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:
Mar. 02, 1999
Filed:
May. 28, 1997
Wen-Liang Wu, Thorofare, NJ (US);
Alan Dutcher, West Deptford, NJ (US);
Checkpoint Systems, Inc., Thorofare, NJ (US);
Abstract
A multiple loop antenna is provided which may be connected to either a transmit circuit, a receive circuit, or a transmit/receive circuit. When powered by a transmit circuit, the antenna generates radio frequency magnetic fields in an area or zone proximate to the antenna, but which are substantially canceled at a distance approximately one wavelength and more from the antenna, thereby defining a surveillance zone proximate to the antenna. The loop antenna includes a first, upper loop and a second, lower loop. The upper and loser loops lie in separate, spaced, parallel planes and are preferably disposed at a fixed angle with respect to the surveillance zone.