A Voltage-Matching Method for Feeding Two-Tower Arrays

This paper describes a novel method for feeding two-tower arrays. If the self-impedance of each tower and the mutual impedance between the towers are known, then the feed-point voltage at each tower can be calculated for an assumed set of base currents. When a transmission line of specified impedance is connected to the base of each tower; the voltage at any point on these two lines can be calculated using transmission-line theory, since the loadend voltages are known. If the voltage phasor at some point on one of the lines is identical to the voltage phasor at some point on the other line, then each antenna feeder can be cut at that particular point and the two ends joined together. The resulting impedance at this "common point" can be transformed to 50 ohms (or any desired value) by a matching network which then connects to a single transmission line extending back to the transmitter. Software for implementing the technique either on a personal computer or programmable calculator is included for those who are interested.