Systems and methods for stirring electromagnetic fields and interrogating stationary RFID tags
US7884725B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 21, 2007 |
| Grant date | Feb 8, 2011 |
| Priority date | — |
| Expiry date | Nov 23, 2028 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05K2201/09127
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
RFID tags are used for many purpose including tracking. RFID interrogators are used to retrieve information from tags. In many applications, RFID interrogators and RFID tags remain stationary during interrogation. Regions of low energy due to interference from either additional antenna or reflections from RFID tags and objects can impede or prohibit the reading of RFID tags residing in such regions. Stirring of the generated electromagnetic field is a method of moving around the regions of low energy, where tags can not be read, during the interrogation process. Mechanical stirring is accomplished by introducing a conductor into the electromagnetic field and moving it about in the field. Solid state stirring is accomplished by introducing a variable conductor into the field and varying the conductivity of the variable conductor. Mathematical stirring is accomplished by use of a plurality of antenna and controlling the phase difference between the antenna in a configuration known as phased antenna arrays.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.