Analysis of Insular Guide Launcher Radiation Loss and Comparison with Microstrip Counterparts

An analysis of a launching configuration enables the radiation loss associated with the feed region of a millimetre wave insular guide to be assessed. Series expansions of the guide fields are used in conjunction with a variational formulation of the launcher loss which is computed for various guide parameters and dimensions. An alternative assessment of loss based on a chopped surface wave distribution is also presented and reveals other effects present. Finally a comparison with typical launching losses for micros trip lines is made and some experimental data is also given. It is concluded that for some circuit and antenna applications the use of micros trip rather than insular guide could lead to an overall lower system loss.