Item finding using RF signalling

A system for locating an item having an RFID tag with a unique identifier, comprising:

• an annunciator for providing item location information to a system user;
• a data input for entering the unique identifier;
• a memory coupled to the data input for storing the unique identifier;
• one or more antennas for transmitting interrogation signals to the RFID tag and receiving responses from the RFID tag, wherein at least one of the one or more antennas is directional so as to have a field of view that is spatially limited in azimuth or elevation and range;
• an RFID tag interrogator coupled to the one or more antennas, wherein the interrogator is adapted to transmit an RFID tag interrogation signal to and receive a response from the RFID tag by means of the one or more antennas, wherein the response includes an identifier for the RFID tag providing the response;
• a processor coupled to the annunciator, the data input, the memory and the interrogator, wherein the processor compares the RFID tag identifier received by the interrogator to the unique identifier stored in the memory and if they match, causes the annunciator to emit a user alert signal dependant on the proximity to the interrogator of the RFID tag providing the matching response.

A method of locating a particular item from among a plurality of items, using an RFID tag interrogator, wherein each item has thereon an RFID) tag containing a unique identifier, comprising:

• obtaining and storing the unique identifier for the particular item desired to be located;
• interrogating the tags of the plurality of items to determine their unique identifiers;
• comparing the unique identifiers obtained from the plurality of items to the stored unique identifier for the particular item desired to be located and, if there is a match,
• presenting to a user relative position dependant data for the tag having the unique identifier for the particular item desired to be located;
• and
• repeating the interrogating, comparing and presenting steps for different locations of the interrogator, thereby obtaining position dependant data pointing to the particular item.

A method by which a user can identify items containing RFID tags using a tag interrogator, comprising:

• interrogating the RFID tags in the field of view of the interrogator;
• obtaining the ID#s associated with the read tags;
• determining whether new ID#s have been obtained and if so,
• providing an announcement to the user for each new ID#, and
• repeating the interrogating, obtaining, determining and providing steps until no new ID#s are obtained.