US Patent 7786828 Waveguide bandstop filter

In a bandstop filter having an input port (2; 3), an output port (3; 2) and a waveguide (1, 1′) connecting the two ports, at least one resonator body (4, 5; 4′ 5) is located in the waveguide (1, 1′), which resonator body has resonance frequency above the limit frequency of the waveguide (1; 1′).