Patent ID: 7372427

Claim:
A dielectrically-loaded antenna for operation at frequencies in excess of 200 MHz, comprising an electrically insulative core of a solid material having a relative dielectric constant greater than 5, a feed connection, and an antenna element structure disposed on or adjacent the outer surface of the core, the material of the core occupying the major part of the volume defined by the core outer surface, wherein the antenna element structure comprises a plurality of laterally opposed groups of conductive elongate elements, said groups being spaced apart on said core outer surface and each group comprising first and second substantially coextensive elongate elements which are coupled together at respective first ends at a location in the region of the feed connection and at respective second ends at a location spaced from the feed connection, wherein the antenna element structure further comprises a linking conductor linking the second ends of the first and second elongate elements of each of the plurality of groups of elements with the second ends of the first and second elements of the other of said plurality of groups of elements, whereby the first and second elements respectively of each of said plurality of groups form parts of different looped conductive paths, said paths having different respective resonant frequencies within an operating frequency band of the antenna and each extending from the feed connection to the linking conductor, and then back to the feed connection, and wherein at least one of the said elongate antenna elements comprises a conductive strip on the outer surface of the core, the strip having opposing edges of different lengths.