L/S-Band Dual-Circularly Polarized Antenna Fed by 3-dB Coupler

A dual-band dual-circularly polarized (CP) antenna fed by a dual-band 3-dB substrate integrated coaxial line coupler is designed, fabricated, and measured. The proposed antenna is excited by two planar L-probes that are connected to two output ports of the coupler. This dual-band dual-CP antenna effectively covers the L-band of 1.62 GHz and S-band of 2.50 GHz, respectively. Simulation and measurement results show that, considering reflection coefficient, gain, and axial ratio together, the relative bandwidth is about 10% at the lower band and about 4% at the upper band. The maximum measured antenna gains are 8.5 and 8.2 dBi, respectively.