Novel coupling schemes for microwave resonator filters

The paper presents novel coupling schemes for microwave resonator filters. Some of these solutions contain more than one main path between the input and output. These paths may be interacting or non-interacting. In other solutions, only some of the direct (main) couplings are zero. It is shown that higher-order filter characteristics can be obtained from lower-order sections, which are connected in parallel between the source and the load, by proper superposition of the individual lower-order responses. Possible applications of these solution to actual design problems are discussed.