Abstract: In order to improve the gain of millimeter wave(MMW) microstrip antenna array, a novel method based on active circuits and phase adjustment by dielectric loaded microstrip line was presented. A MMW microstrip antenna array with high gain was designed and realized, consisting of four subarrays, each having 64 patches fed by a compact MMW power amplifier. The compensated phase difference between every two channels is less than 10° and the antenna realized has a gain of 30dB, proving the efficiency of the method.