ABSTRACT: In this paper, a general and easy procedure for designing the symmetrical Wilkinson pow... more ABSTRACT: In this paper, a general and easy procedure for designing the symmetrical Wilkinson power divider that achieves equal-power split at N arbitrary frequencies is intro-duced. Each quarter-wave branch in the conventional Wilkinson divider is replaced by N sections of transmission lines, and the isolation between the output ports is achieved by using N resistors. The design parameters are the characteristic impedances and lengths of the N transmission line sections, and the N isolation resistors. The even–odd modes of analy-sis are used to derive the design equations. Closed-form expressions, which are suitable for CAD purposes, are derived for the dual-band divider. For N ≥ 3, closed-form expressions are not available, and therefore, the powerful particle swarm optimization method is used to obtain the design parameters. Examples of the dual-, triple-, and quad-band dividers are presented to validate the proposed design procedure, and the results are compared, wher-ever possi...
ABSTRACT: This article reports on the use of the particle swarm optimization (PSO) algorithm in t... more ABSTRACT: This article reports on the use of the particle swarm optimization (PSO) algorithm in the synthesis of the planar interdigital capacitor (IDC). The PSO algorithm is used to optimize the geometry parameters of the IDC in order to obtain a certain capacitance value. The capacitance value of the IDC is evaluated using an artificial neural network (ANN) model with the geometry parameters of the IDC as its inputs. Several design examples are presented that illustrate the use of the PSO algorithm, and the design goal in each example is easily achieved. Full-wave electromagnetic simulations are also performed for some of the studied IDC structures implemented using coplanar waveguide (CPW) technology. The sim-ulation results are in good agreement with those obtained using the ANN/PSO algorithm.
This study presents a comprehensive study of the design and optimisation of linear antenna arrays... more This study presents a comprehensive study of the design and optimisation of linear antenna arrays using the cuckoo search (CS) algorithm. The method is used to control important radiation characteristics of the antenna arrays (such as side-lobe level, beamwidth, nulls) by optimising the parameters of the array elements (amplitude, phase, and position). Different design examples are presented that illustrate the robustness of the CS algorithm and its ability in achieving the design goals. The considered design examples clearly show that the CS algorithm is a simple and yet a powerful optimisation tool that can be used in antenna array design problems with great confidence.
2016 5th International Conference on Electronic Devices, Systems and Applications (ICEDSA), 2016
The main goal of this work is to use the Cuckoo Search (CS) algorithm to optimize Fractional Freq... more The main goal of this work is to use the Cuckoo Search (CS) algorithm to optimize Fractional Frequency Reuse (FFR) of cellular network systems. FFR is an interference management technique well suited to OFDMA based cellular network systems, such as Long Term Evolution system (LTE). This paper proposes a mechanism that selects the optimal value of inner cell region radius in strict FFR that maximize both throughput and User Satisfaction together using CS algorithm. The CS algorithm has been chosen as it is easy to understand and implement and has limited number of arguments to tune when compared with other optimization algorithms.
IEEE Antennas and Propagation Society International Symposium. Digest. Held in conjunction with: USNC/CNC/URSI North American Radio Sci. Meeting (Cat. No.03CH37450), 2003
This paper presents a comparison of three different types of CPW fed slot antennas integrated wit... more This paper presents a comparison of three different types of CPW fed slot antennas integrated with a photodetector. The antennas are driven by optical power converted into microwave power using the photodetector which is directly attached to the antennas without the use of any amplifying devices. The operating frequency of these antennas is around 18.5 GHz. This paper presents the approach for matching a photodetector to a single element or to an array of elements. Measured data and simulations for various antenna/photodetector configurations are compared and discussed.
IEEE Antennas and Propagation Society International Symposium. Transmitting Waves of Progress to the Next Millennium. 2000 Digest. Held in conjunction with: USNC/URSI National Radio Science Meeting (Cat. No.00CH37118), 2000
ABSTRACT A new stacked microstrip antenna structure that enhances the bandwidth without changing ... more ABSTRACT A new stacked microstrip antenna structure that enhances the bandwidth without changing the resonance frequency is proposed and studied in this paper. The effect of the various antenna parameters on the bandwidth is investigated. The resulting antenna using the proposed structure has an ultra-wide bandwidth of 35%, compared to 21.8% for the conventional stacked antenna structure. The proposed structure has a little effect on the antenna radiation characteristics. The analysis of the proposed structure is carried out using the FDTD method
2006 International Conference on Microwaves, Radar & Wireless Communications, 2006
ABSTRACT This paper describes a synthesis method of planar array geometry with minimum sidelobe l... more ABSTRACT This paper describes a synthesis method of planar array geometry with minimum sidelobe level and null control using the particle swarm optimization (PSO) algorithm. The array geometry synthesis is first formulated as an optimization problem with the goal of sidelobe level (SLL) reduction and/or null placement in certain directions, and then solved by the PSO algorithm for optimized elements locations. The steps in the problem formulation are presented along with a design example that illustrates the performance of the PSO algorithm.
ABSTRACT This paper proposes the integration of an antenna with a photodetector for high capacity... more ABSTRACT This paper proposes the integration of an antenna with a photodetector for high capacity wireless communications. The side-illuminated waveguide photodetector (WGPD) is used to convert the RF-modulated optical power into a microwave signal, which in turn is fed to an antenna. The WGPD is a standard p-i-n device grown on a semi-insulating InP substrate and fabricated using conventional techniques. The performance of this RF/photonic antenna in the frequency range 17-20 GHz is studied theoretically and experimentally. An equivalent circuit model for the WGPD is developed to estimate the photodetector impedance as a function of frequency to assist in the impedance matching between the photodetector and the antenna. The agreement between measurement and circuit model results for the WGPD impedance is very good. It is envisioned that a large number of such RF/Photonic antenna elements could be networked together into a star configuration, feeding in and out of a radio hub.
Multifrequency Electronic/Photonic Devices and Systems for Dual-Use Applications, 2001
This paper discusses the principle of operation of an electrically tunable THz detector, working ... more This paper discusses the principle of operation of an electrically tunable THz detector, working around 2.54 THz, integrated with a bowtie antenna. The detection is based on the idea of photon-assisted tunneling (PAT) in a double quantum well (DQW) device. The bowtie antenna is used to collect the THz radiation and feed it to the detector for processing. The Bowtie antenna geometry is integrated with the DQW device to achieve broadband characteristic, easy design, and compatibility with the detector fabrication process. The principle of operation of the detector is introduced first. Then, results of different bowtie antenna layouts are presented and discussed.
The integration of a bowtie antenna with a double electron layer tunneling transistor (DELTT) dev... more The integration of a bowtie antenna with a double electron layer tunneling transistor (DELTT) device for the purposes of THz detection is investigated in this paper. The concept of THz detection, based on photon-assisted tunneling (PAT) between the two electron layers in a double quantum well (DQW) heterostructure, will be explained. The detector is expected to have narrowband, electrically tunable, fast response, and the possibility to operate at relatively high temperatures. Since the active area of the detector is very small, which is necessary to achieve fast response, it is not efficient in collecting THz radiation. Therefore, a broadband bowtie antenna is integrated with the detector to efficiently collect the THz radiation. Characteristics of different bowtie antenna geometries at THz frequencies were studied. An equivalent circuit model of the THz detector was developed, for the first time, to estimate the impedance characteristics at THz frequencies. Such a model is crucial...
2000 IEEE-APS Conference on Antennas and Propagation for Wireless Communications (Cat. No.00EX380), 2000
The characteristics of a micromachined CPW-fed slot antenna array driven by converting optical po... more The characteristics of a micromachined CPW-fed slot antenna array driven by converting optical power into microwave power using RF photodetectors are presented. The CPW line is connected to the active surface of the photodetector, from which the microwave power propagates to feed the radiating slot. The photodetector is fed via an optical fiber from beneath. The output microwave frequency from the photodetector is in the range 15 GHz-30 GHz. The analysis is performed using IE3D(R). The scattering parameters and radiation patterns are obtained for one antenna element and for a four-element antenna array. The results show a very good bandwidth and radiation characteristics of this antenna
ABSTRACT: In this paper, a general and easy procedure for designing the symmetrical Wilkinson pow... more ABSTRACT: In this paper, a general and easy procedure for designing the symmetrical Wilkinson power divider that achieves equal-power split at N arbitrary frequencies is intro-duced. Each quarter-wave branch in the conventional Wilkinson divider is replaced by N sections of transmission lines, and the isolation between the output ports is achieved by using N resistors. The design parameters are the characteristic impedances and lengths of the N transmission line sections, and the N isolation resistors. The even–odd modes of analy-sis are used to derive the design equations. Closed-form expressions, which are suitable for CAD purposes, are derived for the dual-band divider. For N ≥ 3, closed-form expressions are not available, and therefore, the powerful particle swarm optimization method is used to obtain the design parameters. Examples of the dual-, triple-, and quad-band dividers are presented to validate the proposed design procedure, and the results are compared, wher-ever possi...
ABSTRACT: This article reports on the use of the particle swarm optimization (PSO) algorithm in t... more ABSTRACT: This article reports on the use of the particle swarm optimization (PSO) algorithm in the synthesis of the planar interdigital capacitor (IDC). The PSO algorithm is used to optimize the geometry parameters of the IDC in order to obtain a certain capacitance value. The capacitance value of the IDC is evaluated using an artificial neural network (ANN) model with the geometry parameters of the IDC as its inputs. Several design examples are presented that illustrate the use of the PSO algorithm, and the design goal in each example is easily achieved. Full-wave electromagnetic simulations are also performed for some of the studied IDC structures implemented using coplanar waveguide (CPW) technology. The sim-ulation results are in good agreement with those obtained using the ANN/PSO algorithm.
This study presents a comprehensive study of the design and optimisation of linear antenna arrays... more This study presents a comprehensive study of the design and optimisation of linear antenna arrays using the cuckoo search (CS) algorithm. The method is used to control important radiation characteristics of the antenna arrays (such as side-lobe level, beamwidth, nulls) by optimising the parameters of the array elements (amplitude, phase, and position). Different design examples are presented that illustrate the robustness of the CS algorithm and its ability in achieving the design goals. The considered design examples clearly show that the CS algorithm is a simple and yet a powerful optimisation tool that can be used in antenna array design problems with great confidence.
2016 5th International Conference on Electronic Devices, Systems and Applications (ICEDSA), 2016
The main goal of this work is to use the Cuckoo Search (CS) algorithm to optimize Fractional Freq... more The main goal of this work is to use the Cuckoo Search (CS) algorithm to optimize Fractional Frequency Reuse (FFR) of cellular network systems. FFR is an interference management technique well suited to OFDMA based cellular network systems, such as Long Term Evolution system (LTE). This paper proposes a mechanism that selects the optimal value of inner cell region radius in strict FFR that maximize both throughput and User Satisfaction together using CS algorithm. The CS algorithm has been chosen as it is easy to understand and implement and has limited number of arguments to tune when compared with other optimization algorithms.
IEEE Antennas and Propagation Society International Symposium. Digest. Held in conjunction with: USNC/CNC/URSI North American Radio Sci. Meeting (Cat. No.03CH37450), 2003
This paper presents a comparison of three different types of CPW fed slot antennas integrated wit... more This paper presents a comparison of three different types of CPW fed slot antennas integrated with a photodetector. The antennas are driven by optical power converted into microwave power using the photodetector which is directly attached to the antennas without the use of any amplifying devices. The operating frequency of these antennas is around 18.5 GHz. This paper presents the approach for matching a photodetector to a single element or to an array of elements. Measured data and simulations for various antenna/photodetector configurations are compared and discussed.
IEEE Antennas and Propagation Society International Symposium. Transmitting Waves of Progress to the Next Millennium. 2000 Digest. Held in conjunction with: USNC/URSI National Radio Science Meeting (Cat. No.00CH37118), 2000
ABSTRACT A new stacked microstrip antenna structure that enhances the bandwidth without changing ... more ABSTRACT A new stacked microstrip antenna structure that enhances the bandwidth without changing the resonance frequency is proposed and studied in this paper. The effect of the various antenna parameters on the bandwidth is investigated. The resulting antenna using the proposed structure has an ultra-wide bandwidth of 35%, compared to 21.8% for the conventional stacked antenna structure. The proposed structure has a little effect on the antenna radiation characteristics. The analysis of the proposed structure is carried out using the FDTD method
2006 International Conference on Microwaves, Radar & Wireless Communications, 2006
ABSTRACT This paper describes a synthesis method of planar array geometry with minimum sidelobe l... more ABSTRACT This paper describes a synthesis method of planar array geometry with minimum sidelobe level and null control using the particle swarm optimization (PSO) algorithm. The array geometry synthesis is first formulated as an optimization problem with the goal of sidelobe level (SLL) reduction and/or null placement in certain directions, and then solved by the PSO algorithm for optimized elements locations. The steps in the problem formulation are presented along with a design example that illustrates the performance of the PSO algorithm.
ABSTRACT This paper proposes the integration of an antenna with a photodetector for high capacity... more ABSTRACT This paper proposes the integration of an antenna with a photodetector for high capacity wireless communications. The side-illuminated waveguide photodetector (WGPD) is used to convert the RF-modulated optical power into a microwave signal, which in turn is fed to an antenna. The WGPD is a standard p-i-n device grown on a semi-insulating InP substrate and fabricated using conventional techniques. The performance of this RF/photonic antenna in the frequency range 17-20 GHz is studied theoretically and experimentally. An equivalent circuit model for the WGPD is developed to estimate the photodetector impedance as a function of frequency to assist in the impedance matching between the photodetector and the antenna. The agreement between measurement and circuit model results for the WGPD impedance is very good. It is envisioned that a large number of such RF/Photonic antenna elements could be networked together into a star configuration, feeding in and out of a radio hub.
Multifrequency Electronic/Photonic Devices and Systems for Dual-Use Applications, 2001
This paper discusses the principle of operation of an electrically tunable THz detector, working ... more This paper discusses the principle of operation of an electrically tunable THz detector, working around 2.54 THz, integrated with a bowtie antenna. The detection is based on the idea of photon-assisted tunneling (PAT) in a double quantum well (DQW) device. The bowtie antenna is used to collect the THz radiation and feed it to the detector for processing. The Bowtie antenna geometry is integrated with the DQW device to achieve broadband characteristic, easy design, and compatibility with the detector fabrication process. The principle of operation of the detector is introduced first. Then, results of different bowtie antenna layouts are presented and discussed.
The integration of a bowtie antenna with a double electron layer tunneling transistor (DELTT) dev... more The integration of a bowtie antenna with a double electron layer tunneling transistor (DELTT) device for the purposes of THz detection is investigated in this paper. The concept of THz detection, based on photon-assisted tunneling (PAT) between the two electron layers in a double quantum well (DQW) heterostructure, will be explained. The detector is expected to have narrowband, electrically tunable, fast response, and the possibility to operate at relatively high temperatures. Since the active area of the detector is very small, which is necessary to achieve fast response, it is not efficient in collecting THz radiation. Therefore, a broadband bowtie antenna is integrated with the detector to efficiently collect the THz radiation. Characteristics of different bowtie antenna geometries at THz frequencies were studied. An equivalent circuit model of the THz detector was developed, for the first time, to estimate the impedance characteristics at THz frequencies. Such a model is crucial...
2000 IEEE-APS Conference on Antennas and Propagation for Wireless Communications (Cat. No.00EX380), 2000
The characteristics of a micromachined CPW-fed slot antenna array driven by converting optical po... more The characteristics of a micromachined CPW-fed slot antenna array driven by converting optical power into microwave power using RF photodetectors are presented. The CPW line is connected to the active surface of the photodetector, from which the microwave power propagates to feed the radiating slot. The photodetector is fed via an optical fiber from beneath. The output microwave frequency from the photodetector is in the range 15 GHz-30 GHz. The analysis is performed using IE3D(R). The scattering parameters and radiation patterns are obtained for one antenna element and for a four-element antenna array. The results show a very good bandwidth and radiation characteristics of this antenna
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