The spurious-mode filter of a THz-range hollow dielectric waveguide

The spurious HE₁₂ and HE_-11+31 modes are brought about not only in the hollow dielectric waveguide inhomogeneities (namely, bendings, breaks (or discontinuities), etc),but also when the waveguide (along with an operating HE₁₁ mode) becomes energized from the microwave oscillator and the laser. They, much like HE,₁₁ are linearly polarized. In consequence of this, these modes can well be suppressed using the filter built around the resonator acting as a segment bounded by one-dimensional wire gratings. The E vector polarization is parallel to wires.