Waveguide-Based Spatial Power Combiners

The objective of this program was to explore certain extensions of waveguide-based combiner systems in order to extend or enhance operating bandwidth and amplifier capacity. Oversized TEM-mode combiners were originally proposed which promise multi-octave bandwidths, and an enlarged cross-section compared with standard waveguide, which accommodates a larger number of amplifiers. During the program and in consultation with DARPA and ARO program managers, the program thrust was modified to include modeling and development of combiners at K-band, targeting existing commercial and military application demands. Significant progress was made in this effort, resulting in multiple demonstrations of combiner modules that could potentially challenge vacuum electronics in some applications. We have demonstrated a multi-octave 64-way passive combiner system using oversized coaxial waveguide. We also developed an oversized K-band 18-20GHz combiner system that accommodates up to 24 amplifier circuits. In addition, we have developed a design methodology for creating optimum impedance tapers for the finline arrays used in this work.