Multiple antenna diversity on mobile telephone handsets, PDAs and other electrically small radio platforms

1. An antenna device including a dielectric substrate having a first, upper surface and a second, lower surface, a conductive groundplane on the second surface or located between the first and second surfaces, and at least two conductive feedlines formed on the first surface and extending from feed points to predetermined radiating points at edge or corner parts of the first surface, wherein the groundplane does not extend under the radiating points but is configured as to extend between the radiating points, characterised in that the feedlines are provided with discrete dielectric elements at the radiating points.

2. A device as claimed in claim 1 , wherein the feedlines are microstrip feedlines.

3. A device as claimed in claim 1 , wherein there are provided four feedlines and thus four radiating points on the first surface.

4. A device as claimed in claim 3 , wherein the substrate is generally rectangular in shape with four corner parts and four edge parts, and wherein each feedline extends into a respective corner part.

5. A device as claimed in claim 3 , wherein the substrate is generally rectangular in shape with four, corner parts and four edge parts, and wherein two feedlines extend respectively into adjacent corner parts, and two feedlines extend respectively to opposed edge parts each adjacent to one of the adjacent corner parts.

6. A device as claimed in claim 3 , wherein the feedlines are electrically connected to driving circuitry in such a way that the feedlines can be driven pairwise rather than individually.

7. A device as claimed in claim 1 , wherein there are provided two feedlines and thus two radiating points on the first surface.

8. A device as claimed in claim 7 , wherein the two feedlines extend into two adjacent coiner parts of the first surface.

9. A device as claimed in claim 1 , wherein the feedlines are disposed at adjacent radiating points so as to be mutually at tight angles to each other.

10. A device as claimed in claim 1 , wherein the feedlines are widened at the radiating points and configured with rectangular, conical, circular, elliptical, annular or polygonal shapes.

11. A device as claimed in claim 1 , wherein the feedlines are provided with dielectric ceramic elements at the radiating points.

12. A device as claimed in claim 11 , wherein the ceramic elements are soldered onto the feedlines at the radiating points.

13. A device as claimed in claim 11 , wherein the ceramic elements are metallised on surfaces thereof that contact the feedlines.

14. A device as claimed in claim 11 , wherein the ceramic elements are shaped as sectors of a cylinder having a pointed edge and a rounded edge.

15. A device as claimed in claim 14 , wherein the ceramic elements are disposed on the first surface such that the pointed edges point mutually outwardly.

16. A device as claimed in claim 14 , wherein the ceramic elements are disposed on the first surface such that the pointed edges point mutually inwardly.

17. A device as claimed in claim 11 , wherein the ceramic elements have an oblong shape and are disposed in alignment with the feedlines at the radiating points.

18. A device as claimed in claim 1 , wherein the feedlines are widened at the radiating points.

19. An antenna device including a dielectric substrate having a first, upper surface and a second, lower surface, a conductive groundplane on the second surface or located between the first and second surfaces, and four conductive feedlines formed on the first surface and extending from feed points to predetermined radiating points at edge or corner parts of the first surface, wherein the groundplane does not extend under the radiating points but is configured as to extend between the radiating points, characterised in that two of the radiating points are located at adjacent corner parts of the first surface and two of the radiating points are located at opposed edge parts of the first surface.