No abstract

This study presents the realisation of a wideband bandpass filter using a novel compact quadruple‐mode resonator. The quadruple‐mode resonator, which is evolved from the square open‐loop resonator, is an interesting structure for a compact design. The resonator has two odd and two even mode resonant frequencies whose approximate analytical expressions are derived. For a wide bandwidth filter, three short branch‐lines are introduced to the resonator in order to widen the separation between the resonant frequencies. A filter with a 3 dB fractional bandwidth of 96.0% is demonstrated. Simulated and measured results are in good agreement.

Abstract-A new design consideration is explored for a hair-pin resonator. A grounding via at the mid-point of the resonator acts as a perturbation to split the resonant frequencies. The via also suppresses even harmonics of the fundamental. The principle operation of the hair-pin resonator with a via is analyzed and verified by measurement. It is shown that such a hair-pin resonator can be made more compact using stepped impedance line. A compact 4-pole bandpass filter using the modified compact hair-pin resonator with a via is demonstrated. Simulation and measured results showed good agreement.

Abstract-Step-by-step procedures for designing a third order bandpass filter and a sixth order bandpass filter using a triple-mode resonator are described in this paper. The triple-mode resonator is a square open-loop resonator with an open circuited stepped-impedance stub and a grounding via located at the symmetrical plane of the resonator. The equations for approximating the resonant frequencies of the resonator are obtained from odd and even mode analysis. To design a filter, first, the theoretical resonant frequencies for the filter are calculated. Then the basic dimensions of the resonator are approximated using the equations. The filter layouts are fine-tuned by simulation and verified by experiment to conclude the paper. The first spurious response occurs at about 3 times the center frequency of the first passband in both filters. The simulated and measured results are in good agreement.

No abstract