Identification/security tag system employing electronic doppler shifting and/or rectenna structure
US5416486A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 8, 1993 |
| Grant date | May 16, 1995 |
| Priority date | — |
| Expiry date | Nov 8, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S13/78
- WIPO fieldMeasurement
- WIPO sectorInstruments
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.