1. |
- Ding, Liqin, 1988, et al.
(författare)
-
Shannon Capacity of LOS MIMO Channels with Uniform Circular Arrays
- 2022
-
Ingår i: IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC. ; 2022-September
-
Konferensbidrag (refereegranskat)abstract
- The Shannon capacity for the line-of-sight (LOS) multiple-input multiple-output (MIMO) channel between two perfectly aligned uniform circular arrays (UCAs) is derived from the first principles in a tutorial fashion. It is well known that harmonically related complex exponentials (also known in the literature as orbital angular momentum (OAM) modes) are eigenmodes for the spatially continuous channel. We show that the corresponding eigenvalues can be expressed as Bessel functions of the first kind. We also show that the spatially discrete channel between two UCAs with the same finite number of Hertzian dipole antennas on both sides has eigenmodes that are spatially sampled continuous OAM modes, and discrete eigenvalues that are aliased versions of the continuous eigenvalues. Through numerical solution of Maxwell's equations, we verify that the discrete eigenvalues for UCAs with realistic dipole antennas are the same as with the Hertzian dipoles for the studied geometries (1~km hop distance, UCA radius 1 and 2 m, carrier frequency 70 GHz) as long as antenna spacing is not very dense.
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2. |
- Chernikov, Viktor, 1998, et al.
(författare)
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A Teflon-Filled Open-Ended Circular Waveguide Focal-Plane-Array Used for Sway Compensation in W-band 50dB-Gain Backhaul Reflector Antennas
- 2023
-
Ingår i: 2023 International Conference on Electromagnetics in Advanced Applications, ICEAA 2023. ; , s. 340-345
-
Konferensbidrag (refereegranskat)abstract
- The paper introduces a novel focal plane array (FPA) design aimed at enhancing the reliability of millimeter-wave backhaul communication links by compensating for the impact of antenna mounting structures' sways. This FPA is analyzed for an offset parabolic reflector antenna with the 40-cm aperture diameter at W-band frequencies (92-96 GHz). The FPA-fed reflector antenna generates multiple closely-overlapping beams to compensate for the expected antenna tilt range, equivalent to seven beamwidths. This study addresses major challenges associated with FPA design implementation at these high frequencies, including (i) the need for a small (≤ 0.75 λ) inter-element spacing for the required beam overlap, and (ii) manufacturing complexities of an array element ensuring optimal reflector illumination and impedance matching in the presence of mutual coupling effects. An analytical approach to the FPA pattern shaping for optimal reflector illumination is proposed and successfully validated via numerical optimization and measurements. Furthermore, our analysis of the total reflector-FPA system shows promising results, i.e. 56 - 68% antenna aperture efficiency (49 - 50 dBi directivity) for all beams with compliance to the radiation emission constraints (ETSI class 3) within ±89°.
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3. |
- Chernikov, Viktor, 1998, et al.
(författare)
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Design Considerations for Focal-Plane Array Antennas for 6G Millimeter-Wave Backhaul Links
- 2023
-
Ingår i: IEEE Antennas and Propagation Society, AP-S International Symposium (Digest). - 1522-3965. ; 2023-July, s. 765-766
-
Konferensbidrag (refereegranskat)abstract
- We present three designs of W-band Focal-Plane Array (FPA) antennas as possible candidates for the next-generation millimeter-wave (mmWave) backhaul links. The considered FPAs comprise different types of waveguide antenna elements and are optimized to feed a prime-focus reflector with 400 mm aperture diameter. The main design goal is to realize a high directivity (50 dBi) with minimum beam scan loss, while complying with the strick side-lobe level requirements (ETSI class 3).
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4. |
- Iupikov, Oleg, 1983, et al.
(författare)
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Reconfigurable Intelligent Surfaces for OTA Testing: Optimization and Initial Results
- 2023
-
Ingår i: IEEE Conference on Antenna Measurements and Applications, CAMA. - 2474-1760. ; , s. 846-851
-
Konferensbidrag (refereegranskat)abstract
- We discuss a new application of RIS for Over-The-Air (OTA) testing of antenna systems and wireless devices, particularly as a cost-effective alternative to millimeter-wave phased-array plane wave generators (PWGs). We present a general approach for the fast modeling and design of the RIS-based PWG. This includes an optimal beamforming algorithm for a RIS and a strategy for configuring the RIS unit cells (UCs) to emulate far-field conditions in the test zone (TZ) with a controllable angle of arrival (AoA) of the incoming plane wave. The proposed approach has been used to derive requirements for a UC of the 21x21 element RIS-based PWG. Our preliminary numerical results demonstrate that the RIS-based PWG allows for synthesizing a TZ with a high-quality plane wave spectrum, where the peak-to-peak variation in field magnitude remains below 0.7 dB, while phase fluctuations do not exceed 5 deg within the range of AoA from -7 deg to 7 deg.
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5. |
- Ivashina, Marianna, 1975, et al.
(författare)
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Antenna Technologies for Beyond-5G Wireless Communication : Challenges and Opportunities
- 2021
-
Ingår i: 2021 International Symposium on Antennas and Propagation, ISAP 2021. - : Institute of Electrical and Electronics Engineers (IEEE).
-
Konferensbidrag (refereegranskat)abstract
- This paper provides an overview of the Sweden-Taiwan collaborative research framework project 'Antenna Technologies for Beyond-5G Wireless Communication' that has been recently established to develop robust and energy-efficient integrated antenna solutions for frequencies beyond 100 GHz as future enabling technologies for the 5G+ applications. Technological challenges in manufacturing and integration with electronics as well as available opportunities are discussed.
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6. |
- Kletsov, Andrey, et al.
(författare)
-
A General Simulation Framework for Radiative Wireless Power Transfer Systems Based On Phased-Array Transmitters
- 2023
-
Ingår i: IEEE Vehicular Technology Conference. - 1550-2252. ; 2023-June
-
Konferensbidrag (refereegranskat)abstract
- Radiative wireless power transfer (WPT) is an emerging technology for charging moving objects (e.g., vehicles) or static user terminals (e.g., mobile handsets). The most popular radiative WPT techniques employ transmitter (TX) and receiver (RX) phased arrays with dynamic beamforming functionalities. In this paper, we present a simulation approach capable of accurately estimating main WPT characteristics such as received power and power transfer efficiency. The method employs the equivalence principle to approximate TX and RX antenna apertures during the charging process, whereas antenna coupling is computed using the reaction concept. We demonstrate several multi-RX charging examples for different amplitude-only TX autofocusing algorithms. The discussion is complemented by an RX rectifier performance consideration.
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7. |
- Kruglov, Dmitrii, 1994, et al.
(författare)
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Contactless Measurement of a D-Band On-Chip Antenna Using an Integrated Reflective Load Switch
- 2024
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757 .- 1536-1225. ; 23:3, s. 1075-1079
-
Tidskriftsartikel (refereegranskat)abstract
- A novel measurement setup is proposed for the contactless characterization of on-chip antennas. A D-band patch antenna is fabricated on a 100 μm-thick GaAs substrate and is monolithically integrated with a reflective load switch to allow for fast electronic control of the antenna port termination. The antenna under test is illuminated by a reference antenna in the anechoic chamber after which the impedance and gain of the patch antenna are reconstructed from the change in backscattered field due to different port terminations. In our experiment, the over-the-air reconstructed antenna input impedance exhibits a frequency shift of less than 1% with respect to the (non-ideal) on-wafer probe measurement in the 115–130 GHz frequency range. Furthermore, the measured realized gain of 0.9±0.5 dBi is close to the simulated one of 1.1 dBi.
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8. |
- Liao, Wan-Chun, 1985, et al.
(författare)
-
Antenna Mutual Coupling Effects in Highly Integrated Transmitter Arrays
- 2020
-
Ingår i: 14th European Conference on Antennas and Propagation, EuCAP 2020.
-
Konferensbidrag (refereegranskat)abstract
- A scattering parameter re-normalization procedure is proposed to obtain a new set of parameter that directly quantifies the actual coupling and reflection coefficients of power waves in highly integrated array antenna systems employing unequal port terminations. We examine both the intra-element coupling between the radiator and the active circuitry along with the inter-element coupling between the elements of an antenna array and discuss the important differences from the more customary 50-Ohm S-parameters.
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9. |
- Liao, Wan-Chun, 1985, et al.
(författare)
-
mmWave Metal Bowtie Slot Array Element Integrating Power Amplifier MMIC via On-Chip Probe to Enhance Efficiency and Bandwidth
- 2022
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 70
-
Tidskriftsartikel (refereegranskat)abstract
- A Ka-band wideband, wide-scan range, and high-efficiency active integrated array element with a contactless transition at the antenna-power amplifier interface has been developed with the aid of a joint optimization design flow. This element employs a metal cavity-backed bowtie slot to realize the desired optimal interface impedance over a wide frequency band and scan range. The contactless transition in the form of an on-chip E-plane probe provides an electromagnetic coupling to the slot to avoid lossy and narrowband wire bonding, where the probe is integrated onto the custom-designed GaAs pHEMT power amplifier MMIC. The integrated design features a peak power efficiency of 40%, a fractional bandwidth of 11.3% (power efficiency≥20%), peak effective isotropic radiated power of 28 dBm, and a scan range of ±55° and ±40° in the two principal planes at the 1 dB compression point. The behavior of this element in the infinite connected-slot array environment is emulated and experimentally verified by the active waveguide simulator technique.
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10. |
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11. |
- Litun, Vladimir, et al.
(författare)
-
Experimental Study of a Low-profile Wideband Antenna Array Unit Cell with Integrated EBG Structure
- 2019
-
Ingår i: Progress in Electromagnetics Research Symposium. - 1559-9450 .- 1931-7360. - 9781728134031 ; 2019-June, s. 1378-1382
-
Konferensbidrag (refereegranskat)abstract
- The present paper considers the essential peculiarities of simulation and experimental procedures for a performance study of the C-band low-profile antenna array unit cell. Finite array domain decomposition analysis approach employed for numerical analysis. The good agreement was found between simulated S-parameters for the 6-rings model and measured results of the 3-rings test fragment in frequency and space domains. Simulation results validated the 3-rings fragment as a sufficiently large to provide a reliable assessment of the active reflection coefficient magnitude in the required frequency range and beam steering angular sector.
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12. |
- Shepeleva, Elena, et al.
(författare)
-
Integrated W-band Photoconductive Switches in SIW Technology
- 2021
-
Ingår i: IEEE Microwave and Wireless Components Letters. - 1558-1764 .- 1531-1309. ; 31:7, s. 865-868
-
Tidskriftsartikel (refereegranskat)abstract
- A novel approach for the design of mmWave substrate integrated waveguide (SIW) switches is presented. The switch is based on controllable photoconductive elements (PEs), whose conductivity is modulated by a light source. The PE is integrated on the top SIW metal plate and provides either a short-circuit or transmission operation regime, depending on the actuation conditions. Owing to the light actuation, the mmWave and DC control circuitry are naturally decoupled, which, in turn, makes the design low-loss and compact as compared to PIN diode and integrated circuit-based SIW switches implementations. We demonstrate two examples of SIW photoconductive switches (PSs) at W-band: single-pole single-throw (SPST) and single-pole double-throw (SPDT) PSs. Their operation principle, actuation, and parasitic radiation suppression are discussed. Measurements show the peak insertion loss of 0.9 and 2.2 dB, isolation better than 25 and 30 dB, and –10-dB impedance bandwidth of 21 and 15% for the SPST and SPDT PSs, respectively.
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13. |
- Shepeleva, Elena, et al.
(författare)
-
Low-loss K-band Photoconductive Switches in SIW Technology
- 2021
-
Ingår i: 2020 50th European Microwave Conference, EuMC 2020. ; , s. 538-541
-
Konferensbidrag (refereegranskat)abstract
- A design approach for mmWave switches in substrate integrated waveguide (SIW) technology is demonstrated. The switch is based on a photoconductive element (PE) which represents a piece of an intrinsic silicon wafer with light modulated conductivity. Using both dielectric (high-resistivity) and conductive states of the PE, we can design a low-loss mmWave switching element. Owing to the light actuation, the control circuitry of the photoconductive switch (PS) is electrically separated from the high-frequency elements of the device. This solves the bottleneck of conventional mmWave switches based on PIN diodes, MOSFETs, MEMS, etc., which are bulky and lossy due to decoupling filters and matching elements of control and biasing circuits. The proposed approach is generic and can be applied to many mmWave applications within 10 — 100 GHz such as 5G, WiGig, automotive radars, and others.
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14. |
- Shepeleva, Elena, et al.
(författare)
-
MM-wave Patch Antenna with Embedded Photoconductive Elements for 1-bit Phase Shifting
- 2019
-
Ingår i: Progress in Electromagnetics Research Symposium. - 1559-9450 .- 1931-7360. - 9781728134031 ; 2019-June, s. 578-581
-
Konferensbidrag (refereegranskat)abstract
- The paper presents a development approach for mm-wave patch antenna with 1-bit (0/180 degrees) phase shifting. The proposed design employs a stacked patches structure, where the lower patch is excited symmetrically from an embedded single-pole double-throw switch. The switch is based on controllable photoconductive elements, where each element represents a high-resistivity silicon piece, which conductivity is modulated by a light source. Measured results demonstrate achievable (23-26) GHz -10-dB matching bandwidth and radiated field phase switching of (170-173)degrees. The approach can find its applications in beam steering antenna arrays and switchable monopulse antennas.
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15. |
- Shepeleva, Elena, et al.
(författare)
-
Sub-THz U-Slot Coupled Stacked-Patch Radiating Elements for Dual-Polarized MIMO Array Antennas
- 2024
-
Ingår i: 18th European Conference on Antennas and Propagation, EuCAP 2024.
-
Konferensbidrag (refereegranskat)abstract
- Several sub-THz (D-band, 136-148 GHz) dual-polarized array elements (unit cells, UCs) implemented in a multi-layer PCB technology are investigated in the infinite array environment. The elements are stacked-patch antennas with unbalanced aperture-coupled feeds (U-slots), having a slant 45 deg. polarization. We demonstrate that a baseline half-wavelength cavity-backed UC is capable of achieving ≤ 3.7 dB scan loss in the 60 deg. conical scan range and (132-149) GHz bandwidth. For the increased UC size, however, active polarization channel isolation drastically degrades and the element experiences scan blindness. To address this problem, a UC modification is introduced that suggests using a single-row mushroom-type electromagnetic band-gap structure along the UC sidewalls. Simulated results evidence the realized UC decoupling and elimination of the scan-blindness anomalies in the full visible scan range, with scan loss ≤ 4.2 dB in the 55 deg. conical scan range and (136-148) GHz bandwidth.
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16. |
- Tsai, Yu Zhan, et al.
(författare)
-
Millimeter-Wave Holographic Metasurface Leaky-Wave Multi-Beam Antennas with Gain and Polarization Control
- 2023
-
Ingår i: IEEE Antennas and Propagation Society, AP-S International Symposium (Digest). - 1522-3965. ; 2023-July, s. 65-66
-
Konferensbidrag (refereegranskat)abstract
- This paper introduces a holographic multiple-beam leaky-wave antenna (LWA) synthesized by metasurfaces with controllable polarization and amplitude of the radiated beams. The interference pattern is first obtained by the inner product of the reference and object wave vector field functions, the former being that of a cylindrical source surface wave, the latter comprising the vector sum of the phase projections onto the hologram of the various incident plane waves, the directions, amplitudes and polarizations of which are to be reproduced as LWA beams upon illumination of the synthesized hologram by the same source. By DC-biasing and amplitude modulating the sinusoidal interference pattern to fit the surface reactance range of the metasurface patch arrays for the synthesis, the spatial distribution of the required surface impedance over the holographic surface is then devised. Simulations of designs by this approach check well with expected results in terms of the beam direction, amplitude, and polarizations.
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17. |
- Vassilev, Vessen, 1969, et al.
(författare)
-
A 55-105 GHz PIN Diode SPDT Switch
- 2021
-
Ingår i: 2021 International Symposium on Antennas and Propagation, ISAP 2021.
-
Konferensbidrag (refereegranskat)abstract
- A single pole double throw switch (SPDT) realised with PIN diodes and using a commercial process is presented. The switch is characterized between 55-112 GHz and achieves minimum insertion loss of 2.8 dB at 85.2 GHz.
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18. |
- Vilenskiy, Artem, 1988, et al.
(författare)
-
A Compact and Wideband MMIC to Ridge Gap Waveguide Contactless Transition for Phased Array Antenna Front-Ends
- 2024
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757 .- 1536-1225. ; 23:3, s. 990-994
-
Tidskriftsartikel (refereegranskat)abstract
- A concept of a contactless in-line transition between a monolithic microwave integrated circuit (MMIC) and a ridge gap waveguide (RGW) is proposed and investigated at W-band. The transition employs an E-plane waveguide bifurcation obtained by mounting a GaAs MMIC on a supporting PCB in the opening of an RGW top metal lid. Designed this way, multiple contactless transitions can be placed in a row with an electrically small spacing that makes the transition idea suitable for array antenna front-ends. A transition equivalent circuit is constructed employing a single-mode transmission line model, which is verified through a full-wave simulation. An (85–105) GHz transition design is then developed and experimentally investigated in the back-to-back configuration indicating a (0.5–0.75) dB transition insertion loss. Finally, the performance of a 1-bit phase shifter MMIC, integrated into the RGW using two proposed transitions, is demonstrated.
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19. |
- Vilenskiy, Artem, 1988, et al.
(författare)
-
Co-Design and Validation Approach for Beam-Steerable Phased Arrays of Active Antenna Elements with Integrated Power Amplifiers
- 2021
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 69:11, s. 7497-7507
-
Tidskriftsartikel (refereegranskat)abstract
- An approach for designing a beam-steering active phased array of antenna elements with integrated power amplifiers (PAs) is presented. It is based on an amplifying active integrated unit cell (AiUC) concept, where the AiUC comprises a radiating slot element, a GaN high electron mobility transistor (HEMT), its input matching and DC biasing/feeding circuitry. The HEMT is embedded in the antenna element, being directly impedance-matched to HEMT’s drain output, i.e. without using any intermediate and potentially lossy impedance matching network. The proposed co-design approach involves a full-wave analysis of the AiUC passive part (naturally including elements mutual coupling effects) along with the subsequent full system harmonic balance simulations. Furthermore, we extend the standard definition of the scan element pattern (SEP) to the active scan element pattern (ASEP) that accounts for nonlinear effects of PAs on AiUC performance. We show that the ASEP is, in general, power-dependent and has a different shape as compared to the SEP. The proposed approach has been demonstrated for a K-band AiUC design example. It was verified through an active waveguide simulator, which is equivalent to the 23.7° H-plane beam-steering case. Measurements are in good agreement with simulations, revealing AiUC 47% peak drain efficiency and 33 dBm maximum radiated power. The predicted scan range is ±60° and ±37° in the E- and H-plane, respectively.
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20. |
- Vilenskiy, Artem, 1988, et al.
(författare)
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Method for Phased Antenna Array Autofocusing with Amplitude-only Measurements
- 2019
-
Ingår i: Progress in Electromagnetics Research Symposium. - 1559-9450 .- 1931-7360. ; 2019-June, s. 1349-1353
-
Konferensbidrag (refereegranskat)abstract
- The paper presents an approach for fast antenna array autofocusing on a receiver position. The autofocusing procedure provides the maximum output power at receiver's output. At the same time, the receiver is only capable of amplitude measurements. The crucial idea of the suggested method is employment of all phased antenna array's radiators simultaneously, which makes the method suitable for arrays without amplitude control inside channels. We propose the representation of sought-for channel propagation vector as a linear combination of Hadamard matrix rows, whose complex coefficients are found from the suggested measurement procedure. The approach can be useful for different applications such as long-distance wireless power transmission, finding the channel state information matrix in communication systems and for antenna arrays calibration problems.
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21. |
- Vilenskiy, Artem, 1988, et al.
(författare)
-
Methods for Attenuating and Terminating Waves in Ridge Gap Waveguide at W_Band Carbon-Loaded Foam Carbonyl Iron Paint and Nickel Plating
- 2021
-
Ingår i: 2021 51st European Microwave Conference, EuMC 2021. - 9782874870637
-
Konferensbidrag (refereegranskat)abstract
- Several methods for electromagnetic waves matched termination and attenuation in a ridge gap waveguide (RGW) are experimentally investigated at W-band. At these frequencies, the implementation of matched loads and attenuators is especially complicated due to small sizes of RGW design features that limits application of traditional waveguide absorbing structures (e.g., absorbing sheets and finlines, ferrite insets, carbonyl iron walls, etc.). The following three techniques are considered: (i) filling an RGW gap with a carbon-loaded foam; (ii) covering a ridge (and pins) with a carbonyl iron paint; (iii) selective nickel plating of an RGW line segment. It was found that the first method exhibits a great broadband absorbing performance and can be easily implemented in a lab environment, whereas the second method can realize a more accurate and predictable attenuating performance. Finally, nickel plating allows for designing resonant RGW terminations and is more interesting from the industrial perspective.
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22. |
- Vilenskiy, Artem, 1988, et al.
(författare)
-
Millimeter-Wave Array Antenna Architectures Employing Joint Power Combining and Beam Steering for Next-Generation Backhaul Applications
- 2023
-
Ingår i: 2023 17th European Conference on Antennas and Propagation (EuCAP). - 9788831299077 ; , s. 1-5
-
Konferensbidrag (refereegranskat)abstract
- We investigate the capabilities and limitations of joint power-combining and beam-steering techniques for millimeter-wave antenna applications. In this analysis, both functionalities are realized simultaneously through a power-combining and beamforming (PC-BF) network interconnecting an input array of active channels with an array of antenna elements. The first part of the paper provides a review of state-of-the-art hardware architectures of such PC-BF networks and examines their suitability for millimeter-wave applications. The architectures are grouped into two classes depending on the array embedded element patterns properties. Next, a unified PC-BF network is proposed where both functionalities are implemented in a single millimeter-wave waveguiding block. A full-wave model of such a network with 6 inputs and 7 outputs is investigated, with its application demonstrated for a W-band focal-plane array feeding a backhaul reflector antenna.
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23. |
- Vilenskiy, Artem, 1988, et al.
(författare)
-
Millimeter-Wave Quasi-Optical Feeds for Linear Array Antennas in Gap Waveguide Technology
- 2022
-
Ingår i: 2022 16th European Conference on Antennas and Propagation, EuCAP 2022.
-
Konferensbidrag (refereegranskat)abstract
- A realization of the quasi-optical (QO) feed concept for linear millimeter-wave (sub-)array antennas is demonstrated in gap waveguide technology. The proposed feed architecture employs an input transition from a ridge gap waveguide (RGW) to a groove gap waveguide (GGW), a radial (H-plane sectoral) GGW section, and a transition to an output RGW array. A design decomposition approach is presented to reduce simulation complexity. Several 20-element QO feed implementations are investigated at W-band demonstrating a 20% relative bandwidth (85-105 GHz), 0.5 dB insertion loss, and a capability of an amplitude taper control within the 10-20 dB range.
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24. |
- Vilenskiy, Artem, 1988, et al.
(författare)
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Phase Distribution Optimization for 1-Bit Transmitarrays with Near-Field Coupling Feeding Technique
- 2020
-
Ingår i: 14th European Conference on Antennas and Propagation, EuCAP 2020.
-
Konferensbidrag (refereegranskat)abstract
- The paper presents a consideration of the optimum initial phase distribution for 1-bit transmitarrays with near-field coupling feeding technique. The study is based on the array factor decomposition into a series of continuous aperture distributions, which naturally includes the phase quantization errors. The previously proposed virtual focus approach is compared with the optimum quadratic initial phase distribution. Both methods are found to be very similar for specific values of distribution parameters in terms of far-field performance. Some further sidelobes level improvement is proposed.
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25. |
- Vilenskiy, Artem, 1988, et al.
(författare)
-
Quasi-Optical Beamforming Network for Millimeter-Wave Electronically Scanned Array Antennas with 1-Bit Phase Resolution
- 2021
-
Ingår i: 15th European Conference on Antennas and Propagation, EuCAP 2021. ; , s. 1-5
-
Konferensbidrag (refereegranskat)abstract
- State-of-the-art design solutions for electronically scanned array antennas are mostly limited to microwave to low mm-wave frequency bands, while the demand for new designs at higher frequencies (i.e. frequencies beyond 100 GHz) is rapidly growing. We attempt to fill in this knowledge gap by presenting a new linear array antenna architecture as a building block of 2D arrays that can enable efficient beam steering and a simplified array design. This concept is based on the combination of a low-loss quasi-optical (QO) feed, providing predefined antenna port excitation, with 1-bit phase shifters which are co-integrated with the array antenna elements. In this study, we formulate the array design problem as minimization of the sidelobe level (SLL) through an optimum quasi-randomization of phase errors. An analytical expression for the optimum focal ratio of the QO feed has been derived to establish the relationships between the key design parameters. These results are validated through numerical simulations revealing that the optimum focal ratio leads to the minimum SLL.
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26. |
- Vilenskiy, Artem, 1988, et al.
(författare)
-
Reconfigurable Transmitarray with Near Field Coupling to Gap Waveguide Array Antenna for Efficient 2D Beam Steering
- 2020
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 68:12, s. 7854-7865
-
Tidskriftsartikel (refereegranskat)abstract
- A novel array antenna architecture is proposed that can enable 2D (full-space) radiation pattern control and efficient beam steering. This solution is based on a fixed-beam gap wave-guide (GWG) array antenna and a reconfigurable transmitarray (TA) that are coupled in the radiative near field. An equivalent two-port network model of the coupling mechanism is presented and validated numerically. The desired TA reconfiguration capability is realized by an 8×8 array of cavity-backed patch resonator elements, where two AlGaAs PIN-diodes are integrated inside each element providing a 1-bit phase shift. The TA is implemented in an 8-layer PCB, which includes radiating elements, fixed phase-shifting inner-stripline sections, impedance matching and biasing circuitry. The combined antenna design is low-profile (~ 1.7 wavelength) owing to the small separation between two arrays (~ 0.5 wavelength), as opposed to conventional TAs illuminated by a focal source. The design procedure of the proposed architecture is outlined, and the measured and simulated results are shown to be in good agreement. These results demonstrate 23.5 — 25.2 GHz –10-dB impedance bandwidth and 23.3 — 25.3 GHz 3-dB gain bandwidth, a beam-steering range of ±30° and ±40° in the E- and the H-plane with the gain peak of 17.5 dBi, scan loss ≤ 3.5 dB and TA unit cell insertion loss ≤ 1.8 dB.
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27. |
- Vilenskiy, Artem, 1988, et al.
(författare)
-
Wideband Reflection-Type p-i-n Diode Phase Shifters in GaAs MMIC Technology at W-Band
- 2023
-
Ingår i: 2023 18th European Microwave Integrated Circuits Conference, EuMIC 2023. ; , s. 209-212
-
Konferensbidrag (refereegranskat)abstract
- In this paper, we report on developing W-band GaAs p-i-n diode phase shifters (PSs) with a wideband phase and amplitude response. The PSs employ the reflection-Type architecture with reflective loads providing discrete phase tunability through diode dc control. We address the design challenge of having a stable phase shift and a minimal insertion loss imbalance for the diodes with a relatively low commutation quality factor at high millimeter-wave frequencies. Two PS examples, namely 180-and 90-degree bits, are designed for the targeted (85-105) GHz operating band. The circuits were fabricated in the commercial PIN-pHEMT GaAs process with 8 × 8 μm2,p-i-n diodes. Both simulated and measured results are in good agreement demonstrating wideband frequency performance.
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28. |
- Weng, Chuan Kuei, et al.
(författare)
-
Tensor-Free Holographic Metasurface Leaky-Wave Multi-Beam Antennas with Tailorable Gain and Polarization
- 2024
-
Ingår i: Sensors. - 1424-8220. ; 24:8
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Tidskriftsartikel (refereegranskat)abstract
- Recently, the community has seen a rise in interest and development regarding holographic antennas. The planar hologram is made of subwavelength metal patches printed on a grounded dielectric board, constituting flat metasurfaces. When a known reference wave is launched, the hologram produces a pencil beam towards a prescribed direction. Most earlier works on such antennas have considered only a single beam. For the few later ones that studied multiple beams, they were achieved either by having each beam taken care of by a distinct frequency or by partitioning the hologram, thereby depriving each beam of the directivity it could have had it not shared the holographic aperture with other beams. There have been recent studies related to the use of tensor surface impedance concepts for the synthesis of holograms which have attained control over the polarizations and intensities of the beams. However, this approach is complicated, tedious, and time-consuming. In this paper, we present a method for designing a planar holographic leaky-wave multi-beam metasurface antenna, of which each simultaneous beam radiating at the same frequency towards any designated direction has a tailorable amplitude, phase, and polarization, all without hologram partitioning. Most importantly, this antenna is exempted from the need for the cumbersome technique of tensor impedance. Such features of beam configurability are useful in selective multiple-target applications that require differential gain and polarization control among the various beams. Only a single source is needed, which is another benefit. In addition, effective methods to mitigate sidelobes are also proposed here. Designs by simulations according to the method are herein validated with measurements performed on fabricated prototypes.
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29. |
- Yaqoob Chaudhry, Sohaib, 1993, et al.
(författare)
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A Compact W-band Diplexer for Integration with an Electronically Steerable Focal Plane Array Antenna System
- 2023
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Ingår i: Asia-Pacific Microwave Conference Proceedings, APMC. ; , s. 315-317
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Konferensbidrag (refereegranskat)abstract
- A waveguide folded diplexer is presented that is designed to provide frequency division duplex operation of electronically steerable focal-plane-array (FPA) antennas for W-band wireless backhaul links. This design overcomes manufacturing challenges associated with small dimensions at these high frequencies (reaching the required tolerance of ± 15 μ m) and the difficulties of integration with the closely-spaced FPA elements. Bandpass filters for the 94-97 GHz and 106-109GHz bands are synthesized utilizing waveguide cavity TE102 resonators with inductive iris coupling through a combined analytical-numerical optimization approach. The final assembly has a three-fold compact 10th-order configuration and the prototype is manufactured using CNC milling. The measured reflection coefficients are ≤ -15dB, the isolation level is ≥ 55dB, and the insertion loss is 1dB.
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30. |
- Zhang, Yingqi, 1995, et al.
(författare)
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A W-band Quasi-Optical Array Antenna Feeding Network with High Taper Efficiency Using Optimal Ridge Excitation of an H-Plane Sectoral Waveguide
- 2024
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757 .- 1536-1225.
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Tidskriftsartikel (refereegranskat)abstract
- A novel H-plane quasi-optical (QO) feeding network for linear (sub-)array gap waveguide (GWG) antennas intended for beam-steering applications at W-band is presented. The QO feed comprises an H-plane sectoral GWG excited by an input stepped ridge gap waveguide (RGW) and transitioned to an overmoded rectangular groove gap waveguide (GGW) section, the latter being terminated with an array of RGW output probes. This work's key challenge and novelty is engineering the desired modal content in the QO structure for uniform amplitude excitation of array elements to enhance antenna gain with a low insertion loss. This was addressed by (i) realizing an optimal multi-mode excitation of the sectoral GWG and (ii) a proper phasing of a rich modal spectrum of the output overmoded GGW. An eigenmode-based semi-analytic approach was developed to investigate the impact of an input ridge length on the excited modal content and was shown to predict optimal results close to full-wave simulations. The demonstrated QO feed concept, applied to a 20-element array design, significantly outperforms existing solutions by achieving a 97% amplitude taper efficiency and showing less than 0.4 dB insertion loss over a 21% relative bandwidth (85–105 GHz).
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31. |
- Zhang, Yingqi, 1995, et al.
(författare)
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Compact Wide-Scan Dual-Polarized Dielectric Resonator Antenna Array Based on LTCC Technology for Millimeter-Wave Applications
- 2023
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Ingår i: 2023 International Conference on Electromagnetics in Advanced Applications, ICEAA 2023. ; , s. 96-99
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Konferensbidrag (refereegranskat)abstract
- A compact dual-polarized (DP) dielectric resonator antenna (DRA) for two dimensional (2D) wide-angle scanning phased arrays operating at 28 GHz is presented. The proposed design is based on low-temperature co-fired ceramic (LTCC) technology by virtue of the benefits in terms of scalability at millimeter-wave (mmW) frequencies. The developed DRA element integrates two stacked cylindrical dielectric resonators (DRs) surrounded by a metal frame and is fed through a cross-shaped slot. An annular cavity separates the stacked DRs from the metal frame near the antenna aperture to enhance the active impedance-matching to air. The DRA element is analyzed in the infinite array environment and is characterized using an 8 × 8 array architecture consisting of 2 × 2 subarray tiles. This design is optimized for operation in the n261 band (27.5-28.35 GHz) with the active reflection coefficient ||Γ|| ≤ -10 dB across the targeted ±60° scan range. The array features a scan loss ranging from 3.2 dB to 3.9 dB in the H-, D-, and V-planes for both polarizations.
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32. |
- Zhang, Yingqi, 1995, et al.
(författare)
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Mutual Coupling Analysis of Open-Ended Ridge and Ridge Gap Waveguide Radiating Elements in an Infinite Array Environment
- 2022
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Ingår i: 2022 52nd European Microwave Conference, EuMC 2022. ; , s. 696-699
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Konferensbidrag (refereegranskat)abstract
- In this paper, we discuss mutual coupling effects in 2-D beam-steerable antenna arrays based on open-ended ridge and ridge gap waveguide radiating elements. Considering potential applications for beyond-5G systems in W-/D-band, the radiating elements are designed full-metal realizing a high radiation efficiency. Various decoupling structures based on electromagnetic soft surfaces are applied to suppress the surface waves over the array apertures. The infinite array approach is used to analyze antenna unit cells in an isosceles triangular lattice, which results in the active reflection coefficient over a scan and frequency range. The latter is used to extract the values of the mutual coupling coefficients between the elements. The analysis demonstrates the effect of decoupling structures realizing a steep drop of the mutual coupling magnitude (≤ − 20 dB) for closely-spaced array elements. This results in a wideband (≥ 20%) and wide-scan (> 50°) element beam-steering performance.
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33. |
- Zhang, Yingqi, 1995, et al.
(författare)
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W-band Waveguide Antenna Elements for Wideband and Wide-Scan Array Antenna Applications For Beyond 5G
- 2021
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Ingår i: 15th European Conference on Antennas and Propagation, EuCAP 2021. ; , s. 1-5
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Konferensbidrag (refereegranskat)abstract
- Energy-efficient and highly-compact beam-steering array antennas at W- and D-band frequencies are considered as future enabling technologies for beyond-5G applications. However, most existing solutions at these frequencies are limited to the fixed-beam and frequency-dependent beam-steering scenarios. This paper aims to fill in this knowledge gap by investigating various types of antenna elements as potential candidates for wideband and wide-scan arrays at W-band. We consider open-ended ridge and ridge gap waveguide radiating elements that could overcome the physical complexities associated with the integration of elements in large-scale electronically scanned arrays. An infinite array approach is used, where we have adopted a triangular array grid and introduced E- and H-plane grooves to the element design to enhance the scan and bandwidth performance. Cross-comparison of several simulated array designs leads to the final array elements with 25% impedance bandwidth over the scan range of ±40° in both the E- and H-planes.
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34. |
- Zhang, Yingqi, 1995, et al.
(författare)
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Wideband Open-Ended Ridge Gap Waveguide Antenna Elements for 1-D and 2-D Wide-Angle Scanning Phased Arrays at 100 GHz
- 2022
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757 .- 1536-1225. ; 21
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Tidskriftsartikel (refereegranskat)abstract
- A new antenna element type based on the open-ended ridge gap waveguide (RGW) is proposed for beam-steering phased array applications. This element type is of a particular interest at high mm-wave frequencies (≥ 100 GHz) owing to a contactless design alleviating active beam-steering electronics integration. The key challenge addressed here is a realization of a wide fractional bandwidth and scan range with high radiation efficiency. We demonstrate a relatively simple wideband impedance matching network comprised of an aperture stepped ridge segment and a single-pin RGW section. Furthermore, the E- and H-plane grooves are added that effectively suppress antenna elements mutual coupling. Results demonstrate a wide-angle beam steering (≥ 50°) over ≥ 20% fractional bandwidth at W-band with ≥ 89% radiation efficiency that significantly outperforms existing solutions at these frequencies. An experimental prototype of a 1×19 W-band array validates the proposed design concept through the embedded element pattern measurements.
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35. |
- Zhu, Yuqing, 1998, et al.
(författare)
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A Varactor-Based Reconfigurable Intelligent Surface Concept for 5G/6G mm-Wave Applications
- 2024
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Ingår i: 18th European Conference on Antennas and Propagation, EuCAP 2024.
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Konferensbidrag (refereegranskat)abstract
- A varactor-based reconfigurable intelligent surface (RIS) concept is presented for low-cost, high-precision beamforming of 5G/6G mm-waves. To enable this, we maximize the RIS unit cell (UC) phase coverage by (i) employing a varactor diode-tuned slotted-patch UC, and (ii) adding a metallic loop and via fence across the UC boundary, which also improves the bandwidth and angular insensitivity. In an infinite RIS environment, the UC exhibits a phase coverage of 330.7 degrees while maintaining the insensitivity of reflection coefficients up to 50-degree elevation angle. This UC design demonstrates a phase coverage that exceeds 315 degrees with under 0.7-dB reflection loss across a 11.6% bandwidth, where the capacitance tuning ratio of the considered commercial off-the-shelf varactor diode is only 1.8. A 15 × 15 RIS model with a 3-bit phase quantization is used for beam steering performance validation; it predicts the realized gain of 19.5 dBi for the 30-degree beam-steering direction at 28 GHz.
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