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Published By Applied Computational Electromagnetics Society

1054-4887, 1054-4887

2021 ◽  
Vol 36 (7) ◽  
pp. 879-884
Author(s):  
Hao Li ◽  
Lu Xu ◽  
Feng Qian ◽  
Yong Zhou

As a convenient and efficient public transport system, high speed railway (HSR) was rapidly deployed in China. Since the fifth generation (5G) mobile communication system is commercially applied, it is necessary for mobile terminals antennas to cover multiple operating bands to be compatible with various communication systems. Here a HSR-mounted broadband and high-gain monopole antenna is proposed. By using the meander technology and introducing the tapered structure, the proposed antenna operates over a bandwidth of 694-960 MHz and 1350-5975 MHz (VSWR<1.8), which covers both 2G-5G mobile communication and WiFi frequency bands. The dimensions of the proposed antenna are 400 mm × 330 mm × 78 mm. The measured average gain is 6.11 dBi over the entire bandwidth.


2021 ◽  
Vol 36 (7) ◽  
pp. 852-857
Author(s):  
Yongliang Zhang ◽  
Xiuzhu Lv ◽  
Jiaxuan Han ◽  
Shuai Bao ◽  
Yao Cai ◽  
...  

In this paper, a highly efficient dual-band transmitarray antenna using cross and square rings elements is presented for X and Ku bands. The dual-band transmitarray is designed for downlink/uplink frequencies of Ku band satellite communications. The transmitarray element consists of four metal patches and two dielectric substrates. The metal patch is printed on both sides of the substrate. By optimizing the parameters, the transmitarray element can achieve a transmission phase coverage greater than 360° and work independently in both frequency bands. Then, a method to select the size of the element is proposed, so that all the elements in the array can realize the transmission phase of the two frequencies as much as possible. A 201-elements transmitarray antenna is fabricated and measured and the band ratio of the antenna is 1.13. The measured maximum gain at 11.5 GHz is 22.4 dB, corresponding to the aperture efficiency is 52.7%. The measured maximum gain at 13 GHz is 24.2 dB, corresponding to the aperture efficiency is 62.4%. The 1-dB gain bandwidths are 9.7% (10.8-11.9 GHz) at X band and 9% (12.6-13.8 GHz) at Ku band.


2021 ◽  
Vol 36 (7) ◽  
pp. 865-871
Author(s):  
Jin Shi ◽  
Jiancheng Dong ◽  
Kai Xu ◽  
Lingyan Zhang

A novel miniaturized wideband bandpass filter (BPF) using capacitor-loaded microstrip coupled line is proposed. The capacitors are loaded in parallel and series to the coupled line, which makes the filter just require one one-eighth wavelength coupled line and achieve filtering response with multiple transmission poles (TPs) and transmission zeros (TZs). Compared with the state-of-the-art microstrip wideband BPFs, the proposed filter has the advantages of compact size and simple structure. A prototype centered at 1.47 GHz with the 3-dB fractional bandwidth of 86.5% is demonstrated, which exhibits the compact size of 0.003λ2 g (λg is the guided wavelength at the center frequency) and the minimum insertion loss of 0.37 dB.


2021 ◽  
Vol 36 (7) ◽  
pp. 894-900
Author(s):  
Demiao Chu ◽  
Yujun Xiong ◽  
Ping Li

This paper presents a low-profile, high gain, beam-tilted continuous transverse stub (CTS) array antenna at W-band. The antenna compromises 32 radiating slots and is fed by a parallel plate waveguide (PPW) network with a linear source generator. To deflect the outgoing beam, the principle of linear array scanning is adopted to design inverted T-type structure in each stub to introduce wave path difference. PPW network allows the antenna to obtain lower profile compared to other transmission lines. The design procedure, and the antenna characterization are described. The main beam of the antenna is titled 12 degree in H-plane. The simulation and measured results show that this antenna achieves peak gain of 32.4 dB and a 12 degree beam tilt angle at 99GHz. S11 parameters of the antenna is less than -10 dB in a broadband from 96 GHz to 103 GHz. This antenna has an advantage of miniaturization over other high-gain antenna solutions. The promising performance of this proposed CTS antenna reveals the possible candidate for Millimeter wave (MMW) telecommunication applications.


2021 ◽  
Vol 36 (7) ◽  
pp. 838-843
Author(s):  
Haixu Wang ◽  
YingSong Li

This paper introduces a constrained normalized adaptive sparse array beamforming algorithm based on approximate L0-norm and logarithmic cost (L0-CNLMLS). The proposed algorithm can control the sparsity of the array by introducing an approximate function of L0-norm. In addition, the introduction of logarithmic cost improves the stability of the algorithm as well as the convergence rate of the algorithm. The sparsity of the array can be controlled when adjusting related parameter in the proposed algorithm. Simulation results show the better performance of L0-CNLMLS compared with some conventional algorithms.


2021 ◽  
Vol 36 (7) ◽  
pp. 914-921
Author(s):  
Liwei Guo ◽  
Simin Li ◽  
Xing Jiang ◽  
Xin Liao ◽  
Lin Peng

In order to achieve both adjustable wideband and high Polarization Conversion Rate (PCR) of the transmitted waves, a novelty tri-layered structure is proposed for terahertz applications. The Rhombus Hollow Square (RHS) is built up by top and bottom gold gratings on Silicon Dioxide and Polyamide substrate with graphene strips. The proposed polarizer broadens the bandwidth and has well performance. As chemical potential increases, the bandwidth is also broadened by adjusting the graphene. From 0.5 THz to 3 THz, the PCR is greater than 90%, and the relative bandwidth up to 142.9%. The transmission and absorption of polarizer are analyzed at the oblique incidence with chemical potential 0.1eV. By simulating and analyzing the performance, a new result of maintaining broadband and high transmittance in oblique incidence is obtained.


2021 ◽  
Vol 36 (7) ◽  
pp. 830-837
Author(s):  
Qiang Feng ◽  
Yifeng Lin ◽  
Yushan Zheng ◽  
Long Li

In this paper, an improved array factor of the concentric uniform circular array (CUCA) antenna is proposed for the orbital angular momentum (OAM) vortex beam optimization design. From the perspective of the radiation pattern’s power conservation principle, a correction factor is introduced to the conventional array factor of CUCA. Then, based on the improved array factor, by adjusting the rings’ radii parameters of the CUCA, we optimize the vortex beam’s sidelobe level through the generic algorithm (GA). Two different CUCA antenna model are calculated as examples to further illustrate the effectiveness of the improved array factor. Subsequently, an electromagnetic simulation model of two rings CUCA antenna is built at C band for generating low sidelobe vortex beam carrying OAM mode. The electromagnetic simulation model of the designed CUCA antenna is also fabricated and measured. The corresponding antenna far-field vortex beam radiation pattern and near-field vortex wave electric field distributions are measured. The simulation results and the measurement results are in good agreement. The proposed designs of antenna and OAM vortex beam regulation are expected to be used for 5G and 6G communications applications


2021 ◽  
Vol 36 (7) ◽  
pp. 872-878
Author(s):  
Yuan Ye ◽  
Zhao Huang ◽  
Yun Jiang ◽  
Li-an Bian ◽  
Chang Zhu ◽  
...  

A low profile ultra-wideband tightly coupled dipole array is studied. The antenna elements are fed by Marchand baluns of small size and low cost. A metasurface based wide-angle impedance matching (MSWAIM) layer is introduced to replace the traditional dielectric WAIM, improving the beam scan performance and reducing the antenna profile. The simulation shows that the proposed antenna array can operate over 2.4-12.4 GHz, approximately 5:1 bandwidth with maximum scanning angle of 50o for both E plane and 45o for H plane. The antenna profile above the ground is only 0.578λH at the highest operating frequency. This antenna array can find its application in the forthcoming massive MIMO beamforming systems for 5G.


2021 ◽  
Vol 36 (7) ◽  
pp. 928-934
Author(s):  
Wei Kong ◽  
Xiao Yang ◽  
Feng Zhou ◽  
Jia Xie ◽  
Chuan Chen ◽  
...  

In this paper, a new method is proposed to analyze the broadband electromagnetic characteristics of electrically large targets by combining the precorrected-FFT algorithm (P-FFT) with the near-field matrix interpolation technique. The proposed method uses the precorrected-FFT algorithm to reduce the storage and accelerate the matrix vector product of the far field. In order to make the precorrected-FFT algorithm can calculate the broadband characteristics of electrically large targets more quickly, the matrix interpolation method is used to interpolate the near-field matrix of the precorrected-FFT algorithm to improve the efficiency of calculation. The numerical results obtained validate the proposed method and its implementation in terms of accuracy and runtime performance.


2021 ◽  
Vol 36 (7) ◽  
pp. 922-927
Author(s):  
Hong-Yi Gan ◽  
Wen-Sheng Zhao ◽  
Da-Wei Wang ◽  
Jing Wang ◽  
Qi Liu ◽  
...  

This paper presents an active microwave sensor for the characterization of dielectric materials. The sensor is consisted of a microstrip complementary split-ring resonator (MCSRR) structure and an active feedback loop. The loop uses an amplifier to generate negative resistance to compensate the resonator’s loss and increase the loaded quality factor. The developed sensor possesses the advantages of high quality factor, ultra-small electrical size, and high sensitivity. A prototype of the sensor is fabricated and measured for validation.


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