Applied Computational Electromagnetics Society Journal (ACES)

Editorial

Xiaoming Chen, Jianxing Li, Yingsong Li — Fri, 10 Jan 2025 00:00:00 +0100

Antennas and Metasurfaces for Next-Generation Wireless System and Their Testing Techniques

Welcome to the special issue of Applied Computational Electromagnetics Society Journal (ACES) The papers included here are related to Antennas and Metasurfaces for Next-Generation Wireless System and Their Testing Techniques.

Fast Broadband Scattering Computation for Finite Periodic Arrays using the Characteristic Basis Function Method and the Best Uniform Rational Approximation

Fang Li, Hai Rong Zhang, Lin Chen, Xing Wang — Thu, 31 Oct 2024 00:00:00 +0100

In this paper, a hybrid method combining the characteristic basis function method (CBFM) and the best uniform rational approximation (BURA) technique for fast wideband radar cross-section (RCS) prediction of finite periodic arrays is proposed. The traditional CBFM requires reconstructing the reduced matrix at each frequency point, which is very time-consuming when calculating the wideband RCS of the target. By introducing the BURA technique, the hybrid method is proposed to efficiently calculate the wideband RCS. The target is first divided into several easily solvable subdomains. Then, the surface integral equation is solved by the characteristic function method to obtain the equivalent surface current at the Chebyshev node. Afterwards, the surface current in a desired frequency band is represented by the Chebyshev series. To improve accuracy, the Chebyshev series is matched with the Maehly approximation. After obtaining the current coefficients in the whole bandwidth, the current density at any frequency point in the bandwidth can be calculated. Finally, the broadband electromagnetic scattering characteristics of the finite periodic arrays can be obtained.

Improved Mid-field Phased Array Calibration Method Based on Complex Interpolated Signals

Junhao Zheng, Zhengpeng Wang, Binhui Liu, Huaqiang Gao, Xiaoming Chen — Thu, 31 Oct 2024 00:00:00 +0100

In this brief paper, an improved method of separate amplitude and phase interpolations is presented for the mid-field phased array calibration system. Since the amplitude is relatively continuous and the phase suffers from phase wrapping, the proposed method uses linear and phase-unwrapping natural neighbor interpolation methods to reconstruct the amplitude and phase matrices, respectively. When compared with the existing work, the proposed method is more accurate under the cost-effective over-the-air testing environment.

A Focused Metasurface Lens Antenna with Gain Enhancement

Yu Dong, Xing Chen — Thu, 31 Oct 2024 00:00:00 +0100

A specialized metasurface has been developed for lens antenna applications. This innovative metasurface unit cell comprises five metallic layers and four dielectric layers. Each metallic layer consists of a pair of back-to-back split resonant rings. The proposed unit cell is highly effective with a transmission phase coverage exceeding 360^∘ and a transmission amplitude larger than 70% at X-band (8.8-11.2 GHz). The unit cell has been thoroughly designed, fabricated and tested. To verify the present unit cell, a metasurface array with 27×27 elements is designed. An X-band horn antenna is used as the feed source. Simulation and measurement results show that the electromagnetic wave from the feed horn is focused within the operating band, resulting in a measured gain of 16.9 dB at 9 GHz and 19.2 dB at 11 GHz. Thus, a gain enhancement of 5.4 dB at 9 GHz and 5.7 dB at 11 GHz are obtained, making it a good reference for engineering applications.

A Low-profile Wideband Pattern Reconfigurable Antenna with Metasurface

Thu, 31 Oct 2024 00:00:00 +0100

This paper presents a pattern reconfigurable antenna with low-profile and wide bandwidth. The antenna is composed of a patch layer, a metasurface (MS) layer, and a full ground plane. The radiation patch consists of a microstrip-fed square and three parasitic patches. The MS with 4×4 units is added on the top of the patch layer to improve bandwidth as well as tune radiation pattern. Ten of the MS units are available to connect with the ground plane, each of which is loaded with a PIN diode to control the shorting state, providing 12 beam states with reconfigurable beams between ±5^∘ to ±15^∘ both in xoz and yoz planes. The proposed antenna has been fabricated and measured. Measurement shows that the antenna has a wide impedance bandwidth of 4.02-5.72 GHz, a beam scanning range of -16^∘-15^∘ in xoz plane and -13^∘-15^∘ in yoz plane, peak gain range of 4.94-6 dBi. With a planar shape of low profile and full ground plane, the antenna design is a good candidate to be applied in wireless communication systems with conductive surface.

A High-Gain Vivaldi Antenna Loaded with Metasurface for Broadband Applications

Thu, 31 Oct 2024 00:00:00 +0100

In this article, a Vivaldi antenna with broad bandwidth and high gain is proposed. The proposed antenna consists of a coplanar Vivaldi antenna (CVA) configuration etched with two rhombus slots at both sides of the radiation arm to improve bandwidth and gain at the low frequencies as well as maintaining antenna miniaturization. A compact broadband metasurface is loaded in the dielectric region between the two exponentially tapered lines to improve radiation performance in a wide frequency range without increasing antenna size. The antenna has been fabricated and measured, obtaining 1.27-9.4 GHz bandwidth covering L/S/C/X and ultra-wideband (UWB) lower bands. The measured gain ranges from 3 dBi to 9.67 dBi. With a miniaturized size of 100×100×1 mm³, good directional radiation pattern and high gain in the whole working band, the proposed antenna is a good candidate for the applications in multi-band coverage systems.

Architecture and Validation of Wideband Simultaneous Transmit and Receive Phased Array System

Jie Zhang, Hongchao Wu, Lianqing Yu — Thu, 31 Oct 2024 00:00:00 +0100

Because signals of different frequencies exhibit different characteristics after channel coupling, the traditional phased array system only uses phase shifter or antenna beam control to process frames plus amplitude adjustment control, which has the problem of optimizing the parameters of different frequencies to offset the mismatch. Based on the principle of broadband adaptive beamforming, each channel is configured as an adaptive filter with multiple taps to satisfy the precise relationship between interference suppression and frequency. On this basis, combined with the simultaneous application of a multi-element array system, a multi-tap weight optimization method for interference suppression is proposed. At the same time, in order to satisfy the application requirements of the existing phased array system architecture with only one set of controllable and adjustable weights, an adaptive beamforming weight optimization method for phased array system for wideband signals is analyzed and proposed on the basis of simulation analysis and research on the electromagnetic characteristics of the coupled self-interference channel. Through electromagnetic simulation evaluation and principle test verification, a set of weights corresponding to the center frequency of the wideband signal can be used to achieve interference suppression greater than 114 dB in the active transmission domain.

One-to-Multiple RF Power Transmission System Based on High-Gain Phased Array with Beam Control

Xue Bai, Yanjiao Hou, Leijun Xu, Jianfeng Chen, Yiyang Kong — Thu, 31 Oct 2024 00:00:00 +0100

This paper proposes a one-to-multiple RF wireless power transmission (WPT) system that uses multi-mode phased array technology to control beamforming. The proposed system uses array partition mode and time division mode to achieve multi-target WPT. A novel quasi-Yagi antenna with enhanced gain is designed, consisting of a pair of dipoles, three directors, and a single split-ring resonator (SSRR), which is then used to form a 1×8 array for power transmission. The antenna has a bandwidth of 0.35 GHz with a frequency range of 2.25-2.6 GHz and a gain of 9.38 dBi. The total gain of the 1×8 array antenna is 17.23 dBi. An 8-way power divider is designed and implemented to feed the power amplifier (PA) of each array element, with isolation greater than 20 dB and return loss less than −17 dB. A digital phase and attenuation control circuit is also designed to achieve beam control. Measurement results show that at a distance of 3 meters, the maximum received power for single-target and multi-target schemes is 7.5 dBm and −2.6 dBm at each node, respectively. The system’s flexible beam control mode and high gain transmission characteristics can be used in scenarios such as wirelessly powering Internet of Things (IoT) multi-sensor networks.

Dual-band Circularly-polarized Millimeter-wave Substrate Integrated Waveguide Slot Antenna Array with a Small Frequency Ratio

Jianxing Li, Xiaoyan Yu, Sifan Wu, Sen Yan, Kai-Da Xu — Thu, 31 Oct 2024 00:00:00 +0100

In this paper, a 4×4 dual-band circularly-polarized (CP) substrate integrated waveguide (SIW) slot antenna array with a small frequency ratio (FR) is investigated in the Ka-band. The proposed antenna array achieves the small FR by radiating two high-order modes, i.e. TM₁₃₀ and TM₂₃₀, with close resonant frequencies. To realize CP performance, a sequential rotated feeding (SRF) network is used to design a 2×2 subarray. A 4×4 CP antenna array is further developed to enhance the directivity. Measured results show the antenna array achieves impedance bandwidth (|S₁₁| < -10 dB) of 27.35-27.96 GHz at the lower band and 29.62-30.58 GHz at the higher band with an FR of only 1.1. The measured 3-dB axial-ratio (AR) bandwidths are obtained as 27.66-27.78 GHz and 30.34-30.45 GHz with right-handed circularly-polarized (RHCP) peak gains of 16.9 and 16.8 dBi, respectively. The proposed antenna array is a potential candidate for millimeter-wave communication systems.

Wideband Cup Dielectric Resonator Antenna With Stable Omnidirectional Patterns

Thu, 31 Oct 2024 00:00:00 +0100

A wideband omnidirectional cup dielectric resonator antenna (CDRA) is designed by utilizing three modes (DR TM_01δ, coil, and monopole modes) for the first time. It deploys the modified coil feeding structure comprising four coil segments and two close-by probes. The four coil segments provide an equivalent magnetic-current loop and the two probes act as an electric monopole. Thus, the modified feeding structure can excite the DR TM_01δ mode and two neighbor resonances extending the operating bandwidth. All of these modes have omnidirectional characteristics. To verify the idea, a CDRA is designed, fabricated, and measured. The CDRA is 0.61λ₀×0.32λ₀ (where λ₀ is the free-space wavelength at the center frequency) with a bandwidth of 67.7% (3.28-6.64 GHz). The antenna has stable omnidirectional radiation patterns, high radiation efficiencies, and a low cross-polarized level within the operating bandwidth.

Wideband Wide-angle SSPP-fed Leaky-wave Antenna withLow Side-lobe Levels

Yanzhen Shi, Zhibo Fan, Cong Chen, Yongjin Zhou — Thu, 31 Oct 2024 00:00:00 +0100

In this paper, a broadband wide-angle leaky-wave antenna (LWA) with low sidelobe levels (SLL) is proposed. The antenna is composed of two parts: a broadband wide-angle scanning spoof surface plasmon polariton (SSPP)-fed circular patch antenna array and electromagnetic bandgap (EBG) structures tiled on both sides of the antenna array. By controlling the coupling distances between the circular radiation patches and SSPP feeding line, the attenuation constant along the radiation aperture is specially designed in a tapered way to achieve low SLL. EBG structures are adopted to reduce the back-lobe levels. Measured results show that the scanning angle of the proposed antenna reaches 82^∘. The measured realized gains are from 8 to 15.7 dBi in the operating frequency range from 8 to 12 GHz, with a maximum SLL less than -15 dB. The wide-band wide-angle SSPP-fed LWA with low SLL can find applications in radar detection and microwave imaging.

Channel Measurement and Characterization for 5G Cellular Network with Passive Sounding Method at 2.6 GHz

Hao Sun, Lei Li, Wenqiang Tian — Thu, 31 Oct 2024 00:00:00 +0100

The fifth generation (5G) communication, which is capable of realizing wireless communication with a extremely low latency and high data rate, has been put into commercial use widely. The propagation channel is of great significance for design, performance evaluation, and improvement of 5G system. As to investigate the wireless channel of 5G network, a channel measurement system based on passive sounding method is proposed in this paper. By utilizing the 5G downlink signal, e.g., synchronization signal block (SSB) and channel state information reference signal (CSI-RS), the proposed system is able to extract the multipath parameters of 5G propagation environment. Moreover, a measurement campaign is conducted at an urban macro-cellular (uMa) environment with the passive sounding system. The measured results is briefly analysed and compared with the 3rd generation partnership project (3GPP) results.