Analysis of Field Coupling to Nonuniform Transmission Lines

This paper is concerned with the study of coupling of an external electromagnetic wave to a nonuniform transmission line (NTL) of finite-length suspended above a conducting ground plane. The excited NTL is approximated by a cascaded series of uniform transmision lines (UTLs) together with a suitable set of equivalent distributed sources along the line to account for the effect of the external sources. To confirm the validity of this theory, the numerical results are compared to those by the method of moment (MoM) and laboratory experiments, for a few typical NTL structures terminated by arbitrary loads. Comparison of this approach with the rigorous MoM solution shows that this simple circuit-theory-based method provides reliable results.