Phase correction techniques for reducing errors due to edge diffraction in reflectarray

Abstract

Phase correction due to finite reflectarray (RA) antenna size and edge diffraction (ED) is proposed. The process is based on the numerical full wave analysis. The edge diffraction is mainly caused because of amplitude and phase ripples at sharp knife-edges of the outer perimeter of the RA antenna. The diffracted fields at the edges is diffracted in all directions resulting in disturbing the original phase and amplitude distribution, which further affect the pre-expected performance of the antenna. This could cause increasing of sidelobe level (SLL) and reducing aperture efficiency. The degradation in the antenna performance can be reduced by using serrated-edge ground, slotted GND and rolled-over edges with corner blended ground plane in the bottom of RA. The proposed methods provide RA performance when compared with RA antenna using sharp knife-edge (KED) ground plane. The proposed methods are analyzed by designing 19∗19 RA antenna in fullwave analysis in the Ka-Band using size varying multi-bowtie radiating elements. The antenna performance is evaluated based on the achieved gain, aperture efficiency, SLL, and cross polarization. The proposed technique's result are compared with original RA using knife-edge ground plane. The best antenna performance is obtained using rolled-over edges GND plane. The antenna provides maximum gain of 26.36 dB, aperture efficiency of 59.5 %, SLL of −17.1 dB and 1-dB gain bandwidth of 11.2%, evaluated at center frequency 30 GHz. Near field analysis is also done for phase correction authentication.