Dual-Band Shared-Aperture Reflectarray Antenna Element at Ku-Band for the TT&C Application of a Geostationary Satellite

A dual-band reflectarray microstrip patch antenna element is presented in this paper. The concept of polarization diversity is effectively utilized in the design with the cross-polarization level obtained well below -25dB in both the principal planes. This supports the implementation of dual-band operation from the same element. The two orthogonal modes of a rectangular patch: TM01, and TM10, are exploited for the dual-band operation. The inherent narrow bandwidth of the element fulfils the requirement of the present work at both the downlink and uplink frequencies of 11.4 GHz and 13.2 GHz respectively. The bandwidth is measured to be 2% to 3%, which effectively keeps the design simple. Also, a good port isolation of 27 dB at downlink band and 20 dB at uplink band are observed. A measured return loss of 17.7 dB at 11.4 GHz and 26 dB at 13.2 GHz are obtained with an acceptable deviation of only 0.65% (75 MHz) at downlink frequency. Based on this element a configuration for dual-band reflectarray is also proposed.