UHF RFID device for communicating with UHF RFID tags within a small cavity
View Patent ↗A UHF radiofrequency identification (RFID) device operating at an UHF wavelength for enabling communication of an UHF RFID reader with UHF RFID tags positioned within a cavity having an internal volume with a largest dimension that is below twice said UHF wavelength. The device comprises a wire wave guide having an entry extremity and at least one exit extremity and positioned within said at least one cavity above a ground surface, wherein said entry extremity is fed by said UHF RFID reader and said at least one exit extremity is connected to said ground surface via a load.
1. A UHF radiofrequency identification (RFID) device operating at an Ultra-High Frequency (UHF) wavelength to enable communication of a UHF radio frequency identification (RFID) reader with a number of UHF RFID tags positioned within at least one cavity of a container or a toolbox having an internal volume with a largest dimension, wherein said largest dimension is below twice said UHF wavelength and wherein said UHF RFID device comprises a wire wave guide positioned above a ground surface within said at least one cavity, configured to generate a propagative non-radiating UHF electromagnetic wave within said at least one cavity and having an entry extremity and at least one exit extremity, wherein said entry extremity is fed by said UHF RFID reader and said at least one exit extremity is connected to said ground surface via a load.
2. The UHF RFID device according to claim 1 , wherein said ground surface is a cavity side whose area is the largest.
3. The UHF RFID device according to claim 1 , wherein said wire wave guide is positioned along a longest dimension of the cavity.
4. The UHF RFID device according to claim 1 , wherein said load is a 50 ohm resistor.
5. The UHF RFID device according to claim 1 , wherein said wire wave guide is composed of a conductive line.
6. The UHF RFID device according to claim 1 , wherein said wire wave guide is composed of two conductive lines positioned in parallel and wherein a feed line of one of said two conductive lines is a half wave length longer than a feed line of the other conductive line.
7. The UHF RFID device according to claim 6 , wherein each of said two conductive lines are positioned at a distance above said ground surface within the range 2 mm to 4 mm and at a distance from cavity sides adjacent to said ground surface within the range 2 mm to 4 mm.
8. The UHF RFID device according to claim 1 , wherein said conductive line is composed of two straight conductors made of discontinued conductive segments positioned side by side so that the line discontinuities are distributed alternatively along said two straight conductors and with at the extremity of each of said two straight conductors an end segment whose length is half the length of the other said segments.
9. The UHF RFID device according to claim 1 , wherein said conductive line is a micro-strip made of copper or aluminum lines drawn on an insulating support.
10. The UHF RFID device according to claim 1 , wherein said entry extremity of said wire wave guide is fed by said UHF RFID reader via a directional coupler, which is connected to a same number of UHF RFID devices as a number of said at least one cavity.
11. A toolbox with a plurality of compartments, the bottom of which forms a ground surface, wherein each compartment comprises a respective Ultra-High Frequency (UHF) radio frequency identification (RFID) device, the UHF RFID devices which operate at an UHF wavelength to enable communication of a UHF RFID reader with UHF RFID tags positioned within at least one cavity of a container or a toolbox having an internal volume with a largest dimension, wherein said largest dimension is below twice said UHF wavelength and wherein said UHF RFID device comprises a wire wave guide positioned above a ground surface within said at least one cavity, configured to generate a propagative non-radiating UHF electromagnetic wave within said at least one cavity and having an entry extremity and at least one exit extremity, wherein said entry extremity is fed by said UHF RFID reader and said at least one exit extremity is connected to said ground surface via a load.
12. The toolbox of claim 11 , wherein the UHF RFID reader is external to the toolbox and is configured with a coaxial cable adapted to be connected onto a BNC connector, which is connected to said directional coupler installed in the toolbox.
13. A method for enabling communication of an Ultra-High Frequency (UHF) radio frequency identification (RFID) reader with UHF RFID tags operating at an UHF wavelength and positioned within at least one cavity of a container or a toolbox, whose largest dimension is below twice said UHF wavelength, comprising: positioning within said at least one cavity above a ground surface a wire wave guide having an entry extremity and at least one exit extremity, wherein said wire wave guide is configured to generate a propagative non-radiating UHF electromagnetic wave within said at least one cavity and wherein said entry extremity of said wire wave guide is fed by said UHF RFID reader and said at least one exit extremity of said wire wave guide is connected to said ground surface via a load, and reading the information of said UHF RFID tags.
14. The method as claimed in claim 13 , wherein said ground surface is formed by one of the conductive sides of each of said at least one cavity.