Independent Control over Passbands in Highly Selective and Compact Triple-band Bandpass Filter Based on Substrate Integrated Waveguide

Abstract

This paper proposes a method of independent control over each passband in a high performance triple bandpass filter, which is an essential requirement in the field of microwave communication systems. Individual techniques are presented here to control the excited modes that are responsible for the generation of triple passbands based on substrate integrated waveguide loaded with semi-circular mushroom resonators. Initially, a circular substrate integrated waveguide (CSIW) loaded with two cascaded semi-circular mushroom resonators (ScMRs) with distinct modifications and orientations in the schematic is employed to generate three passbands. The fundamental mode and next higher order mode of the entire resonator structure are utilized to generate three passbands, and distinct techniques of mode perturbations and variation in coupling strength are introduced to independently control the excited modes. Subsequently, the methods established to control the excited modes are employed to independently control the center frequencies (CFs) of three passbands. All those methods established to control the CFs of the three passbands are verified with experimental results which show good agreement with the simulated ones.