Compact $S$ -Band Coaxial Cavity Resonator Filter Fabricated By 3-D Printing

This letter presents a novel fourth-order coaxial cavity resonator bandpass filter with a Chebyshev response. The filter operates at a center frequency of 3 GHz and has a bandwidth of 90 MHz. The filter is formed of four coupled coaxial cavity resonators. To make the filter compact, the first resonator is embedded inside the inner conductor of the second resonator and the fourth resonator is embedded inside the central conductor of the third resonator. The filter is fabricated stereolithography apparatus 3-D by printing process that allows such a design with a complex structure to be fabricated accurately at a reasonable cost. The filter is tested and good agreement between measured and simulated results is obtained.