Patent ID: 8279134

Claim:
A dielectrically loaded antenna for operation at a frequency in excess of 200 MHz, comprising a dielectric core of a solid material having a relative dielectric constant greater than 5, an antenna element structure disposed on or adjacent an outer surface of the core, and, coupled to the antenna element structure, a feed structure extending through a passage in the core between a distal surface portion of the core and an oppositely directed proximal surface portion of the core, wherein a cavity is formed into the base of the dielectric core, a base of the cavity forming the proximal surface portion, wherein the antenna element structure comprises a plurality of elongate antenna elements extending from connections with the feed structure at or adjacent the distal end of the passage through the core, and over laterally directed surface portions of the core to connections with a linking element in the form of an outer conductive layer extending around the core, which layer extends from the connections to an inner conductive layer on the wall of the cavity, the inner conductive layer being connected to the feed structure at or adjacent the other end of the passage through the core and wherein the radial extent of the cavity is greater than the radial extent of the passage.