3mm波电磁特性测量雷达

3mm wave electromagnetic characteristic measurement radar

为了对非静止的烟幕进行插损、反射、辐射等电磁特性的测量,采用锁相技术研制了3mm波雷达反射截面积(RCS)测量雷达和3mm波辐射特性测量雷达(辐射计).前者采用收发分置的连续波双天线体制,可根据目标尺寸和反射的大小更换天线;采用毫米波固定衰减器和远近程切换,以及FFT积累的数字接收,提高灵敏度和动态范围.后者是超外差中频迪克式体制,用硬件和软件积分相结合的方式保证灵敏度.系统每2m s可给出一个测试结果,实现了动态测量.

For measuring insertion loss,reflection and radiation of smoke screen,a 3mm wave electromagnetic characteristic measurement radar has been fabricated,which comprises a 3mm wave radar cross section（RCS） measurement radar and a 3mm wave radiometer.The transmitter and receiver of the former are separated,and each antenna of them can be chosen among three kinds of antennas with different beam width or gain,according to the sizes of object and the power of reflection signal.In order to fit the tremendous changes of power between transmission and reflection,the sensitivity and the dynamic range of the system is improved by millimeter wave fixed attenuator,switching between long range and short range,and digital intermediate frequency（IF） receiver with signal accumulating by Fast Fourier Transform Algorithm（FFT）.In the 3mm wave super-heterodyne IF Dicke-radiometer,hardware integral and soft integral are both used to achieve high sensitivity.All the millimeter wave oscillators in the system are phase-locked.The interval between two adjacent data is 2ms,which is suitable for suspending and movable smoke screen.