A circularly-polarized aperture array antenna with a corporate-feed hollow-waveguide circuit in the 60 GHz-band

The authors proposed a circular-polarized array antenna by using hexagonal radiating apertures in the 60 GHz-band. The hexagonal radiating aperture is designed, and the good axial ratio characteristics are achieved in the boresight. We analyze the full structure of the 16 × 16-element array that combines the 2×2-element subarrays and a 64-way divider. The reflection is less than -14 dB over 4.9% bandwidth where the axial ratio is less than 2.5 dB. High antenna efficiency of 88.7% is obtained at 61.5 GHz with the antenna gain of 33.3 dBi including losses. The 1 dB-down gain bandwidth is 6.8%.