systems, the escalating demand for seamless connectivity has propelled the imperative for avant garde, versatile, and high-performance antennas to unprecedented heights [...] Full article

(This article belongs to the Topic Antennas)

18 pages, 7205 KiB

Open AccessArticle

Optimal Pattern Synthesis of Linear Array Antennas Using the Nonlinear Chaotic Grey Wolf Algorithm

by Kunxia Zhao, Yan Liu and Kui Hu

Electronics 2023, 12(19), 4087; https://doi.org/10.3390/electronics12194087 - 29 Sep 2023

Cited by 5 | Viewed by 1228

Abstract

The grey wolf optimization (GWO) algorithm is a new nature-inspired meta-heuristic algorithm inspired by the social hierarchy and hunting behavior of grey wolves. In this paper, the GWO algorithm is improved to overcome previous shortcomings of being easily trapped in local optima and [...] Read more.

The grey wolf optimization (GWO) algorithm is a new nature-inspired meta-heuristic algorithm inspired by the social hierarchy and hunting behavior of grey wolves. In this paper, the GWO algorithm is improved to overcome previous shortcomings of being easily trapped in local optima and having a low convergence rate. The proposed enhancement of the GWO algorithm utilizes logistic-tent double mapping to generate initialized populations, which enhances its global search capability and convergence rate. This improvement is called the nonlinear chaotic grey wolf optimization (NCGWO) algorithm. The performance of the NCGWO algorithm was evaluated with four representative benchmark functions. Then, the NCGWO algorithm was applied to perform an optimal pattern synthesis of linear array antennas (LAAs) using two distinct approaches: optimizing the amplitudes of the antenna currents while preserving uniform spacing and optimizing the positions of the antennas while assuming uniform excitation. To validate the effectiveness of the proposed approach, the results obtained by the NCGWO algorithm were compared with those obtained by other intelligent algorithms. Additionally, the NCGWO algorithm was applied to a more complex planar antenna array to further validate its performance. Our results demonstrate that the NCGWO algorithm exhibits superior performance regarding electromagnetic optimization problems compared to widely recognized algorithms. Full article

(This article belongs to the Topic Antennas)

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11 pages, 7342 KiB

Open AccessArticle

W-Band Broadband Circularly Polarized Reflectarray Antenna

by Zhicheng Wang, Rui Zhang, Wenke Song, Bingchuan Xie, Xiaobo Lin, Haixuan Li and Lu Tian

Electronics 2023, 12(18), 3849; https://doi.org/10.3390/electronics12183849 - 12 Sep 2023

Cited by 1 | Viewed by 1252

Abstract

We propose a W-band circularly polarized reflectarray antenna in this article, which contains a single-layer reflectarray and a linearly polarized horn feed. To realize the proposed antenna, we designed a novel W-band multi-resonant element containing a Rogers RT5880 substrate with copper patches printed [...] Read more.

We propose a W-band circularly polarized reflectarray antenna in this article, which contains a single-layer reflectarray and a linearly polarized horn feed. To realize the proposed antenna, we designed a novel W-band multi-resonant element containing a Rogers RT5880 substrate with copper patches printed on its both surfaces. Then, a circular reflectarray with 12.25 λ₀ (39.1 mm) aperture diameter was designed based on the proposed multi-resonant element, whose center frequency is 94 GHz. We further fabricated the proposed circular reflectarray and tested its performance. In the measured results, we can see that the obtained 1 dB gain bandwidth is 19.1% (91~109 GHz) and the obtained 2 dB gain bandwidth can reach as wide as 27.6% (89~115 GHz). Moreover, the 3 dB axial ratio bandwidth is 13.8% (89~102 GHz). The measured gain of our proposed reflectarray antenna at 94 GHz is 29.1 dBi and the corresponding aperture efficiency can reach as high as 52.0%. Those results show that our proposed antenna may be prospective in wireless communication applications due to its strengths in broadband and high aperture efficiency. Full article

(This article belongs to the Topic Antennas)

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10 pages, 9444 KiB

Open AccessCommunication

Design of a Crossed Dielectric Resonator-Loaded, Dual-Band Dual-Polarized Differential Patch Antenna with Improved Port Isolation and Gain

by Dongdong Wang, Yudong Liu and Jia Liang

Electronics 2023, 12(17), 3570; https://doi.org/10.3390/electronics12173570 - 24 Aug 2023

Cited by 1 | Viewed by 779

Abstract

To meet the urgent requirement for more channel capacity in modern wireless communication systems, antennas with more operation bands are demanded. However, large amounts of antennas suffer from low radiation gains and low port isolation levels. In view of this, a differentially fed, [...] Read more.

To meet the urgent requirement for more channel capacity in modern wireless communication systems, antennas with more operation bands are demanded. However, large amounts of antennas suffer from low radiation gains and low port isolation levels. In view of this, a differentially fed, dual-wideband, dual-polarized patch antenna is proposed in this paper. Compared with conventional crossed-feeding structures, the proposed crossed dielectric resonator (CDR) can provide extra resonances with improved isolation levels and radiation gain. Further, four shorting pins are introduced to the radiating patch to help improve the impedance-matching performance. In addition, the proposed antenna also has a very compact size of 0.46λ × 0.46λ × 0.12λ. Finally, a prototype of the proposed antenna is fabricated to validate the design concept. The measured results show that the proposed antenna generates dual wide bands of 1.86–2.52 GHz and 3.26–3.72 GHz for |S₁₁| < −10 dB. High radiation gains of 8.9 ± 0.9 dBi and 10.8 ± 1.2 dBi are also obtained, as well as high port isolation levels of better than 38.4 dB and 36.2 dB at the two bands. The excellent performance of the proposed antenna makes it a promising candidate for 4G/5G wireless communication systems. Full article

(This article belongs to the Topic Antennas)

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34 pages, 23062 KiB

Open AccessArticle

Linear Antenna Array Sectorized Beam Scanning Approaches Using Element Position Perturbation in the Azimuth Plane

by Safaa I. Abd Elrahman, Ahmed M. Elkhawaga, Amr H. Hussein and Abd Elhameed A. Shaalan

Sensors 2023, 23(14), 6557; https://doi.org/10.3390/s23146557 - 20 Jul 2023

Cited by 2 | Viewed by 1406

Abstract

In this paper, two sector beam scanning approaches (BSAs) based on element position perturbations (EPPs) in the azimuth plane are introduced. In EPP-BSA, the elements’ excitations are kept constant and the elements’ positions in the direction normal to the array line are changed [...] Read more.

In this paper, two sector beam scanning approaches (BSAs) based on element position perturbations (EPPs) in the azimuth plane are introduced. In EPP-BSA, the elements’ excitations are kept constant and the elements’ positions in the direction normal to the array line are changed according to a predetermined EPP pattern. The magnitude and repetition rate of the selected EPP pattern determines the steering angle of the main beam. However, EPP-BSA results in a wide scanning range with a significant increase in the side lobe level (SLL). To mitigate this drawback, a reduction in the SLL of the array pattern is firstly performed using the single convolution/genetic algorithm (SC/GA) technique and then perturbing the elements’ positions in the azimuth plane. This combination between SLL reduction and EPP-BSA (SLL/EPP-BSA) results in a smaller scanning range with a relatively constant half power beamwidth (HPBW) and a much lower SLL. In addition, keeping the synthesized excitation coefficients constant without adding progressive phase shifters facilitates the manufacturing process and reduces the cost of the feeding network. Furthermore, a planar antenna array thinning approach is proposed to realize the EPP-BSA. The results are realized using the computer simulation technology (CST) microwave studio software package, which provides users with an optimized modeling environment and results in realizable and realistic designs. Full article

(This article belongs to the Topic Antennas)

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26 pages, 2757 KiB

Open AccessArticle

Flexible Antenna with Circular/Linear Polarization for Wideband Biomedical Wireless Communication

by Mohammed E. Yassin, Khaled F. A. Hussein, Qammer H. Abbasi, Muhammad A. Imran and Shaimaa A. Mohassieb

Sensors 2023, 23(12), 5608; https://doi.org/10.3390/s23125608 - 15 Jun 2023

Cited by 10 | Viewed by 2349

Abstract

A wideband low-profile radiating G-shaped strip on a flexible substrate is proposed to operate as biomedical antenna for off-body communication. The antenna is designed to produce circular polarization over the frequency range 5–6 GHz to communicate with WiMAX/WLAN antennas. Furthermore, it is designed [...] Read more.

A wideband low-profile radiating G-shaped strip on a flexible substrate is proposed to operate as biomedical antenna for off-body communication. The antenna is designed to produce circular polarization over the frequency range 5–6 GHz to communicate with WiMAX/WLAN antennas. Furthermore, it is designed to produce linear polarization over the frequency range 6–19 GHz for communication with the on-body biosensor antennas. It is shown that an inverted G-shaped strip produces circular polarization (CP) of the opposite sense to that produced by G-shaped strip over the frequency range 5–6 GHz. The antenna design is explained and its performance is investigated through simulation, as well as experimental measurements. This antenna can be viewed as composed of a semicircular strip terminated with a horizontal extension at its lower end and terminated with a small circular patch through a corner-shaped strip extension at its upper end to form the shape of “G” or inverted “G”. The purpose of the corner-shaped extension and the circular patch termination is to match the antenna impedance to 50

Ω

over the entire frequency band (5–19 GHz) and to improve the circular polarization over the frequency band (5–6 GHz). To be fabricated on only one face of the flexible dielectric substrate, the antenna is fed through a co-planar waveguide (CPW). The antenna and the CPW dimensions are optimized to obtain the most optimal performance regarding the impedance matching bandwidth, 3dB Axial Ratio (AR) bandwidth, radiation efficiency, and maximum gain. The results show that the achieved 3dB-AR bandwidth is 18% (5–6 GHz). Thus, the proposed antenna covers the 5 GHz frequency band of the WiMAX/WLAN applications within its 3dB-AR frequency band. Furthermore, the impedance matching bandwidth is 117% (5–19 GHz) which enables low-power communication with the on-body sensors over this wide range of the frequency. The maximum gain and radiation efficiency are 5.37 dBi and 98%, respectively. The overall antenna dimensions are 25 × 27 × 0.13 mm

^{3}

and the bandwidth-dimension ratio (BDR) is 1733. Full article

(This article belongs to the Topic Antennas)

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13 pages, 4369 KiB

Open AccessArticle

A Patch Antenna with Enhanced Gain and Bandwidth for Sub-6 GHz and Sub-7 GHz 5G Wireless Applications

by Shehab Khan Noor, Muzammil Jusoh, Thennarasan Sabapathy, Ali Hanafiah Rambe, Hamsakutty Vettikalladi, Ali M. Albishi and Mohamed Himdi

Electronics 2023, 12(12), 2555; https://doi.org/10.3390/electronics12122555 - 6 Jun 2023

Cited by 14 | Viewed by 6779

Abstract

This paper presents a novel microstrip patch antenna design using slots and parasitic strips to operate at the n77 (3.3–4.2 GHz)/n78 (3.3–3.8 GHz) band of sub-6 GHz and n96 (5.9–7.1 GHz) band of sub-7 GHz under 5G New Radio. The proposed antenna is [...] Read more.

This paper presents a novel microstrip patch antenna design using slots and parasitic strips to operate at the n77 (3.3–4.2 GHz)/n78 (3.3–3.8 GHz) band of sub-6 GHz and n96 (5.9–7.1 GHz) band of sub-7 GHz under 5G New Radio. The proposed antenna is simulated and fabricated using an FR-4 substrate with a relative permittivity of 4.3 and copper of 0.035 mm thickness for the ground and radiating planes. A conventional patch antenna with a slot is also designed and fabricated for comparison. A comprehensive analysis of both designs is carried out to prove the superiority of the proposed antenna over conventional dual-band patch antennas. The proposed antenna achieves a wider bandwidth of 160 MHz at 3.45 GHz and 220 MHz at 5.9 GHz, with gains of 3.83 dBi and 0.576 dBi, respectively, compared to the conventional patch antenna with gains of 2.83 dBi and 0.1 dBi at the two frequencies. Parametric studies are conducted to investigate the effect of the parasitic strip’s width and length on antenna performance. The results of this study have significant implications for the deployment of high-gain compact patch antennas for sub-6 GHz and sub-7 GHz 5G wireless communications and demonstrate the potential of the proposed design to enhance performance and efficiency in these frequency bands. Full article

(This article belongs to the Topic Antennas)

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11 pages, 1718 KiB

Open AccessCommunication

Maximizing Antenna Array Aperture Efficiency for Footprint Patterns

by Cibrán López-Álvarez, María Elena López-Martín, Juan Antonio Rodríguez-González and Francisco José Ares-Pena

Sensors 2023, 23(10), 4982; https://doi.org/10.3390/s23104982 - 22 May 2023

Viewed by 1658

Abstract

Despite playing a central role in antenna design, aperture efficiency is often disregarded. Consequently, the present study shows that maximizing the aperture efficiency reduces the required number of radiating elements, which leads to cheaper antennas with more directivity. For this, it is considered [...] Read more.

Despite playing a central role in antenna design, aperture efficiency is often disregarded. Consequently, the present study shows that maximizing the aperture efficiency reduces the required number of radiating elements, which leads to cheaper antennas with more directivity. For this, it is considered that the boundary of the antenna aperture has to be inversely proportional to the half-power beamwidth of the desired footprint for each

ϕ

-cut. As an example of application, it has been considered the rectangular footprint, for which a mathematical expression was deduced to calculate the aperture efficiency in terms of the beamwidth, synthesizing a rectangular footprint of a 2:1 aspect ratio by starting from a pure real flat-topped beam pattern. In addition, a more realistic pattern was studied, the asymmetric coverage defined by the European Telecommunications Satellite Organization, including the numerical computation of the contour of the resulting antenna and its aperture efficiency. Full article

(This article belongs to the Topic Antennas)

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16 pages, 6207 KiB

Open AccessArticle

Multi-Layer Beam Scanning Leaky Wave Antenna for Remote Vital Signs Detection at 60 GHz

by Solomon Mingle, Despoina Kampouridou and Alexandros Feresidis

Sensors 2023, 23(8), 4059; https://doi.org/10.3390/s23084059 - 17 Apr 2023

Cited by 1 | Viewed by 1797

Abstract

A multi-layer beam-scanning leaky wave antenna (LWA) for remote vital sign monitoring (RVSM) at 60 GHz using a single-tone continuous-wave (CW) Doppler radar has been developed in a typical dynamic environment. The antenna’s components are: a partially reflecting surface (PRS), high-impedance surfaces (HISs), [...] Read more.

A multi-layer beam-scanning leaky wave antenna (LWA) for remote vital sign monitoring (RVSM) at 60 GHz using a single-tone continuous-wave (CW) Doppler radar has been developed in a typical dynamic environment. The antenna’s components are: a partially reflecting surface (PRS), high-impedance surfaces (HISs), and a plain dielectric slab. A dipole antenna works as a source together with these elements to produce a gain of 24 dBi, a frequency beam scanning range of

30 °

, and precise remote vital sign monitoring (RVSM) up to 4 m across the operating frequency range (58–66 GHz). The antenna requirements for the DR are summarised in a typical dynamic scenario where a patient is to have continuous monitoring remotely, while sleeping. During the continuous health monitoring process, the patient has the freedom to move up to one meter away from the fixed sensor position.The proposed multi-layer LWA system was placed at a distance of 2 m and 4 m from the test subject to confirm the suitability of the developed antenna for dynamic RVSM applications. A proper setting of the operating frequency range (58 to 66 GHz) enabled the detection of both heart beats and respiration rates of the subject within a

30 °

angular range. Full article

(This article belongs to the Topic Antennas)

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12 pages, 9281 KiB

Open AccessCommunication

Experimental Demonstration of Beam Scanning of Dual-Metasurface Antenna

by Lucia Teodorani, Francesco Vernì, Giorgio Giordanengo, Rossella Gaffoglio and Giuseppe Vecchi

Electronics 2023, 12(8), 1833; https://doi.org/10.3390/electronics12081833 - 12 Apr 2023

Cited by 3 | Viewed by 1933

Abstract

Beam-scanning antennas are employed in a wide range of applications, such as in satellite communications and 5G networks. Current commercial solutions rely mostly on electronically reconfigurable phased arrays, which require complex feeding networks and are affected by high losses, high costs, and are [...] Read more.

Beam-scanning antennas are employed in a wide range of applications, such as in satellite communications and 5G networks. Current commercial solutions rely mostly on electronically reconfigurable phased arrays, which require complex feeding networks and are affected by high losses, high costs, and are often power-hungry. In this paper, a novel beam scanning architecture employing a pair of planar metasurfaces, for use in thin reconfigurable antennas, is presented and experimentally demonstrated. The structure consisted of a radiative passive (non-reconfigurable) modulated metasurface, and a second metasurface that controls beam pointing, operating as a variable-impedance ground plane. Unlike other existing approaches, surface impedance variation was obtained by on-plane varactor diodes, no vias and a single voltage bias. This paper presents a design procedure based on an approximate theoretical model and simulation verification; a prototype of the designed antenna was fabricated for operation in X band, and a good agreement between measured results and simulations was observed. In the presented simple embodiment of the concept, the angular scanning range was limited to

10^{°}

; this limitation is discussed in view of future applications. Full article

(This article belongs to the Topic Antennas)

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19 pages, 12389 KiB

Open AccessArticle

Design of Broadband Low-RCS Array Antennas Based on Characteristic Mode Cancellation

by Jialiang Han, Dan Jia, Biao Du, Guodong Han, Yongtao Jia and Zekang Zhao

Electronics 2023, 12(7), 1536; https://doi.org/10.3390/electronics12071536 - 24 Mar 2023

Cited by 2 | Viewed by 1714

Abstract

In this letter, a design method for low radar cross section (RCS) array antennas based on characteristic mode cancellation (CMC) is presented. Based on the characteristic mode theory (CMT), two novel microstrip elements are designed by introducing rectangular slots and cross slots, which [...] Read more.

In this letter, a design method for low radar cross section (RCS) array antennas based on characteristic mode cancellation (CMC) is presented. Based on the characteristic mode theory (CMT), two novel microstrip elements are designed by introducing rectangular slots and cross slots, which produce 180° scattering phase difference by adjusting the size of slots. The dominant characteristic modes of the two elements achieve broadband dual-linear polarization CMC and similar radiation performances. The 4 × 4 array antenna consisting of these two antenna elements is designed. The operating band is from 4.55 GHz to 5.49 GHz (relative bandwidth 18.7%). The gain loss of the proposed array is about 0.1 dB compared to the reference array. The monostatic RCS is reduced for dual−linear polarized waves, and the 6 dB radar cross section reduction (RCSR) bandwidths are 62.3% and 35.7%, respectively. The prototype is fabricated and measured. The measured results of radiation pattern and RCS are in good agreement with the simulated results. Full article

(This article belongs to the Topic Antennas)

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14 pages, 3686 KiB

Open AccessCommunication

Compact UWB MIMO Antenna for 5G Millimeter-Wave Applications

by Mohamed Atef Abbas, Abdelmegid Allam, Abdelhamid Gaafar, Hadia M. Elhennawy and Mohamed Fathy Abo Sree

Sensors 2023, 23(5), 2702; https://doi.org/10.3390/s23052702 - 1 Mar 2023

Cited by 22 | Viewed by 3200

Abstract

This paper presents a printed multiple-input multiple-output (MIMO) antenna with the advantages of compact size, good MIMO diversity performance and simple geometry for fifth-generation (5G) millimeter-wave (mm-Wave) applications. The antenna offers a novel Ultra-Wide Band (UWB) operation from 25 to 50 GHz, using [...] Read more.

This paper presents a printed multiple-input multiple-output (MIMO) antenna with the advantages of compact size, good MIMO diversity performance and simple geometry for fifth-generation (5G) millimeter-wave (mm-Wave) applications. The antenna offers a novel Ultra-Wide Band (UWB) operation from 25 to 50 GHz, using a Defective Ground Structure (DGS) technology. Firstly, its compact size makes it suitable for integrating different telecommunication devices for various applications, with a prototype fabricated having a total size of 33 mm × 33 mm × 0.233 mm. Second, the mutual coupling between the individual elements severely impacts the diversity properties of the MIMO antenna system. An effective technique of orthogonally positioning the antenna elements to each other increased their isolation; thus, the MIMO system provides the best diversity performance. The performance of the proposed MIMO antenna was investigated in terms of S-parameters and MIMO diversity parameters to ensure its suitability for future 5G mm-Wave applications. Finally, the proposed work was verified by measurements and exhibited a good match between simulated and measured results. It achieves UWB, high isolation, low mutual coupling, and good MIMO diversity performance, making it a good candidate and seamlessly housed in 5G mm-Wave applications. Full article

(This article belongs to the Topic Antennas)

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14 pages, 9989 KiB

Open AccessFeature PaperArticle

Antipodal Linearly Tapered Slot Antenna with Quasi-Hemispherical Pattern Using Subwavelength Elements

by Rui Wang, Dashuang Liao and Feng Yang

Electronics 2023, 12(3), 628; https://doi.org/10.3390/electronics12030628 - 27 Jan 2023

Viewed by 1799

Abstract

Antennas with quasi-hemispherical radiation patterns are preferred in many wide−area wireless communication systems which require the signals to uniformly cover a wide two−dimensional region. In this work, a simple but effective beamwidth broadening technique based on an antipodal linearly tapered slot antenna (ALTSA) [...] Read more.

Antennas with quasi-hemispherical radiation patterns are preferred in many wide−area wireless communication systems which require the signals to uniformly cover a wide two−dimensional region. In this work, a simple but effective beamwidth broadening technique based on an antipodal linearly tapered slot antenna (ALTSA) is first proposed and then experimentally verified. Compared with most of the reported designs, the proposed antenna can significantly widen beamwidth and achieve a quasi-hemispherical radiation pattern without increasing the overall size and structural complexity. Only two rows of subwavelength metallic elements (eight elements in total) are simply and skillfully printed at specified positions on the dielectric substrate (relative permittivity ε_r = 2.94 and thickness h = 1.5 mm) of a general ALTSA whose peak gain is 11.7 dBi, approximately 200% half-power beamwidth (HPBW) enlargement can be obtained in all cut-planes containing the end-fire direction at the central frequency of 15 GHz, and the HPBW extensions in different cut-planes have good consistency. Thus, a quasi-hemispherical beam pattern can be acquired. Thanks to the simplicity of this method, the antenna size and structural complexity do not increase, resulting in the characteristics of easy fabrication and integration, being lightweight, and high reliability. This proposed method provides a good choice for wide−beam antenna design and will have a positive effect on the potential applications of wide-area wireless communication systems. Full article

(This article belongs to the Topic Antennas)

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16 pages, 8089 KiB

Open AccessArticle

A Single-Fed Wideband Circularly Polarized Cross-Fed Cavity-Less Magneto-Electric Dipole Antenna

by Linyu Cai and Kin-Fai Tong

Sensors 2023, 23(3), 1067; https://doi.org/10.3390/s23031067 - 17 Jan 2023

Cited by 3 | Viewed by 2327

Abstract

In this paper, we proposed a new wideband circularly polarized cross-fed magneto-electric dipole antenna. Different from conventional cross-dipole or magneto-electric dipole antennas, the proposed simple geometry realizes a pair of complementary magnetic dipole modes by utilizing the two open slots formed between the [...] Read more.

In this paper, we proposed a new wideband circularly polarized cross-fed magneto-electric dipole antenna. Different from conventional cross-dipole or magneto-electric dipole antennas, the proposed simple geometry realizes a pair of complementary magnetic dipole modes by utilizing the two open slots formed between the four cross-fed microstrip patches for achieving circular polarization and high stable gain across a wide frequency band. No parasitic elements are required for extending the bandwidths; therefore, both the radiation patterns and in-band gain are stable. The simulated field distributions demonstrated the phase complementarity of the two pairs of magnetic and electric dipole modes. A parametric study was also performed to demonstrate the radiation mechanism between the electric and magnetic dipole modes. The radiating elements are realized on a piece of double-sided dielectric substrate fed and mechanically supported by a low-cost commercial semirigid cable. The overall thickness of the antenna is about 0.22λ_o at the center frequency of axial ratio bandwidth. The measured results show a wide impedance bandwidth (|S₁₁| < −10 dB) of 70.2% from 2.45 to 5.10 GHz. The in-band 3-dB axial ratio bandwidth is 51.5% from 3.0 to 5.08 GHz. More importantly, the gain of the antenna is 9.25 ± 0.56 dBic across the 3-dB axial ratio bandwidth. Full article

(This article belongs to the Topic Antennas)

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25 pages, 18266 KiB

Open AccessArticle

A Novel Integrated UWB Sensing and 8-Element MIMO Communication Cognitive Radio Antenna System

by D Srikar, Anveshkumar Nella, Ranjith Mamidi, Ashok Babu, Sudipta Das, Sunil Lavadiya, Abeer D. Algarni and Walid El-Shafai

Electronics 2023, 12(2), 330; https://doi.org/10.3390/electronics12020330 - 8 Jan 2023

Cited by 6 | Viewed by 2700

Abstract

In this article, a cognitive radio (CR) integrated antenna system, which has 1 sensing and 24 communication antennas, is proposed for better spectrum utilization efficiency. In the 24 communication antennas, 3 different operating band antennas are realized with an 8-element MIMO configuration. The [...] Read more.

In this article, a cognitive radio (CR) integrated antenna system, which has 1 sensing and 24 communication antennas, is proposed for better spectrum utilization efficiency. In the 24 communication antennas, 3 different operating band antennas are realized with an 8-element MIMO configuration. The sensing antenna linked to port 1 is able to sense the spectrum that ranges from 2 to 12 GHz, whereas the communication 8-element MIMO antennas linked with ports 2 to 9, ports 10 to 17 and ports 18 to 25 perform operations in the 2.17–4.74 GHz, 4.57–8.62 GHz and 8.62–12 GHz bands, respectively. Mutual coupling is found to be less than −12 dB between the antenna elements. Peak gain and radiation efficiency of the sensing antenna are better than 2.25 dBi and 82%, respectively, whereas the peak gains and radiation efficiencies of all communication antennas are more than 2.5 dBi and 90%, respectively. Moreover, diversity characteristics of the MIMO antenna are assessed by parameters such as DG, ECC and CCL. It is found that ECC and CCL are less than 0.42 and 0.46 bits/s/Hz, respectively, and also DG is more than 9.1 dB. Full article

(This article belongs to the Topic Antennas)

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12 pages, 2410 KiB

Open AccessArticle

A Composite Right/Left-Handed Phase Shifter-Based Cylindrical Phased Array with Reinforced Particles Responsive to Magneto-Static Fields

by Muhammad Ayaz, Adnan Iftikhar, Benjamin D. Braaten, Wesam Khalil and Irfan Ullah

Electronics 2023, 12(2), 306; https://doi.org/10.3390/electronics12020306 - 6 Jan 2023

Cited by 9 | Viewed by 2081

Abstract

A conformal cylindrical phased array antenna excited with composite right/left-handed (CRLH) phase shifters is proposed. The phase tuning of the CRLH phase shifter is achieved by embedding novel magneto-static field-responsive micron-sized particles in its structure. It is shown that through the tiny magnet [...] Read more.

A conformal cylindrical phased array antenna excited with composite right/left-handed (CRLH) phase shifters is proposed. The phase tuning of the CRLH phase shifter is achieved by embedding novel magneto-static field-responsive micron-sized particles in its structure. It is shown that through the tiny magnet activation of these novel magneto-static particles at appropriate locations along the length of CRLH stub and inter-digital fingers, variable phase shifts are obtained. The proposed particle-based CRLH phase shifter operates in C-band (5–6) GHz with a low insertion loss and phase error. The 1 × 4 cylindrical phased array is excited with the four unit cells of the proposed particle-embedded CRLH transmission line phase shifters to scan the main beam at desired scan angles. A prototype of a 1 × 4 cylindrical phased array excited with the particle-based CRLH phase shifters was fabricated, and the results show that the simulated results are in close agreement with the measured results. The conformal cylindrical array with the proposed particle-based CRLH phase shifters has great potential for use in printed and flexible electronics design where commercially available phase shifters have a definite drawback. Full article

(This article belongs to the Topic Antennas)

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20 pages, 18366 KiB

Open AccessArticle

Design of 1 × 2 MIMO Palm Tree Coplanar Vivaldi Antenna in the E-Plane with Different Patch Structure

by Nurhayati Nurhayati, Eko Setijadi, Alexandre Maniçoba de Oliveira, Dayat Kurniawan and Mohd Najib Mohd Yasin

Electronics 2023, 12(1), 177; https://doi.org/10.3390/electronics12010177 - 30 Dec 2022

Cited by 2 | Viewed by 2483

Abstract

In this paper, 1 × 2 MIMO of Palm Tree Coplanar Vivaldi Antenna is presented that simulated at 0.5–4.5 GHz. Some GPR applications require wideband antennas starting from a frequency below 1 GHz to overcome high material loss and achieve deeper penetration. However, [...] Read more.

In this paper, 1 × 2 MIMO of Palm Tree Coplanar Vivaldi Antenna is presented that simulated at 0.5–4.5 GHz. Some GPR applications require wideband antennas starting from a frequency below 1 GHz to overcome high material loss and achieve deeper penetration. However, to boost the gain, antennas are set up in MIMO and this is costly due to the large size of the antenna. When configuring MIMO antenna in the E-plane, there is occasionally uncertainty over which antenna model may provide the optimum performance in terms of return loss, mutual coupling, directivity, beam squint, beam width, and surface current using a given substrate size. However, the configuration of E-plane antenna in MIMO has an issue of mutual coupling if the distance between elements is less than 0.5λ. Furthermore, it produces grating lobes at high frequencies.We implement several types of patch structures by incorporating the truncated, tilt shape, Hlbert and Koch Fractal, Exponential slot, Wave slot, the lens with elips, and metamaterial slot to the radiator by keeping the width of the substrate and the shape of the feeder. The return loss, mutual coupling, directivity, beam squint, beamwidth, and surface current of the antenna are compared for 1 × 2 MIMO CVA. A continuous patch MIMO has a spacing of 0.458λ at 0.5 GHz, which is equivalent to its element width. From the simulation, we found that Back Cut Palm Tree (BCPT) and Horizontale Wave Structure Palm Tree (HWSPT) got the best performance of return loss and mutual scattering at low-end frequency respectively. The improvement of directivity got for Metamaterial Lens Palm Tree (MLPT) of 4.453 dBi if compared with Regular Palm Tree-Coplanar Vivaldi Antena (RPT) at 4 GHz. Elips Lens Palm Tree (ELPT) has the best beam squint performance across all frequencies of 0°. It also gots the best beamwidth at 4.5 GHz of 3.320. In addition, we incorporate the MLPT into the radar application. Full article

(This article belongs to the Topic Antennas)

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15 pages, 4190 KiB

Open AccessArticle

Evolutionary Computation for Sparse Synthesis Optimization of CCAAs: An Enhanced Whale Optimization Algorithm Method

by Bohao Tang, Lihua Cai, Shuai Yang, Jiaxing Xu and Yi Yu

Future Internet 2022, 14(12), 347; https://doi.org/10.3390/fi14120347 - 22 Nov 2022

Cited by 1 | Viewed by 1342

Abstract

Concentric circular antenna arrays (CCAAs) can obtain better performance than other antenna arrays. However, high overhead and excessive sidelobes still make its application difficult. In this paper, we consider the sparse synthesis optimization of CCAAs. Specifically, we aim to turn off a specific [...] Read more.

Concentric circular antenna arrays (CCAAs) can obtain better performance than other antenna arrays. However, high overhead and excessive sidelobes still make its application difficult. In this paper, we consider the sparse synthesis optimization of CCAAs. Specifically, we aim to turn off a specific number of antennas while reducing the sidelobe of CCAAs. First, we formulate an optimization problem and present the solution space. Then, we propose a novel evolutionary method for solving the optimization problem. Our proposed method introduces hybrid solution initialization, hybrid crossover method, and hybrid update methods. Simulation results show the effectiveness of the proposed algorithm and the proposed improvement factors. Full article

(This article belongs to the Topic Antennas)

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11 pages, 3874 KiB

Open AccessArticle

Design of a Dual-Polarization Dipole Antenna for a Cylindrical Phased Array in Ku-Band

by Ning Zhang, Zhenghui Xue, Pei Zheng, Lu Gao and Jia Qi Liu

Electronics 2022, 11(22), 3796; https://doi.org/10.3390/electronics11223796 - 18 Nov 2022

Cited by 2 | Viewed by 3105

Abstract

This paper proposes a dual-polarization dipole antenna for a cylindrical phased array working in Ku-band. The dipole antenna is double-layer structured and is composed of two orthogonal butterfly shaped dipole radiators, two ground co-planar waveguide (GCPW) feeding structures and vias. Each dipole is [...] Read more.

This paper proposes a dual-polarization dipole antenna for a cylindrical phased array working in Ku-band. The dipole antenna is double-layer structured and is composed of two orthogonal butterfly shaped dipole radiators, two ground co-planar waveguide (GCPW) feeding structures and vias. Each dipole is in the shape of a butterfly. The dipole patch is grooved triangularly and one side of it is bent into an N shape, which effectively expands the working frequency band of the antenna. The double-layer structure improves the isolation between the antenna ports. The antenna works between 15 GHz to 16.2 GHz and the isolation between the antenna’s two feeding ports in this band is better than 20 dB. The proposed dipole antenna is applied in a 32-element cylinder array. The simulation and measured results show that the array can scan between −60° to +60° in the azimuth plane with a gain fluctuation less than 2.5 dB. Therefore, the proposed design is an attractive candidate for conformal devices at Ku-band frequencies, and it also has a great potential for application in larger antenna arrays. Full article

(This article belongs to the Topic Antennas)

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16 pages, 11015 KiB

Open AccessArticle

Radio Astronomical Antennas in the Central African Region to Improve the Sampling Function of the VLBI Network in the SKA Era?

by Marcellin Atemkeng, Patrice Okouma, Eric Maina, Roger Ianjamasimanana and Serges Zambou

Sensors 2022, 22(21), 8466; https://doi.org/10.3390/s22218466 - 3 Nov 2022

Cited by 1 | Viewed by 1979

Abstract

On the African continent, South Africa has world-class astronomical facilities for advanced radio astronomy research. With the advent of the Square Kilometre Array project in South Africa (SA SKA), six countries in Africa (SA SKA partner countries) have joined South Africa to contribute [...] Read more.

On the African continent, South Africa has world-class astronomical facilities for advanced radio astronomy research. With the advent of the Square Kilometre Array project in South Africa (SA SKA), six countries in Africa (SA SKA partner countries) have joined South Africa to contribute towards the African Very Long Baseline Interferometry (VLBI) Network (AVN). Each of the AVN countries aims to construct a single-dish radio telescope that will be part of the AVN, the European VLBI Network, and the global VLBI network. The SKA and the AVN will enable very high sensitivity VLBI in the southern hemisphere. In the current AVN, there is a gap in the coverage in the central African region. This work analyses the increased scientific impact of having additional antennas in each of the six countries in central Africa, i.e., Cameroon, Gabon, Congo, Equatorial Guinea, Chad, and the Central African Republic. A number of economic human capital impacts of having a radio interferometer in central Africa are also discussed. This work also discusses the recent progress on the AVN project and shares a few lessons from some past successes in ground stations retrofitting. Full article

(This article belongs to the Topic Antennas)

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Decommissioned 32-m large satellite earth station antennas in Gabon. Full article ">Figure 2
Green points: locations of the Kuntunse antenna in Ghana, the MeerKAT stations in South Africa, and the EVN. Red points: locations of abandoned old telecommunication satellite facilities in the ECCAS region and/or possible sites to build new radio telescopes. Full article ">Figure 3
The EVN combined with the MeerKAT telescope (left panels) and the EVN combined with the MeerKAT telescope and the Kuntunse antenna in Ghana (right panels). Full article ">Figure 4
ECCAS antennas <math display="inline"><semantics> <mrow> <mi>u</mi> <mi>v</mi> </mrow> </semantics></math>-coverage at 1.4 GHz at four declinations (<math display="inline"><semantics> <mrow> <mo>−</mo> <mn>20</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mo>+</mo> <mn>20</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mo>+</mo> <mn>45</mn> </mrow> </semantics></math>, and <math display="inline"><semantics> <mrow> <mo>+</mo> <mn>60</mn> </mrow> </semantics></math> deg), 10 h observation, and 16 MHz total bandwidth showing a lot of holes or gaps. Full article ">Figure 5
Performance of the global VLBI <math display="inline"><semantics> <mrow> <mi>u</mi> <mi>v</mi> </mrow> </semantics></math>-coverage. The ECCAS antennas are correlated with the Kuntunse antenna, the MeerKAT telescope, and the EVN. The <math display="inline"><semantics> <mrow> <mi>u</mi> <mi>v</mi> </mrow> </semantics></math>-coverage is well-filled because of the extra medium-length baselines that relate the EVN and MeerKAt telescope to the ECCAS antennas. Full article ">Figure 6
Simulated sky model with two point sources: a 1 Jy point source at the phase centre and a far-field point source with 5 Jy brightness located at 6 arcmin from the phase centre as seen by the EVN + MeerKAT + Kuntunse telescope (left) and by the EVN + MeerKAT + Kuntunse + ECCAS telescope (right) for a simulated observation at 16 GHz. To corrupt the simulation, 1 Jy Gaussian noise per visibility is used. The data are sampled during a total period of 10 h with 1 s integration time and using a total bandwidth of 16 MHz divided into 64 channels. Then, a few pixels are imaged to visualise only the source at the phase centre. Full article ">

9 pages, 6093 KiB

Open AccessArticle

A Simple and Effective Approach for Scattering Suppression in Multiband Base Station Antennas

by Madiha Farasat, Dushmantha Thalakotuna, Zhonghao Hu and Yang Yang

Electronics 2022, 11(21), 3423; https://doi.org/10.3390/electronics11213423 - 22 Oct 2022

Cited by 3 | Viewed by 2353

Abstract

The high band pattern distortions in an 1810–2690 MHz frequency band, introduced due to low band radiators working in 690–960 MHz, are mitigated by a simple yet effective change to the low band-radiating elements. A novel horizontal and vertical radiating element is designed [...] Read more.

The high band pattern distortions in an 1810–2690 MHz frequency band, introduced due to low band radiators working in 690–960 MHz, are mitigated by a simple yet effective change to the low band-radiating elements. A novel horizontal and vertical radiating element is designed instead of a conventional slant polarized low band-radiating element to reduce the scattering. The slant polarization is achieved from the horizontal and vertical dipoles, using a 180° hybrid coupler. The vertical dipole length is optimized to improve the high band patterns. The experimental results verified that the proposed horizontal and vertical low band dipole result in the reduction of high band pattern distortions. The low band-radiating elements provide >12 dB return loss over the entire frequency band 690–960 MHz and provide comparable pattern performance to a conventional slant low band dipole. Full article

(This article belongs to the Topic Antennas)

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18 pages, 2995 KiB

Open AccessArticle

Beamforming with 1 × N Conformal Arrays

by Irfan Ullah, Benjamin D. Braaten, Adnan Iftikhar, Symeon Nikolaou and Dimitris E. Anagnostou

Sensors 2022, 22(17), 6616; https://doi.org/10.3390/s22176616 - 1 Sep 2022

Cited by 1 | Viewed by 2093

Abstract

The rapid growth of wireless spectrum access through cellular and IoT devices, for example, requires antennas with more capabilities such as being conformal and self-adapting beamforming. In this paper, the adaptive beamforming patterns of microstrip patch antenna arrays on changing flexible (or conformal) [...] Read more.

The rapid growth of wireless spectrum access through cellular and IoT devices, for example, requires antennas with more capabilities such as being conformal and self-adapting beamforming. In this paper, the adaptive beamforming patterns of microstrip patch antenna arrays on changing flexible (or conformal) curved surfaces are developed by deriving array coefficients based on the projection method that includes the mutual coupling between elements. A linear four-element microstrip patch antenna array is then embedded on two deformed conformal surfaces to investigate the projection method for desired beamforming patterns. The generated beamforming radiation patterns using the computed weighting coefficients are validated with theoretical equations evaluated in MATLAB, full-wave simulations in HFSS and measurement results. The measured results of the fabricated system agree with the simulated results. Furthermore, new guidelines are provided on the effects of mutual coupling and changing conformal surfaces for various beam-forming patterns. Such demonstrations pave the way to an efficient and robust conformal phased-array antenna with multiple beam forming and adaptive nulling capabilities. Full article

(This article belongs to the Topic Antennas)

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18 pages, 19247 KiB

Open AccessCommunication

Coplanar Meta-Surface-Based Substrate-Integrated Waveguide Antennas with Broadband and Low Reflections for K-Band Beam Scanning

by Chunli Wang, Dongxing Gao, Likai Liang and Yanling Wang

Sensors 2022, 22(17), 6353; https://doi.org/10.3390/s22176353 - 24 Aug 2022

Viewed by 2292

Abstract

Four novel substrate-integrated waveguide (SIW) antennas are proposed, in order to obtain K-band beam scanning through the coplanar meta-surfaces of properly devised complementary split-ring resonators. More specifically, coplanar rhombus- and hexagon-shaped meta-surfaces replace the metallized via holes in the traditional SIW structure, achieving [...] Read more.

Four novel substrate-integrated waveguide (SIW) antennas are proposed, in order to obtain K-band beam scanning through the coplanar meta-surfaces of properly devised complementary split-ring resonators. More specifically, coplanar rhombus- and hexagon-shaped meta-surfaces replace the metallized via holes in the traditional SIW structure, achieving low reflection and wide bandwidth, respectively. Another trapezoid-shaped meta-surface is introduced, in order to realize good leaky-wave radiation performance with high-gain beam scanning in both rhombus- and hexagon-shaped SIW components. These designs are further extended to two different mixed types of two-row meta-surfaces, with the rhombus and hexagon structures combined in different orders to enhance the complex SIW transmission lines and antennas, which can simultaneously obtain good reflection and bandwidth with different priority, depending on the arrangement. We explain the performance differences with rhombus and hexagon meta-surfaces through the analysis of relevant equivalent circuit models and extracting the effective medium parameters, and we verify the bandwidths and radiations of four SIW antennas both numerically and experimentally. The maximum gains of the four antennas are 18.1 dBi, 17.0 dBi, 18.8 dBi and 17.1 dBi, where the corresponding relative bandwidths are 10.74%, 19.42%, 14.13% and 18.38%. The maximum simulated radiation efficiency and aperture efficiency of the proposed antennas are 91.20% and 61.12%, respectively. Our approach for generating flexible and selectable tuned electromagnetic fields from SIWs is applicable for the development of mm-Wave antennas or sensors on PCB-integrated platforms for highly directive scanning radiation. Full article

(This article belongs to the Topic Antennas)

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13 pages, 10638 KiB

Open AccessCommunication

A Compact Four-Port MIMO Antenna for UWB Applications

by Aiting Wu, Mingyang Zhao, Pengquan Zhang and Zhonghai Zhang

Sensors 2022, 22(15), 5788; https://doi.org/10.3390/s22155788 - 3 Aug 2022

Cited by 17 | Viewed by 2725

Abstract

A compact four-port multiple-input multiple-output (MIMO) antenna for ultrawideband (UWB) applications is presented in this paper. The proposed antenna has four unit cell antennas. Each unit cell is placed orthogonal to its adjacent elements. The radiation element of each unit cell is composed [...] Read more.

A compact four-port multiple-input multiple-output (MIMO) antenna for ultrawideband (UWB) applications is presented in this paper. The proposed antenna has four unit cell antennas. Each unit cell is placed orthogonal to its adjacent elements. The radiation element of each unit cell is composed of a cut semicircular patch and a stepped microstrip feed line. The whole ground on the back side consists of four parts of defective ground and their extended branches, which are connected through a “卍” structure. The main decoupling technology used in the MIMO antenna is polarization diversity. In addition, protruded ground and parasitic elements are added to achieve a higher isolation. This compact antenna has a small area of 45 mm × 45 mm and is printed on a single layer substrate (FR4) with an ε_r = 4.4 and a thickness of 1.6 mm. This antenna has an impedance bandwidth (S11 < −10 dB) of 3.1–13.1 GHz (123%) and an isolation of less than −17 dB. The envelope correction coefficient (ECC) is less than 0.02 and the average gain is 4 dBi. The ultrawide bandwidth and compact size of the proposed antenna make it a promising candidate for UWB applications. Full article

(This article belongs to the Topic Antennas)

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16 pages, 5442 KiB

Open AccessArticle

Advanced Marine Predator Algorithm for Circular Antenna Array Pattern Synthesis

by Eunice Oluwabunmi Owoola, Kewen Xia, Samuel Ogunjo, Sandrine Mukase and Aadel Mohamed

Sensors 2022, 22(15), 5779; https://doi.org/10.3390/s22155779 - 2 Aug 2022

Cited by 12 | Viewed by 1849

Abstract

The pattern synthesis of antenna arrays is a substantial factor that can enhance the effectiveness and validity of a wireless communication system. This work proposes an advanced marine predator algorithm (AMPA) to synthesize the beam patterns of a non-uniform circular antenna array (CAA). [...] Read more.

The pattern synthesis of antenna arrays is a substantial factor that can enhance the effectiveness and validity of a wireless communication system. This work proposes an advanced marine predator algorithm (AMPA) to synthesize the beam patterns of a non-uniform circular antenna array (CAA). The AMPA utilizes an adaptive velocity update mechanism with a chaotic sequence parameter to improve the exploration and exploitation capability of the algorithm. The MPA structure is simplified and upgraded to overcome being stuck in the local optimum. The AMPA is employed for the joint optimization of amplitude current and inter-element spacing to suppress the peak sidelobe level (SLL) of 8-element, 10-element, 12-element, and 18-element CAAs, taking into consideration the mutual coupling effects. The results show that it attains better performances in relation to SLL suppression and convergence rate, in comparison with some other algorithms for the optimization case. Full article

(This article belongs to the Topic Antennas)

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19 pages, 10700 KiB

Open AccessArticle

Portable Wideband Directional Antenna Scheme with Semicircular Corrugated Reflector for Digital Television Reception

by Bancha Luadang, Rerkchai Pukraksa, Pisit Janpangngern, Khanet Pookkapund, Sitthichai Dentri, Sompol Kosulvit and Chuwong Phongcharoenpanich

Sensors 2022, 22(14), 5338; https://doi.org/10.3390/s22145338 - 17 Jul 2022

Cited by 1 | Viewed by 1997

Abstract

This research proposed a portable wideband horizontally-polarized directional antenna scheme with a radome for digital terrestrial television reception. The operating frequency band of the proposed antenna scheme is 470–890 MHz. The portable antenna scheme was an adaptation of the Yagi-Uda antenna, consisting of [...] Read more.

This research proposed a portable wideband horizontally-polarized directional antenna scheme with a radome for digital terrestrial television reception. The operating frequency band of the proposed antenna scheme is 470–890 MHz. The portable antenna scheme was an adaptation of the Yagi-Uda antenna, consisting of a folded bowtie radiator, a semicircular corrugated reflector, and a V-shaped director. Simulations were carried out, and an antenna prototype was fabricated. To validate, experiments were undertaken to assess the antenna performance, including the impedance bandwidth (|S₁₁| ≤ −10 dB), gain, and unidirectionality. The measured impedance bandwidth was 75.93%, covering 424–943 MHz, with a measured antenna gain of 2.69–4.84 dBi. The radiation pattern was of unidirectionality for the entire operating frequency band. The measured xz- and yz-plane half-power beamwidths were 150°, 159°, 160° and 102°, 78°, 102° at 470, 680, and 890 MHz, with the corresponding cross-polarization below −20 dB and −40 dB. The radome had a negligible impact on the impedance bandwidth, gain, and radiation pattern. The power obtained for the outdoor test, at 514 MHz, was 38.4 dBµV (−70.4 dBm) with a carrier-to-noise ratio (C/N) of 11.6 dB. In addition, the power obtained for the indoor test was 26.6 dBµV (−82.2 dBm) with a C/N of 10.9 dB. The novelty of this research lies in the concurrent use of the Yagi-Uda and bowtie antenna technologies to improve the impedance bandwidth and directionality of the antenna for digital terrestrial television reception. Full article

(This article belongs to the Topic Antennas)

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13 pages, 3787 KiB

Open AccessArticle

A Flower-Shaped Miniaturized UWB-MIMO Antenna with High Isolation

by Weidong Mu, Han Lin, Zhonggen Wang, Chenlu Li, Ming Yang, Wenyan Nie and Juan Wu

Electronics 2022, 11(14), 2190; https://doi.org/10.3390/electronics11142190 - 13 Jul 2022

Cited by 17 | Viewed by 2045

Abstract

An ultra-wideband (UWB) multiple-input, multiple-output (MIMO) antenna with a reasonably compact size of 30 × 18 × 1.6 mm³ is presented in this paper. The proposed antenna contains two radiating components, each of which is made up of three elliptically shaped patches [...] Read more.

An ultra-wideband (UWB) multiple-input, multiple-output (MIMO) antenna with a reasonably compact size of 30 × 18 × 1.6 mm³ is presented in this paper. The proposed antenna contains two radiating components, each of which is made up of three elliptically shaped patches situated 60 degrees apart, and resembles the shape of a flower. Moreover, the proposed antenna design incorporates a T-like ground branch that functions as a decoupling structure, and is composed of two modified inverted-L branches and an I-shaped stub, offering an isolation of more than 20 dB over the whole operation band (4.3–15.63 GHz). Furthermore, the proposed antenna system was fabricated and tested, and the envelope correlation coefficient (ECC), diversity gain (DG), and total active reflection coefficient (TARC), as well as the radiation characteristics and MIMO performance, were analyzed. The proposed UWB-MIMO antenna may be a suitable candidate for diverse UWB applications, based on the simulated and measured results of this study. Full article

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20 pages, 44792 KiB

Open AccessArticle

Performance Analysis of Wearable Dual-Band Patch Antenna Based on EBG and SRR Surfaces

by Abdul Wajid, Ashfaq Ahmad, Sadiq Ullah, Dong-you Choi and Faiz Ul Islam

Sensors 2022, 22(14), 5208; https://doi.org/10.3390/s22145208 - 12 Jul 2022

Cited by 14 | Viewed by 3129

Abstract

This paper presents the performance comparison of a dual-band conventional antenna with a split-ring resonator (SRR)- and electromagnetic bandgap (EBG)-based dual-band design operating at 2.4 GHz and 5.4 GHz. The compactness and dual-frequency operation in the legacy Wi-Fi range of this design make [...] Read more.

This paper presents the performance comparison of a dual-band conventional antenna with a split-ring resonator (SRR)- and electromagnetic bandgap (EBG)-based dual-band design operating at 2.4 GHz and 5.4 GHz. The compactness and dual-frequency operation in the legacy Wi-Fi range of this design make it highly favorable for wearable sensor network-based Internet of Things (IoT) applications. Considering the current need for wearable antennas, wash cotton (with a relative permittivity of 1.51) is used as a substrate material for both conventional and metamaterial-based antennas. The radiation characteristics of the conventional antenna are compared with the EBG and SRR ground planes-based antennas in terms of return loss, gain, and efficiency. It is found that the SRR-based antenna is more efficient in terms of gain and surface wave suppression as well as more compact in comparison with its two counterparts. The compared results are found to be based on two distinct frequency ranges, namely, 2.4 GHz and 5.4 GHz. The suggested SRR-based antenna exhibits improved performance at 5.4 GHz, with gains of 7.39 dbi, bandwidths of 374 MHz, total efficiencies of 64.7%, and HPBWs of 43.2 degrees. The measurements made in bent condition are 6.22 db, 313 MHz, 52.45%, and 22.3 degrees, respectively. The three considered antennas (conventional, EBG-based, and SRR-based) are designed with a compact size to be well-suited for biomedical sensors, and specific absorption rate (SAR) analysis is performed to ensure user safety. In addition, the performance of the proposed antenna under bending conditions is also considered to present a realistic approach for a practical antenna design. Full article

(This article belongs to the Topic Antennas)

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10 pages, 72923 KiB

Open AccessArticle

Dual-Band High-Gain Shared-Aperture Antenna Integrating Fabry-Perot and Reflectarray Mechanisms

by Xianjin Yi, Lin Zhou, Shuji Hao and Xing Chen

Electronics 2022, 11(13), 2017; https://doi.org/10.3390/electronics11132017 - 27 Jun 2022

Cited by 2 | Viewed by 2304

Abstract

This work presents a dual-band high-gain shared-aperture antenna. The proposed antenna integrates both the Fabry-Perot and reflectarray mechanisms; the antenna works as a Fabry-Perot cavity antenna (FPCA) in the S-band (2.45 GHz) and as a reflectarray antenna (RA) in the X-band [...] Read more.

This work presents a dual-band high-gain shared-aperture antenna. The proposed antenna integrates both the Fabry-Perot and reflectarray mechanisms; the antenna works as a Fabry-Perot cavity antenna (FPCA) in the S-band (2.45 GHz) and as a reflectarray antenna (RA) in the X-band (10 GHz). The antenna has a simple structure made up of only two printed circuit board layers. The bottom layer acts as a source antenna, a ground plane for the FPCA, and as a reflective surface for the RA. The upper layer contains the source antenna for the RA and serves as a partially reflective superstrate for the FPCA. The FPCA and RA thus share the same physical aperture but function independently. As an example, we design, fabricate, and characterize an antenna that operates at 2.45 and 10 GHz with an aperture size of 300 × 300 mm². The measured results are found to be in good agreement with the simulations. We show that the proposed antenna achieves a gain of 16.21 dBi at 2.45 GHz and 21.6 dBi at 10 GHz with a −10 dB impedance bandwidths of 2.39–2.66 GHz and 9.40–10.28 GHz. The isolation between the two antenna ports is found to be larger than 30 dB. Full article

(This article belongs to the Topic Antennas)

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11 pages, 8661 KiB

Open AccessArticle

On-Chip Polarization Reconfigurable Microstrip Patch Antennas Using Semiconductor Distributed Doped Areas (ScDDAs)

by Rozenn Allanic, Denis Le Berre, Cédric Quendo, Douglas Silva De Vasconcellos, Virginie Grimal, Damien Valente and Jérôme Billoué

Electronics 2022, 11(12), 1905; https://doi.org/10.3390/electronics11121905 - 17 Jun 2022

Cited by 1 | Viewed by 1675

Abstract

This paper presents two polarization reconfigurable patch antennas using semiconductor distributed doped areas (ScDDAs) as active components. One proposed antenna has a switching polarization between two linear ones, while the other one has a polarization able to commute from a linear to a [...] Read more.

This paper presents two polarization reconfigurable patch antennas using semiconductor distributed doped areas (ScDDAs) as active components. One proposed antenna has a switching polarization between two linear ones, while the other one has a polarization able to commute from a linear to a circular one. The antennas are designed on a silicon substrate in order to have the ScDDAs integrated in the substrate, overcoming the needs of classical PIN diodes. Therefore, the proposed co-design method between the antenna and the ScDDAs permits us to optimize the global reconfigurable function, designing both parts in the same process flow. Both demonstrators have a resonant frequency of around 5 GHz. The simulated results fit well with the measured ones. Full article

(This article belongs to the Topic Antennas)

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14 pages, 17274 KiB

Open AccessArticle

Electromechanical Coupling and Application of High-Frequency Communication Antenna Channel Capacity

by Yuefei Yan, Yan Wang, Baoqing Han, Xinlan Hu, Peiyuan Lian, Zhihai Wang, Kunpeng Yu, Meng Wang, Yang Wu, Guojun Leng and Congsi Wang

Electronics 2022, 11(12), 1857; https://doi.org/10.3390/electronics11121857 - 11 Jun 2022

Cited by 1 | Viewed by 1787

Abstract

The next-generation communication base station antennas represented by phased array antennas are towards high frequency, high gain, high density, and high pointing accuracy. The influence of mechanical structure factors on communication system channel quality is obviously increasing, and the electromechanical coupling problem is [...] Read more.

The next-generation communication base station antennas represented by phased array antennas are towards high frequency, high gain, high density, and high pointing accuracy. The influence of mechanical structure factors on communication system channel quality is obviously increasing, and the electromechanical coupling problem is becoming more prominent. To effectively guarantee the realization of 5G/6G communication in complex working environments and accelerate the commercial process of future communication systems, an electromechanical coupling channel capacity model is established in comprehensive consideration of the positional shift, attitude deflection, and temperature change of the communication base station phased array antennas. It can be used to rapidly evaluate the communication index degradation of RF devices within the heating environment. Moreover, a sensitivity model of the electric field strength and array antenna channel capacity to the random position error of each element is constructed. The influence of the random positioning error of each element on the communication indicators is analyzed and compared under different working conditions. The simulation results show that the proposed model can effectively provide a theoretical basis and guiding role for the design and manufacture of high-frequency array base station antennas. Full article

(This article belongs to the Topic Antennas)

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13 pages, 3974 KiB

Open AccessArticle

Complementary Multi-Band Dual Polarization Conversion Metasurface and Its RCS Reduction Application

by Fengan Li and Baiqiang You

Electronics 2022, 11(10), 1645; https://doi.org/10.3390/electronics11101645 - 21 May 2022

Cited by 7 | Viewed by 2309

Abstract

In this paper, we present a metasurface composed of complementary units that can realize orthogonal linear and linear-to-circular polarization conversion in multi-band. Linear polarization conversion has seven high-conversion frequency bands: 9.1–9.7 GHz, 15.6–17.6 GHz, 19.4–19.7 GHz, 21.2–23.1 GHz, 23.5–23.8 GHz, 26.2 GHz, and [...] Read more.

In this paper, we present a metasurface composed of complementary units that can realize orthogonal linear and linear-to-circular polarization conversion in multi-band. Linear polarization conversion has seven high-conversion frequency bands: 9.1–9.7 GHz, 15.6–17.6 GHz, 19.4–19.7 GHz, 21.2–23.1 GHz, 23.5–23.8 GHz, 26.2 GHz, and 27.9 GHz. Linear-to-circular polarization conversion also has seven frequency bands with axial ratios (ARs) less than 3 dB: 8.9–9.0 GHz, 9.9–14.7 GHz, 19.1–19.3 GHz, 23.2–23.35 GHz, 23.4 GHz, 24.1–25.4 GHz, and 27.2–27.8 GHz, with the generation of multiple bands extended by the combination of complementary units. Then, we utilize the combined polarization conversion unit’s mirror placement to form a 4 × 4 array to realize the phase difference cancellation of the reflective field, giving the metasurface the radar cross section (RCS) reduction function and the dual-band 10-dB monostatic RCS reduction bandwidth: 8.9–9.7 GHz and 15.5–26.1 GHz. The measured and simulated results were essentially identical. Because the design uses the complementary units to form an array to expand the polarization conversion frequency bands, it provides a novel idea for future designs and can be applied to multiple microwave frequency bands. Full article

(This article belongs to the Topic Antennas)

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13 pages, 5350 KiB

Open AccessArticle

A Novel Meander Line Metamaterial Absorber Operating at 24 GHz and 28 GHz for the 5G Applications

by Syed Aftab Naqvi, Muhammad Abuzar Baqir, Grant Gourley, Adnan Iftikhar, Muhammad Saeed Khan and Dimitris E. Anagnostou

Sensors 2022, 22(10), 3764; https://doi.org/10.3390/s22103764 - 15 May 2022

Cited by 12 | Viewed by 2862

Abstract

Fifth generation (5G) communication systems deploy a massive MIMO technique to enhance gain and spatial multiplexing in arrays of 16 to 128 antennas. In these arrays, it is critical to isolate the adjacent antennas to prevent unwanted interaction between them. Fifth generation absorbers, [...] Read more.

Fifth generation (5G) communication systems deploy a massive MIMO technique to enhance gain and spatial multiplexing in arrays of 16 to 128 antennas. In these arrays, it is critical to isolate the adjacent antennas to prevent unwanted interaction between them. Fifth generation absorbers, in this regard, are the recent interest of many researchers nowadays. The authors present a dual-band novel metamaterial-based 5G absorber. The absorber operates at 24 GHz and 28 GHz and is composed of symmetric meander lines connected through a transmission line. An analytical model used to calculate the total number of required meander lines to design the absorber is delineated. The analytical model is based on the total inductance offered by the meander line structure in an impedance-matched electronic circuit. The proposed absorber works on the principal of resonance and absorbs two 5G bands (24 GHz and 28 GHz). A complete angular stability analysis was carried out prior to experiments for both transverse electric (TE) and transverse magnetic (TM) polarizations. Further, the resonance conditions are altered by changing the substrate thickness and incidence angle of the incident fields to demonstrate the functionality of the absorber. The comparison between simulated and measured results shows that such an absorber would be a strong candidate for the absorption in millimetre-wave array antennas, where elements are placed in proximity within compact 5G devices. Full article

(This article belongs to the Topic Antennas)

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15 pages, 2696 KiB

Open AccessCommunication

Standing-Wave Feeding for High-Gain Linear Dielectric Resonator Antenna (DRA) Array

by Kerlos Atia Abdalmalak, Ayman Abdulhadi Althuwayb, Choon Sae Lee, Gabriel Santamaría Botello, Enderson Falcón-Gómez, Luis Emilio García-Castillo and Luis Enrique García-Muñoz

Sensors 2022, 22(8), 3089; https://doi.org/10.3390/s22083089 - 18 Apr 2022

Cited by 10 | Viewed by 3362

Abstract

A novel feeding method for linear DRA arrays is presented, illuminating the use of the power divider, transitions, and launchers, and keeping uniform excitation to array elements. This results in a high-gain DRA array with low losses with a design that is simple, [...] Read more.

A novel feeding method for linear DRA arrays is presented, illuminating the use of the power divider, transitions, and launchers, and keeping uniform excitation to array elements. This results in a high-gain DRA array with low losses with a design that is simple, compact and inexpensive. The proposed feeding method is based on exciting standing waves using discrete metallic patches in a simple design procedure. Two arrays with two and four DRA elements are presented as a proof of concept, which provide high gains of 12 and

15 dBi

, respectively, which are close to the theoretical limit based on array theory. The radiation efficiency for both arrays is about 93%, which is equal to the array element efficiency, confirming that the feeding method does not add losses as in the case of standard methods. To facilitate the fabrication process, the entire array structure is 3D-printed, which significantly decreases the complexity of fabrication and alignment. Compared to state-of-the-art feeding techniques, the proposed method provides higher gain and higher efficiency with a smaller electrical size. Full article

(This article belongs to the Topic Antennas)

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14 pages, 5676 KiB

Open AccessArticle

Design of a Low-Profile Wideband Magnetoelectric Dipole Antenna with Reduced Gain Drop

by Zhiyi Li, Xing Chen, Yuzhu Tang, Liangbing Liao, Linwan Deng and Zhifan Zhao

Electronics 2022, 11(7), 1156; https://doi.org/10.3390/electronics11071156 - 6 Apr 2022

Cited by 2 | Viewed by 2504

Abstract

In this paper, a novel low-profile magnetoelectric (ME) dipole antenna with wideband is presented. The conventional vertical fixing structure is bended four times from the center to the sides. The Γ-shaped feeding structure is bended two times to lower the height of the [...] Read more.

In this paper, a novel low-profile magnetoelectric (ME) dipole antenna with wideband is presented. The conventional vertical fixing structure is bended four times from the center to the sides. The Γ-shaped feeding structure is bended two times to lower the height of the antenna step by step. The effect of three kinds of vertical wall is discussed to show their influence on boresight gain. Through comparison, only one vertical wall is erected on the left side of the ground to decrease the boresight gain drop at 2.2 GHz. Both simulation and analysis are made to sufficiently explain the working principle. At last, the proposed ME dipole antenna has only 0.095λ₀ (λ₀ is the center operating wavelength in free space) in height, and the wideband property is still maintained. By simulation, the relative bandwidth for VSWR < 2.0 is 47.9% (from 1.35 to 2.2 GHz). The boresight gain ranges from 8.1 to 9.6 dBi in the operating band. The measured relative bandwidth for VSWR < 2.0 is 50.3% (from 1.34 to 2.24 GHz), and the boresight gain ranges from 7.38 to 8.73 dBi. The gain drop on boresight is less than 1.4 dBi. Radiation patterns show a unidirectional characteristic in the whole operating band. Additionally, the cross-polarization level is less than −25 dB on boresight. The simulating and measuring results agree well with each other. Therefore, the proposed antenna is suitable for applications of limited height and wideband. Full article

(This article belongs to the Topic Antennas)

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10 pages, 11431 KiB

Open AccessCommunication

Wideband Filtering Slot Antenna Design with Stable Gain Using Characteristic Mode Analysis

by Chao Ni, Biyang Wen, Weijun Wu and Ping Ren

Sensors 2022, 22(7), 2780; https://doi.org/10.3390/s22072780 - 5 Apr 2022

Cited by 8 | Viewed by 2565

Abstract

A filtering slot antenna with a simple structure combination using characteristic mode analysis (CMA) is proposed. To realize filtering characteristics, characteristic magnetic currents of line and ring slots are analyzed and designed. Then, the folding-line slot and double-ring slot are selected to realize [...] Read more.

A filtering slot antenna with a simple structure combination using characteristic mode analysis (CMA) is proposed. To realize filtering characteristics, characteristic magnetic currents of line and ring slots are analyzed and designed. Then, the folding-line slot and double-ring slot are selected to realize radiation null separately and combined to construct the basic slot antenna. By properly exciting the selected characteristic modes, a wide filtering bandwidth and a stable gain are obtained. To validate the design process, a prototype antenna with a finite ground plane of about 1.1 λ × 1.1 λ is designed and fabricated. Simulated and measured results agree well, which both show a sharping roll rate in the lower and higher frequency and a flat gain realization in the pass band. The filtering bandwidth is 32.7%, the out-of-band suppression level at the higher frequency is over 20 dB, and the gain in the working frequency varies from 3.9 to 5.2 dB. Full article

(This article belongs to the Topic Antennas)

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12 pages, 3935 KiB

Open AccessCommunication

A Conformal Frequency Reconfigurable Antenna with Multiband and Wideband Characteristics

by Niamat Hussain, Adnan Ghaffar, Syeda Iffat Naqvi, Adnan Iftikhar, Dimitris E. Anagnostou and Huy H. Tran

Sensors 2022, 22(7), 2601; https://doi.org/10.3390/s22072601 - 29 Mar 2022

Cited by 28 | Viewed by 3467

Abstract

A compact flexible multi-frequency antenna for smart portable and flexible devices is presented. The antenna consists of a coplanar waveguide-fed slotted circular patch connected to a rectangular secondary resonator (stub). A thin low-loss substrate is used for flexibility, and a rectangular stub in [...] Read more.

A compact flexible multi-frequency antenna for smart portable and flexible devices is presented. The antenna consists of a coplanar waveguide-fed slotted circular patch connected to a rectangular secondary resonator (stub). A thin low-loss substrate is used for flexibility, and a rectangular stub in the feedline is deployed to attain wide operational bandwidth. A rectangular slot is etched in the middle of the circular patch, and a p-i-n diode is placed at its center. The frequency reconfigurability is achieved through switching the diode that distributes the current by changing the antenna’s electrical length. For the ON state, the antenna operates in the UWB region for −10 dB impedance bandwidth from 2.76 to 8.21 GHz. For the OFF state of the diode, the antenna operates at the ISM band (2.45/5.8 GHz), WLAN band (5.2 GHz), and lower X-band (8 GHz) with a minimum gain of 2.49 dBi and a maximum gain of 5.8 dBi at the 8 GHz band. Moreover, the antenna retains its performance in various bending conditions. The proposed antenna is suitable for modern miniaturized wireless electronic devices such as wearables, health monitoring sensors, mobile Internet devices, and laptops that operate at multiple frequency bands. Full article

(This article belongs to the Topic Antennas)

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9 pages, 2708 KiB

Open AccessCommunication

A Wideband Circularly Polarized Magnetoelectric Dipole Antenna for 5G Millimeter-Wave Communications

by Hussain Askari, Niamat Hussain, Md. Abu Sufian, Sang Min Lee and Nam Kim

Sensors 2022, 22(6), 2338; https://doi.org/10.3390/s22062338 - 17 Mar 2022

Cited by 22 | Viewed by 3698

Abstract

In this paper, a wideband circularly polarized (CP) magnetoelectric (ME) dipole antenna operating at 28 GHz band was proposed for 5G millimeter-wave (mm-wave) communications. The antenna geometry included two metallic plates with extended hook-shaped strips at its principal diagonal position, and two corners [...] Read more.

In this paper, a wideband circularly polarized (CP) magnetoelectric (ME) dipole antenna operating at 28 GHz band was proposed for 5G millimeter-wave (mm-wave) communications. The antenna geometry included two metallic plates with extended hook-shaped strips at its principal diagonal position, and two corners of truncated metallic plates at the secondary diagonal position. The pair of metallic vias connected the modified strips to the ground plane to create the magnetic dipole. The L-shaped probe feed between the strips was used to excite the antenna. The antenna showed stable gain and wideband characteristics. The simulated and measured results showed that the proposed CP ME dipole antenna had an overlapping (|S₁₁|< −10 dB impedance and 3 dB axial ratio) bandwidth of 18.1% (25–30 GHz), covering the frequency bands dedicated for 5G new radio communications. Moreover, an average gain of 8 dBic was achieved by the antenna throughout the operating bandwidth. The measured data verified the design concept, and the proposed antenna had a small footprint of 0.83 λ_o × 0.83 λ_o × 0.125 λ_o (λ_o is free space wavelength at the lowest operating frequency), suitable for its application in 5G smart devices and sensors. Full article

(This article belongs to the Topic Antennas)

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23 pages, 690 KiB

Open AccessArticle

Hardware Efficient Massive MIMO Systems with Optimal Antenna Selection

by Shenko Chura Aredo, Yalemzewd Negash, Yihenew Wondie Marye, Hailu Belay Kassa, Kevin T. Kornegay and Feyisa Debo Diba

Sensors 2022, 22(5), 1743; https://doi.org/10.3390/s22051743 - 23 Feb 2022

Cited by 7 | Viewed by 2409

Abstract

An increase in the number of transmit antennas (M) poses an equivalent rise in the number of Radio Frequency (RF) chains associated with each antenna element, particularly in digital beamforming. The chain exhibits a substantial amount of power consumption accordingly. Hence, to alleviate [...] Read more.

An increase in the number of transmit antennas (M) poses an equivalent rise in the number of Radio Frequency (RF) chains associated with each antenna element, particularly in digital beamforming. The chain exhibits a substantial amount of power consumption accordingly. Hence, to alleviate such problems, one of the potential solutions is to reduce the number of RFs or to minimize their power consumption. In this paper, low-resolution Digital to Analogue Conversion (DAC) and transmit antenna selection at the downlink are evaluated to favour reducing the total power consumption and achieving energy efficiency in mMIMO with reasonable complexity. Antenna selection and low-resolution DAC techniques are proposed to leverage massive MIMO systems in free space and Close In (CI) path-loss models. The simulation results show that the power consumption decreases with antenna selection and low-resolution DAC. Then, the system achieves more energy efficiency than without low-resolution of DAC and full array utilization. Full article

(This article belongs to the Topic Antennas)

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15 pages, 6604 KiB

Open AccessArticle

A Study on Conformal Metasurface Influences on Passive Beam Steering

by Ruisi Ge, Ryan Striker and Benjamin Braaten

Electronics 2022, 11(5), 674; https://doi.org/10.3390/electronics11050674 - 22 Feb 2022

Cited by 2 | Viewed by 2373

Abstract

Beam-steering has drawn significant interest due to the expansion of network capacity. However, a traditional beam steering system involves active phase shifters and controlling networks which can be complex. This work studied the influence of passive conformal metasurface on conventional patch antenna. The [...] Read more.

Beam-steering has drawn significant interest due to the expansion of network capacity. However, a traditional beam steering system involves active phase shifters and controlling networks which can be complex. This work studied the influence of passive conformal metasurface on conventional patch antenna. The phase shifting was achieved by changing the curvature of a conformal metasurface. In addition, three low-cost conformal prototypes were fabricated and tested using different techniques such as 3D printing. The simulations and measurement results indicate up to 20° of beam shifting and reasonable gain increase. Compared with other research in the similar topic, the antenna system is completely passive, and the conformal metasurface is independent of the conventional patch antenna. Therefore, such study will be easy to implement with other antenna research especially for low power consumption beam steering systems. Full article

(This article belongs to the Topic Antennas)

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12 pages, 18989 KiB

Open AccessArticle

Research on Ultra-Low-Frequency Communication Based on the Rotating Shutter Antenna

by Faxiao Sun, Feng Zhang, Xiaoya Ma, Zhaoqian Gong, Yicai Ji and Guangyou Fang

Electronics 2022, 11(4), 596; https://doi.org/10.3390/electronics11040596 - 15 Feb 2022

Cited by 4 | Viewed by 2548

Abstract

This paper proposes a rotating shutter antenna that can directly generate 2FSK signals in the ULF band and it is expected to be used as the transmitter for magnetic induction (MI) underground communication systems. The antenna was modeled using ANSYS Maxwell and the [...] Read more.

This paper proposes a rotating shutter antenna that can directly generate 2FSK signals in the ULF band and it is expected to be used as the transmitter for magnetic induction (MI) underground communication systems. The antenna was modeled using ANSYS Maxwell and the magnetic field distribution was simulated. The results show that the interaction between the high-permeability shutter and the mutual cancellation of magnets decreased the transmitting magnetic moment of the antenna. A prototype antenna was manufactured and the time and frequency properties of the measured B

_{z}

field were the same as the simulated results, while the magnitude of the measured signal was larger. The propagation characteristics of the antenna in air–soil–rock were simulated using FEKO and the results show that the signal strength was greater than 1 fT at a depth of 450 m from the antenna whose magnetic moment as 1 Am

^{2}

. The relationship between different magnetic components and azimuth could be used to enhance the signal strength. The formula of the B

_{z}

field was derived using the measured magnitude versus distance and the path loss was also analyzed. Finally, the 2FSK modulation property of the antenna was verified by indoor communication experiments with a code rate of 12.5 bps in the ULF band. Full article

(This article belongs to the Topic Antennas)

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12 pages, 3052 KiB

Open AccessTechnical Note

Over-the-Air Testing of a Massive MIMO Antenna with a Full-Rank Channel Matrix

by Kazuhiro Honda

Sensors 2022, 22(3), 1240; https://doi.org/10.3390/s22031240 - 6 Feb 2022

Cited by 6 | Viewed by 2075

Abstract

This paper presents an over-the-air testing method in which a full-rank channel matrix is created for a massive multiple-input multiple-output (MIMO) antenna system utilizing a fading emulator with a small number of scatterers. In the proposed method, in order to mimic a fading [...] Read more.

This paper presents an over-the-air testing method in which a full-rank channel matrix is created for a massive multiple-input multiple-output (MIMO) antenna system utilizing a fading emulator with a small number of scatterers. In the proposed method, in order to mimic a fading emulator with a large number of scatterers, the scatterers are virtually positioned by rotating the massive MIMO antenna. The performance of a 64-element quasi-half-wavelength dipole circular array antenna was evaluated using a two-dimensional fading emulator. The experimental results reveal that a large number of available eigenvalues are obtained from the channel response matrix, confirming that the proposed method, which utilizes a full-rank channel matrix, can be used to assess a massive MIMO antenna system. Full article

(This article belongs to the Topic Antennas)

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11 pages, 2700 KiB

Open AccessArticle

A Planar Four-Element UWB Antenna Array with Stripline Feeding Network

by Marek Garbaruk

Electronics 2022, 11(3), 469; https://doi.org/10.3390/electronics11030469 - 5 Feb 2022

Cited by 4 | Viewed by 2445

Abstract

This paper proposes a four-element ultrawideband (UWB) planar antenna array with elliptical-shaped radiators and a stripline excitation network designed for the 6–8.5 GHz UWB frequency band allowed in Europe by the European Commission. The designed antenna array has a symmetrical structure in which [...] Read more.

This paper proposes a four-element ultrawideband (UWB) planar antenna array with elliptical-shaped radiators and a stripline excitation network designed for the 6–8.5 GHz UWB frequency band allowed in Europe by the European Commission. The designed antenna array has a symmetrical structure in which the radiators are placed along one line in the central conducting layer, arranged between two layers of a dielectric. Radiating elements are fed by the stripline excitation network that provides uniform power distribution. The dimensions of the elliptical radiators’ axes are 14 mm × 16 mm. Two variants of array are proposed. The distance between the radiators’ centers is L = 19 mm for a shorter variant and L = 24 mm for a longer one. The presented antenna array structures have a size of 81 mm × 41 mm and 96 mm × 41 mm. These arrays present a measured gain of 6.4–10.6 dBi for the shorter variant and 8.5–10.8 dBi for the longer one and a fair impedance matching. The measured |S₁₁| is less than −8.7 dB and −9.7 dB for the shorter and longer corresponding variants. Full article

(This article belongs to the Topic Antennas)

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Geometry of proposed single prototype UWB antenna (dimensions in mm). Full article ">Figure 2
Geometry of proposed four-element antenna arrays in yz-plane (dimensions in mm): (a) Shorter variant of UWB antenna array; (b) Longer variant of UWB antenna array. Full article ">Figure 3
Photographs of proposed antennas: (a) Central metallic layer of shorter variant of four-element antenna array; (b) Central metallic layer of longer variant of four-element antenna array; (c) Fabricated antennas. Full article ">Figure 4
Simulated and measured |S11| of proposed antennas. Full article ">Figure 5
Longer variant of four-element antenna array in anechoic chamber during measurements. Full article ">Figure 6
Simulated and measured gain of proposed antennas in direction perpendicular to antenna surface (along +/− x-axis). Full article ">Figure 7
Simulated and measured radiation pattern of the proposed arrays in xy-plane at different frequencies: (a) 6 GHz; (b) 7.2 GHz; (c) 8.4 GHz. Full article ">

18 pages, 8738 KiB

Open AccessArticle

Analysis and Design of an X-Band Reflectarray Antenna for Remote Sensing Satellite System

by Shimaa A. M. Soliman, Eman M. Eldesouki and Ahmed M. Attiya

Sensors 2022, 22(3), 1166; https://doi.org/10.3390/s22031166 - 3 Feb 2022

Cited by 13 | Viewed by 3517

Abstract

This paper presents the analysis and design of an X-band reflectarray. The proposed antenna can be used for a medium Earth orbit (MEO) remote sensing satellite system in the 8.5 GHz band. To obtain a nearly constant response along the coverage area of [...] Read more.

This paper presents the analysis and design of an X-band reflectarray. The proposed antenna can be used for a medium Earth orbit (MEO) remote sensing satellite system in the 8.5 GHz band. To obtain a nearly constant response along the coverage area of this satellite system, the proposed antenna was designed with a flat-top radiation pattern with a beam width of around 29° for the required MEO system. In addition, broadside pencil beam and tilted pencil beam reflectarrays were also investigated. The feeding element of the proposed reflectarray antennas is a Yagi–Uda array. The amplitude and phase distribution of the fields due to the feeding element on the aperture of the reflectarray antenna are obtained directly by numerical simulation without introducing any approximation. The required phase distribution along the aperture of the reflectarray to obtain the required flat-top radiation pattern is obtained using the genetic algorithm (GA) optimization method. The reflecting elements of the reflectarray are composed of stacked circular patches. This stacked configuration was found to be appropriate for obtaining a wide range of reflection phase shift, which is required to implement the required phase distribution on the reflectarray aperture. The antenna was fabricated and measured for verification. Full article

(This article belongs to the Topic Antennas)

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21 pages, 3718 KiB

Open AccessFeature PaperArticle

Optimal Field Sampling of Arc Sources via Asymptotic Study of the Radiation Operator

by Raffaele Moretta, Giovanni Leone, Fortuna Munno and Rocco Pierri

Electronics 2022, 11(2), 270; https://doi.org/10.3390/electronics11020270 - 14 Jan 2022

Cited by 1 | Viewed by 1385

Abstract

In this paper, the question of how to efficiently sample the field radiated by a circumference arc source is addressed. Classical sampling strategies require the acquisition of a redundant number of field measurements that can make the acquisition time prohibitive. For such reason, [...] Read more.

In this paper, the question of how to efficiently sample the field radiated by a circumference arc source is addressed. Classical sampling strategies require the acquisition of a redundant number of field measurements that can make the acquisition time prohibitive. For such reason, the paper aims at finding the minimum number of basis functions representing the radiated field with good accuracy and at providing an interpolation formula of the radiated field that exploits a non-redundant number of field samples. To achieve the first task, the number of relevant singular values of the radiation operator is computed by exploiting a weighted adjoint operator. In particular, the kernel of the related eigenvalue problem is first evaluated asymptotically; then, a warping transformation and a proper choice of the weight function are employed to recast such a kernel as a convolution and bandlimited function of sinc type. Finally, the number of significant singular values of the radiation operator is found by invoking the Slepian–Pollak results. The second task is achieved by exploiting a Shannon sampling expansion of the reduced field. The analysis is developed for both the far and the near fields radiated by a 2D scalar arc source observed on a circumference arc. Full article

(This article belongs to the Topic Antennas)

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17 pages, 7168 KiB

Open AccessArticle

A Robust Design for Aperture-Level Simultaneous Transmit and Receive with Digital Phased Array

by Mingcong Xie, Xizhang Wei, Yanqun Tang and Dujuan Hu

Sensors 2022, 22(1), 109; https://doi.org/10.3390/s22010109 - 24 Dec 2021

Cited by 12 | Viewed by 2729

Abstract

Aperture-level simultaneous transmit and receive (ALSTAR) attempts to utilize adaptive digital transmit and receive beamforming and digital self-interference cancellation methods to establish isolation between the transmit and receive apertures of the single-phase array. However, the existing methods only discuss the isolation of ALSTAR [...] Read more.

Aperture-level simultaneous transmit and receive (ALSTAR) attempts to utilize adaptive digital transmit and receive beamforming and digital self-interference cancellation methods to establish isolation between the transmit and receive apertures of the single-phase array. However, the existing methods only discuss the isolation of ALSTAR and ignore the radiation efficiency of the transmitter and the sensitivity of the receiver. The ALSTAR array design lacks perfect theoretical support and simplified engineering implementation. This paper proposes an adaptive random group quantum brainstorming optimization (ARGQBSO) algorithm to simplify the array design and improve the overall performance. ARGQBSO is derived from BSO and has been ameliorated in four aspects of the ALSTAR array, including random grouping, initial value presets, dynamic probability functions, and quantum computing. The transmit and receive beamforming carried out by ARGQBSO is robust to all elevation angles, which reduces complexity and is conducive to engineering applications. The simulated results indicate that the ARGQBSO algorithm has an excellent performance, and achieves 166.8 dB of peak EII, 47.1 dBW of peak EIRP, and −94.6 dBm of peak EIS with 1000 W of transmit power in the scenario of an 8-element array. Full article

(This article belongs to the Topic Antennas)

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11 pages, 658 KiB

Open AccessArticle

Floquet Spectral Almost-Periodic Modulation of Massive Finite and Infinite Strongly Coupled Arrays: Dense-Massive-MIMO, Intelligent-Surfaces, 5G, and 6G Applications

by Hamdi Bilel and Aguili Taoufik

Electronics 2022, 11(1), 36; https://doi.org/10.3390/electronics11010036 - 23 Dec 2021

Cited by 3 | Viewed by 3873

Abstract

In this study, we introduce a new formulation based on Floquet (Fourier) spectral analysis combined with a spectral modulation technique (and its spatial form) to study strongly coupled sublattices predefined in the infinite and large finite extent of almost-periodic antenna arrays (e.g., metasurfaces). [...] Read more.

In this study, we introduce a new formulation based on Floquet (Fourier) spectral analysis combined with a spectral modulation technique (and its spatial form) to study strongly coupled sublattices predefined in the infinite and large finite extent of almost-periodic antenna arrays (e.g., metasurfaces). This analysis is very relevant for dense-massive-MIMO, intelligent-surfaces, 5G, and 6G applications (used for very small areas with a large number of elements such as millimeter and terahertz waves applications). The numerical method that is adopted to model the structure is the method of moments simplified by equivalent circuits MoM GEC. Other numerical methods (such as the ASM-array scanning method and the windowing Fourier method) used this analysis in their kernel to treat periodic and pseudo-periodic (or quasi-periodic) arrays. Full article

(This article belongs to the Topic Antennas)

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Construction of <math display="inline"><semantics> <mrow> <msub> <mi>f</mi> <mi>α</mi> </msub> <mrow> <mo>(</mo> <mi>x</mi> <mo>)</mo> </mrow> </mrow> </semantics></math> as given in Equations (<a href="#FD9-electronics-11-00036" class="html-disp-formula">9</a>)–(<a href="#FD11-electronics-11-00036" class="html-disp-formula">11</a>). Full article ">Figure 2
Spectral representation of the interactions of a unit cell with its neighbors (infinite and finite cases) (valid for strong coupling interaction by using Floquet phases). Full article ">Figure 3
Impedance variation against frequency band around 24 GHz: obtained by the MoM-GEC method. Full article ">Figure 4
Impedance variation against frequency band around 77 GHz: obtained by the MoM GEC method. Full article ">Figure 5
<math display="inline"><semantics> <msub> <mi>S</mi> <mn>11</mn> </msub> </semantics></math>-parameter (dB) variation against frequency band around 24 GHz: a comparison between the MoM-GEC and a MATLAB tool (see references [<a href="#B41-electronics-11-00036" class="html-bibr">41</a>,<a href="#B42-electronics-11-00036" class="html-bibr">42</a>]). Full article ">Figure 6
Variation of radiation pattern against Floquet states and application of superposition theorem for 10 elements of antenna array (uni-dimentionnal configuration) at 77 GHz: obtained by the MoM-GEC method. Full article ">Figure 7
Variation of radiation pattern against Floquet states and application of superposition theorem for 100 elements of antenna array (uni-dimentionnal configuration) at 77 GHz: obtained by the MoM-GEC method. Full article ">

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