A narrow band UHF filter bank using SAW TCRFs

This paper elaborates the design and realization of a UHF band single input single output n on-switch able four channel narrow band filter bank. The filter bank consists of a power divider at the input followed by 4 narrow band filters and a power combiner at the output. To achieve precise narrow band filtering Surface Acoustic Wave (SA W) Transversely Coupled Resonator Filters (TCRFs) are used which can conventionally provide narrow band filtering typically of the order of 0.03 % fractional bandwidth. However, the application environment, which is an on-board frequency channelizer, required the filter band widths to be of the order of 0.05% to 0.06%. The challengesfaced in achieving these wide band widths using SA W TCRFs, together with good out of band rejection specifications are presented including a discussion on return loss and passband flatness performance optimization.