| 1. |
- Ding, Liqin, 1988, et al.
(författare)
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Shannon Capacity of LOS MIMO Channels with Uniform Circular Arrays
- 2022
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Ingår i: IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC. ; 2022-September
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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
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Ingår i: 2023 International Conference on Electromagnetics in Advanced Applications, ICEAA 2023. ; , s. 340-345
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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
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Ingår i: IEEE Antennas and Propagation Society, AP-S International Symposium (Digest). - 1522-3965. ; 2023-July, s. 765-766
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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
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Ingår i: IEEE Conference on Antenna Measurements and Applications, CAMA. - 2474-1760. ; , s. 846-851
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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
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Ingår i: 2021 International Symposium on Antennas and Propagation, ISAP 2021. - : Institute of Electrical and Electronics Engineers (IEEE).
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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)
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A General Simulation Framework for Radiative Wireless Power Transfer Systems Based On Phased-Array Transmitters
- 2023
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Ingår i: IEEE Vehicular Technology Conference. - 1550-2252. ; 2023-June
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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
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757 .- 1536-1225. ; 23:3, s. 1075-1079
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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)
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Antenna Mutual Coupling Effects in Highly Integrated Transmitter Arrays
- 2020
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Ingår i: 14th European Conference on Antennas and Propagation, EuCAP 2020.
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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)
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mmWave Metal Bowtie Slot Array Element Integrating Power Amplifier MMIC via On-Chip Probe to Enhance Efficiency and Bandwidth
- 2022
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 70
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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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