Multistatic antenna configuration for radio frequency identification (RFID) systems

• US 8,350,701 B2
• Filed: 05/29/2009
• Issued: 01/08/2013
• Est. Priority Date: 03/01/2005
• Status: Active Grant

• Current Assignee: RUIZHANG TECHNOLOGY LIMITED COMPANY
• Original Assignee: Alien Technology Corporation
• Inventors: Carrender, Curtis L., Price, John Michael
• Primary Examiner(s): MULLEN, THOMAS J
• Application Number:
  US12/475,166
• Publication Number:
  US 20090231105A1
• Time in Patent Office: 1,320 Days
• Field of Search: 340/572.4, 340/572.7, 340/10.1, 340/825.49, 340/8.1
• US Class Current: 340/572.7
• CPC Class Codes: G06K 7/10346 the antenna being of the far field type, e.g. HF types or dipoles
• CPC Class Codes: G06K 7/10356 using a plurality of antennas, e.g. configurations including means to resolve interference between the plurality of antennas
• CPC Class Codes: H01Q 1/2216 used in interrogator/reader equipment
• CPC Class Codes: H01Q 3/24 varying the orientation by switching energy from one active radiating element to another, e.g. for beam switching
• CPC Class Codes: H01Q 3/44 varying the electric or magnetic characteristics of reflecting, refracting, or diffracting devices associated with the radiating element

Abstract

Methods and apparatuses for configuring antennae of radio frequency identification reader systems. In one aspect of an embodiment, a radio frequency identification (RFID) reader system, includes: a receiver; a radio frequency (RF) source for signal transmission; and a switch matrix coupled with the receiver and the radio frequency source to selectively couple the receiver and the radio frequency source to a plurality of non-collocated antennae. When in a first mode, the switch matrix connects the radio frequency source to a first one of the antennae for signal transmission and the receiver to a second one of the antennae for signal reception; and when in a second mode, the switch matrix connects the first one of the antennae for signal reception and, in one example, the second one or another one of the antennae to the RF source for signal transmission.

Claims

1. A radio frequency identification (RFID) reader, comprising:

a plurality of antennae;

a radio frequency (RF) source for signal transmission;

a receiver to receive backscattered modulated signals from at least one RFID tag; and

a phase comparison circuit coupled with the receiver, wherein the phase comparison circuit is configured to compare relative phases of backscatter received from at least two of the plurality of antennae.

2. The RFID reader of claim 1, wherein the plurality of antennae are non-collocated antennae.

3. The RFID reader of claim 2, further comprising a processor coupled with the phase comparison circuit to determine location information of the at least one RFID tag from the comparison of relative phases of backscatter received from at least two of the plurality of antennae.

4. The RFID reader of claim 2, further comprising a processor coupled with the phase comparison circuit to determine distance information of the at least one RFID tag from the comparison of relative phases of backscatter received from at least two of the plurality of antennae.

5. The RFID reader of claim 2, further comprising a processor coupled with the phase comparison circuit to determine a length of the signal path of the at least one RFID tag from the comparison of relative phases of backscatter received from at least two of the plurality of antennae.

6. The RFID reader of claim 1, further comprising a low noise amplifier coupled with the receiver and one of the plurality of antennae for signal reception.