Circular waveguide BPF composed of artificial dielectric resonators

A bandpass filter (BPF) made of a circular waveguide loaded with two artificial dielectric resonators is investigated. The resonators which take circular shapes are placed in the center of circular waveguide and separated each other in a certain distance. Each resonator is made artificially from a foam dielectric material with some cylindrical conductors incorporated concentrically in the center along with the direction of electric line field in the TM₀₁ mode. The characteristics of BPF are investigated through resonators by changing the distance between resonators, the thickness of resonators, and the number of cylindrical conductors incorporated in resonators. After fabrication of artificial dielectric resonators for realizing the BPF, the characterization of circular waveguide BPF is carried out experimentally through parameters measurement. In spite of the discrepancy occurs between the simulated and measured results, it shows that the circular waveguide BPF has been successfully realized using artificial dielectric resonators in which the measurement result with center frequency of 3.763GHz and -3dB working bandwidth of 298MHz is obtained.