Design And Implementation Of RF Front End For Microwave Life Detection Radar

With the development of radar detection technology,radars have been widely utilized in various fields including military and civilian uses.Microwave life detection,in particular through-wall life detection,has been a key direction of radar technology.As one of countries with the most frequent geological disasters in the world,China has faced increasingly difficult rescues after geological disasters due to the increment of buildings with reinforced concrete structures in recent years.Microwave life detection has gradually been the mainstream direction of life detection fields due to its penetrability,non-contact and high efficiency of detecting micro animals.For microwave life detection,compared with other types of radars,the step frequency radar has wonderful penetrability and implementability as well as a simple structure.As a result,the step frequency radar system was used for the system design.First of all,the existing life detection techniques and the development situations of microwave life detection radars were introduced in the paper.The basic principles of the step frequency radar for detecting life signals and the attenuation characteristics of microwave through-wall were researched as well.And then the system solution was designed according to index requirements;the key technology such as frequency synthesis and superheterodyne reception and the main principles of critical devices,such as DDS and phase-locked loop,in the system were introduced,and the key indexes of a transceiver was analyzed as well.The hardware of the system includes a radio frequency module composed of frequency source,a transmitter and a receiver,a power supply module and a control module.In the frequency source,the phase-locked loop excites DDS to generate step frequency signals and generate required frequency via a frequency multiplier transmitting links.In the system,the frequency band of transmitting signals is 1420MHz~2420MHz.A receiver with superheterodyne structure was used to enhance system performance.And 20 MHz was used for intermediate frequency.The design thoughts,device selection,device indexes and designs for all the components of the system as well as actual problems and solutions were introduced in detail in the paper.In the meantime,the diagrams of internal structures for key devices,electric schematic diagrams and the PCB diagrams and pictures of the whole transceiver were provided as well.In addition,an ADS simulation was performed for key modules to verify the rationality of the design.Finally,the debugging and testing for the PCB was accomplished,the problems of the system were summarized,and the train of thoughts for improvements was illustrated.