Research On Miniaturization Of 0.4~18 Ghz Ultra-wideband Radar Receiver

Reconnaissance radar receiver should have wide instantaneous bandwidth as far as possible to receive all kinds of useful signals we need,have large instantaneous dynamic range to still receive normal useful signals in the case of distortion between multiple strong signals or aliasing pulse under the high density pulse,have high sensitivity to detect small signals over a long distance and high performance while pursuing its miniaturization.This paper studied an ultra-wideband superheterodyne receiver with two stages of mixers, which operating frequency coverage from 0.4GHz to 18 GHz, with 1.2GHz IF output. The thesis discussed the limiter, Switch matrix, pre-selector and variabling frequency channel in three chapters. The miniaturization of filter and the key problems of the UWB were the main concern in the design of the variabling frequency channel.The difficulty of UWB lies in the magnitude consistency and signal interference; the difficulty of channel miniaturization lies in the size of filters. This paper solved the problem of the gain flatness and stability by choosing appropriate device, optimizing matching of link and multistage equalizer; solved mirror frequency interference other combinations interference by Reasonable frequency division, designing high-performance filters and power supply isolation; designed miniaturized cavity filter by loading capacitance and dielectric; designed small microstrip filter by using coupled-line and transmission line with inductive elements; Using the traditional two levels of structure with PIN to design the limiter in satisfy limiting protection at the same time lower its insertion loss as much as possible to reduce the deterioration of RF channel noise factor. Using compound structure designed one point eight switch with low insertion loss and high isolation.