60-ghz wideband circularly polarized antenna array based on TE340-mode SIC and sequential rotation feeding technique

The authors propose a 4 x 4 circularly polarized (CP) antenna array with wide impedance bandwidth and axial-ratio (AR) bandwidth and design the same for 60-GHz applications. The overall structure of the proposed antenna array consists of a cavity-back circular patch array and two layer feed-networks. The upper feed-network is with four TE340 high-order mode substrate integrated cavities (SIC). Fed with SIC, circular patches with a pair of 42 degrees-inclined slits can achieve circular polarization. In order to improve the AR bandwidth and gain performance, the substrate integrated waveguide (SIW) sequential rotation feeding technique is utilized in the lower feed-network. For proof of concept, the 4 x 4 array is fabricated and measured. Measured results show that -10-dB impedance bandwidth of the proposed antenna array is 27.2% from 52 to 68.4 GHz and 3-dB AR bandwidth is 18.9% from 55.7 to 67.3 GHz. Furthermore, the 3-dB gain bandwidth is 26.2% from 53 to 69 GHz with a peak gain reaching 19.3 dBic at 62 GHz.