A Miniaturized Dual Circular Polarization Antenna Element for K/Ka Band

In this paper, a miniaturized dual-polarized antenna unit is proposed. By adding dielectric material to the septum circular polarizer, the antenna size is reduced by 38.6%, with dimensions of 6.2mm×7.2mm×40mm. A wedge-shaped structure and a parallel-coupled microstrip bandpass filter effectively address the degradation in isolation between the two ports due to size reduction. The antenna demonstrates good impedance matching and isolation performance of no less than 33dB in the K-band (18.9-21.6GHz) and Ka-band (29.4-31.7GHz). Due to its reduced size, the antenna can be effectively used as a unit in dual-band co-aperture phased array antennas, achieving sidelobe-free beam scanning effects in azimuth and elevation directions up to ±35° with a unit spacing of 6.2mm.