Effects of Dielectric and Conductor Losses on the Current Spectrum Excited by a Gap Voltage Source on a Printed-Circuit Line

In the past, the high-frequency current excited on a lossless microstrip line by a gap voltage source has been examined. The present work studies some interesting effects that practical conductor and dielectric loss have on the current. These loss effects have been neglected in past analyses, although all practical microstrip lines have both conductor and dielectric loss. Our analysis and results reveal that the loss attenuates the bound mode of propagation in the expected manner (causing it to decay exponentially), while the continuous-spectrum current is hardly affected by the loss. The consequence of this is that the nature of the strip current far away from the source is dramatically affected by the presence of loss. The type of spurious effects that are observed due to the interference between the bound mode and the continuous-spectrum currents may also be significantly affected by the loss. In the lossy case, the spurious effects may actually increase with distance from the source.