The wave antenna: A new type of highly directive antenna

Determination of Constants from Input Impedance. Fig. 61 shows a generator (or oscillator) supplying alternating current to a line. This results in waves which travel from A to B. Assuming for the time being that there is no reflection at B and no return waves, the relation of voltage to current is E/I = Z in which Z is the surge impedance of the line. When the generator makes the point A positive with respect to ground it supplies a current in the direction A — B. Let us now imagine the generator and the absorbing terminal circuit interchanged so that the generator supplies current to the end B and the waves travel from B to A. The impedance measured at the terminals of the generator will be the same as before, but when the line is positive with respect to ground the current will be flowing in the direction B — A. Therefore if we define the voltage as positive when the line is positive with respect to ground, and the current as positive when in the direction A — B, then for waves traveling in the direction A — B the voltage is E = + Z I, but for waves traveling in the direction B — A the relation is E = — Z I.