| 1. |
- Lui, H., et al.
(författare)
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Mutual Coupling in Antenna Arrays 2013
- 2014
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Ingår i: International Journal of Antennas and Propagation. - : Hindawi Limited. - 1687-5869 .- 1687-5877. ; 2014
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The invention of antenna arrays opened up the door for microwave sensing and communications. Most applications of antenna arrays are in the defense and wireless communications areas. The introduction of multiple-input-multiple-output (MIMO) concept in recent years has opened up further opportunities in that the system performance can be maintained with a smaller number of antennas. The existence of mutual coupling effect, that is, the electromagnetic interaction between antenna elements, appears as an undesirable effect in most of these cases. The transmitted and received signals can be significantly distorted such that the signals no longer depend solely on the antenna elements, but also on the array structure and the surrounding environment. Such distortions result in the reduction of channel capacities in communications applications, as well as poor accuracies in ranging and direction finding. In most applications, the mutual coupling effect is unknown. A major challenge is then to characterize this undesirable effect and to accurately estimate the unknown parameters (range, direction) without a priori knowledge of the signal environment.This special issue, which is the third one in its series, provides an international forum for researchers to disseminate their results and ideas to tackle some of these challenging research problems. Five dedicated papers have contributed to this special issue. These papers concern the mutual coupling and its impacts on MIMO communications, direction finding, and MIMO radar. To help interested readers with a quick reference to the main themes of these papers, we briefly introduce them as follows.The first paper entitled “Self-interference cancellation-based mutual-coupling model for full-duplex single-channel MIMO systems,” concerns the mutual coupling problem in MIMO communications. The paper addresses the self-interference and mutual-interference of a full-duplex single-channel MIMO communications system.In the presence of mutual coupling, the array manifold is perturbed, which results in poor accuracies in direction finding. The paper “Accurate DOA estimations using microstrip adaptive arrays in the presence of mutual coupling effect” proposes a method to calibrate the undesirable mutual coupling effect for arrays with non-omni-directional radiating elements. The third paper, entitled “2-D direction of arrival estimation for cross array in the presence of mutual coupling,” introduces a noniterative algorithm based on the Propagation Method for accurate two-dimensional direction finding problems using a cross array in the presence of mutual coupling. The paper “AR model-based direction-of-arrival estimation of coherent signals in the presence of unknown mutual coupling” provides a novel signal processing solution based on a spatial autoregression (AR) model for coherent direction finding of uniform linear arrays.The fifth paper of this special issue, entitled “Root-MUSIC based angle estimation for MIMO radar with unknown mutual coupling,” explores the direction finding solutions in MIMO radar. A Root-MUSIC based solution is proposed to estimate the incoming signal direction with unknown mutual coupling.All papers appearing in this special issue have been subject to a strict peer-reviewing process. They are of high quality and address the mutual coupling problem from different perspectives. Through this special issue, we have provided a medium of dissemination for valuable ideas and conclusions on mutual coupling research. At the same time, we hope that more research innovations can be stimulated for future advances on this subject.
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| 2. |
- Wang, Enlin, 1998, et al.
(författare)
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Monopulse Feeding Network Based on New Gap Waveguide Planar Magic-Tees
- 2022
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Ingår i: 2022 International Symposium on Antennas and Propagation, ISAP 2022. ; , s. 101-102
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Konferensbidrag (refereegranskat)abstract
- A compact low-loss monopulse feeding network based on gap waveguide (GW) with two new planar GW magic-Ts is proposed. The four ports of the two planar Magic-Ts are in the same plane, which makes it possible to cascade magic-Ts to achieve a monopulse feeding network in a single plate for one polarization. The bandwidth of simulated reflection coefficient below -10 dB of this monopulse feeding network is 23.5%, covering 30-38GHz. This network is a good candidate for planar monopulse antennas.
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| 3. |
- Cao, Jianyin, et al.
(författare)
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W-band high-gain low profile circularly polarized magneto-electric dipole antenna array with gap waveguide feeding technology
- 2018
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Ingår i: IET Conference Publications. ; 2018:CP741
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Konferensbidrag (refereegranskat)abstract
- In this paper, a high gain circularly polarized (CP) aperture-coupled magneto-electric (ME) dipole antenna array excited by the air cavity in gap waveguide (GWG) feeding technology in W-band is proposed. This antenna array is composed of two layers, upper CP ME-dipole antenna subarrays and lower metallic GWG feeding networks. The planar antenna array structure is realized by the high mode air cavity feeding network, which is realized by extending the 1×2 cavity to 3×2 cavity using more shorted pins to split the electromagnetic field. The whole single-layer GWG feeding network is composed of a ridge gap waveguide (RGWG) transmission structure and short-ended vertical polarized groove gap waveguide (VP-GGWG) high mode air cavities. The transmission loss caused by the coupling and the fabrication tolerance can be reduced by combining the RGWG and GGWG in the same layer. In addition, the feeding network is fabricated all in metal with no substrate loss. Transverse slots are etched at the right position of the printed circuit board (PCB) backside to excite the CP ME-dipoles. The antenna element has stable radiation patterns and wide axial-ratio (AR) bandwidth. The proposed 3×8 planner antenna array has a maximum boresight gain of 22 dBi and an AR bandwidth of 10.8% for AR < 3 dB. In the frequency band from 87.7 to 97.7 GHz, a boresight gain above 20 dBi is achieved.
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| 4. |
- Fan, Jin, et al.
(författare)
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Design of Octave-bandwidth Phased Array Feed for Large Radio Telescope
- 2019
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Ingår i: 13th European Conference on Antennas and Propagation, EuCAP 2019.
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Konferensbidrag (refereegranskat)abstract
- This paper presents design scenarios of Octave-bandwidth Phase Array Feed (PAF) based on a novel wideband dual polarized tightly-fed Bowtie antenna element. The PAF is optimized for the 4 - 8GHz band aiming to possible later integration in the SKA pathfinder PHAROS2. The proposed design can be a good candidate of PAF for the Five hundred meter Aperture Spherical Telescope (FAST) and Qi Tai Telescope (QTT) as well as other large radio telescopes.
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| 5. |
- Fan, Jin, et al.
(författare)
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Investigation of ultra-wideband Bowtie antennas for phased array feed application
- 2020
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Ingår i: International Journal of RF and Microwave Computer-Aided Engineering. - : Hindawi Limited. - 1096-4290 .- 1099-047X. ; 30:11
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Tidskriftsartikel (refereegranskat)abstract
- In this article, two new ultra-wideband (UWB) dual-polarized Bowtie antennas are investigated as the elements for a phased array feed for reflectors. In addition to its UWB impedance matching characteristic, the Bowtie antennas have stable large beam-width and a low cross-polar level over a wide frequency band with a compact size, which is an essence for phased array applications. The simulated and measured results state a low ohmic loss, good impedance matching (S11 below −15 dB) and good radiation performance, with a simple structure for easy manufacturing. The proposed antennas can be good candidates for phased array feed (PAF) in FAST and the SKA (square kilometer array) pathfinder PHAROS2 projects, and massive MIMO antennas in wireless communication systems.
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| 6. |
- Glazunov, Andres Alayon, 1969, et al.
(författare)
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Semi-Analytical Model of the Rician K-Factor
- 2020
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Ingår i: Radio Science. - 0048-6604 .- 1944-799X. ; 55:11
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Tidskriftsartikel (refereegranskat)abstract
- The analysis of the performance of 5G wireless communication systems employing Massive MIMO at millimeter-wave frequencies is of great practical relevance. Of special relevance are the signal fluctuations. In the present paper, we introduce a semi-analytical model for a generic scattering environment by using randomly distributed resonant scatterers to investigate the impact of the size of the scattering environment, the scatterer density, and the number of scatterers on the signal variability in terms of the Rician K-factor as a function of frequency. We further present an investigation of the impact of scattering on the frequency dependence of the signal fading statistics in the 500 MHz–100 GHz band. The simplified model is also verified against full-wave simulation using the Method of Moments (MoM).
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| 7. |
- Huang, Jin, 1989, et al.
(författare)
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Design of Circularly Polarized End-fire Antenna on Gap Waveguide for Automotive Radar Application
- 2021
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Ingår i: 2021 IEEE International Symposium on Antennas and Propagation and North American Radio Science Meeting, APS/URSI 2021 - Proceedings. ; , s. 1952-1953
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Konferensbidrag (refereegranskat)abstract
- This paper presents an end-fire antenna with circu-lar polarization utilizing gap waveguide technology for 77 GHz automotive radar band. The proposed device contains a 1 × 4 planar array antenna and a gap waveguide part consisting of a 4-way power divider on ridge gap waveguide and a transitive groove gap waveguide. The impedance and 3-dB axial ratio bandwidths of 74.8 79.2 GHz and 75.6 78.0 GHz are achieved in simulation, which can cover the 77 GHz radar band well. A stable end-fire beam and a gain in the range of 11.6 to 13.4 dBic are obtained as well over the whole operation band.
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| 8. |
- Khanal, Prabhat, 1993, et al.
(författare)
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A Contactless Feeding Network Design Using MetaCoax Coupler
- 2022
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Ingår i: 2022 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting, AP-S/URSI 2022 - Proceedings. ; , s. 1760-1761
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Konferensbidrag (refereegranskat)abstract
- A novel contactless capacitively coupled PCB-to-PCB coupler is proposed in this paper. The coupler is used to couple a 2×2 element circularly polarized antenna array PCB to its feeding layer PCB and connectors. The simulated results of the antenna array alone and the antenna array with the couplers matches well, indicating the good performance of the contactless feeding network. The antenna array with the couplers has 18% bandwidth and a maximum gain of 11.15 dBi, which is only 4% and 0.13 dBi smaller than that of the directly excited antenna array.
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| 9. |
- Khanal, Prabhat, 1993, et al.
(författare)
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Integration of Airborne Early Warning Radar Platforms on Aircraft
- 2020
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The need for a long-range and complete Air Picture has long since motivated the presence of airborne early warning (AEW) radar platforms. Later developments, such as stealth and advancing threats at low altitudes or hypersonic speeds have nothing but reinforce the need for increased-performance AEW. However, the high costs for the platform, integration, and operations restrict the number of platforms to a point where these high-value assets become sensitive to preemptive actions by an adversary. Therefore, SAAB has within the NFFP7 framework launched a series of studies aiming at smaller, adapted, and cost-efficient unmanned AEW platforms with extreme endurance. Thus, the aerodynamic performance of the carrier plus radar must be optimized, which implies that the projected area of the radar must be minimized. In this project, we study the possibility of integrating the antenna layer in the fuselage structure of the aircraft, thus gaining (i) body width and (ii) a more optimal wet geometry.
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| 10. |
- Mansouri Moghaddam, Sadegh, 1987, et al.
(författare)
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Wideband Dual-Polarized Linear Array Antenna for Random-LOS OTA Measurement
- 2018
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 66:5, s. 2365-2373
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, an 8×1 dual-polarized linear array antenna is proposed for a random line-of-sight over-the-air measurement system. The proposed array antenna operates over the frequency band of 1.6-2.7 GHz. A self-grounded bowtie is optimized as the array element. A compact wideband two-port feeding network is designed and manufactured to differentially excite each element, while each port excites one of the two orthogonal polarizations. Corrugated plates have been employed in the transverse plane of the linear array in order to achieve the same beamwidth for both polarizations over the entire band. A prototype has been manufactured and the measured reflection coefficient is better than -10 dB. The realized gain and the half-power beamwidth of the array in the transverse plane of the array remain fairly constant over the entire band of interest.
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