Circularly Polarized Elliptical Cavity-Backed Patch Antenna Array for Millimeter-Wave Applications

This work introduces cost-effective solution for a millimeter-wave (mmW) antenna array development. We suggest an elliptical cavity-backed patch antenna array to achieve a wideband and high-gain circularly polarized (CP) at mmW frequencies. The whole array only uses two PCBs and a metallic fixture to build. We introduce a new configurable subarray with $2\times $ 1 radiating elements that are formed by two partially overlapped elliptical cavities to generate the radiation together with the driven patches of the subarray. The subarray can produce a wide impedance bandwidth of 37%, a wide 3 dB axial ratio (AR) bandwidth of 29.6%, and a maximum gain of 11.6 dBic. Based on the result from the subarray, we design a 32-element antenna array by a $4 \times $ 4 antenna array configuration. The power distribution is realized by a 1-to-16 full-corporate feed network. The measured results show that the proposed CP array obtains an impedance bandwidth of 31.5% and a 3 dB AR bandwidth of 24%. In addition, the gain of the array is from 19.1 to 21 dBic within the 3 dB AR bandwidth. With wide impedance and AR bandwidths, the proposed antenna array can find potential applications in long-range mmW communications.