Feed Antenna Optimization of W Band Active Millimeter Wave Imaging System

In recent years, with the rapid development of millimeter-wave technology, millimeter-wave imaging technology has been widely used in the security field. Active millimeter wave imaging uses the feed antenna to radiate electromagnetic wave to the measured target, and carries out image reconstruction according to the echo information, so the feed antenna plays a very important role in active millimeter wave imaging system. In this paper, a coaxial cavity horn antenna with a main lobe width greater than 100°, a relative bandwidth greater than 10%, and a heart-shaped pattern at 94GHz is designed. Then, on the basis of the horn antenna, the medium rod structure is added to reduce the main lobe width of the medium rod horn antenna to 23% and achieve the maximum gain of 18.7dB. It meets the requirements of the design indicators and the simultaneous imaging is better. It has theoretical guiding significance for the design of the feed antenna of the active millimeter-wave imaging system.