Distributed RFID antenna array utilizing circular polarized helical antennas

Abstract

In accordance with the teachings described herein, RFID systems are provided that include a distributed RFID antenna array utilizing one or more circular polarized helical antennas. A plurality of RFID tags may be used, with each RFID tag including a linear polarized antenna for communicating RFID tag signals. One or more receiver antennas may be used for receiving the RFID tag signals from the RFID tags. An RFID tag signal reader may be used to process RFID tag signals received by the receiver antennas. In one example, the receiver antennas may include a circular polarized helical antenna element. One or more transmitter antennas may be used for transmitting an RF signal to the plurality of RFID tags, the transmitter antennas including a circular polarized helical antenna element. A transmitter may be used to generate the RF signal for transmission by the transmitter antennas. In one example, the RFID tag signal reader and the transmitter may be included in a single reader/transmitter unit.

1 . A coreless helical antenna structure, comprising: 
 a dielectric base structure;    an antenna element extending away from the dielectric base structure in a spiral pattern and having a circular polarized radiation pattern; and    a plurality of support structures that attach the antenna element to the dielectric base structure.    
   
   
       2 . The coreless helical antenna structure of  claim 1 , wherein the plurality of support structures are configured to maintain the spiral pattern of the antenna element.  
   
   
       3 . The coreless helical antenna structure of  claim 1 , wherein the antenna element includes a single radiating arm that extends away from the dielectric base structure in the spiral pattern.  
   
   
       4 . The coreless helical antenna structure of  claim 3 , wherein the single radiating arm of the antenna element forms a single turn helix antenna.  
   
   
       5 . The coreless helical antenna structure of  claim 3 , wherein the single radiating arm is formed from a single antenna wire.  
   
   
       6 . The coreless helical antenna structure of  claim 1 , further comprising: 
 a metallic antenna backplane that adds directivity to the circular polarized radiation pattern of the antenna element.    
   
   
       7 . The coreless helical antenna structure of  claim 6 , wherein the metallic antenna backplane is integral to the dielectric base structure.  
   
   
       8 . The coreless helical antenna structure of  claim 1 , wherein the plurality of support structures include openings and the antenna element is supported within the openings.  
   
   
       9 . The coreless helical antenna structure of  claim 3 , wherein the plurality of support structures maintain a desired pitch of the antenna element with respect to the dielectric base structure.  
   
   
       10 . The coreless helical antenna structure of  claim 9 , wherein the antenna element has a total length and the pitch is about equal to ⅕ the total length of the antenna element.  
   
   
       11 . The coreless helical antenna structure of  claim 1 , wherein the plurality of support structures are made of a dielectric material.  
   
   
       12 . The coreless helical antenna structure of  claim 11 , wherein the plurality of support structures are plastic.  
   
   
       13 . The coreless helical antenna structure of  claim 1 , further comprising an amplifier circuit coupled to the antenna element and operable to amplify a signal received by the antenna element.  
   
   
       14 . The coreless helical antenna structure of  claim 1 , wherein the coreless helical antenna structure is configured as a receiver antenna for an RFID system.  
   
   
       15 . The coreless helical antenna structure of  claim 1 , wherein the coreless helical antenna structure is supported within an enclosure.  
   
   
       16 . A coreless helical antenna structure, comprising: 
 a dielectric base structure;    an antenna element that includes a single radiating arm extending away from the dielectric base structure in a spiral pattern and having a circular polarized radiation pattern; and    a support structure that attaches the antenna element to the dielectric base structure and that is configured to maintain a desired pitch of the antenna element with respect to the dielectric base structure.