Current Issue : April - June Volume : 2019 Issue Number : 2 Articles : 5 Articles
This paper proposes a low-complexity estimation algorithm for weighted subspace fitting (WSF) based on the Genetic Algorithm\n(GA) in the problem of narrow-band direction-of-arrival (DOA) finding. Among various solving techniques for DOA, WSF is one\nof the highest estimation accuracy algorithms. However, its criteria is a multimodal nonlinear multivariate optimization problem.\nAs a result, the computational complexity of WSF is very high, which prevents its application to real systems. The Genetic\nAlgorithm (GA) is considered as an effective algorithm for finding the global solution of WSF. However, conventional GA\nusually needs a big population size to cover the whole searching space and a large number of generations for convergence,\nwhich means that the computational complexity is still high. To reduce the computational complexity of WSF, this paper\nproposes an improved Genetic algorithm. Firstly a hypothesis technique is used for a rough DOA estimation for WSF. Then, a\ndynamic initialization space is formed around this value with an empirical function. Within this space, a smaller population size\nand smaller amount of generations are required. Consequently, the computational complexity is reduced. Simulation results\nshow the efficiency of the proposed algorithm in comparison to many existing algorithms....
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According to the communication demands of communication system used in the UAV (Unmanned Aerial Vehicle)\ncommunication system, a ladder-shaped open-slotted antenna design is presented. The impedance effects and directional\nradiation performance of designed antenna are improved with adopting a pair of L-shaped narrow slot and a passive resonator\namong the antenna structures. The measured results show that the impedance bandwidth of the antenna is about 90%, the\nfrequency range can cover from 3 GHz to 12 GHz, and the antenna has a relative small size just as 22mmÃ? 24 mm. The antenna\nis realized through adopting improved ground structure, and its electrical length is increased simultaneously. To improve its\nimpedance matching effect, the ladder structure is adopted in the antenna. The measured results show that the proposed design\nscheme is useful and effective, the antenna size can be controlled within the size of 22mmÃ? 24mm and the good impedance\nbandwidth can also be obtained, its frequency bandwidth is from 3 GHz to 13.2 GHz, and the designed antenna has good group\ndelay characteristics at the same time....
Radiation from a cavity-backed circular aperture array antenna enclosed by a frequency\nselective surface (FSS) radome is studied using the hybrid analysis method, by combining the mode\nmatching method, the ray tracing technique, and Huygensâ??s principle. The equivalent magnetic\nsurface currents on the apertures are derived from the aperture electromagnetic fields, which are\ncalculated based on the mode matching method. The rays are generated from the equivalent magnetic\nsurface currents and used to analyze the FSS radome based on the ray tracing technique. After being\nobtained from both the mode matching method and the ray tracing technique, electromagnetic fields\non an outermost radome are transformed into the equivalent electric and magnetic surface currents\nusing Huygensâ??s principle. The radiated fields are computed from the equivalent surface currents\nand compared with the measured data....
This paper presents a dual polarized antenna with high isolation for a wide-angle scanning phased array radar. For the proposed\nantenna, the electronic and magnetic resources are realized through a printed monopole antenna and a slot ring antenna,\nrespectively. A metal reflector ground was introduced to achieve the unidirectional pattern, and the ratio of front to back of the\npattern was improved. The printed monopole and slot ring antenna are fed by the coaxial and electromagnetic couplings,\nrespectively. The radiation fields emitted by the electronic current resource and magnetic current resource are approximately\northogonal to each other among large space ranges. The measured port isolation of the designed antenna is above 20 dB, and the\nwide beam performance can be observed. The feasibility of the proposed antenna scheme is verified....
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