Adaptive Antenna Array Pattern Synthesis for Suppressed Sidelobe Level and Controlled Null Using Genetic Algorithm

This paper contains optimal radiation pattern of linear adaptive antenna array obtained using Genetic Algorithm (GA) for reducing the sidelobe level (SLL) and imposing nulls at prescribed interfering directions. Different Fitness functions have been used for performance study of GA for achieving optimal current distribution on the array aperture. Null imposition is considered in this paper in three different ways such as null at single point, multiple directions and nulls in a wide spatial range. The same fitness function has been used here to impose deeper nulls at various desired directions as well as for creating wide nulls. The minimum SLL is achieved for a 20 element isotropic array at approximately -51dB whereas a deeper null of approximately -99dB has been imposed at 40 degrees. The relation between the fitness functions and the excitations are also discussed herewith. Obtained results show that the resultant patterns have SLL and null-performance as per requirement. It also shown that the SLL reduction approach can be extended to the array pattern with main beam steered to desired user. Multiple objectives such as null placement as well as sidelobe suppression are simultaneously achieved with a single fitness function in single-stage optimization.