Low loss layered cover for an antenna

1. A portable radio device, comprising:

an outer cover and

a radiating antenna element at a location inside said outer cover;

wherein

the portable radio device is configured to be holdable by a user;

the outer cover comprises a layered structure at least at a location corresponding to the location of the radiating antenna element,

the layered structure comprising a layer of thermoplastic material having a loss tangent value less than 0.005 and

a coating that is one of: diamond coating, diamond-like coating, diamond-based nanocomposite coating.

2. A portable radio device according to claim 1 , wherein said radiating antenna element is attached to an inner surface of said outer cover.

3. A portable radio device according to claim 1 , wherein said layer of thermoplastic material constitutes essentially the whole outer cover.

4. A portable radio device according to claim 3 , wherein said coating covers essentially the whole outer surface of the outer cover.

5. A portable radio device according to claim 1 , wherein said layer of thermoplastic material constitutes a patch in an outer cover part made of other material.

6. A portable radio device according to claim 5 , wherein said coating extends to cover significantly larger parts of the outer cover than said patch.

7. A portable radio device according to claim 5 , wherein said coating is limited to co-exist with only said patch.

8. A portable radio device according to claim 1 , wherein:

the portable radio device comprises a ground plane,

the outer cover comprises, at a location corresponding to the location of the ground plane, thermoplastic material the loss tangent value of which is less than 0.005, and

the outer cover comprises, on the outer surface thereof and at a location corresponding to the location of the ground plane, a coating that is one of: diamond coating, diamond-like coating, diamond-based nanocomposite coating.

9. A portable radio device according to claim 1 , wherein the outer cover comprises paint or lacquer on an outer surface thereof.

10. An outer cover part for a portable radio device, wherein:

the outer cover part comprises a layered structure at least at a location adapted to correspond to a location of a radiating antenna element in the portable radio device, wherein

the layered structure comprises a layer of thermoplastic material having a loss tangent value less than 0.005, and

a coating that is one of: diamond coating, diamond-like coating, diamond-based nanocomposite coating.

11. An outer cover part according to claim 10 , wherein said thermoplastic material constitutes essentially the whole outer cover part.

12. An outer cover part according to claim 10 , wherein said layer of thermoplastic material constitutes a patch in another material that constitutes a frame of the outer cover part.

13. An outer cover part according to claim 10 , wherein the outer cover part comprises paint or lacquer on an outer surface thereof.

14. A radio frequency module for a portable radio device, comprising:

an outer cover and

a radiating antenna element at a location inside said outer cover;

wherein:

the radio frequency module is configured for a portable radio device that is holdable by a user;

the outer cover comprises a layered structure at least at a location corresponding to the location of the radiating antenna element,

the layered structure comprising a layer of thermoplastic material having a loss tangent value less than 0.005, and

a coating that is one of: diamond coating, diamond-like coating, diamond-based nanocomposite coating.

15. A radio frequency module according to claim 14 , wherein:

the radio frequency module comprises a ground plane,

the outer cover comprises, at a location corresponding to a location of the ground plane, thermoplastic material having a loss tangent value less than 0.005, and

the outer cover comprises, on an outer surface thereof and at a location corresponding to the location of the ground plane, a coating that is one of: diamond coating, diamond-like coating, diamond-based nanocomposite coating.

16. An antenna structure for a portable radio device, comprising:

an outer cover part and

a radiating antenna element at a location inside said outer cover part;

wherein:

the outer cover part comprises a layered structure at least at a location corresponding to the location of the radiating antenna element,

the layered structure comprising a layer of thermoplastic material having a loss tangent value less than 0.005, and

a coating that is one of: diamond coating, diamond-like coating, diamond-based nanocomposite coating.

17. A method for manufacturing an antenna structure for a portable radio device, comprising:

producing an outer cover part and

producing a radiating antenna element at a location inside said outer cover part;

making the outer cover part comprise a layered structure at least at a location corresponding to the location of the radiating antenna element, the layered structure comprising a layer thermoplastic material having a loss tangent value less than 0.005, and

coating at least the layered structure with a coating that is one of: diamond coating, diamond-like coating, diamond-based nanocomposite coating.

18. A method according to claim 17 , wherein the method comprises producing the outer cover part in an injection molding process and embedding said radiating antenna element into the injection molded material of said outer cover part.