Equations are derived for the current induced in an infinitely long, thin, straight wire of nonzero surface impedance when the wire is connected to a flanged coaxial line. Also, radiation field patterns are computed and the input conductance determined. It is found that the current (and likewise the input conductance) can be separated into two components, one of which is a propagating or modal current. Graphs are presented from which the efficiency of excitation of the propagating current can be computed.A second structure consisting of a single wire between perfectly conducting parallel plates is solved as a boundary‐value problem. The solution is used in the discussion of the physical behavior of a finite single‐wire transmission line. In particular it is found that the usual transmission line concepts are valid under certain restricting conditions.