A 4 × 4 multi-feed array antenna-in-package (AiP) is presented for high-power combinations and various polarization syntheses, which operates at D-band. The multi-feed antenna element was designed considering N-number (K × K) of array antennas from the beginning. Hence, the proposed antenna can provide four input ports while achieving impedance bandwidth of 27%, port-to-port isolation higher than 10 dB, and cross-polarization discrimination (XPD) over 20 dB. In addition, the power combination and polarization synthesis can be achieved using various excitation states. A 4 × 4 antenna array from simulated results achieves a gain of up to 18.2 dBi, radiation efficiency of 81%, and XPD of over 20 dB. For verification purposes, the proposed antennas were designed with power dividers for different polarization states. An −10 dB impedance bandwidth of over 27% and a coverage of over ±60°were measured from the experiment.INDEX TERMS D-band, multi-feed, multilayer printed PCB, antenna array.