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In this article, a quantized water cycle algorithm (QWCA) is used for the antenna array pattern synthesis with low side-lobe levels (SLLs) and nulls at desired directions by using four-bit digital phase shifters. In addition to the standard features as a metaheuristic algorithm, QWCA has an internal quantization mechanism and a precalculated array factor method. The latter provides an accelerated procedure to QWCA under favour of the digitized values that can be stored in a three-dimensional array. This acceleration is based on the reality that the accessing data in the memory need less time than the usage of the mathematical functions throughout the optimization process. The internal quantization mechanism of QWCA is utilized to achieve digital values matching to the discrete values of the phase shifter instead of the simple rounding up/down routines after optimization. The numerical results showed that QWCA can obtain very good SLLs and null depth levels (NDLs) on the synthesized pattern. Moreover, the results are achieved in remarkably short optimization times. SLL and NDL values obtained by QWCA are also compared with the available literature values. The comparisons reveal that QWCA is able to produce better results than the other compared alternatives. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:21–29, 2015.

A backtracking search optimization algorithm (BSA) is proposed for the synthesis of concentric circular antenna arrays (CCAAs) with the low sidelobe levels at a fixed beamwidth. Several numerical examples of CCAA patterns with the single, multiple, and broad nulls imposed at the directions of interference are also given to illustrate the performance and flexibility of the proposed algorithm. BSA is a relatively new population based evolutionary optimization algorithm. The numerical results show that the design of CCAA using BSA provides good sidelobe levels with a fixed beamwidth. The nulling patterns obtained by BSA are also very good. The quality of results obtained by the BSA is checked by comparing with that of several metaheuristic algorithms in the literature. BSA is also compared with differential search (DS) and bacterial foraging algorithms (BFA) in terms of iterative performances.

In this article, a stochastic search technique based on seeker optimization algorithm (SOA) is proposed for null steering of linear antenna arrays by controlling the position-only, phase-only, and amplitude-only. The SOA is relatively new optimization algorithm based on the concept of simulating the act of humans' intelligent search with their memory, experience, and uncertainty reasoning. Several numerical examples of Chebyshev pattern with the single, multiple, and broad nulls imposed at the directions of interference are given to illustrate the performance and flexibility of the proposed algorithm. For a comparison, the nulling patterns obtained by simulated annealing (SA) and tabu search (TS) algorithms are also given. Furthermore, the results of SOA are statistically compared with those of SA and TS algorithms. The statistical results of simulations show that SOA is superior to the other compared algorithms. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011. © 2011 Wiley Periodicals, Inc.

Three formulas for the narrow and wide aperture dimensions of the pyramidal horn are improved, and the improved formulas give lower average percentage errors (0.00452, 0.01566, and 0.00809%), compared to the average percentage errors of three available formulas (0.01497, 0.27561, and 0.07268%). The agreement between the desired gains and the computed gains of the horns designed by using the improved formulas is very good, having average percentage errors of approximately 0.0017–0.0063%. © 2003 Wiley Periodicals, Inc. Int J RF and Microwave CAE 13: 239–245, 2003.

A new and flexible method is presented that is based on the ant colony optimization algorithm for the pattern synthesis of linear antenna arrays with the prescribed nulls. Nulling of the pattern is achieved by controlling only the amplitude of each array element. To show the versatility of the present method, some design specifications such as the side lobe level, null depth, and dynamic range ratio are considered by introducing a set of weighting factors in the cost function constructed for the ant colony optimization algorithm. Several illustrative examples of Chebyshev patterns with the imposed single, multiple, and broad nulls are given. © 2002 Wiley Periodicals, Inc. Int J RF and Microwave CAE 12: 375–383, 2002. Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mmce10034

A technique, simple and easy to use, is presented to design the optimum gain pyramidal horn. The optimum gain pyramidal horn design equation available in the literature is improved. Design parameters are computed from the simple and explicit analytical formulas. The pyramidal horn gain is determined with no path length error approximation. Several design examples are given to show the performance of the improved design technique. © 2001 John Wiley & Sons, Inc. Int J RF and Microwave CAE 11: 188–193, 2001.