Circularly Polarized Waveguide Antenna With Dual Pairs of Radiation Slots at Ka-Band

Abstract

In this letter, a circularly polarized (CP) waveguide antenna with dual pairs of slots is presented for Ka-band applications. Circular polarization is realized by combining two orthogonal linear polarizations, which are generated by two pairs of radiation slots on a cavity surface, respectively. Two approaches of radiation slots, i.e., edge slots and corner slots, are discussed. The corner slots approach is employed to design a CP waveguide antenna at Ka-band. The measured axial ratio (AR) is below 3 dB from 29.69 to 30.06 GHz, or 1.2% relative bandwidth, with a minimal value of 0.4 dB at 29.9 GHz. The measured antenna gain is 9.8 dBi at 30 GHz, and the return loss is below -13 dB within the 3 dB AR bandwidth. The all-metal structure of the proposed antenna is very appropriate for tough environment applications.