Ka-Band Cavity-Backed Detached Crossed Dipoles for Circular Polarization

An implementation of circularly polarized crossed dipoles in millimeter-wave band is presented in this paper. Novel detached crossed dipoles have been designed to tackle the problems confronted by single-fed crossed dipoles in mm-wave band. An evolution procedure from conventional crossed dipoles to the proposed ones is given. Meanwhile, a metallic ridge is added in the cavity to provide a robust feeding structure. Measurements of an optimized antenna prototype show that it can achieve a bandwidth from 27 to 36.8 GHz for both AR ≤ 3 dB and |S11| ≤ -10 dB and an average broadside gain of 12.4 dBi. The measured results agree reasonably well with simulations. For reference to practical designs, studies on five critical parameters have also been performed in this paper.