Wideband SIW Cavity-backed Microstrip Antenna for Wide-angle Scanning Phased Array

In this paper, a novel Ka-band wideband substrate integrated waveguide (SIW) cavity-backed slot antenna with wide-angle scanning is proposed, which consists of the SIW cavity, the spindle-shaped aperture and the stacked patches. The SIW cavity-backed and four slots etched on the top patch are adopted to achieve a wideband antenna. Moreover, the SIW cavity helps to decrease mutual coupling between adjacent antennas. A 5x5 rectangular lattice array is designed and analyzed by HFSS. The results show that the element antenna can achieve about 11.5% bandwidth (33–37 GHz), and the main beam of the E-plane scanning array antenna can scan from 0 to 60 degrees in the frequency band with a gain fluctuation of less than 4.3 dB and the sidelobe level of less than -13 dB. For the H-plane, when the array scans from 0 to 60 degrees at different frequencies, the peak gain of the array decreases by 3.8 dB.