We present in this paper an integrated cavity-backed patch antenna operating at 75 GHz. The design was optimized using a full-wave software based on the integral-equation method. The antenna was realized using micromachining technologies on two wafers: a silicon one supporting a membrane and a radiating patch and a Pyrex one constituting the feeding element. The measurements are in good agreement with the theoretical predictions. (C) 2000 John Wiley & Sons, Inc.