A Novel Dual-Polarization Total Power Radiometer with Single Channel

A dual-polarization total power millimeter wave (MMW) radiometer with single channel was proposed in this paper. It completed the subtraction of two orthogonally polarized signals in the RF front end. The system used one channel to achieve the function of two channels. On the basis of discussing the theory and the configuration of the system, the performance of the system and the ability to identify the false target were analyzed and simulated. The results showed the radiometer could solve the problem that the performance of dual-polarization radiometer becomes weak because of gain inconformity with two channels. The system was cheap and small and could identify the false target which has different apparent temperatures at vertical- and horizontal-polarized radiations. 1. Introduction Passive millimeter wave (MMW) detecting technique is to scan and detect the target area by using MMW radiometer. The target will be detected, identified, and located based on the different intensity levels of the target and background. Since MMW radiometer can easily identify metal and nonmetal, it can be applied in searching and rescuing cars, aircraft navigation, and safety checking in severe environment. One of its applications is in the terminal guidance of smart ammunition [1–3]. False targets like pond which has similar MMW radiation characteristic with metal targets are usually met in passive MMW detecting experimental study. Their MMW radiation temperature is lower than background temperature, so they can hardly be distinguished by general single-polarization millimeter wave radiometer with single channel. A Ka band dual-polarization direct detection total power MMW radiometer is designed in the literature [4]; this system receives targets and background radiation signal’s horizontal polarization component and vertical polarization component through dual-channel receiver; after comparing the differences, the system detects and identifies some false targets whose level and polarization have great difference in temperature. This project can solve false target problem like ponds easily, but it has a high demand on the consisting of the two receivers which can hardly be guaranteed at current technologic level; besides, using two receivers leads to the huge volume and high cost. In this paper, sum-difference network technology in monopulse antenna [5] is applied to MMW dual-polarization radiometer; then a new dual-polarization total power MMW radiometer system with single channel is designed; it not only finishes the subtraction of two orthogonal polarization signals