Beacon Source And Antenna Design For Microwave Listening Systems

Microwave interception is a kind of effective means for Intelligence agency to obtain the voice information of specific people secretly.This paper is around the beacon and interceptor antennas used in the microwave interception system,with a focus on the design of the radio frequency parts of the beacon and low-sidelobe antenna.(1)RCS of original passive beacon used in microwave interception is quite small,increasing the difficulty of signal processing.A novel beacon is introduced in this article to extend the range of interception on the basis of target simulator for continuous wave radar.Special signal modulation based on microwave mixing and signal transceiving using microwave antenna are applied to ensure the improved performance.(2)A model for voice signal is established where the signal is multiplied by local oscillator in a mixer.The circulator's characteristic of isolation is used in order to inhibit the leakage on the mixer's radio frequency(RF)interface during the transceiving process of beacon's antenna and also to achieve the unidirectional transmission of signal flow.Based on how the RF part of beacon is working,designs for a beacon's antenna and a ferrite circulator as well as a double-balanced mixer are respectively completed along with the accomplishment of calculation,modeling and debugging for their basic parameters in HFSS and ADS.The results of simulation proved that these designs can meet technical requirements.(3)For the propose of suppressing interference of ground clutter to intercepting radar,the feed-level distribution is optimized by the correlation between the window function Fourier transform and the antenna directivity function,and the sidelobe level is effectively reduced in the waveguide antenna design.A waveguide gap coupling structure is used to reduce the size of the feed structure.An adjustment method of resonance point shift controlled by the piston is proposed to improve errors introduced by machining accuracy.Simulation results show that the design meets the requirements.In this paper,the design and simulation of the beacon and interception antenna are completed.The test results of the beacon antenna meet the requirements,and provide the reference for the system.