Measured Characteristics of Selected S-Band Coaxial-to-Waveguide Adaptors

Report No. ARL-TN-220
Authors: William O. Coburn
Date/Pages: July 2004; 22 pages
Abstract: A design procedure for a leaky wave antenna fabricated in slitted waveguide was developed based on the analysis of Goldstone and Oliner (1). The use of dielectric loading in slitted rectangular or dual-ridged waveguide is one way to influence the antenna performance. An experimental fixture to evaluate the transmission line characteristics of miniaturized dual-ridged waveguide was fabricated to allow for dielectric loading in the ridge section. The goal is to obtain experimental validation of the theory as applied to a specific leaky dual-ridged waveguide loaded with conventional engineering plastics. As a first step the effect of the coaxial-to-waveguide adaptors needed to feed and terminate the experimental fixture must be determined. The offset short method is used to characterize commercial microwave adaptors requiring at least three different waveguide lengths. Five different lengths of S-Band waveguide sections were available although some choices are more appropriate than others depending on the frequency range of interest. The experimental results are used to calculate the scattering parameters for five different microwave adaptors over the frequency range 2.8 to 3.2 GHz. The method and the limitations imposed by not being able to use optimized waveguide lengths are described. A summary of the adaptor characteristics is provided for the reference of other researchers so that the most appropriate part can be chosen for a given application.
Distribution: Approved for public release
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Last Update / Reviewed: July 1, 2004