Analysis of Multiconductor Transmission Lines, 2nd Edition

11

INCIDENT FIELD EXCITATION OF TWO-CONDUCTOR LINES

In this chapter, we will examine the solution of the transmission-line equations for a two-conductor line that is excited by an external, incident electromagnetic field. This will represent, for example, airport surveillance radars and AM/FM radio station transmitters as well as near-field sources. We will provide a simple derivation of the transmission-line equations for the case of two-conductor lines and extend that in the next chapter to multiconductor transmission lines (MTLs). Once the transmission-line equations are derived and solved, the terminal constraints of the line are incorporated to give the solution for the terminal voltages and currents.

Incorporation of the effects of incident electromagnetic fields into the transmission line equations was considered for two-conductor lines in [1–5]. The transmission-line formulation for two-conductor lines has been compared to the full-wave method of moments (MoM) solution in [H.6,H.7] and to experimental results in [H.8]. A literal solution for the two-wire case was obtained in [H.9,H.11]. The formulation has also been adapted to twisted pairs [6] and to shielded cables [7]. The investigation of higher-order modes on these two-conductor lines was given in [8].

11.1 DERIVATION OF THE TRANSMISSION-LINE EQUATIONS FOR INCIDENT FIELD EXCITATION

The process of excitation of the line by an external, incident electromagnetic field can be thought of in the following way. The incident ...