A New Transmitting Antenna System for Very Low Radio Frequencies

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. Recent widespread interest in very low-frequency radio propagation has increased the importance of developing adequate vlf transmitting systems. After briefly examining conventional vertical vlf antennas, a system is presented which employs resonant loading circuits to convert a section of an existing power line into a horizontal vlf transmitting antenna. The simplicity, low cost, and useful radiation pattern of this horizontal antenna are well suited for many experimental applications. The theoretical antenna problem is solved using a normal mode expansion of the current distribution. A matrix method is developed to compute the current distribution of a thin, linear antenna loaded with lumped-circuit elements. The series is found to converge relatively fast. A digital computer is used to solve the matrix equations. Results are obtained for a full-wave linear antenna symmetrically loaded with real impedances [...], one half-wavelength apart. Current distributions, feedpoint impedances, radiation patterns, etc., are presented as functions of [...]. Results of the idealized problem are applied to the power-line antenna. The matrix method can also be extended to the general linear antenna with any type of loading or feeding. System components and performance of the Dinkey Creek power-line antenna are described. The problem of interference with nearby audio-frequency communication systems is examined. The 8.4 kc propagation experiments using the Dinkey Creek antenna are described. The series of whistler-mode propagations to probe the exosphere has not been completed. However, ionospheric soundings have yielded considerable information about the properties of the ionosphere at vlf. Successful long-distance propagation experiments are also described, and samples of the results are presented