Synthesis of $L$-band diplexer for high power operation

The efficient combined technique is proposed for synthesis of $L$-band diplexer for high power operation which is necessary, for example, in radar applications. The original diplexer modification is implemented on the base of coaxial cavity resonators with the jump of characteristic impedance. The suggested mushroom design of coaxial resonator provides the compact size due to reducing the electric length of resonator and it is appropriate for high-power operation. The original design of the coaxial-to-strip-line bifurcation is introduced into diplexer as the matching circuit. Synthesis technique of diplexer includes the application of the coupling matrixes technique, solving the eigen-value problems for single resonator and two coupled resonators, full-wave simulation based on finite element technique. As a result of synthesis high electrical performances of diplexer were obtained. Within frequency bands of diplexer 1024–1036/1084–1096 MHz the reflection coefficient is less than S$_{11}<$ -22 dB, the channels isolation is better -70 dB, insertion loss is -0.4 dB, maximal operational power is 2 kW. The proposed design of diplexer is appropriate for implementation within the operational frequency bands of mobile and satellite communications.