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 subreflector for polarization selection. A 2x2 patch array is used as a feed antenna unlike conventional horn antennas. The main reflector is a 10x10 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.