Long Wave Reception and the Elimination of Strays on Ground Wires (Subterranean and Submarine)

The question of optimum length of (buried) ground wires for reception at a given wave length is discussed, and experimental data are given. The signal strength obtainable on such wires under various conditions is considered. The signal-to-stray ratio on ground wires as compared to that on loop receivers (rectangles) is found to be more advantageous, particularly under carefully chosen conditions. After considering a number of methods of reducing strays which have already penetrated into the receiver circuits, there are described a number of more effective methods for reducing strays before their entrance into the receiver. Thus strays can be balanced out by using a sea wire and a land wire as opposing collectors, with an adjustable-phase differential coupling of some sort. The wiring of the arrangements used and the practical adjustment are given, together with some of the experimental results obtained therewith. The distance of origin of strays (or interfering signals) can be adjusted for in balancing these out, so that an interesting "focussing effect" is obtainable wherein the effect of a stray (or signal) in the receiver depends on the distance to its source. The ratio of improvement in readability of signals thru strays obtained by the above arrangement is given conservatively as 8.6-to-1. Certain remarkable variations in directional effect sometimes obtained are then discussed.