Differentially-Fed Dual-Polarized 2D Multibeam Antenna Array for Millimeter-Wave Applications

A dual-polarized 2D multibeam antenna array working at millimeter-wave (mmWave) frequencies is presented in this paper. In conventional multibeam antenna arrays, low polarization discrimination (XPD) is observed when beams scan off the boresight. In our design, the differential feeding technique is employed in antenna element design to achieve high port isolation and high cross-polarization discrimination (XPD) for all beams. To validate this concept, the antenna array and the multibeam feeding network operating at 28 GHz are designed and fabricated. High XPD, high port isolation and stable radiation patterns are obtained in the designed antenna. The measured results show that the XPD for all beams are higher than 28 dB and port isolations are greater than 20 dB over the bandwidth 26.8 GHz-29.2 GHz. The proposed antenna is a promising candidate for future wireless communication systems due to good radiation performance, easy integration, low cost, and low profile.