Investigation into transmission line radiation
Abstract
An empirical study has been performed to investigate the radiation mechanisms that yield emissions from two-conductor transmission line circuits at microwave frequencies up to 8.5~GHz. The measured signal levels established by radiation from the test configurations within a reverberation chamber were compared with the levels radiated by a wideband dual-ridge antenna in the same environment. Three basic test configurations were considered, one in which the transmission line segment and full feed structure, including balun and feed plate, were contained within the chamber cavity, one in which the feed structure and feed plate could be isolated from the cavity, and a third with two distinct environments measurements of radiation from the feed structure and feed plate as well as radiation from the transmission line could be performed simultaneously. The measurements show that radiation from the line terminations dominates the emission within the cavity that contains it, including when only bulkhead SMA pin adapters were exposed to the cavity, independent of whether the line was a parallel-conductor, twin-lead line, or a twisted pair. Measured emissions from the two lines were only consistent with transmission line theory when the lines were passed through apertures in the chamber walls. The results suggest that the emissions can be modeled by adding a radiation resistance element at the connector location to standard transmission line theory.
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- OSU Theses [15752]