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. 16, 1995
Filed:
Nov. 08, 1993
Peter Koert, Washington, DC (US);
George M Metze, Gaithersburg, MD (US);
Mark Machina, Alexandria, VA (US);
APTI, Inc., , DE (US);
Abstract
An identification/security tag system, including miniaturized tags which can be readily concealed, utilizes a concept of 'electronic' Doppler shifting to generate a frequency shifted signal in response to an interrogation signal. The frequency shifted signal is used to identify individual tags. The implementation of electronic Doppler shifting permits the utilization of conventional police/sport radar guns as a combined transmitter and receiver unit, thereby greatly reducing the expense of the system. The high frequency operation of the system permits size of the tag to be significantly reduced with respect to the size of tags used in conventional tag systems. Rectenna circuitry is further employed to eliminate the need for an active power supply in the tag in some applications.