Strip dual mode filter in which a resonance width of a microwave is adjusted and dual mode multistage filter in which the strip dual mode filters are arranged in series

摘要

A dual mode multistage filter comprises   a series of closed loop-shaped strip lines (33, 283 and 286) respectively having an electric length equivalent to one wavelength of a first microwave signal and having a first coupling point, a second coupling point, a third coupling point and a fourth coupling point spaced one quarter-wavelength of the first microwave signal in that order for respectively resonating the first microwave signal to maximize intensity of the electric field of the first microwave signal at the first and third coupling points according to a first resonance mode and respectively resonating a second microwave signal to maximize intensity of the electric field of the second microwave signal at the second and fourth coupling points according to a second resonance mode orthogonal to the first resonance mode.