Broadband SIW cavity-backed circularly polarized antenna element and array

A novel substrate integrated waveguide (SIW) cavity-backed circularly polarized antenna element and 2×2 array is proposed. Taking advantages of low loss and low profile of SIW, the antenna element and array have high efficiency and can be fabricated in the standard print circuit board (PCB) process. By adding SIW cavity around the corner-truncated patch antenna, the bandwidth of the circularly polarized (CP) antenna can be broadened. For the element, an impedance bandwidth of 15% and an axial ratio (AR) bandwidth of 4.3% can be achieved. For the 2×2 array with sequential feeding, the impedance bandwidth and the AR bandwidth can be enhanced to 27% and 13%, respectively.