Electromagnetic enhancement and decoupling
Apparatus and methods for providing a substantially surface independent tagging system are disclosed. A resonant dielectric cavity is defined between upper and lower conducting layers, and closed at one end by a conducting base portion. Incident radiation couples into the cavity and is resonantly enhanced. An electronic device or tag paced at the edge of the cavity experiences a high electric field strength on account of this enhancement and is driven into operation.
1. A substantially surface independent EM tag comprising:
an electromagnetic radiation decoupler comprising a cavity structure which comprises a conducting base portion connected to a first conducting side wall formed by a first conducting layer and a second conducting side wall formed by a second conducting layer, the first conducting side wall and the second conducting side wall being substantially parallel to each other, said first and second conducting layers respectively defining upper and lower layers;
a cavity structure area of absence; and
an electronic device mounted in the cavity structure area of absence, the electronic device comprising a chip coupled to an integral antenna.
2. The EM tag of claim 1 wherein a dielectric material is disposed within the cavity structure.
3. The EM tag of claim 1 wherein the first conducting side wall has a continuous length of approximately λ d /4 measured from the conducting base portion, where λ d is the wavelength, in the dielectric material, of EM radiation at the frequency of operation ν.
4. The EM tag according to claim 1 wherein a dielectric material is disposed within the cavity structure as a continuous layer adjacent the conducting base portion which extends for substantially as long as the first conducting side wall.
5. The EM tag according to claim 1 wherein a dielectric material is disposed within the cavity structure and extends beyond the end of the first conducting side wall.
6. The EM tag according to claim 1 wherein the first and second conducting side walls and conducting base portion comprise a continuous layer of material.
7. The EM tag according to claim 1 the decoupler comprises more than one cavity structure.
8. The EM tag as claimed in claim 1 wherein where in electronic device is mounted in the vicinity of the edge of the first conducting side wall.
9. The EM tag as claimed in claim 8 wherein the electronic device is low Q-tag having a small, unturned antenna.
10. The EM tag as claimed in claim 1 wherein the cavity is a resonant dielectric cavity which is suitable for enhancing an incident electric field at an open edge of said cavity.
11. The EM tag according to claim 10 , wherein said electronic device is powered by differential capacitive coupling.