Patent ID: 8070065

Claim:
A distributed antenna array system with a centralized data reader/transmitter for determining presence and location of linearly polarized RF tags comprising: at least one designated area in a facility; a plurality of sub-areas in each of the at least one designated area; a plurality of RF tags dispersed in each sub-area, wherein each of the tags is associated with a particular respective object present in the sub area; a single backscatter reader/transmitter (BRT) in each of the at least one designated area; and a distributed antenna array in the facility comprising: at least one transmitting antenna electronically coupled to the single BRT and positioned to interrogate at least a portion of the plurality of RF tags present in each sub-area with a carrier signal, wherein a single transmitting antenna is operable to interrogate a plurality of sub-areas; a single RF signal receiving antenna present in each sub-area; and each of the single RF signal receiving antennas present in each sub-area receiving data from each of the RF tags in the sub area that have been interrogated by the at least one transmitting antenna and transferring the received tag data to the BRT, wherein wherein each RF tag comprises an antenna with two Â¼Î»; a switch coupled to one of the Â¼Î» antennas element for selectively closing and connecting both antenna elements together to form a Â½Î» antenna that reflects the BRT carrier signal and for opening to create two Â¼Î» antenna elements that absorb at least some of the BRT carrier signal; and a backscatter frequency generator on the tag and coupled to the switch for selectively opening and closing the switch and generating tag data; and wherein a master BRT is coupled to and is operable to collect the received tag data from each of a plurality of interconnected BRTs and from its respective designated area, and wherein the collected and received tag data is processed to determine the presence and location of the RF tags in a particular facility.