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:
May. 17, 1983
Filed:
Oct. 31, 1980
Michael N Cooper, Flushing, NY (US);
Knogo Corporation, Hicksville, NY (US);
Abstract
An electronic theft detection apparatus for detection of saturable magnetic targets has transmitter and receiver antennas formed of single turn loops of rigid metal pipe. The antennas are rectangular and have a width, in the direction of passage, through the interrogation zone, less than the length of a shopping cart. The transmitter antenna is in the form of a rectangular loop and the receiver antenna is of the same overall size and configuration but is bisected with a conductor to form two balanced loops. The antennas are purely inductive and a series resonant circuit is inductively coupled into the transmitter antenna and a parallel resonant circuit is inductively coupled out of the receiver antenna. Special circuits are also provided for temporarily disabling the apparatus when a related lower harmonic frequency signal decreases in amplitude.