Miniaturized loop resonator filter using capacitively loaded transmission lines

Abstract

This thesis details the design and investigation of a miniaturized microstrip closed loop resonator using slow wave structures in the form of capacitively loaded microstrip lines. A novel miniaturized closed loop resonator structure that achieves both miniaturization and improved coupling has been developed. The miniaturized resonator is demonstrated to achieve a 37% reduction in area when compared against a square closed loop resonator of equivalent resonant frequency. Also developed are feed structures to provide improved control of external QL. To aid resonator design, a methodology to synthesize the new structure based on frequency requirements is provided.A 3rd order Chebyshev filter using the new resonator structure has been fabricated. In comparison to a filter synthesized using a closed loop resonator of similar size, the new structure achieves a 22% lower resonant frequency and also an additional area reduction of 6% which is possible due to space savings provided by the structure.