DIELECTRICALLY-LOADED ANTENNA
First Claim
1. A dielectrically-loaded loop 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 pair of laterally opposed groups of conductive elongate elements, each group comprising first and second substantially coextensive elongate elements which have different electrical lengths at a frequency within an operating frequency band of the antenna and 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, the antenna element structure further comprising a linking conductor linking the second ends of the first and second elongate elements of one group with the second ends of the first and second elements of the other group, whereby the first elements of the two groups form part of a first looped conductive path, and the second elements of the two groups form part of a second looped conductive path, such that the said paths have different respective resonant frequencies within the said band and each extend from the feed connection to the linking conductor, and then back to the feed connection, wherein at least one of the said elongate antenna elements comprises a conductive strip having non-parallel edges.
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Accused Products
Abstract
A dielectrically-loaded loop antenna with a cylindrical dielectric core, a feeder structure passing axially through the core, a sleeve balun encircling one end portion of the core and helical antenna elements extending from a feed connection with the feeder structure at the other end of the core to the rim of the balun. The antenna elements are arranged as a pair of laterally opposed groups of conductive elongate helical elements each having at least first and second conductive elements of different electrical lengths to form a plurality of looped conductive paths. By forming at least one of the conductive elements in each group as a conductive strip with one or both edges meandered, such that the edges of the strip are non-parallel and have different electrical lengths, additional modes of resonance are created, yielding an improvement in bandwidth.
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Citations
23 Claims
- 1. A dielectrically-loaded loop 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 pair of laterally opposed groups of conductive elongate elements, each group comprising first and second substantially coextensive elongate elements which have different electrical lengths at a frequency within an operating frequency band of the antenna and 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, the antenna element structure further comprising a linking conductor linking the second ends of the first and second elongate elements of one group with the second ends of the first and second elements of the other group, whereby the first elements of the two groups form part of a first looped conductive path, and the second elements of the two groups form part of a second looped conductive path, such that the said paths have different respective resonant frequencies within the said band and each extend from the feed connection to the linking conductor, and then back to the feed connection, wherein at least one of the said elongate antenna elements comprises a conductive strip having non-parallel edges.
- 15. 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 pair of laterally opposed groups of conductive elongate elements, each group comprising first and second substantially coextensive elongate elements which have different electrical lengths at a frequency within an operating frequency band of the antenna and 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, the antenna element structure further comprising a linking conductor linking the second ends of the first and second elongate elements of one group with the second ends of the first and second elements of the other group, whereby the first elements of the two groups form part of a first looped conductive path, and the second elements of the two groups form part of a second looped conductive path, such that the said paths have different respective resonant frequencies within the said band and each extend from the feed connection to the linking conductor, and then back to the feed connection, 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.
- 21. A dielectrically-loaded loop antenna for operation at frequencies in excess of 200 MHz, comprising an electrically insulative core of a solid dielectric 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, wherein the core has end surfaces and side surfaces and an axis of symmetry passing through the end surfaces, and wherein the antenna element structure comprises a pair of laterally opposed groups of elongate antenna elements, each group forming part of each of a plurality of looped conductive paths extending from a first terminal to a second terminal of the feed connection, and each group comprising first and second substantially coextensive elongate radiating elements which have different electrical lengths at a frequency within an operating band of the antenna and which run side-by-side on or adjacent the side surfaces of the core, wherein at least one of the said elongate elements on or adjacent the side surfaces comprises a conductive strip having non-parallel edges.
Specification