Micro reentrant cavity for 100 GHz klystron

A micro reentrant rectangular cavity for klystrons operating at 100 GHz is proposed. The cavity is designed for higher order mode operation. This permits relative larger dimensions compatible with a realization by mechanical micromachining or high-aspect ratio lithographic fabrication process. Three-dimensional electromagnetic simulations demonstrate the properties of the cavity suitable to be used in a 100 GHz klystron.