Design of Combline Cavity Diplexer for Two Channel Ultra High Frequency Bands

A Combline cavity diplexer was designed with two channels operating at ultra-high frequency bands of 698-806 MHz and 824-960 MHz and was simulated using CST tool. Channel 1 of 698-806 MHz with combline cavity model was designed first and the parametric analysis of each physical parameter was done. The variation of physical parameters and analysis lead to the simple modification physical parameters to obtain the second channel model i.e., 824-960 MHz This proved the post manufacturing tunable capabilities with the variation in tuning screw depths. Aluminum was the material used for the model. The insertion loss with ripples accounted was less than 1dB and return loss was found to be -12dB for both the channels. The post manufacturing tunability provides the option for the tuning of the bands and reduction in ripples.