Multifrequency notch filter for sub-THz applications based on photonic bandgaps in corrugated circular waveguides

Sensitive millimeter wave diagnostics need often to be protected against unwanted radiation like, for example, stray radiation from high power Electron Cyclotron Resonance Heating applied in nuclear fusion. A notch filter based on a waveguide Bragg reflector (photonic bandgap) can provide several stop bands of defined width within up to two standard waveguide frequency bands.