Integrated Design of X-band Dual Circularly Polarized Antenna and Filter

A magneto-electric dipole antenna is designed and loaded with a three-branch directional coupler to achieve a dual circularly polarized function, which is fed through an L-shaped probe. A low-profile, low insertion loss sixth-order cavity filter is also designed for left-hand and right-hand circular polarization feeding through two ports, respectively. After connecting the antenna to the filter, the resulting structure has a return loss of less than -10 dB at 7.5-9 GHz, an axial ratio of less than 2 dB, isolation of less than -20 dB at the center frequency, and a realized gain of 5.2 dB at 8.25GHz.