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Locating RFID tags on a surface using signal strength differentiation

IP.com Disclosure Number: IPCOM000099121D
Publication Date: 2005-Mar-14
Document File: 1 page(s) / 36K

Publishing Venue

The IP.com Prior Art Database

Abstract

ID691330

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Locating RFID tags on a surface using signal strength differentiation

Prior art: Position determination of RFID tags is a well known problem with a bunch of solutions. One is to use separate antennas at each location. One further is the use of longish antennas arranged in rows and columns. Normally the field strength at each position is more or less equal.

Novelty: Antenna or arrangement of antennas surrounding multiple positions provided for communicating with a transponder, having such a design that different efficiencies or signal strengths respectively are provided for each position.

Hence a transponder brought to a certain position provides a signal with a unique strength. Since each position is associated with a certain signal strength location of the transponder can be determined.

In the following several embodiments are shown each providing lowest efficiency/signal strength for position (1) and highest for (5). This is achieved by surrounding different positions with a different count of windings.

Yet another possibility is having a couple of identical antennas each coupled to a different resistance (not shown).

It is possible to locate transponders even with one single antenna. Hence a multiplexer having a lot of external contacts providing the connection of a bunch of antennas can be avoided as it is used in prior art systems. Can be used for smart shelves, toys (in particular board games), etc.

(a)

(c)

(e)

(b)

(d)


(1) (3) (4)


(2)


(1) (3) (4)

(1) (2) (3...