The design of a wideband single-layer dual-band reflectarray antenna based on an optimized element

Abstract

A design for a broadband single-layer dual-band reflectarray antenna is presented. A genetic algorithm is employed to design and optimize the element of the antenna. The basic idea to improve the bandwidth of the proposed antenna is based on increasing the range of the linear region of the phase response of the microstrip element. The definition of the fitness function plays an important role in the design process for the optimized unit cell. Three different unit cells with various fitness functions are proposed. Two reflectarrays with 185 elements were designed and simulated based on two different optimized cells. One of the simulated reflectarrays, containing the simpler cells, is fabricated. The designed reflectarrays exhibits a wider gain bandwidth compared with other reflectarray structures proposed in literature. The 3-dB gain bandwidth of the fabricated antenna in the X and Ku bands is 39 % and 44 %, respectively. The gain of the proposed antenna is 21.8 and 26.6 dB at 7.8 and 12.2 GHz, respectively. The proposed design procedure is flexible and could be used to design reflector array antennas with various and arbitrary properties.