Antennas

Author: Edmund A. Laport

An example of a very-low-frequency antenna closely resembling a transmission-line problem is that of the Rocky Point type of antenna (see Fig. 1.39).

Fig. 6.7 :

Fig. 6.8 :

The dimensions of the flat-top cross section are shown in Fig. 6.8. The configuration is symmetrical and so can be analyzed with six potential equations for the 12 wires. All wires are at the same potential to ground, and one may wish to know the ratio of currents in the various wires or the capacitance per meter of length for the wire system only.

One proceeds with logarithmic potentials by writing the potential of each wire, numbers 1 to 6. The equation for wire 1 is, for example,

After solving all six such equations simultaneously, the charge (current) ratios are found to be

Proceeding through the successive steps to solve for Z₀, it is found to be 201 ohms. The capacitance is 16.6 micromicrofarads per meter.

An obstacle to the application of logarithmic potentials to many of the problems of engineering is the enormous labor of solving large blocks of simultaneous equations. Electronic calculators for several simultaneous equations facilitate such work and thus make it feasible to study a large variety of such problems rapidly. The above charge ratios were solved with the RCA Simultaneous Equation Computor in less than 10 minutes. A great deal of new information can be obtained with such a calculator by eliminating the tedious arithmetical labor required by manual solution, which has always impeded comparative analyses of complicated systems.