Ultra compact pseudo-elliptic inline waveguide bandpass filters using bypass coupling

This paper presents an ultra compact waveguide bandpass filter that exhibits a pseudo-elliptic response. The transmission zero created in the upper stopband to form a rapid roll off is produced through a bypass coupling with higher order modes. A 3rd order filter is designed at the centre frequency of 9.4 GHz with a 5.3% fractional bandwidth. The proposed structure's size is 38% smaller than one of a 3rd order E-plane extracted pole filter with comparable response. Additionally, this configuration allows larger span of different bandwidths. The filter has been fabricated and tested using E-plane waveguide technology, which has benefits of being inexpensive and having mass producible capabilities. Measurements of such a fabricated filter validate the simulated results.

Compact filters using metal-dielectric inserts

A novel filter based on e-plane metal-dielectric insert in rectangular waveguide is proposed. Properties of the structure containing metallic septa, C- and I-shaped resonators placed in waveguide are investigated. Pseudo-elliptic cross-coupled filter with direct source-load coupling is designed, simulated and fabricated. Experimental results are presented to prove feasibility of the filter. Significant size reduction is achieved.