Anti-collision interrogation pulse focusing system for use with multiple surface acoustic wave identification tags and method of operation thereof

Abstract

The present invention provides a system for avoiding code collisions from multiple SAW identification tags and a method of operating such system. In one embodiment the invention provides for (1) focusing an interrogation pulse to within a defined space; and (2) discriminating between coded responses returned from tags located within such defined space.

1 . A system for avoiding code collisions from multiple SAW identification tags, comprising: 
 a focusing means for focusing an interrogation pulse by concentrating said interrogation pulse to within a defined space; and    a discrimination means for discriminating between coded responses returned from tags located within said defined space.    
   
   
       2 . The system as described in  claim 1  wherein beam steering is used to focus said interrogation pulse within said defined space.  
   
   
       3 . The system as described in  claim 1  wherein an antenna is used to focus said interrogation pulse within said defined space.  
   
   
       4 . The system as described in  claim 3  wherein said antenna is a parallel conductor pair.  
   
   
       5 . The system as described in  claim 3  wherein said antenna is a helical antenna.  
   
   
       6 . The system as described in  claim 3  wherein said antenna is a dielectric waveguide antenna.  
   
   
       7 . The system as described in  claim 3  further comprising a reflector coupled to said antenna.  
   
   
       8 . The system as described in  claim 7  wherein said reflector is an elliptical trough.  
   
   
       9 . The system as described in  claim 7  wherein said reflector is selected from the group consisting of: 
 a circular reflector;    a curved reflector;    a parabolic reflector;    a re-entrant cavity; and    an elliptical reflector.    
   
   
       10 . The system as described in  claim 1  wherein said interrogation pulse is focused within said defined space by a waveguide.  
   
   
       11 . The system as described in  claim 10  wherein said waveguide projects a circular polarized beam.  
   
   
       12 . The system as described in  claim 10  wherein said waveguide has a first feed of about one-quarter wave length positioned at about a 90° position relative to a second feed of about one-quarter wave length.  
   
   
       13 . The system as described in  claim 10  wherein a reflector is coupled to said waveguide.  
   
   
       14 . The system as described in  claim 13  wherein said reflector is selected from the group consisting of: 
 a circular reflector;    a curved reflector;    a parabolic reflector;    a re-entrant cavity; and    an elliptical reflector.    
   
   
       15 . A method for operating a system for avoiding code collisions from multiple SAW identification tags, comprising: 
 focusing an interrogation pulse to concentrate said interrogation pulse to within a defined space; and    discriminating between coded responses returned from tags located within said defined space.    
   
   
       16 . The method as described in  claim 15  wherein said focusing uses beam steering.  
   
   
       17 . The method as described in  claim 15  wherein said focusing uses an antenna.  
   
   
       18 . The method as described in  claim 17  wherein said antenna is a parallel conductor pair.  
   
   
       19 . The method as described in  claim 17  wherein said antenna is a helical antenna.  
   
   
       20 . The method as described in  claim 17  wherein said antenna is a dielectric antenna.  
   
   
       21 . The method as described in  claim 17  further comprising a reflector coupled to said antenna.  
   
   
       22 . The method as described in  claim 21  wherein said reflector is an elliptical trough.  
   
   
       23 . The method as described in  claim 21  wherein said reflector is selected from the group consisting of: 
 a circular reflector;    a curved reflector;    a parabolic reflector;    a re-entrant cavity; and    an elliptical reflector.    
   
   
       24 . The method as described in  claim 15  wherein said focusing uses a waveguide.  
   
   
       25 . The method as described in  claim 24  wherein said waveguide projects a circular polarized beam.  
   
   
       26 . The method as described in  claim 24  wherein said waveguide has a first feed of about one-quarter wave length positioned at about a 90° position relative to a second feed of about one-quarter wave length.  
   
   
       27 . The method as described in  claim 24  wherein a reflector is coupled to said waveguide.  
   
   
       28 . The method as described in  claim 27  wherein said reflector is selected from the group consisting of: 
 a circular reflector;    a curved reflector;    a parabolic reflector;    a re-entrant cavity; and    an elliptical reflector.    
   
   
       29 - 41 . (canceled)