Means for tuning a loaded coil antenna
First Claim
1. A tunable antenna loading apparatus, comprising:
- a loading coil having an antenna connection means adjacent one end thereof and a ground connection means adjacent the other end thereof and a feed connection means intermediate said antenna connection means and ground connection means, said loading coil being fixedly supported with respect to said antenna connection means and ground connection means, said loading coil comprising a multiple turn conductor;
a conductive member close spaced from said coil and having at least a portion arranged to face at least a portion of said coil, such that said conductive member and said coil simulate the opposed plates of a capacitor, said conductive member being electrically connected to said ground connecting means;
dielectric means interposed between said coil and conductive member to act as a dielectric of a capacitor, said conductive member being adjustably movable with respect to said coil to vary the distributive capacitance supplied by the relationship of said coil and conductive member and with the inductance of said coil to adjust the resonant frequency of the antenna apparatus;
a conductive ground strip electrically conneced to said ground connecting means adjacent said other end of said coil and extending lengthwise along said coil toward said one coil end and being electrically insulated from said coil by said dielectric means, said conductive member being in electrical contact with said ground strip, said conductive member comprising a conductive vane pivotally fixed on said ground strip in radial opposition to said coil for pivotal movement into and out of capacitance relation with sets of turns of said coil.
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Accused Products
Abstract
A loading coil connects between an antenna and ground and has an intermediate feed point. A conductive member opposes at least several turns of the loading coil and is disposed in distributed capacitive relationship therewith. The conductive member and coil are separated by a dielectric member. The conductive member is preferably movable with respect to the coil to change the resonant frequency of the antenna and may be a conductive ring or disk axially shiftable with respect to the coil or a vane pivotable with respect to such coil. In one embodiment, the conductive member is fixed and the dielectric member, having a dielectric constant different from air, is shiftable to change the distributed capacitance of the conductive member and coil and hence the resonant frequency of the antenna apparatus.
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Citations
8 Claims
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1. A tunable antenna loading apparatus, comprising:
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a loading coil having an antenna connection means adjacent one end thereof and a ground connection means adjacent the other end thereof and a feed connection means intermediate said antenna connection means and ground connection means, said loading coil being fixedly supported with respect to said antenna connection means and ground connection means, said loading coil comprising a multiple turn conductor; a conductive member close spaced from said coil and having at least a portion arranged to face at least a portion of said coil, such that said conductive member and said coil simulate the opposed plates of a capacitor, said conductive member being electrically connected to said ground connecting means; dielectric means interposed between said coil and conductive member to act as a dielectric of a capacitor, said conductive member being adjustably movable with respect to said coil to vary the distributive capacitance supplied by the relationship of said coil and conductive member and with the inductance of said coil to adjust the resonant frequency of the antenna apparatus; a conductive ground strip electrically conneced to said ground connecting means adjacent said other end of said coil and extending lengthwise along said coil toward said one coil end and being electrically insulated from said coil by said dielectric means, said conductive member being in electrical contact with said ground strip, said conductive member comprising a conductive vane pivotally fixed on said ground strip in radial opposition to said coil for pivotal movement into and out of capacitance relation with sets of turns of said coil.
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2. A tunable antenna loading apparatus, comprising:
a loading coil having an antenna connection means adjacent one end thereof and a ground connection means adjacent the other end thereof and a feed connection means intermediate said antenna connection means and ground connection means, said loading coil being fixedly supported with respect to said antenna connection means and ground connection means, said loading coil comprising a multiple turn conductor;
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3. a conductive member close spaced from said coil and having at least a portion arranged to face at least a portion of said coil, such that said conductive member and said coil simulate the opposed plates of a capacitor, said conductive member being electrically connected to said ground connecting means;
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dielectric means interposed between said coil and conductive member to act as a dielectric of a capacitor, said dielectric means being adjustably movable with respect to said coil to vary the distributive capacitance supplied by the relationship of said coil and conductive member and with the inductance of said coil to adjust the resonant frequency of the antenna apparatus; a conductive ground strip electrically connected to said ground connecting means adjacent said other end of said coil and extending lengthwise along said coil toward said one coil end and being electrically insulated from said coil by said dielectric means, said conductive member being in electrical contact with said ground strip, in which said conductive member is fixed with respect to said coil and extends lengthwise thereof in close spaced relation thereto, said dielectric means comprising a dielectric member having a dielectric constant different than that of air and disposed for axially adjustable movement between said conductive member and said coil. - View Dependent Claims (5, 7, 8)
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4. A tunable antenna loading apparatus, comprising:
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an elongate, multiple turn loading coil having an antenna connection adjacent its upper end and a ground connection adjacent its lower end, the upper and lower parts of the coil joining at a feed connection spaced intermediate said antenna connection and ground connection; an elongate insulating sleeve extending substantially the length of said coil and snugly housing the coil therein, said ground and antenna connections being at the top and bottom of said insulating sleeve; a conductive ring axially shorter than said upper coil part and axially slidably engaged by said insulating sleeve, said conductive ring having a range of axial positions in which it radially overlies only a fraction of the turns of said upper part of said coil and yet does not extend upward beyond said antenna connection and downward beyond said feed connection, permitting said ring to capacitively couple to but a few turns of the coil even when at the upper end of the coil; a circumferentially thin, conductive ground strip fixed axially on said insulative sleeve and connected to the ground connection at the base of said sleeve and extending substantially to the top of said coil, the major circumference of said coil below said ring being free of conductive shielding, said narrow strip being slidably engaged by said ring to ground said ring to said ground connection. - View Dependent Claims (6)
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Specification