The Experts below are selected from a list of 16098 Experts worldwide ranked by ideXlab platform
John L. Volakis - One of the best experts on this subject based on the ideXlab platform.
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Characteristic Excitation Taper for Ultrawideband Tightly Coupled Antenna Arrays
IEEE Transactions on Antennas and Propagation, 2012Co-Authors: Ioannis Tzanidis, Kubilay Sertel, John L. VolakisAbstract:We propose a novel technique to calculate a quasi- optimal aperture excitation for finite size, ultrawideband arrays. The approach is based on using the characteristic modes of the array's mutual impedance matrix. Unlike standard excitation tapers, primarily used for beam shaping, the proposed characteristic mode taper provides for wideband matching of all array elements, including those at the edges of the finite array. As such, it maximizes aperture efficiency and is particularly attractive for finite size, tightly Coupled Antenna arrays. Our method solely relies on the N × N mutual impedance matrix of the array which is precomputed (or measured). We demonstrate this novel excitation method for an 8 × 8 array of tightly Coupled dipole elements. When compared to uniform excitation, the characteristic mode excitation achieves very low VSWRs for all elements over a large bandwidth. Improvements in realized gain are also demonstrated. Due to its simplicity, this new method can be incorporated into a design process to optimize element and array geometries, leading to further performance improvements.
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narrowband and wideband metamaterial Antennas based on degenerate band edge and magnetic photonic crystals
Proceedings of the IEEE, 2011Co-Authors: John L. Volakis, Kubilay SertelAbstract:Historically, Antennas and microwave devices relied on isotropic media. This provided for limited degrees of freedom (one for dielectric and another for magnetic) in the design process. In contrast, anisotropic media introduce several more degrees of freedom (at least three more for dielectrics and three additional ones for magnetic) opening a new direction in designing radio-frequency (RF) communication devices and wireless systems. A focus of the paper is the introduction of anisotropic media parameters emulated using simple printed, but highly Coupled, transmission lines (TRLs). The paper begins by introducing the equivalence between in-plane anisotropy and Coupled TRLs to realize degenerate band edge (DBE) and magnetic photonic crystal (MPC) modes. This is followed by the design of miniature Antenna elements via dispersion engineering, demonstrating their performance on small finite substrates. The second part of the paper is focused on concatenating DBE and MPC Antenna elements to realize smaller size wideband arrays. Such arrays exploit the current sheet Antenna (CSA) concept to achieve the coveted goal of small wideband metamaterial arrays. For example, by constructing an array of Antenna elements ~ λ/10tλ/10 in size, highly conformal (very thin) apertures delivering 5 : 1 bandwidth are demonstrated while avoiding grating lobes. In contrast to transitional approaches, the proposed method exploits (rather than suppressing) the metallic ground plane inductance. Instead, the capacitance of the tightly Coupled Antenna elements is used to cancel the inductance over wide bandwidths. By further employing small size array elements, large bandwidths can be achieved using a smaller footprint.
Lizhi You - One of the best experts on this subject based on the ideXlab platform.
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a broadband impedance matching method for proximity Coupled microstrip Antenna
IEEE Transactions on Antennas and Propagation, 2010Co-Authors: Dan Sun, Lizhi YouAbstract:In a proximity-Coupled microstrip Antenna, when a laminate used is too thick for the Antenna layer, the coupling will be decreased. And it is hard to achieve broadband impedance matching. The authors present a method to optimize impedance matching through narrow cavity backed configuration. A prototype Antenna is designed with this method and fabricated. Simulation and measurement results indicate that the bandwidth of the Antenna exceeds 40% (VSWR < 2.0). The Antenna has a larger effective coupling as compared with the conventional proximity-Coupled Antenna without the narrow cavity backed configuration. It is easier to enhance the bandwidth with a thicker laminate. Meanwhile, this Antenna is benefit for manufacturing and assembling to an array due to its simple configuration.
Christina F Jou - One of the best experts on this subject based on the ideXlab platform.
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studies of suppression of the reflected wave and beam scanning features of the Antenna arrays
IEEE Transactions on Antennas and Propagation, 2005Co-Authors: Iyu Chen, Chienjen Wang, Hualin Guan, Christina F JouAbstract:This paper describes a two-directional linear scanned design by integrating a short leaky-wave Antenna (LWA) with aperture-Coupled patch Antenna arrays. This architecture proposes a technique not only having the advantage of suppressing the back-lobe due to the reflected wave in the short LWA but also producing two separate linearly scanned beams, each of them radiating in a different region of space (in both the front side and backside of the LWA). In this design, most of the reflected wave of the short LWA is Coupled to the patch Antenna arrays on the backside of the substrate. The phase of this Coupled signal to each Antenna element is adjusted by tuning the individual phase shifter in order to control electronically the patch Antenna main beam in the cross plane (x 0) by changing the operating frequency. Hence, the two linear beam-scanning radiation patterns of individual direction can be created independently, including a narrow beam in the elevation plane (xy plane at x>0) at the front side and a broadside beam in the cross plane (xz plane at x<0) on the backside. The measured results show that the reflected wave of the short LWA in the proposed design is suppressed 8 dB as compared with a traditional short LWA without the aperture-Coupled Antenna arrays at 10.5 GHz. As a result, this novel architecture provides more flexibility both in the upward elevation plane (H plane) and the downward cross plane (backside-E plane) for possible beam-scanning applications in microwave communications and remote identification.
Trevor S. Bird - One of the best experts on this subject based on the ideXlab platform.
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A Wideband Low-Profile Tightly Coupled Antenna Array With a Very High Figure of Merit
IEEE Transactions on Antennas and Propagation, 2019Co-Authors: Alpha O. Bah, Pei-yuan Qin, Richard W. Ziolkowski, Y. Jay Guo, Trevor S. BirdAbstract:A wideband, low-profile, tightly Coupled Antenna array with a simple feed network is presented. The dipole and feed networks in each unit cell are printed on both sides of a single RT/Duroid 6010 substrate with a relative dielectric constant of 10.2. The feed network, composed of meandered impedance transformer and balun sections, is designed based on Klopfenstein tapered microstrip lines. The wide-angle impedance matching is empowered by a novel wideband metasurface superstrate. For the optimum design, scanning to 70° along the E-plane is obtained together with a very high array figure of merit PA = 2.84. The H-plane scan extends to 55°. The broadside impedance bandwidth is 5.5:1 (0.80–4.38) GHz with an active voltage standing-wave ratio value ≤2. The overall height of the array above the ground plane is $0.088\lambda _{\mathrm {L}}$ , where $\lambda _{\mathrm {L}}$ is the wavelength at the lowest frequency of operation. A prototype was fabricated and tested to confirm the design concepts.
Hong Wonbin - One of the best experts on this subject based on the ideXlab platform.
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Broadband and Wide-Angle Scanning Capability in Low-Coupled mm-Wave Phased-Arrays Incorporating ILA With HIS Fabricated on FR-4 PCB
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2021Co-Authors: Lee Jae-yeong, Choi Jaehyun, Choi Dongkwon, Youn Youngno, Hong WonbinAbstract:This paper presents a compact millimeter-wave (mm-Wave) phased array incorporating inverted-L Antenna (ILA) with high-impedance electromagnetic surfaces (HIS) based on single-layer FR-4 PCB for user equipment (UE). In order to realize mm-Wave UE in low production cost, the design methodology of phased array Antenna in single-layer FR-4 PCB is proposed without any additional packaging process. The presented Antenna consists of low-Coupled Antenna element and low loss feeding networks in compressed linear array configuration with 0.39 lambda(0) inter-element spacing. First, in order to realize broadband characteristics, the ILA is integrated with one-dimensional electromagnetic bandgap (1-D EBG) structures featuring HIS via slow-wave behavior. Due to high-impedance properties of the embedded via wall structures in common ground plane between each Antenna element, the mutual coupling path through surface-current can be reduced. Second, in order to minimize leakage power caused by surface-waves, low loss coplanar waveguide ground (CPWG) feeding networks with via wall structures and island-shape pads are realized. The fabricated 4-elements and 8-elements phased array Antennas including Antenna element and feeding network based on FR-4 PCB achieve wide 3 dB beam coverage while featuring low beam squint in the Ka-band. In order to investigate over-the-air (OTA) system performance at three beam steering scenarios (boresight and +/- 60 degrees scan angle), the measured maximum error vector magnitude (EVM) in QPSK modulation scheme is 16.6%. The coverage efficiency beyond 50% for the realized gain of -1.5 dBi from 26 to 36 GHz is demonstrated.1
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J-Band Arrays Incorporating 1-D EBG Antenna in Nanoscale CMOS Process
한국전자파학회, 2021Co-Authors: Lee Jaeyeong, Lee, Kang Seop, Jaehyun Choi, Song, Ho Jin, Hong WonbinAbstract:This paper presents a J-band arrays incorporating inverted-L Antenna (ILA) with 1-D EBG and SRR structures based on nanoscale CMOS process for sub-terahertz (sub-THz) applications. In order to realize reliable fast design and performance verification of array Antenna on CMOS process, the precedent researches on the transmission line test samples for effective dielectric material properties extraction of dummy filling have been investigated. The Antenna based on the effective material properties is designed and characterized using 1×8 T-junction power dividers and low-Coupled Antenna element in compressed linear array configuration with 0.39λ0 inter-element spacing.2
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Broadband and Wide-Angle Scanning Capability in Low-Coupled mm-Wave Phased-Arrays Incorporating ILA With HIS Fabricated on FR-4 PCB
'Institute of Electrical and Electronics Engineers (IEEE)', 2021Co-Authors: Lee Jae-yeong, Choi Jaehyun, Choi Dongkwon, Youn Youngno, Hong WonbinAbstract:This paper presents a compact millimeter-wave (mm-Wave) phased array incorporating inverted-L Antenna (ILA) with high-impedance electromagnetic surfaces (HIS) based on single-layer FR-4 PCB for user equipment (UE). In order to realize mm-Wave UE in low production cost, the design methodology of phased array Antenna in single-layer FR-4 PCB is proposed without any additional packaging process. The presented Antenna consists of low-Coupled Antenna element and low loss feeding networks in compressed linear array configuration with 0.39 lambda(0) inter-element spacing. First, in order to realize broadband characteristics, the ILA is integrated with one-dimensional electromagnetic bandgap (1-D EBG) structures featuring HIS via slow-wave behavior. Due to high-impedance properties of the embedded via wall structures in common ground plane between each Antenna element, the mutual coupling path through surface-current can be reduced. Second, in order to minimize leakage power caused by surface-waves, low loss coplanar waveguide ground (CPWG) feeding networks with via wall structures and island-shape pads are realized. The fabricated 4-elements and 8-elements phased array Antennas including Antenna element and feeding network based on FR-4 PCB achieve wide 3 dB beam coverage while featuring low beam squint in the Ka-band. In order to investigate over-the-air (OTA) system performance at three beam steering scenarios (boresight and +/- 60 degrees scan angle), the measured maximum error vector magnitude (EVM) in QPSK modulation scheme is 16.6%. The coverage efficiency beyond 50% for the realized gain of -1.5 dBi from 26 to 36 GHz is demonstrated.11Nsciescopu
