Implementation of 94 GHz One-dimensional Passive Imaging Radar System

• Main Authors: Chiang, Chih-Chien, 江志謙
• Other Authors: Chung, Shyh-Jong
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/68888398434661541871

碩士 === 國立交通大學 === 電機學院通訊與網路科技產業專班 === 99 === The thesis introduces to the W-band passive imaging radar system. The system integrates elements, including lens 、an antenna with high directivity、a low-noise amplifier、a power detector and an operation amplifier. By means of the difference of natural thermal radiation power resulted from different objects, we can use the output voltage difference to tell different objects. In order to distinguish the little voltage difference efficiently, we measure key elements to ensure their characteristics., including the efficiency of the lens, antenna patterns, the gain and the impedance of the low noise amplifier, the sensitivity and the impedance of the power detector, the gain of the operation amplifier. According to the characteristics of the elements, we design proper transition between the antenna and the back-end circuits to reduce the loss resulted from impedance mismatch of the module. For the baseband circuits, we use NI PXI-5122 to convert the output voltage from analog signal to digital signal. To avoid the dc signal degradation caused by high frequency noise, we implement signal integration technique to improve the signal quality. Through hot- and cold-source measurement, we can observe output voltage difference, which can be applied to calculate the thermal sensitivity of the whole module. Based on the calculated sensitivity, we can verify the voltages resulted from a human body, coppers and air. In addition, the key points to the system performance are discussed. Finally, the W-band passive imaging radar system with a single channel shows one-dimensional image by mechanical scanning. Therefore, we achieve the goal of distinguishing human bodies and coppers or other objects.