M-Shaped Under-Bridge Feeding Method for a Low-Profile Dual-Band Dual-Polarized Antenna-on-Package in the 6G Upper Midband

A 2 $\,\times \,$ 4 dual-feed antenna-on-package (AoP) for 6G upper midband supports high power and dual-polarization, with a compact structure enabling potential use in smartphones and dense multiple-input–multiple-output (MIMO) base stations. The dual-feed antenna element is designed considering dual-linear polarization and dual-band operation. Consequently, the proposed antenna can provide dual-band, achieving a –6 dB impedance bandwidth of 32.3% (9.77 GHz to 13.45 GHz), port-to-port isolation higher than –15 dB, and the envelope correlation coefficient lesser than 0.02. The 2$\,\times \,$ 4 antenna array for a MIMO antenna is fabricated for the evaluation of radiation characteristics. The proposed antennas are measured and verified by vertical probing system. Each element was measured with –6 dB impedance bandwidth of over 6.83% in low band and 4.9% in high band. The measured gain of boresight is achieved to 6.45 dBi at 10.25 GHz, and 6.7 dBi at 12.7 GHz, and the measured envelope correlation coefficients are all less than 0.04 in the dual-bandwidth.