Current Issue : January - March Volume : 2021 Issue Number : 1 Articles : 5 Articles
This paper presents the low profile, planar, and small-size antenna design for WWAN, LTE, and 5G (5th generation wireless\nsystems) for use in portable communication equipment............................
Antenna array synthesis is one of the most popular topics in the electromagnetic field. Since achieving a desired antenna radiation\npattern is a mathematical problem, in the literature, there are various optimization algorithms applied to the synthesis process of\ndifferent kinds of antenna arrays. In this study, Multiverse Optimizer (MVO) and modified MVO (MMVO) are used to perform\ncircular antenna array (CAA) synthesis. During the exploration, exploitation, and local search phases of calculation, MVO uses\nthree concepts in cosmology; white hole, black hole, and wormhole. Convergence capability of this nature-inspired algorithm is\nemployed for finding optimum amplitude and position values of CAA elements in order to achieve an array pattern with low\nmaximum sidelobe level (MSL) and minimum circumference. The performance of MVO and MMVO was tested on five design\nexamples of pattern synthesis, and the obtained results were compared with ten different algorithms. The simulation results show\nthat MVO and MMVO provide low MSLs with small circumferences....
For the traditional target localization algorithms of frequency diverse array (FDA), there are some problems such as angle and\ndistance coupling in single-frequency receiving FDA mode, large amount of calculation, and weak adaptability. This paper\nintroduces a good learning and predictive method of target localization by using BP neural network on FDA, and FDA-IPSO-BP\nneural network algorithm is formed. The improved particle swarm optimization (IPSO) algorithm with nonlinear weights is\ndeveloped to optimize the neural network weights and biases to prevent BP neural network from easily falling into local minimum\npoints. In addition, the decoupling of angle and distance with single frequency increment is well solved. The simulation experiments\nshow that the proposed algorithm has better target localization effect and convergence speed, compared with FDA-BP\nand FDA-MUSIC algorithms....
Electromagnetic metasurface lenses with the characteristic of being conformal to a cylindrical geometry are presented in this\nstudy. Based on the formulated principle of the cylindrical metasurface lens operating with transmission or reflection mode, the\ntransmission or reflection phase gradient varying along the circumferential direction of a cylinder is implemented. A focused\nbeam is observed at the objective focal point for each lens illuminated by a plane electromagnetic wave with transverse magnetic or\ntransverse electric polarization. A coaxial-fed microstrip patch antenna element is used as a feeding of cylindrical metasurface\nlenses and positioned at their focal points, so as to evaluate their application in the enhancement of antenna gain along the\nboresight direction. By virtue of the focusing ability of presented lenses, effectively enhanced boresight gain from the cylindrical\nmetasurface lens antennas are obtained, in comparison with the freestanding feeding antenna. The agreement between simulation\nand measurement validates the designs. Conformal integration or embedment of the electromagnetic lens into a certain platform\nskin with cylindrical characteristics is therefore potentially demonstrated, which implies an enhancement of boresight gain\nwithout obviously disturbing the local shape of the skin by apparent weight or drag....
This paper introduces a 2D angle-of-arrival (AoA) estimator, which has a 6â??18 GHz 7-element nonuniformly spaced array (NSA)\nand a Direct Data Domain- (D3-) based AoA algorithm for a 2D isotropic-element planar array (IEPA). A 2D calibration and\ndata-transformation method is developed to convert the NSA data to the output of the IEPA, so that the NSA-measured data can\nbe used in the D3 algorithm. Using the steering vector (SV) of the IEPA and the results derived from the D3 method, a new 2D\nAoA searching method is also developed, which offers frequency-independent performance defined by the probability of AoA\nestimation, when the required estimation accuracy and signal-to-noise ratio (SNR) are given. For the applications of electronic\nsupport measures, this paper also presents the use of precalculated SV and data-transformation matrix databases built on\npreselected frequency points and a 2D-angle grid that is close to uniformly distributed directions...............................
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