Minimizing cosecant-squared pattern side lobe level of linear array antenna by genetic algorithm and optimizing feed network

This paper designs and synthesizes a 12-element linear array of microstrip patch antenna with cosecant-squared pattern for radar applications at the frequency 9.6 GHz. The antenna array consists of three microstrip sublayers including two lower sublayers designed for feed network, and radiating patches located on the upper sublayer which are excited through a slot in the ground plate. One of the most important advantages of this antenna array is the cross-polarization discrimination of less than 50 dB which is the result of removing undesirable and unwanted radiations caused by feed network. The Genetic Algorithm (GA) optimization method has been used to synthesize cosecant-squared pattern with considering the mutual coupling effect of array elements. In this method, the amplitude and phase of each element in the far field has been calculated by taking into account the mutual coupling effect, and applied in the optimization process. Finally, the feed network has been designed according to the amplitudes and phases obtained from the GA. The simulation results confirm the validity of all design and synthesis stages.