Dual-Band Dual Circular Polarization Filter Antenna Based on Transmission Line Feed

Abstract

The uplink and downlink of modern satellite communication systems operate on different frequency bands. A novel dual-band dual circular polarization filter antenna with a single port is proposed in this paper. The dual-band characteristic of the antenna is obtained by exciting stacked patches. The antenna supports right-handed circular polarization (RHCP) at lower frequency band and left-handed circular polarization (LHCP) at higher frequency band, respectively. The feeding network is realized with a strip line, and the antenna can be equivalent to a parallel circuit. If the lower frequency patch works, the higher frequency patch presents high impedance, and vice versa. Therefore, the antenna has excellent filtering performance. The measurements of antenna prototype are in good agreement with the simulation results. The impedance bandwidth is 5.80-6.10 GHz and 9.20-10.64 GHz, and the axial ratio (AR) bandwidth is 40 MHz for lower band and 180 MHz for higher band, respectively. Meanwhile, the radiation pattern is stable in the operation frequency bands.