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14 pages, 2389 KiB

Open AccessCommunication

A QoS-Adaptive Interference Alignment Technique for In-Band Full-Duplex Multi-Antenna Cellular Networks

by Ki-Hun Lee, Gyudong Park and Bang Chul Jung

Sensors 2022, 22(23), 9417; https://doi.org/10.3390/s22239417 - 2 Dec 2022

Cited by 1 | Viewed by 1847

Abstract

In this paper, we propose a novel interference alignment (IA) technique for an in-band full-duplex (IBFD) multiple-input multiple-output (MIMO) cellular network where a base station (BS) and user equipment (UE) are equipped with multiple antennas, and the local channel state information (CSI) is [...] Read more.

In this paper, we propose a novel interference alignment (IA) technique for an in-band full-duplex (IBFD) multiple-input multiple-output (MIMO) cellular network where a base station (BS) and user equipment (UE) are equipped with multiple antennas, and the local channel state information (CSI) is available at all nodes. Considering a practical IBFD MIMO cellular network, it is assumed that only the BS operates with full-duplex (FD) communication while UE operate in half-duplex (HD) mode. These IBFD networks introduce a new type of interference called cross-link interference (CLI), in which uplink UE affects downlink UE. The proposed IA technique consists of two symmetric IA schemes according to the number of antennas in the uplink and downlink UE, and both schemes effectively mitigate CLI in the IBFD MIMO network. It is worth noting that both IA schemes are adaptively applicable according to the network’s quality-of-service (QoS) requirements, such as uplink and downlink traffic demands. Furthermore, we theoretically characterize and prove the achievable sum-degrees-of-freedom (DoF) of the proposed IA technique. Simulation results show that the proposed IA technique significantly improves the sum rate performance compared to conventional HD communications (multi-user MIMO) while achieving the same achievable DoF as the interference-free IBFD MIMO network. Full article

(This article belongs to the Special Issue Antenna Design and Sensors for Internet of Things)

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14 pages, 3226 KiB

Open AccessArticle

Monopole Antenna with Enhanced Bandwidth and Stable Radiation Patterns Using Metasurface and Cross-Ground Structure

by Patrick Danuor, Kyei Anim and Young-Bae Jung

Sensors 2022, 22(21), 8571; https://doi.org/10.3390/s22218571 - 7 Nov 2022

Cited by 3 | Viewed by 4149

Abstract

In this paper, a printed monopole antenna with stable omnidirectional radiation patterns is presented for applications in ocean buoy and the marine Internet of Things (IoT). The antenna is composed of a rectangular patch, a cross-ground structure, and two frequency-selective surface (FSS) unit [...] Read more.

In this paper, a printed monopole antenna with stable omnidirectional radiation patterns is presented for applications in ocean buoy and the marine Internet of Things (IoT). The antenna is composed of a rectangular patch, a cross-ground structure, and two frequency-selective surface (FSS) unit cells. The cross-ground structure is incorporated into the antenna design to maintain consistent monopole-like radiation patterns over the antenna’s operating band, and the FSS unit cells are placed at the backside of the antenna to improve the antenna gain aiming at the L-band. In addition, the FSS unit cells exhibit resonance characteristics that, when incorporated with the cross-ground structure, result in a broader impedance bandwidth compared to the conventional monopole antenna. To validate the structure, a prototype is fabricated and measured. Good agreement between the simulated and measured results show that the proposed antenna exhibits an impedance bandwidth of 83.2% from 1.65 to 4 GHz, compared to the conventional printed monopole antenna. The proposed antenna realizes a peak gain of 4.57 dBi and a total efficiency of 97% at 1.8 GHz. Full article

(This article belongs to the Special Issue Antenna Design and Sensors for Internet of Things)

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37 pages, 26894 KiB

Open AccessArticle

A New Compact Triple-Band Triangular Patch Antenna for RF Energy Harvesting Applications in IoT Devices

by Chemseddine Benkalfate, Achour Ouslimani, Abed-Elhak Kasbari and Mohammed Feham

Sensors 2022, 22(20), 8009; https://doi.org/10.3390/s22208009 - 20 Oct 2022

Cited by 4 | Viewed by 2685

Abstract

This work proposes a new compact triple-band triangular patch antenna for RF energy harvesting applications in IoT devices. It is realized on Teflon glass substrate with a thickness of 0.67 mm and a relative permittivity of 2.1. Four versions of this antenna have [...] Read more.

This work proposes a new compact triple-band triangular patch antenna for RF energy harvesting applications in IoT devices. It is realized on Teflon glass substrate with a thickness of 0.67 mm and a relative permittivity of 2.1. Four versions of this antenna have been designed and realized with inclinations of 0°, 30°, 60° and 90° to study the impact of the tilting on their characteristics (S₁₁ parameter, radiation pattern, gain) and to explore the possibilities of their implementation in the architectures of electronic equipment according to the available space. The antenna is also realized on waterproof paper with a thickness of 0.1 mm and a relative permittivity of 1.4 for biomedical domain. All the antennas (vertical antenna, tilted antennas and antenna realized on waterproof paper) have a size of 39 × 9 mm² and cover the 2.45 GHz and 5.2 GHz Wi-Fi bands and the 8.2 GHz band. A good agreement is obtained between measured and simulated results. Radiation patterns show that all the antennas are omnidirectional for 2.45 GHz and pseudo-omnidirectional for 5.2 GHz and 8.2 GHz with maximum measured gains of 2.6 dBi, 4.55 dBi and 6 dBi, respectively. The maximum measured radiation efficiencies for the three antenna configurations are, respectively, of 75%, 70% and 72%. The Specific Absorption Rate (SAR) for the antenna bound on the human body is of 1.1 W/kg, 0.71 W/kg and 0.45 W/kg, respectively, for the three frequencies 2.45 GHz, 5.2 GHz and 8.2 GHz. All these antennas are then applied to realize RF energy harvesting systems. These systems are designed, realized and tested for the frequency 2.45 GHz, −20 dBm input power and 2 kΩ resistance load. The maximum measured output DC power is of 7.68 µW with a maximum RF-to-DC conversion efficiency of 77%. Full article

(This article belongs to the Special Issue Antenna Design and Sensors for Internet of Things)

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21 pages, 4510 KiB

Open AccessArticle

Cost-Driven Design of Printed Wideband Antennas with Reduced Silver Ink Consumption for the Internet of Things

by Nicolas Claus, Jo Verhaevert and Hendrik Rogier

Sensors 2022, 22(20), 7929; https://doi.org/10.3390/s22207929 - 18 Oct 2022

Cited by 6 | Viewed by 1869

Abstract

The Internet of Things (IoT) accelerates the need for compact, lightweight and low-cost antennas combining wideband operation with a high integration potential. Although screen printing is excellently suited for manufacturing conformal antennas on a flexible substrate, its application is typically limited due to [...] Read more.

The Internet of Things (IoT) accelerates the need for compact, lightweight and low-cost antennas combining wideband operation with a high integration potential. Although screen printing is excellently suited for manufacturing conformal antennas on a flexible substrate, its application is typically limited due to the expensive nature of conductive inks. This paper investigates how the production cost of a flexible coplanar waveguide (CPW)-fed planar monopole antenna can be reduced by exploiting a mesh-based method for limiting ink consumption. Prototypes with mesh grids of different line widths and densities were screen-printed on a polyethylene terephthalate (PET) foil using silver-based nanoparticle ink. Smaller line widths decrease antenna gain and efficiency, while denser mesh grids better approximate unmeshed antenna behavior, albeit at the expense of greater ink consumption. A meshed prototype of

34.76 \times 58.03 mm

with almost 80% ink reduction compared to an unmeshed counterpart is presented. It is capable of providing wideband coverage in the IMT/LTE-1/n1 (1.92–2.17 GHz), LTE-40/n40 (2.3–2.4 GHz), 2.45 GHz ISM (2.4–2.4835 GHz), IMT-E/LTE-7/n7 (2.5–2.69 GHz), and n78 5G (3.3–3.8 GHz) frequency bands. It exhibits a peak radiation efficiency above 90% and a metallized surface area of

2.46

cm² (yielding an ink-to-total-surface ratio of 12.2%). Full article

(This article belongs to the Special Issue Antenna Design and Sensors for Internet of Things)

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18 pages, 7606 KiB

Open AccessArticle

Compact Quad Band MIMO Antenna Design with Enhanced Gain for Wireless Communications

by Sanjukta Nej, Anumoy Ghosh, Sarosh Ahmad, Adnan Ghaffar and Mousa Hussein

Sensors 2022, 22(19), 7143; https://doi.org/10.3390/s22197143 - 21 Sep 2022

Cited by 19 | Viewed by 2796

Abstract

In this paper, a novel microstrip line-fed meander-line-based four-elements quad band Multiple Input and Multiple Output (MIMO) antenna is proposed with a gain enhancement technique. The proposed structure resonates at four bands simultaneously, that is, 1.23, 2.45, 3.5 and 4.9 GHz, which resemble [...] Read more.

In this paper, a novel microstrip line-fed meander-line-based four-elements quad band Multiple Input and Multiple Output (MIMO) antenna is proposed with a gain enhancement technique. The proposed structure resonates at four bands simultaneously, that is, 1.23, 2.45, 3.5 and 4.9 GHz, which resemble GPS L2, Wi-Fi, Wi-MAX and WLAN wireless application bands, respectively. The unit element is extended to four elements MIMO antenna structure exhibiting isolation of more than 22 dB between the adjacent elements without disturbing the resonant frequencies. In order to enhance the gain, two orthogonal microstrip lines are incorporated between the antenna elements which result in significant gain improvement over all the four resonances. Furthermore, the diversity performance of the MIMO structure is analyzed. The Envelope Co-Relation Coefficient (ECC), Diversity Gain (DG), Channel Capacity Loss (CCL), Mean Effective Gain (MEG) and Multiplexing Efficiency are obtained as 0.003, 10 dB, 0.0025 bps/Hz, −3 dB (almost) and 0.64 (min.), respectively, which are competent and compatible with practical wireless applications. The Total Active Reflection Coefficient (TARC) resembles the characteristic of the individual antenna elements. The layout area of the overall MIMO antenna is 0.33 λ × 0.29 λ, where λ is the free-space wavelength corresponding to the lowest resonance. The advantage of the proposed structure has been assessed by comparing it with previously reported MIMO structures based on number of antenna elements, isolation, gain, CCL and compactness. A prototype of the proposed MIMO structure is fabricated, and the measured results are found to be aligned with the simulated results. Full article

(This article belongs to the Special Issue Antenna Design and Sensors for Internet of Things)

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18 pages, 4196 KiB

Open AccessArticle

An On-Film AMC Antenna Insert-Molded in Earbuds with Enhancement in In-Ear and In Situ Received-Signal Sensing

by Yejune Seo, Inyeol Moon, Junghyun Cho, Yejin Lee, Jiyeon Jang, Morimoto Shohei, Kurosaki Toshifumi and Sungtek Kahng

Sensors 2022, 22(12), 4523; https://doi.org/10.3390/s22124523 - 15 Jun 2022

Cited by 2 | Viewed by 2103

Abstract

In this paper, a novel thin and flexible antenna is proposed for earbuds to gain an improvement in their wireless signal-sensing capability as a film-based artificial magnetic conductor (AMC) structure. As antenna designs for earbuds face challenges of being embedded beneath the top [...] Read more.

In this paper, a novel thin and flexible antenna is proposed for earbuds to gain an improvement in their wireless signal-sensing capability as a film-based artificial magnetic conductor (AMC) structure. As antenna designs for earbuds face challenges of being embedded beneath the top cover of the earbud, conformal to curved surfaces, and very close to metallic ground and touch-panel parts, as well as scarce degrees of freedom from feeding conditions and functional degradation by human tissue, unlike conventional techniques such as quasi quarter-wavelength radiators on LDS and epoxy molding compounds (relatively thick and pricy), an antenna of a metal pattern on a film is made with another film layer as the AMC to mitigate problems of the antenna in a small and curved space of an insert-molded wireless device. The antenna was designed, fabricated, and embedded in earbud mockups to work for the 2.4 GHz Bluetooth RF link, and its functions were verified by RF and antenna measurement, showing that it could overcome the limitations in impedance matching with only lumped elements and poor radiation by the ordinary schemes. The input reflection coefficient and antenna efficiency were 10 dB and 9% better than other methods. In particular, the on-film AMC antenna (OFAA) presents robustness against deterioration by the human tissue, when it is placed in the ear phantom at the workbench and implemented in an in situ test using a large zorb ball mimicking a realistic sensing environment. This yielded an RSSI enhancement of 20–30 dB. Full article

(This article belongs to the Special Issue Antenna Design and Sensors for Internet of Things)

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16 pages, 3912 KiB

Open AccessArticle

Developing Broadband Microstrip Patch Antennas Fed by SIW Feeding Network for Spatially Low Cross-Polarization Situation

by Farzad Karami, Halim Boutayeb, Ali Amn-e-Elahi, Alireza Ghayekhloo and Larbi Talbi

Sensors 2022, 22(9), 3268; https://doi.org/10.3390/s22093268 - 24 Apr 2022

Cited by 15 | Viewed by 5445

Abstract

A stacked multi-layer substrate integrated waveguide (SIW) microstrip patch antenna with broadband operating bandwidth and low cross-polarization radiation is provided. A complete study on the propagating element bandwidth and cross polarization level is presented to demonstrate the importance of the design. The proposed [...] Read more.

A stacked multi-layer substrate integrated waveguide (SIW) microstrip patch antenna with broadband operating bandwidth and low cross-polarization radiation is provided. A complete study on the propagating element bandwidth and cross polarization level is presented to demonstrate the importance of the design. The proposed antenna includes three stacked printed circuit board (PCB) layers, including one layer for the radiating 2 × 2 rectangular patch elements and two SIW PCB layers for the feeding network. There are two common methods for excitation in cavity-backed patch antennas: probe feeding (PF) and aperture coupling (AC). PF can be used to increase the bandwidth of the antenna. Although this method increases the antenna’s bandwidth, it produces a strong cross-polarized field. The AC method can be used to suppress cross-polarized fields in microstrip patch antennas. As microstrip patch antennas are inherently narrowband, the AC method has little effect on their bandwidth. This paper proposes an antenna that is simultaneously fed by AC and PF. As a result of this innovation, the operating bandwidth of the antenna has increased, and cross-polarization has been reduced. Actually, the combination of probe feeding and aperture coupling schemes leads to achieving a broadband operating bandwidth. The arrangement of radiator elements and cavities implements a mirrored excitation technique while maintaining a low cross-polarization level. In both numerical and experimental solutions, a less than −30 dB cross-polarization level has been achieved for all of the main directions. A fractional impedance bandwidth of 29.8% (10.55–14.25 GHz) for

S_{11}

< −10-dB is measured for the proposed array. Simulated and measured results illustrate good agreement. Having features like low cost, light weight, compactness, broadband, integration capabilities, and low cross-polarization level makes the designed antenna suitable for remote-sensing and satellite applications. Full article

(This article belongs to the Special Issue Antenna Design and Sensors for Internet of Things)

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16 pages, 6095 KiB

Open AccessArticle

Design and Realization of an UHF Frequency Reconfigurable Antenna for Hybrid Connectivity LPWAN and LEO Satellite Networks

by Abdellatif Bouyedda, Bruno Barelaud and Laurent Gineste

Sensors 2021, 21(16), 5466; https://doi.org/10.3390/s21165466 - 13 Aug 2021

Cited by 10 | Viewed by 4817

Abstract

UHF satellite communication for Internet of Things (IoT) technology is rapidly emerging in monitoring applications as it offers the possibility of lower-costs and global coverage. At the present time, Low Power Wide Area Network (LPWAN) solutions offer low power consumption, but still suffer [...] Read more.

UHF satellite communication for Internet of Things (IoT) technology is rapidly emerging in monitoring applications as it offers the possibility of lower-costs and global coverage. At the present time, Low Power Wide Area Network (LPWAN) solutions offer low power consumption, but still suffer from white zones. In this paper, the authors propose an UHF frequency reconfigurable Antenna for hybrid connectivity LoRaWAN (at 868 MHz) and UHF satellite communication (Tx at 401 MHz and Rx at 466 MHz) with the Low Earth Orbit (LEO) Kineis constellation. The antenna is based on a meandered line structure loaded with lumped components and a PIN diode to control the antenna resonant frequencies. It resonates at 401 and 868 MHz when the PIN diode is forward-biased (ON state) and 466 MHz in reverse-biased configuration (OFF state). The antenna is designed inside the enclosure with the presence of all the parts of the connected device. The results of EM simulations and parametric studies on the values of the lumped components and the PIN diode equivalent model, which are obtained with HFSS, are presented. The antenna is prototyped and has dimensions of 78 mm × 88 mm × 1.6 mm. The paper proposes a fast and practical method to reduce time development and compensate the frequency shift between measurement and simulation. Full article

(This article belongs to the Special Issue Antenna Design and Sensors for Internet of Things)

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Review

Jump to: Research

18 pages, 1866 KiB

Open AccessReview

Circularly Polarized Hybrid Dielectric Resonator Antennas: A Brief Review and Perspective Analysis

by Rajasekhar Nalanagula, Naresh K. Darimireddy, Runa Kumari, Chan-Wang Park and R. Ramana Reddy

Sensors 2021, 21(12), 4100; https://doi.org/10.3390/s21124100 - 15 Jun 2021

Cited by 22 | Viewed by 4999

Abstract

Recently, it has been a feasible approach to build an antenna, in view of the potential advantages they offer. One of the recent trends in dielectric resonator antenna research is the use of compound and hybrid structures. Several considerable investigations have been already [...] Read more.

Recently, it has been a feasible approach to build an antenna, in view of the potential advantages they offer. One of the recent trends in dielectric resonator antenna research is the use of compound and hybrid structures. Several considerable investigations have been already underway showing quite interesting and significant features in bandwidth, gain, and generation of circular polarization. A critical review on a journey of circularly polarized hybrid dielectric resonator antennas is presented in this article. A general discussion of circular polarization and DR antennas are provided at the forefront. Evolution, significant challenges, and future aspects with new ideas in designing hybrid dielectric resonator antennas are indicated at the end of the review. State-of-the-art advances and associated design challenges of circularly polarized hybrid DR antennas and related empirical formulas used to find resonance frequency of different hybrid modes produced are discussed in this paper. Full article

(This article belongs to the Special Issue Antenna Design and Sensors for Internet of Things)

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Figure 1
Venn Diagram representation for dielectric antenna technology. Full article ">Figure 2
A few examples of hybrid dielectric resonator antenna technology. (a) microstrip disc loaded dielectric antennas, and (b) dielectric loaded microstrip patch antennas. Full article ">Figure 3
(a) 3D-view and (b) Top-view of hybrid structure (Reference [<a href="#B116-sensors-21-04100" class="html-bibr">116</a>]). Full article ">Figure 4
Representation of simulated and measured (a) S11 (b) AR plots, along with orthogonal modes. (Reference [<a href="#B116-sensors-21-04100" class="html-bibr">116</a>]). Full article ">Figure 4 Cont.
Representation of simulated and measured (a) S11 (b) AR plots, along with orthogonal modes. (Reference [<a href="#B116-sensors-21-04100" class="html-bibr">116</a>]). Full article ">Figure 5
Diagonally arranged two-element multiple inputs multiple output (MIMO) hybrid structure (a) Side view, (b) Top view (Reference [<a href="#B117-sensors-21-04100" class="html-bibr">117</a>]). Full article ">Figure 6
Configuration of dual-sense polarized hybrid DRA. (a) Top view, and (b) side view (Reference [<a href="#B128-sensors-21-04100" class="html-bibr">128</a>]). Full article ">

32 pages, 12665 KiB

Open AccessReview

Liquid-Based Reconfigurable Antenna Technology: Recent Developments, Challenges and Future

by Habshah Abu Bakar, Rosemizi Abd Rahim, Ping Jack Soh and Prayoot Akkaraekthalin

Sensors 2021, 21(3), 827; https://doi.org/10.3390/s21030827 - 26 Jan 2021

Cited by 15 | Viewed by 5591

Abstract

Advances in reconfigurable liquid-based reconfigurable antennas are enabling new possibilities to fulfil the requirements of more advanced wireless communication systems. In this review, a comparative analysis of various state-of-the-art concepts and techniques for designing reconfigurable antennas using liquid is presented. First, the electrical [...] Read more.

Advances in reconfigurable liquid-based reconfigurable antennas are enabling new possibilities to fulfil the requirements of more advanced wireless communication systems. In this review, a comparative analysis of various state-of-the-art concepts and techniques for designing reconfigurable antennas using liquid is presented. First, the electrical properties of different liquids at room temperature commonly used in reconfigurable antennas are identified. This is followed by a discussion of various liquid actuation techniques in enabling high frequency reconfigurability. Next, the liquid-based reconfigurable antennas in literature used to achieve the different types of reconfiguration will be critically reviewed. These include frequency-, polarization-, radiation pattern-, and compound reconfigurability. The current concepts of liquid-based reconfigurable antennas can be classified broadly into three basic approaches: altering the physical (and electrical) dimensions of antennas using liquid; applying liquid-based sections as reactive loads; implementation of liquids as dielectric resonators. Each concept and their design approaches will be examined, outlining their benefits, limitations, and possible future improvements. Full article

(This article belongs to the Special Issue Antenna Design and Sensors for Internet of Things)

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