Grid mixers and power grid oscillators

Power-combining schemes involving planar grids of solid-state devices quasi-optically coupled in free space are an efficient means of combining power at microwave and millimeter-wave frequencies. The quasi-optical coupling of these grid circuits makes them ideal for millimeter-wave and submillimeter-wave applications by eliminating waveguide sidewall losses and machining difficulties. The planar property of the grids potentially allows thousands of devices to be integrated monolithically. In this thesis, a grid mixer suitable for mixing or detecting quasi-optical signals is presented. The mixer is a planar grid structure periodically loaded with diodes. The grid mixer power handling and dynamic range scales as the number of devices in the grid. The conversion loss and noise figure of the grid are equal to that of a conventional mixer. A variation of the grid mixer, the sideband generator grid, is shown to be an efficient package for increasing the theoretical operating frequency and output power of monolithic planar diodes at terahertz frequencies. Techniques for designing power grid oscillators to produce Watt-level output powers are described. Designs and experimental results for MESFET grid oscillators operating in X-band with output powers of 0.9 W to 10.3 W are presented in detail. Methods that make use of finite-element electromagnetic solvers for analyzing grid structures of arbitrary shape are discussed