Frequency-Separating Devices for Secondary Surveillance Radar Systems

A frequency-separating device (FSD) with low insertion losses has been developed that provides electrical strength at high input power and combines the functions of several typical elements of the feeder path of a secondary surveillance radar (SSR): a receive/transmit switch, a harmonic filter, and a receiving band-pass filter. The issues of synthesis, analysis, and optimization of filters for the receiving and transmitting channels of the FSD are considered. Two options for the implementation of an FSD with insertion loss in the channel bandwidths within 0.7 dB, a harmonic suppression level of more than 40 dB, channel isolation, and attenuation at a deviation of ±60 MHz from the center frequencies of the passbands of at least 50 dB are proposed, the devices operate at frequencies of the FSD and of the seventh range of SSR systems with input pulse power up to 12 kW. The main dimensions of the FSD design, the results of numerical simulation, and the data  of experimental verification of the characteristics are given. A comparative analysis of theoretical and experimental results is given.