The radiation characteristics in millimeter-wave band of the metal objects are complicated particularly those with complex three-dimensional structures. The complicated electromagnetic environment, in which the stereoscopic metal objects reflect the radiation energy in all directions with arbitrary incident angles, makes this problem even more challenging. In this paper, the surface panel method and the ray tracing theory are used to analyze the bins of the stereoscopic metal targets surface and their corresponding radiation sources in the reflection path. In addition, in 3mm band the radiometric images of the metal ball and the metal column are given by practical measurements. By comparing the single radiation scanning curves of the selected metal targets, the influence of the three-dimensional structures on the brightness temperature was analyzed and verified. Furthermore, the differences of the radiation patterns of different stereoscopic structures are also summarized.
Working all-day and all-weather, the passive millimeter wave radiometer is widely used in remote sensing, guidance and other fields. In order to solve the increasingly serious problem of water pollution, especially the pollution caused by the rapidly breed of the aquatic plants, a simple and effective method to monitor the water environment is proposed. Aquatic plants can be distinguished through millimeter wave system, as they have high bright temperature compared to Water. The 8mm radiometer is used to measure the radiation characteristics of aquatic plants and image. The simulation results and radiation imaging experiments prove the feasibility and effectively of monitoring aquatic plants by millimeter wave radiometer. This study will contribute to monitoring the aquatic plants growth and decreasing the pollution.
For the purpose of security inspection, an alternating current (AC) radiometer is used in passive THz Wave (0.1THz)
imaging for the first time in china. Giving a comparison of structure and spectrum characteristic between direct current
(DC) radiometer and AC radiometer, we discussed the AC radiometer imaging mechanism and the noise image disposal
method based on the medium filtering. Simulating the requirement of safety inspection in airports, ports etc, a 2-D
imaging experiment of the person with canceled object has been did indoor, by THz Wave AC radiometer mechanical
scanning. The results show that THz Wave AC radiometer possesses higher sensitivity and can be used to inspect the
concealed metal objects hidden in the passenger body and their luggage.