Microwave single/multi-band planar filters with Bagley-polygon-type four-port power dividers

This work reports a planar signal-interference filter structure based on Bagley-polygon-type four-port power dividers. It is shaped by the cascade of two identical transversal filtering sections made up of this power splitter and applied to synthesize single/multi-band responses with sharp-rejection characteristics. Analytical equations helping in the theoretical design of this filter approach are provided. Besides, its practical viability is proven with the building and testing of three microstrip filter prototypes.