Random Noise Illumination for Passive Millimeter Wave Imaging System

Passive millimeter wave (MMW) systems have been used in many applications. Given the lack of detection capability at small temperature differences, we use noise sources as illumination to improve the detection performances. In this paper, we design a miniaturized passive MMW system operating in the frequency band of 75-110 GHz. The system has the temperature sensitivity of 0.5K and achieves good imaging indoor results of human body. The noise source consists of the amplifier directly connected to a matched load. We experimented with the imaging performance of different objects in pure passive mode and noise exposure mode, including metal sphere, metal sheet, and FR-4. The practical effect is the same as the theoretical analysis and proves that noise irradiation can detect objects that cannot be detected in passive mode.