Concentric Circular Array Antenna Null Steering Synthesis by Using Modified Hybrid Ant Colony System Algorithm

In this article, a hybrid optimization method has been proposed consisting of modified ant colony systems (ACSs) and constrained nonlinear programming (NLP) to solve the problems of null synthesis of concentric rings circular array antenna consist of parallel center feeding dipoles elements with two complex nonlinear optimization problems. In the first problem, a synthesis of concentric circular array radiation pattern with many interface signals is considered. In the second problem, the hybrid optimization algorithm is used to achieve wide nulls in the concentric circular array radiation pattern. The optimization process is achieved by finding the optimal values of the excitation coefficients of each element in the circular rings array. Several examples are considered here to verify the validity of this method. The results obtained by this method show that it is possible to obtain an array radiation pattern with wide null width of 90 o with a depth equal to -60dB and two nulls on both sides of the main lobe with about -112.9 dB depth level. Comparisons were made between the results of this proposed method and the results obtained by many other evolutionary optimization algorithms, and it is clearly shown that this method is more efficient and flexible in solving the problems of concentric circular array antenna performance optimization.