Periodic-surface-lattices for mm-wave Cherenkov sources

Periodic surface lattices (PSLs) are passive components that when combined in appropriate configurations with an electron beam can create active RF devices that include novel mm-wave sources of radiation. A two-dimensional (2D) PSL can be obtained by creating shallow periodic perturbations on a metal surface. The periodic perturbations on the surface facilitate resonant coupling of surface fields and near cut-off volume fields which leads to the observation of a high-impedance surface, or effective metadielectric. Coupled volume and surface fields synchronise the radiation from individual lattice elements to form a cavity eigenmode. Cavities based on a PSL of cylindrical topology have been studied and an analytical description of the lattice dispersive properties is presented. Variations of the lattice dispersive properties for different parameter values are shown, illustrating the ability to tailor the electromagnetic properties of the structure. Under certain conditions, dispersion plots demonstrate the potential to create novel Cherenkov sources of coherent high power radiation.