The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 09, 1998
Filed:
Mar. 15, 1996
Donald Lionel Hore, Stoke Bishop, GB;
Alan John Hopkin, Bradley Stoke, GB;
Radiodetection Limited, Bristol, GB;
Abstract
Two vertical, parallel, horizontally spaced signal coils are connected in series but in opposite phase across an a.c. source. Thus a buried conductor located centrally beneath the coils experiences an alternating magnetic field whose strength is due to the addition of the fields induced by the two coils. The field strength may be further enhanced by one or more of: providing a ferromagnetic flux diverter between the upper ends of the coils; placing a conductive nonmagnetic screen between them; connecting a tuning capacitor in parallel with the coils; or providing a tuning circuit having series-connected secondary coils which are flux-linked to respective signal coils and are in parallel with a capacitor. There may be a switch arrangement for switching the signal coils to in-phase connection, for use when they are oriented horizontally.