Dielectrically loaded antenna and a handheld radio communication unit including such an antenna
First Claim
1. An 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, 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 single pair of elongate antenna elements which are disposed in an opposing configuration on or adjacent the core outer surface and which are co-extensive, with each element extending between axially spaced-apart positions, and wherein said elongate antenna elements each have a first end and a second end, the first ends being interconnected so that said antenna elements form together a path of conductive material around the core, the second ends of the antenna elements constituting a feed connection.
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Accused Products
Abstract
A miniature antenna for operation at frequencies in excess of 200 MHz has a ceramic core in the form of a cylindrical rod having a relative dielectric constant greater than 5. Plated on the outer surfaces of the core is an antenna element structure comprising a single pair of oppositely disposed helical elements having a common central axis coincident with the central axis of the core. At a distal end of the antenna, they are connected to a coaxial feeder structure passing axially through the core, and at their proximal ends they are connected to the rim of a cylindrical trap conductor which, at the proximal end of the core is coupled to the screen of the feeder structure. At the operating frequency, the antenna behaves as a loop, the radiation response having nulls directed generally perpendicularly on each side of a plane containing the central axis of the core and the connections of the 6 helical elements with the feeder structure and with the conductive sleeve. The antenna is intended primarily for a handheld communication unit such as a cellular or cordless telephone handset, the presence of the nulls in the radiation pattern reducing radiation into the user'"'"'s head.
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Citations
39 Claims
- 1. An 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, 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 single pair of elongate antenna elements which are disposed in an opposing configuration on or adjacent the core outer surface and which are co-extensive, with each element extending between axially spaced-apart positions, and wherein said elongate antenna elements each have a first end and a second end, the first ends being interconnected so that said antenna elements form together a path of conductive material around the core, the second ends of the antenna elements constituting a feed connection.
- 28. An antenna for operation at frequencies in excess of 200 MHz, comprising an electrically insulative core having a central axis and being formed of a solid material having a relative dielectric constant greater than 5, 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 single pair of elongate antenna elements which are disposed in an opposing configuration so that said antenna elements form a loop extending around the core and terminated at a feed connection, the antenna having a radiation pattern which is omni-directional with the exception of a null centred on a null axis passing through the core transversely with respect to said central axis.
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34. A handheld radio communication unit having a radio transceiver, an integral earphone for directing sound energy from an inner face of the unit which, in use, is placed against the user'"'"'s ear, and an antenna coupled to the transceiver and located in the region of the earphone, wherein the antenna comprises:
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an electrically insulative core having a relative dielectric constant greater than 5, an antenna element structure including a pair of antenna elements disposed co-extensively in an opposing configuration on or adjacent the core outer surface and connected together to form a loop, the antenna element structure thereby having a radiation pattern which has a null in a direction transverse to the antenna elements, and wherein the antenna is so mounted in the unit that the null is directed generally perpendicularly to said inner face of the unit to reduce the level of radiation from the unit in the direction of the user'"'"'s head. - View Dependent Claims (35, 36)
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- 37. A radio telephone handset antenna comprising a substantially cylindrical electrically insulative core which is formed of a solid material having a relative dielectric constant greater than 5 and which defines a central antenna axis, 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 comprise a single pair of axially co-extensive and coaxial half-turn helical elements disposed in a diametrically opposed configuration, the elements being interconnected at respective ends to form a loop of conductive material around the core, the other ends of the elements constituting a feed connection, whereby the antenna constitutes a dielectrically foreshortened antenna with a radiation pattern having a null directed transversely to the axis for mounting on a handset body with the null oriented so as to be directed towards the user'"'"'s head thereby to reduce radiation into the head.
Specification