Helical antenna having a solid dielectric core
First Claim
1. An antenna for operation at a frequency in excess of 200 MHz, comprising an electrically insulative antenna core of a solid material having a relative dielectric constant greater than 5, the core having distal and proximal ends, a three-dimensional antenna element structure which includes a plurality of longitudinally extending conductive elements, the structure being disposed on or adjacent an outer surface of the core and defining an interior volume, and a feeder structure which is connected to the antenna element structure and passes through the core from the proximal end of the core to connections with the distal ends of the longitudinally extending conductive elements, the material of the core occupying the major part of said interior volume.
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Accused Products
Abstract
An antenna for use at UHF and upwards has a cylindrical ceramic core with a relative dielectric constant of at least 5. A three-dimensional radiating element structure, consisting of helical antenna elements on the cylindrical surface of the core and connecting radial elements on a distal end face of the core, is formed by conductor tracks plated directly on the core surfaces. At the distal end face the elements are connected to an axially located feed structure in a plated axial passage of the core. The antenna elements are grounded on a plated sleeve covering a proximal part of the core which, in conjunction with the feeder structure, forms an integral balun for matching to an unbalanced feeder.
448 Citations
43 Claims
- 1. An antenna for operation at a frequency in excess of 200 MHz, comprising an electrically insulative antenna core of a solid material having a relative dielectric constant greater than 5, the core having distal and proximal ends, a three-dimensional antenna element structure which includes a plurality of longitudinally extending conductive elements, the structure being disposed on or adjacent an outer surface of the core and defining an interior volume, and a feeder structure which is connected to the antenna element structure and passes through the core from the proximal end of the core to connections with the distal ends of the longitudinally extending conductive elements, the material of the core occupying the major part of said interior volume.
- 13. An antenna for operation at a frequency in excess of 200 MHz, comprising a solid electrically insulative antenna core which has distal and proximal ends and a central longitudinal axis and is made of a material having a relative dielectric constant greater than 5, a feeder structure extending through the core on the central axis from the proximal end of the core, and, disposed on the outer surface of the core, a plurality of antenna elements which are connected to the feeder structure at the distal end of the core and extend in the direction of the proximal end of the core to a common grounding conductor, wherein the feeder structure is housed in an axial passage in the material of the core, the width of the passage being at most half the overall width of the core.
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23. An antenna for operating at a frequency in excess of 200 MHz, comprising:
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a solid electrically insulative antenna core which has a central longitudinal axis, which is made of a material having a relative dielectric constant greater than 5, and which has at least a portion having a constant external cross-section in the axial direction; a feeder structure extending through the core on the central axis; a plurality of antenna elements formed as conductors on the outer surface of the core and each comprising (a) a conductor element extending longitudinally over the portion of the core having a constant external cross-section, and (b) a radial conductor element connecting the longitudinally extending element to the feeder structure at one end of the core, said antenna elements extending in the direction of the opposite end of the core to a common grounding conductor; and a conductive sleeve extending over part of the length of the core from a connection with the feeder structure at said opposite end of the core. - View Dependent Claims (24, 25)
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26. An antenna for operation at a frequency in excess of 200 MHz, comprising a solid electrically insulative antenna core which has a central longitudinal axis and is made of a material having a relative dielectric constant greater than 5, a feeder structure extending through the core on the central axis, and, disposed on the outer surface of the core, a plurality of antenna elements which are connected to the feeder structure at one end of the core and extend in the direction of the opposite end of the core to a common grounding conductor;
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wherein the core is a solid cylinder, and wherein the antenna elements comprise at least four longitudinally extending elements on the cylindrical outer surface of the core and corresponding radial elements on a distal end face of the core connecting the longitudinally extending elements to the conductors of the feeder structure; wherein the longitudinally extending elements are of different lengths; and wherein the antenna elements comprise four longitudinally extending elements, two of which are of greater length than the other two by virtue of following meandered paths on the outer surface of the core. - View Dependent Claims (27)
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- 28. An antenna for operation at a frequency in excess of 200 MHz, comprising an antenna element structure in the form of at least two pairs of helical elements formed as helices having a common central axis, a substantially axially located feeder structure having an inner feed conductor and an outer screen conductor with each helical element having one end coupled to a distal end of the feeder structure and its other end connected to a common grounding conductor, and a balun comprising a conductive sleeve located coaxially around the feeder structure, the sleeve being spaced from the outer screen of the feeder structure by a coaxial layer of insulative material having a relative dielectric constant greater than 5, with the proximal end of the sleeve connected to the feeder structure outer screen.
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31. A method of manufacturing a plurality of antennas each such antenna comprising an antenna for operation at a frequency in excess of 200 MHz, comprising a solid electrically insulative antenna core which has a central longitudinal axis and is made of a material having a relative dielectric constant greater than 5, a feeder structure extending through the core on the central axis, and, disposed on the outer surface of the core, a plurality of antenna elements which are connected to the feeder structure at one end of the core and extend in the direction of the opposite end of the core to a common grounding conductor wherein the core has a constant external cross-section in the axial direction, with the antenna elements being conductors plated on the surface of the core and the antenna elements comprise a plurality of conductor elements extending longitudinally over the portion of the core having a constant external cross-section, and a plurality of radial conductor elements connecting the longitudinally extending elements to the feeder structure at the said one end of the core, each antenna including an integral balun formed by a conductive sleeve extending over part of the length of the core from a connection with the feeder structure at the said opposite end of the core;
- the method comprising
providing a batch of the dielectric material; making from the batch at least one test antenna core; forming the balun structure on the test antenna core by metallising on the core a balun sleeve having a predetermined nominal dimension which affects the frequency of resonance of the balun structure; measuring the resonant frequency to derive an adjusted value of the balun sleeve dimension for obtaining a required balun structure resonant frequency, and to derive at least one dimension for the antenna elements giving a required antenna elements frequency characteristic; and manufacturing from the same batch of material the plurality of antennas with a balun sleeve and antenna elements having the derived dimensions. - View Dependent Claims (32, 33, 34, 35, 36)
- the method comprising
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37. An antenna for an unbalanced signal, the antenna comprising:
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a substantially annular core having a distal end and a proximal end, the core defining an inner cylindrical feed having an inner feed surface extending from the proximal to the distal end and an outer cylindrical surface and a distal outer surface and a proximal outer surface, the annular core having a length; metal disposed on the inner feed surface and the proximal outer surface; a metallic feed disposed within the inner cylinder feed extending from the proximal to the distal ends; a conductive, cylindrical sleeve formed partly along the length on the outer surface starting from adjacent the proximal surface and coupled to the metal disposed on the inner feed surface to form a balun with the metallic feed such that signals at the distal end of the feed are substantially balanced; and a plurality of metal strips formed along the outer surface extending from the sleeve to the distal end, the pattern of the metal strips resulting in the antenna having a predefined polarization.
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38. An antenna for operation at frequencies in excess of 200 MHz comprising:
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a solid, elongate, electrically insulative core having a central longitudinal axis and made of a material having a relative dielectric constant greater than 5; a feeder structure extending through the core on the central axis; disposed on the outer surface of the core, a plurality of antenna elements which are connected to the feeder structure at one end of the core and extend in the direction of the opposite end of the core; and a conductive sleeve extending over part of the length of the core from a connection with the feeder structure at said opposite end of the core. - View Dependent Claims (39, 40)
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- 41. An antenna for operation at frequencies in excess of 200 MHz, the antenna comprising an elongate antenna element structure in the form of at least a pair of generally longitudinally extending antenna elements which are arranged in a laterally opposing configuration with respect to a central longitudinal axis of the antenna, a substantially axially located feeder structure having an inner feed conductor and an outer screen conductor with each element of said pair of antenna elements having one end coupled to the feeder structure and its other end connected to a common conductor, and a balun comprising a conductive sleeve located coaxially around the feeder structure, the sleeve being spaced from the outer screen of the feeder structure by a coaxial layer of insulative material having a relative dielectric constant greater than 5, with the proximal end of the sleeve connected to the feeder structure outer screen.
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43. An antenna for operation at a frequency in excess of 200 MHz, comprising an electrically insulative antenna core of a solid material having a relative dielectric constant greater than 5, the core having distal and proximal ends, a three-dimensional antenna element structure disposed on or adjacent an outer surface of the core and defining an interior volume, and a feeder structure which is connected to the antenna element structure at or adjacent the distal end of the core and passes through the core to the proximal end of the core, the material of the core occupying the major part of said interior volume.
Specification