Design and development of folded stub loaded microstrip reflectarray antenna

Design and measurement results of a folded microstrip reflectarray antenna are presented. This antenna contains of a feed antenna, a main reflector for focusing and twisting and a sub-reflector for polarization selection. A 2×2 patch array is used as a feed antenna unlike conventional horn antennas. The main reflector is a 10×10 microstrip patch array and each microstrip patch in the array is attached with two open ended stubs for beam focusing and twisting the polarization. The sub-reflector is placed above the main reflector which consists of parallel metal lines printed on dielectric substrate. The sub-reflector is transparent to the signal incident in orthogonal polarization and opaque for the parallel polarization. The proposed antenna exhibits a measured gain of 22dB and side lobe level of -20dB at designed frequency of 10GHz. The proposed folded reflectarray antenna has low profile and exhibits wide impedance bandwidth (9.6-10.4GHz) with VSWR <; 1.5.