Low-pass filter with deep and wide stop band and controllable rejection bandwidth

Abstract

Novel design of low-pass microwave filters based on cascading of identical unit cells is proposed. Dispersion relation is used to determine the cell parameters for a given relative stop-band width. For a filter consisting of two cells, each made of single- or two-section transmission lines, the design formulas and curves are presented. Based on them typical filters are designed, fabricated, and measured. The presented filters feature a deep stop band and a wide rejection band, which can be controlled within the proposed design procedure. The design procedure and the simulation results are verified experimentally by measurement of the fabricated structures containing two and three cells.