Design Of FM Continuous Wave Doppler Radar

Doppler radar is a mature airborne navigation device that can be equipped with a navigation computer to form a Doppler navigation system and can also be used as part of a combined navigation system.The Doppler radar can automatically continuously measure the speed information of the aircraft relative to the ground without ground equipment,a nd its work is not limited by geographical and meteorological conditions.At the same time,Doppler radar has the characteristics of high real-time measurement,no time accumulation of speed errors,small size,light weight,and high reliability.Therefore,Doppler radar has been widely used at home and abroad,and is heavily equipped with various aircraft,missiles and spacecraft.Most of the airborne Doppler radars in service abroad are FM continuous wave systems and have an automatic ocean correction function,of which accurate speed can be measured over land and sea,while the domestic ones are continuous wave systems.There is no FM continuous wave Doppler product yet.Manual corrections are required with domestic Doppler radars when working on the sea.The speed measurement error on the sea surface is large.This paper compares the performance of Doppler radar at home and abroad.In view of the characteristics of FMCW Doppler radar,it studies the design of antenna and transceiver for FMCW Doppler radar in depth.The main research results are :(1)The study on ocean correction antenna.Aiming at the disadvantages of large distortion of sea surface echo spectrum and large error of speed measurement,a new antenna pointing angle design method is proposed,which can greatly reduce the distortion of sea surface echo spectrum and reduce the error of sea surface offset velocity measurement.No manual ocean corrections are required and there is an automatic ocean correction capability.(2)The study on the performance characteristics of FMCW Doppler radar.This paper introduces the design scheme of transceiver,analyzes the requirements of antenna isolation and receiver sensitivity,and determines the optimal system parameters through simulation.The conclusions in this paper can provide reference and guidance for the engineering practice of FMCW Doppler radar.Among them,the design method of antenna pointing angle can be applied not only to FMCW Doppler radar,but also to CW Doppler radar,so that the Doppler radar has automatic ocean correction capabilities.