Tunable planar combline filter with multiple source/load coupling

In this paper a topology of planar combline filter that provide additional transmission zeros is present. The filter uses multiple coupling between source/load and the resonators to generate up to three transmission zeros. The coupling takes place by means of coupled lines of the source and the load to the resonators. In order to demonstrate the viability of topology a microstrip filter has been constructed. This very selective structure provides responses for the adjacent channels reject in systems that analog and digital channels shared (DVB and analog TV).