Embedded Near-Field Probing Antenna for Enhancing the Performance of 37-41 GHz Linear and Dual -Polarized Phased Antenna Arrays

This paper proposes a new wideband near-field probing antenna embedded in millimeter-phased antenna arrays to produce the feedback signals necessary for carrying-out array calibration and digital predistortion training. The proposed NF probing antenna is devised to avoid disturbing the antenna array's radiation pattern while providing a coupling to its surrounding antenna elements with flat magnitude and constant group delay in both vertical and horizontal polarizations. Proof-of-concept prototypes of a 2x2 dual-polarized passive and a 4x4 linear-polarized active antenna arrays with embedded NF probing antenna(s) operating over the frequency band of 37-41 GHz were designed. The measurement confirmed the negligible impact of the NF probing antennas on the antenna array's radiation pattern. Furthermore, the embedded NF probing antennas were successfully used to train a DPD function which then enabled the effective isotropic radiated power to be increased from 32 dBm to 34.1 dBm while maintaining an error vector magnitude below 3.5%.