A focal plane array for millimeter wave imaging comprising a three dimensional stack of antenna elements and radiometer microwave monolithic integrated circuits (MMICs) embedded in polymer dielectric layers built on top of a silicon substrate. Each radiometer MMIC and antenna element comprise a radiometer pixel. The silicon substrate contains integrated circuits to collect and process the signals from each radiometer pixel and generate a full-frame video signal. The array can be fabricated on a single silicon wafer or can be constructed from structures fabricated on multiple silicon wafers.