A miniaturized net-type microstrip bandpass filter using /spl lambda//8 resonators

A novel miniaturized three-pole net-type bandpass filter using /spl lambda//8 resonators has been proposed. Asymmetric frequency characteristics of this filter exhibit a single transmission zero on the lower side of the passband at finite frequency, which is attributed to multi-path effect. Full-wave simulator IE3D is used to extract the coupling coefficients and external quality factor in order to determine the physical dimensions of this filter. The measured results are in good agreement with the simulated predictions. The overall size of the filter is only about 0.22/spl lambda//sub g/ by 0.2 /spl lambda//sub g/. As a result, the filter has not only a small size but also a wider upper stopband up to 6.5 f/sub 0/.