Study on 12/21-GHz dual-circularly polarized feed antenna for satellite broadcasting reception

NHK started test satellite broadcasting of UHDTV in August 2016, and practical broadcasting will begin in 2018. Test broadcasting is provided in the 12-GHz (11.7 to 12.75 GHz) band by using right-hand circular polarization. For practical broadcasting, multiple UHDTV programs will be provided using left-hand circular polarization in the same frequency band. We have also been studying a satellite broadcasting using the 21-GHz (21.4 to 22.0 GHz) band. Therefore, we designed a 12/21-GHz dual-circularly polarized feed antenna composed of two 2 × 2 microstrip antenna arrays. Simulation results showed the VSWR of the 12-GHz and 21-GHz bands were 1.15 and 1.37, respectively. We also calculated the radiation pattern of a 45-cm reflector antenna with the designed feed. The aperture efficiency was 66% in the 12-GHz band and 56% in the 21-GHz band. The XPD of the reflector antenna was more than 31 dB. Thus, our antenna is valid for receiving 12- and 21-GHz band satellite broadcasting.