Natural-Frequency Approach to the Synthesis of Narrow-Band Waveguide Absorption Filters

An approach to the synthesis of the waveguide resonator sections filled with a lossy dielectric and absorbing up to 50% of the input power is proposed. The approach is based on the procedure of searching for complex-valued natural frequencies of the resonator sections that provide the required characteristics of a corresponding natural oscillation. Using this approach is promising to design the multi-resonator filters absorbing completely the input power at the desired frequency. The exact numerical results of designing the three-resonator narrow-band absorption filters in the WR-75 rectangular waveguide are presented.