Cold measurement of a Ka-band Metal PBG waveguide

In this article, we report the design and cold measurement of a Ka-band Metal Photonic Band Gap (MPBG) waveguide with a coupling from an external rectangular waveguide (WR-28) transition using a wraparound co-axial coupler. The metal PBG waveguide was realized by a triangular lattice of metal posts with a defect (removal of seven metal posts) at the center. The circular TE₀₁ travelling electromagnetic mode was supported by this defect portion without any mode competition. The circuit was fabricated and experimentally tested for its cold behavior. The circuit offered a wide band width of ~ 6 % of the centre frequency and this result has been close in agreement with simulations. This metal PBG waveguide circuit is suitable for gyro-TWT as an RF interaction circuit at microwave/millimeter wave higher harmonic operation.