Photonic-band-gap (PBG) and metamaterial RF-structures for high power millimeter and THz wave electron beam devices

Novel photonic band gap (PBG) waveguides and metamaterial (MM) cavities have been designed in the effort to develop high power millimeter and THz sources. The designed structures are comprised of a periodically corrugated channel sandwiched between two PBG slabs and a multi-cell cavity-resonator designed with fishnet apertures. The simulation analysis shows that trapped non-PBG modes are effectively suppressed down to ~ - 14.3 dB/cm, while PBG modes propagated with ~ 2 dB of insertion loss, corresponding to ~1.14 dB/cm attenuation. The preliminary modeling analysis on the fishnet-embedded cavity shows noticeable improvement of Q-factor and field gradient of the operating mode (TM₀₁₀) compared to those of typical pillbox- or PBG-cavities. The Ka-band PBG-waveguide and S-band fishnet cavity structures will be tested with a microwave test bench/8510C Network Analyzer and 5.5 MW S-band klystron. These structures can be applied to stable short-bunch formation and mono-energetic radiation in high frequency electron beam devices.