MAINTAINING A CIRCULARLY POLARIZED MAGNETIC FIELD AT A MOVING POINT

• US 3,656,161 A
• Filed: 12/31/1969
• Issued: 04/11/1972
• Est. Priority Date: 12/31/1969
• Status: Expired due to Term

• Current Assignee: William Frederick Macpherson
• Original Assignee: William Frederick Macpherson
• Inventors: MacPherson, William Frederick
• Primary Examiner(s): Farley, Richard A.
• Assistant Examiner(s): Potenza, J. M.
• Application Number:
  US04/889,464
• Time in Patent Office: 832 Days
• Field of Search: 343/1PE,112D 340/25,195,183,258,195,25 61/72.5 175/45
• US Class Current: 342/365
• CPC Class Codes: F41G 7/24 Beam riding guidance systems conical-scan beam beacons therefor G01S1/42
• CPC Class Codes: H04B 13/02 Transmission systems in which the medium consists of the earth or a large mass of water thereon, e.g. earth telegraphy

Abstract

A circularly polarized magnetic field is maintained at the location of a subsoil penetrator traveling beneath a dipolequadrupole field propagating antenna which serves as a reference frame with respect to which the penetrator is guided.

Claims

1. A method for maintaining a circularly polarized magnetic field at a moving point, comprising the steps of:

energizing an antenna, consisting of dipole and quadrupole legs, with first and second sinusoidal signals respectively each of frequency omega f, the signals having a phase separation Beta ;

multiplying the field-induced voltages in two mutually perpendicular coils located at said moving point by terms cos omega mt and sin omega mt, where omega m <

<

omega f;

summing the resultant two products;

multiplying the resultant sum by cos omega ft in a first channel and by cos ( omega ft + Beta ) in a second channel;

filtering from said said channel all signals associated with the term omega f;

computing a phase separation angle Psi between the signals in said first and second channels;

adjusting the energization of said dipole leg unTil the peak magnitude of said second channel signal is equal to a set reference voltage denoting a desired minimum dipole field strength;

adjusting the energization of said quadrupole leg until the peak magnitude of said second channel signal is equal to the peak magnitude of said first channel signal; and

adjusting said phase separation Beta until that angle plus the phase separation angle Psi are supplementary.

2. Apparatus for maintaining circular polarization of a magnetic field at a specified point R, Psi beneath a field-propagating antenna, the field created by two vectors having peak values D, Q and rotating at a frequency omega f with phase separation Beta , comprising:

two mutually perpendicular coils located at said point;

means for multiplying the field-induced voltages in said coils by terms sin omega mt and cos omega mt respectively where omega m <

<

omega f;

means for summing the resultant two products;

means for multiplying the resultant sum by cos omega ft in a first channel and by cos ( omega ft + Beta ) in a second channel;

means for filtering from each said channel all signals associated with the term omega f;

means for monitoring the magnitudes and phase differences of the remaining signals in the respective channels; and

means for adjusting said magnetic field using the monitored terms to satisfy the relationships D Q and Psi + Beta pi radians.

3. Method pursuant to claim 1 wherein said moving point is in soil and said coils are mounted in a subsoil penetrator, said antenna as laid out above said soil constituting a reference frame with respect to which said penetrator is to be guided.

4. Apparatus pursuant to claim 2 wherein said specified point is in soil and said coils are mounted in a subsoil penetrator, said antenna as laid out above said soil constituting a reference frame with respect to which said penetrator is to be guided.