| The passive millimeter-wave imaging for target detection based on small unmanned aerial vehicle(UAV)receives the thermal radiation of the observed scene and reconstructs the brightness temperature distribution image of the observed scene.The target can be detected from the image due to the difference between the brightness temperature of the object and that of the background.The goal of this paper was to design an all-time,all-weather,small-size,and mobile passive millimeter-wave imaging system for target detection.The technology of passive millimeter-wave imaging and that of small UAV were studied.The main contents of this paper are as follows:(1)Firstly,the fundamentals of millimeter-wave passive imaging were presented,and the model of low-altitude air-to-ground millimeter-wave passive imaging detection system was established.Based on the model,the difference between the brightness temperature of the object and that of the background were simulated.The results show that there was a significant difference in apparent brightness,which can be utilized for target detection.(2)The overall implementation scheme of passive millimeter-wave imaging system was designed.The design of 94 GHz passive imaging detection subsystem was carried out.According to the requirement of its weight and imaging performances,the design of the small UAV platform was carried out.The stability of small UAV platform was measured by outdoor experiments.The experimental data was processed by the neural network algorithm for detection and tracking.(3)For passive millimeter-wave imaging,two kinds of scanning mechanism,U-shaped scanning imaging and frequency scanning imaging were studied.U-shaped scanning imaging refers to the use of U-shaped Path Planning by the system,and the main beam of the real-aperture antenna is sequentially scanned according to the flight path.Frequency scanning imaging refers to changing the frequency of the frequency sweep antenna to change the main beam direction of the antenna to scan the different positions on both sides of the flight path when the route of the system flight path is a straight line.Finally,the system was used to simulate to monitor the metal target on the ground and water.The simulation results showed that the system imaging detection performance was good. |
