Patent ID: 6690336
Filing Date: 2004-02-10
Classification: H01Q,H04B

Abstract:
An antenna for operation at frequencies in excess of 200 MHz comprising:an insulative core of a solid material having a relative dielectric constant greater than 5, the outer surface of the core defining a volume the major part of which is occupied by the solid material; a feeder structure comprising a length of transmission line; an electrically conductive structure including a plurality of radiating elements connected to the transmission line at a first position, and a link element separately connecting the radiating elements to the transmission line at a second position, spaced from the first position along the feeder structure, the electrically conductive structure being disposed on or adjacent the outer surface of the core; wherein the core and conductive structure are configured such that the antenna has at least two modes of resonance of differing types which are coupled thereby to define together an operating frequency band for signals fed to or received from the transmission line, said two modes of resonance of differing types I) occurring at different frequencies and being associated with different respective radio frequency (r.f.) current patterns in the conductive structure, each pattern including the said radiating elements and II) characterized by different overall conducting paths through which the r.f current flows over part of the conductive structure.