Electromagnetic radiation decoupler
An electromagnetic radiation decoupler for decoupling radiation in the wavelength range λ min to λ max . The decoupler has a first conductor layer in contact with a dielectric layer which comprises at least one area of absence and the thickness of the decoupler is less than λ min /4n, where n is the refractive index of the dielectric. The dielectric layer may be sandwiched between two conductor layers, one of which has the structure described above. The invention is also directed to methods of using and various articles comprising such a decoupler.
1. A decoupled RFID tag comprising at least one dielectric layer sandwiched between at least one first conductor layer and at least one second conductor layer, wherein the at least one first conductor layer has at least one area of absence where the first conductor layer does not overlie the dielectric layer such that, in use, an incident electromagnetic field is enhanced in the vicinity of the area of absence of the first conductor layer wherein an RF tag is located in the vicinity of the area of absence of the first conductor layer and wherein the decoupled RFID tag is capable of decoupling radiation from a conducting surface.
2. The decoupled RFID tag of claim 1 wherein the RF tag is directly connected to the first conductor layer.
3. The decoupled RFID tag of claim 1 wherein a spacer lies between the RF tag and the first conductor layer.
4. The decoupled RFID tag of claim 2 wherein the second conductor layer is the conducting surface from which radiation is decoupled.
5. The decoupled RFID tag of claim 2 wherein the RF tag is located at an edge of the dielectric layer.
6. The decoupled RFID tag of claim 2 wherein at least one edge of the dielectric layer forms at least a portion of the at least one area of absence.
7. The decoupled RFID tag of claim 2 wherein the at least one area of absence is located on the decoupler substantially at a point which corresponds to an increased dielectric field.
8. The decoupled RFID tag of claim 2 wherein the length of the first conductor layer and second conductor layers are different.
9. The decoupled RFID tag of claim 2 including two or more RF tags.
10. The decoupled RFID tag of claim 2 including a plurality of areas of absence.
11. The decoupled RFID tag of claim 2 wherein the RF tag is a low-Q tag.
12. The decoupled RFID tag of claim 2 wherein a spacer separates the RF tag from the decoupler.
13. The decoupled RFID tag of claim 2 wherein a protective housing covers the decoupler.
14. The decoupled RFID tag of claim 2 where the RF tag has a resonant frequency and wherein the decoupler has a selected resonant frequency that substantially matches a resonant frequency of the RF tag.