Dual Circularly Polarized Diplexer-Antenna Array with Low Sidelobe Level Based on Gap Waveguide at Ka-Band

In this letter, a 1×8-element dual circularly polarized (CP) diplexer-antenna array with a low sidelobe level is proposed at Ka-band for satellite communication links. Integrated diplexer to the antenna is achieved by embedding filter-splitters consisting of a cascade of resonators in the feeding network. The dual CP is obtained by asymmetric feeding on both sides of the slot element. The sidelobe level is suppressed by weighting the current amplitude of the antenna element by the Chebyshev array. Finally, the proposed dual CP diplexer-antenna array prototype is fabricated. The measured results show that the realized gains are higher than 17.3 and 17.9 dBic in both of the two operating passbands (34-35 GHz and 36-37 GHz), and the efficiency is greater than 60%. The sidelobe level on the yz plane is lower than -19.4 dB for the dual CP radiation. Moreover, the isolation between the two ports is up to 60 dB, achieving extremely low interference between dual channels. IEEE