Broadband Instantaneous Frequency Measurement Receiver Rf Front-end Research

Instantaneous frequency measurement is an important part of radar receiver; it takes on detecting the carrier frequency of radar. As long as access to the radar carrier frequency, enemy radar interference can be successfully avoided and anti-interference can be implemented.this paper mainly studies the design of RF front-end of broadband instantaneous frequency measurement receiver, focusing on the design of 4～8GHz broadband microwave correlator.Therefore,this receiver in broadband instantaneous frequency measurement field has broad application prospects.First, the technology background, development of domestic and foreign and various types of receivers of the instantaneous frequency measurement are briefly introduced.Then, the basic principles of interferometer phase-comparison are described in detail. Formula derivation and error analysis in time-domain are implemented. Combined with the frequency measurement precision and error analysis, a two-channel system with the delay time ratio of four and running in parallel is proposed.Secondly, this article focuses on the broadband correlator circuit design. Frequency range is 4～8GHz. The basic design theory and design methods of broadband 3dB Plane coupling line directional coupler, broadband 3dB power splitter, broadband phase detector are described, Ansoft HFSS 11.0 and ADS 2008U2 are used for circuit design and simulation optimization. According to the connect way of external ports, high frequency capacitor and coplanar waveguide structure are as the crossover. So two structures form of wideband microwave correlator are implemented. The physical circuit is Produced and installed, the physical circuit is tested with the vector network analyzer, and the test results meet the system design requirements.Finally, the work of this paper is concluded, and some question which needs improvement and further study are proposed.