Compact low loss L-band diplexer for space applications

A compact low-loss diplexer developed for application in satellite multibeam arrays is described. Consideration is given to branch filters using temperature compensated cylindrical dielectric resonators mounted in a circular cut-off waveguide. Techniques for manufacturing the resonators with LiNbO3 have been developed and bandpass filters with uniform and temperature invariant properties fabricated. Small, L-band diplexers have been manufactured, which have less than 0.5 dB loss in 15 MHz passbands and up to 80 dB rejection in a 15 MHz band 100 MHz from passband centers.