Experimental Hot Test Results from a Compact Metamaterial Slow Wave Structure

The University of New Mexico (UNM) has been studying the design of a high power microwave (HPM) slow wave structure (SWS) to generate > 100 MW of power in L-band in a very compact size. 1 The unit cell of the metamaterial SWS is based on two oppositely-oriented circular, broadsidecoupled split ring resonators (SRRs) and 14 rings were ultimately used. The SRRs provide negative permeability and inserting the structure in waveguide that is below cutoff for the frequency being generated provides negative permittivity, thus yielding a branch of the dispersion curve with negative slope. HFSS was used to calculate the dispersion relation and the double negative behavior was corroborated using a parameter extraction technique proposed by Tretyakov. 2 In addition, a crudely manufactured structure was experimentally cold-tested and these results also agreed with the HFSS simulations and the results from the parameter extraction technique.