04163977 is referenced by 26 patents and cites 4 patents.

A double loop receiver used in conjunction with a transmitter broadcasting at low frequencies as a vertical magnetic dipole. The two loops are connected with their planes parallel in a resonant circuit, thereby cancelling atmospherics generated by distant thunderstorms and allowing the receiver to receive only the signal produced by the near transmitter. The loops are rotated around a horizontal axis perpendicular to the connecting line between the loops until a maximum signal is obtained. The direction of the connecting line is varied until the maximum signal shows the gradient and the direction to the transmitter. By noting the position of the loops and the loop angles with respect to the horizontal, the position of a transmitter buried in the ground can be determined. This system has particular utility in locating lost miners buried in a cave-in. Additionally, the double loop receiver concept can be used to detect subsurface ore deposits.

Title
Double loop receiver-transmitter combination
Application Number
5/862905
Publication Number
4163977
Application Date
December 21, 1977
Publication Date
August 7, 1979
Inventor
Jurgen K Polstorff
702 Drake Ave., Huntsville, 35802
AL, US
Agent
Mitchell B Wasson
IPC
H04B 15/00
H04B 5/00
G01S 5/16
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