| 1. |
- Bagheri, Alireza, et al.
(author)
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A ±45° Dual-Polarized Antenna for 5G mmWave Applications Based on Gap Waveguide Technology
- 2019
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In: 2019 International Symposium on Antennas and Propagation, ISAP 2019 - Proceedings.
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Conference paper (peer-reviewed)abstract
- A ±45° dual-polarized antenna is designed based on the gap waveguide technology which offers a low loss and easy-to-manufacture solution at the mmWave frequencies. Dual-polarized antennas help to increase the capacity and coverage of a wireless system and also decrease the overall cost. Two parallel arrays of 8 slots each are employed to create the orthogonal polarizations. The antenna operates in the 24.25 - 27.25 GHz frequency band. The simulated average gain of each polarization is 14.5 dBi while achieving a cross-polarization isolation of at least 15 dB.
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| 2. |
- Bagheri, Alireza, et al.
(author)
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Micro strip to Ridge Gap Waveguide Transition for 28 GHz Steerable Slot Array Antennas
- 2020
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In: 2020 14TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION (EUCAP 2020). - 2164-3342. - 9788831299008
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Conference paper (peer-reviewed)abstract
- In this paper three types of contactless vertical transitions from microstrip to double ridge waveguide are presented. The designs are compact in size and robust, with improved isolation by employing a pin structure, making them ideal for SG mmWave phased arrays. All transitions cover the 26.5 - 29.5 GHz band, their dimensions are less than half a wavelength in pitch and have insertion losses less than 0.6 dB. The three designs apply different matching strategies and offer a trade-off between bandwidth and PCB areas. Finally, the behavior within an array configuration is analyzed.
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| 3. |
- Bencivenni, Carlo, et al.
(author)
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5G mmWave Beam Steering Antenna Development and Testing
- 2019
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In: 13th European Conference on Antennas and Propagation, EuCAP 2019. - 9788890701887
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Conference paper (peer-reviewed)abstract
- mmWave frequencies offer unprecedented capacity but also new technical challenges. Current solutions typically adopt integrated PCB antennas, however they still face issues when it comes to coverage, power consumption and cost. Instead, we present a SG mmWave antenna platform demonstrating a different approach based on Gapwaves technology. The proposed design is an integrated all-metal multi-layer assembly, offering low-loss feeding, high-gain subarray, high-Q filters and exceptional thermal handling. To support these claims, active measurement of beam steering, EIRP and temperature are presented. Results from this small demonstration unit are very encouraging and show performance challenging that of much larger systems.
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| 4. |
- Bencivenni, Carlo, 1986, et al.
(author)
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Towards Integrated Active Antennas for 5G mm-wave Applications at Gapwaves
- 2018
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In: 2018 IEEE Antennas and Propagation Society International Symposium and USNC/URSI National Radio Science Meeting, APSURSI 2018 - Proceedings. ; , s. 415-416
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Conference paper (peer-reviewed)abstract
- Recently, in preparation for the upcoming 5G systems, the telecom industry has been showing a great interest in high frequency active antennas. We present a brief overview of the innovative design solution developed at Gapwaves for mmwave digital beamforming applications, capable of addressing all the associated technical issues. We review the general antenna architecture and components and explain how gapwaves technology enables us to achieve high performance, highly integrated active antennas in a cost effective way.
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| 5. |
- Haddadi, Abolfazl, et al.
(author)
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Low-profile planar eleven antenna over a magnetic plane
- 2016
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In: 2016 10th European Conference on Antennas and Propagation, EuCAP 2016. - 9788890701863 ; , s. Art. no. 7481553-
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Conference paper (peer-reviewed)abstract
- The eleven antenna has been greatly used in many applications to achieve low reflection coefficient and stable-pattern over ultra-wide-bands. However, arraying in the eleven configuration forces the antenna designer to tilt the antenna over an electric conducting ground plane, and this makes it mechanically complicated and increases the profile of the antenna. Seeking new capabilities, the theory of putting log-periodic dipoles in the eleven configuration over magnetic ground is developed. The eleven antenna is formed by two printed folded-dipoles, and we evaluate the performance for a single-pair of dipoles and five-pairs of dipoles. The results are extracted for the cases of PEC ground, PMC ground and without ground. The results are in a good agreement with theory. Also, some discussions are provided for the realization of the artificial-magnetic-ground.
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| 6. |
- Kildal, Per-Simon, 1951, et al.
(author)
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Numerical Validation of Arecibo-Based Analytical Hat Antenna Theory Using Canonical PEC/PMC Strip Grids
- 2016
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In: 2016 IEEE Antennas and Propagation Society International Symposium, APSURSI 2016, Fajardo, Puerto Rico, 26 June - 1 July 2016. - 9781509028863 ; , s. 1877-1878
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Conference paper (peer-reviewed)abstract
- The hat antenna is a self-supported rear-radiating waveguide feed used in the Comhat reflector that has been manufactured in more than 1M pieces for use in radio links. The design of hat feeds is done by numerical simulations taking advantage of its rotational symmetry. There exists an early analytical model for the far-field of the hat feed including the axial waveguide, and treating the hat brim as a PEC/PMC strip grid. The purpose of the present paper is to validate the theoretical model by simulations using COMSOL Multiphysics.
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| 7. |
- Van De Ven, Coen, et al.
(author)
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Automotive RADAR Planar Antenna Optimization Based on Conformal Transformation Optics
- 2023
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In: 17th European Conference on Antennas and Propagation, EuCAP 2023.
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Conference paper (peer-reviewed)abstract
- A novel approach to mitigate diffraction effects from finite ground planes in antenna design is presented. The method is based on the conformal transformation optics. A computational framework has been developed to optimize the shape of the ground plane since it has a great impact on the beam ripple and width of the radiation pattern of an antenna. Due to the limited thickness of the outer wall of slotted waveguide antennas, it is not possible to shape this outer wall, which acts as the ground plane of the antenna. Conformal transformation optics presents a solution to virtually add a deformation without needing to change the physical shape of the ground plane. Although conformal transformation optics can also be applied to transverse-magnetic waves, large fluctuations in the dielectric constant with respect to the wavelength cannot be supported in practice. In order to mitigate this problem, we have proposed a rescaling of the dielectric constant. Furthermore, we derive the connection between conformal transformation optics and transverse electromagnetic modes, which serve as a tool for joint optimization of the radiation pattern together with the conformal transformation. This method is then used to optimize the radiation pattern of a slot antenna and evaluated for increasing curvature within the conformal transformation.Numerical computations have shown promising results, i.e. a reduction of the farfield ripple from 1.92 dB to 0.64 dB at a half-power beam-width of 112° at 77 GHz. This is a promising result for designing automotive radars with a wide field of view, especially, for advanced driver-assistance systems used in the corner radars. This will contribute to further improving safety on the roads.
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| 8. |
- Vosoogh, Abbas, 1984, et al.
(author)
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W-Band Low-Profile Monopulse Slot Array Antenna Based on Gap Waveguide Corporate-Feed Network
- 2018
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In: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 66:12, s. 6997-7009
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Journal article (peer-reviewed)abstract
- This paper presents a gap waveguide-based compact monopulse array antenna, which is formed with four unconnected layers, for millimeter-wave tracking applications at W-band (85–105 GHz). Recently developed gap waveguide technology removes the need for galvanic contact among metallic layers of waveguide structures, and thereby, makes the proposed antenna suitable for easy and low-cost manufacturing. In this context, a low-loss planar Magic-Tee is designed to be used in a monopulse comparator network consisting of two vertically stacked layers. The gap waveguide planar monopulse comparator network is integrated with a high-efficiency 16x16 corporate-fed slot array antenna. The measured results of the comparator network show the amplitude and phase imbalance values to be less than 0.5 dB and 2°, respectively, over the frequency band of interest. The fabricated monopulse array antenna shows relative impedance bandwidths of 21% with input reflection coefficients better than −10 dB for the sum and difference ports. The null in the difference radiation pattern is measured to be 38 dB below the peak of the sum radiation pattern at 94 GHz. The measured gain is about 30 dBi for the same frequency. The low-loss performance of the comparator network and the feed network of the proposed array, together with the simple and easy manufacturing and mechanical assembly, makes it an excellent candidate for W -band compact direction-finding systems.
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| 9. |
- Yong, Wai Yan, et al.
(author)
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A Bandwidth-Enhanced Cavity-Backed Slot Array Antenna for mmWave Fixed-Beam Applications
- 2020
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In: IEEE Antennas and Wireless Propagation Letters. - 1548-5757 .- 1536-1225. ; 19:11, s. 1924-1928
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Journal article (peer-reviewed)abstract
- A bandwidth-enhanced 8\times 8 cavity-backed slot array antenna for fixed beam applications is presented. The antenna consists of four 2\times 2 subarrays fed by ridge gap waveguide and a modified bow-tie coupling slot in the cavity layer. The proposed bow-tie coupling slot provides additional \text{10}\% impedance bandwidth as compared to the traditional rectangular coupling slot. The fabricated prototype demonstrates an S 11 leq -10,dB fractional impedance bandwidth and a 3\,dB gain-drop bandwidth of approximately \text{28}\% and \text{25}\%, respectively, with peak gain of 26.4\,dBi, aperture efficiency >\text{60}\% and cross-polar discrimination >40\,dB. Measurements show good agreement with simulations. Moreover, we show the impact of the dimensions and shape of the cavity coupling slot on the bandwidth enhancement. The bandwidth enhancement is explained by the double-ridge slot behavior of the bow-tie coupling slot, which shows a more wideband behavior than the traditional rectangular coupling slot behaving like a cross section of a waveguide.
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| 10. |
- Yong, Wai Yan, et al.
(author)
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Wideband Cavity-Backed Slot Subarray Fed by Gap Ridge Waveguide for 5G mmWave Base Station
- 2019
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In: 2019 International Symposium on Antennas and Propagation, ISAP 2019 - Proceedings.
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Conference paper (peer-reviewed)abstract
- This paper proposes a bandwidth-improved cavity-backed unit cell slot subarray antenna fed by a gap ridge waveguide for Line-of-Sight (LoS) 5G mmWave applications. The proposed subarray is comprised of three layers. The top layer is the antenna layer in a 2 × 2 slots configuration, the cavity layer is in the middle and the ridge gap waveguide feeding is in the bottom layer. We propose to enhance the bandwidth of the unit cell subarray antenna by modifying the coupling slot in the cavity layer. The main advantage of the proposed method is that the bandwidth enhancement can be achieved without adding an extra tuning pin in the cavity layer, which eases mass production. The proposed structure is simulated with the CST software in an infinite array environment. The simulation results show that the S11 is below -10 dB over 24 - 31.5 GHz frequency band covering a 27% bandwidth and the directivity is approximately 33.8 dBi when evaluated as a 16 × 16 element slot array. It is envisaged that the method can be advantageous for bandwidth enhancement of a practical cavity-backed slot array antenna.
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