In this work, a new topology of waveguide combline filters based on flat metallic strip resonators is presented.

The main advantages of this new topology are the ability to implement transmission zeros (TZ) and low-cost practical realization. Furthermore, the position of the TZs can be controlled using offset resonators, thus achieving more selective filter responses. The design of several bandpass filter examples with finite-frequency TZs is also discussed. Two different commercial software tools (Ansys HFSS and CST Studio Suite) have been used to verify the correct operation of the designed filters, thus validating both the proposed topology and the employed design

procedure.