Study Of Microstrip Reflectarray Antenna Based On Aperture-Coupled Structure

As microstrip reflectarrays possesses various attractive features like low-profile, low cost, easily conformed to a planar surface, easily folded, easily portable and easily disguised, it has been widely used in wireless communication systems such as satellite communication and space exploration. Microstrip reflectarrays combine certain advantages of phased arrays and parabolic antenna. The feeding mechanism reduces the dissipative losses, thus providing a higher efficiency; on the other hand, they can offer beam steering using low loss electronic phase shifter. However, the application range is limited because of the narrow-bandwidth behavior of traditional reflectarrays.This paper, aimed at the problem of narrow-bandwidth of traditional reflectarrays, Analyzed the causations of bandwidth limitation of reflectarray and investigated the method how to expand the bandwidth using aperture-coupled elements, based on basic work principle of rflectarrays and phase compensate principle. The numerical method has been proposed for aperture-coupled microstrip reflectarrays based on the study to three aperture-coupled elements. It is proved that the excellent whole performance can be acquired by aperture stacked patches (ASP) element, through the simulation to three small-sized reflectarrays make up of different aperture-coupled elements. A microstrip reflectarray is designed, which is composed by 225 elements and pyramidal horn. The simulation results show that the main beam point to preconcerted direction (departure normal 20 degree), the maximum gain in central frequency over 26dBi and the bandwidth for a 1.5dB gain variation is 33%. Compared with congener reflectarray antenna, there is 12% enhancement in bandwidth. Finally, a reflectarray antenna is manufactured according to simulated data. The radiate pattern and gain are measured, and the measured results have a good agreement with simulated results. It is proved the practicability and validity of this reflectarray antenna, and provided significant reference value for congener reflectarray antenna.