A broadband frequency converter with enhanced dynamic range for a nonlinear radar

A ring frequency converter (FC) is described whose dynamic range is increased due to the use of parallel RC-circuits in each arm of the diode bridge, unified mean components of the diode currents, and the application of a positive bias in order to obtain a cutoff angle of the heterodyne voltage close to 90 degrees. The performance characteristics of the frequency converter are as follows: the input-signal frequency range is 20-470 MHz, the transmission band is 0.01-0.7 MHz, the conversion gain is -1 dB for a 75-Omega load, the dynamic range with respect to third-order intermodulation (which corresponds to the desensitization level of the receiver channel of a nonlinear radar) is no less than 87 dB, the FC noise factor in the frequency band of an input signal is less than or equal to 8.5 dB, the VSWR of signal and heterodyne inputs is no greater than 1.7, and the threshold sensitivity is -108 dBm for the noise factor of the amplifier following the FC equal to 1.8 dB.