US4387378A — Antenna having electrically positionable phase ce…

Claim 1

Independent Claim 140 words

A tracking antenna including electromagnetic energy directing means for directing electromagnetic energy to or from a vertex, and a tracking feed located at said vertex, said tracking feed comprising primary radiating/receiving means for receiving or transmitting electromagnetic energy and having a unidirectional radiating pattern, a plurality of paracletic means fixedly positioned about said unidirectional radiating pattern of said primary radiating/receiving means, each having at least two selectable impedance states for controllably shifting the position of the phase center of said tracking feed relative to said directing means, and means for controlling said impedance states of said plurality of paracletic means so as to shift the position of said phase center in a known manner, whereby a signal received by said primary radiating/receiving means is modulated by said controlled phase center shifting and may be processed to derive tracking information therefrom.

Claim 2

Dependent Claim 140 words

A tracking antenna including electromagnetic energy directing means for directing electromagnetic energy to or from a vertex, and a tracking feed located at said vertex, said tracking feed comprising primary radiating/receiving means for receiving or transmitting electromagnetic energy and having a unidirectional radiating pattern, a plurality of paracletic means fixedly positioned about said unidirectional radiating pattern of said primary radiating/receiving means, each having at least two selectable impedance states for controllably shifting the position of the phase center of said tracking feed relative to said directing means, and means for controlling said impedance states of said plurality of paracletic means so as to shift the position of said phase center in a known manner, whereby a signal received by said primary radiating/receiving means is modulated by said controlled phase center shifting and may be processed to derive tracking information therefrom.

Claim 3

Dependent Claim 47 words

A tracking antenna as set forth in claim 1 wherein said paracletic means comprise variable reactances switchable between at least first and second reactance value, said switching affecting the position of the phase center of said tracking feed without substantially affecting the amplitude pattern of said antenna.

Claim 4

Dependent Claim 52 words

A tracking antenna as set forth in claim 1, wherein each of said paracletic means comprises at least one dipole having two dipole arms joined through a circuit switchable between a first, high impedance state and a second, low impedance state, the state of said circuit being controlled by said control means.

Claim 5

Dependent Claim 35 words

A tracking antenna as set forth in claim 1, wherein said control means includes means for controlling said paracletic means so as to cause said phase center to cyclically rotate about said primary receiving/radiating means.

Claim 6

Dependent Claim 18 words

A tracking antenna as set forth in claim 1, wherein said directing means comprises a parabolic dish reflector.

Claim 7

Dependent Claim 130 words

An antenna comprising main radiating means for receiving or transmitting electromagnetic energy said radiating means having a unidirectional radiating pattern centered about an axis, at least one paracletic element positioned relative to said main radiating means at a location which is spaced apart therefrom both along and transverse to said axis, whereby said at least one element is located generally within said unidirectional pattern but off to one side of said axis, said paracletic element being switchable between at least first and second impedance states affecting the position of the phase center of said antenna with respect to said main radiating means, and control means for controlling the states of said at least one paracletic elements so as to thereby control the location of the phase center of said antenna.

Claim 8

Dependent Claim 130 words

An antenna comprising main radiating means for receiving or transmitting electromagnetic energy said radiating means having a unidirectional radiating pattern centered about an axis, at least one paracletic element positioned relative to said main radiating means at a location which is spaced apart therefrom both along and transverse to said axis, whereby said at least one element is located generally within said unidirectional pattern but off to one side of said axis, said paracletic element being switchable between at least first and second impedance states affecting the position of the phase center of said antenna with respect to said main radiating means, and control means for controlling the states of said at least one paracletic elements so as to thereby control the location of the phase center of said antenna.

Claim 9

Dependent Claim 64 words

An antenna as set forth in claim 6, wherein said paracletic elements are variable reactances switchable between a first reactance value wherein the position of said phase center of said antenna is essentially unaffected by said paracletic elements, and at least one of other reactance value wherein the position of said phase center is shifted without substantially affecting the amplitude pattern of said antenna.

Claim 10

Dependent Claim 50 words

An antenna as set forth in claim 6, wherein said paracletic elements each comprise at least one dipole having two dipole arms joined through a circuit switchable between a first, high impedance state and a second, low impedance state, the state of said circuit being controlled by said control means.

Claim 11

Dependent Claim 33 words

An antenna as set forth in claim 8, wherein the length of said dipole, measured along said dipole arms, is less than 0.35 times the wavelength of the operating frequency of said antenna.

Claim 12

Dependent Claim 65 words

An antenna as set forth in claim 8, wherein said circuit comprises a shorted stub joining said dipole arms, at least one diode for shorting said dipole arms together at said dipole arms, and means for applying a forward or reverse bias voltage across said diode so as to switch said diode into either a low impedance, conductive state, or a high impedance, non-conductive state.

Claim 13

Dependent Claim 116 words

An antenna as set forth in claim 6, wherein said main radiating means comprises a pair of orthogonal dipoles having substantially coincident centers, and a ground plane positioned substantially parallel to the plane of said orthogonal dipoles whereby the radiation pattern of said dipoles is substantially perpendicular to said ground plane, and further wherein said paracletic elements comprise a plurality of variable reactances switchable between at least first and second reactance states and positioned about said dipole pair, said variable reactances being structured and positioned so that said reactances interact with said dipole pair to shift the position of the phase center of said antenna when switched between said at least first and second reactance states.

Claim 14

Dependent Claim 82 words

Apparatus comprising: an antenna having a directional amplutude pattern; non-parasitic reactance means positioned proximal said antenna but offset therefrom in a direction transverse to said directional amplitude pattern for electromagnetically interacting with said antenna to shift its phase center by an amount dependent upon the reactance of said reactance means, said means having a controllable reactance; and control means for controlling the reactance of said non-parasitic reactance means so as to thereby control the location of the phase center of said antenna.

Claim 15

Dependent Claim 82 words

Apparatus comprising: an antenna having a directional amplutude pattern; non-parasitic reactance means positioned proximal said antenna but offset therefrom in a direction transverse to said directional amplitude pattern for electromagnetically interacting with said antenna to shift its phase center by an amount dependent upon the reactance of said reactance means, said means having a controllable reactance; and control means for controlling the reactance of said non-parasitic reactance means so as to thereby control the location of the phase center of said antenna.

Claim 16

Dependent Claim 82 words

Apparatus comprising: an antenna having a directional amplitude pattern; non-parasitic reactance element electromagnetically interactive with said antenna and positioned proximal said antenna but offset therefrom in a direction transverse to said directional amplitude pattern, said element being switchable between first and second reactance states differently effecting the location of the phase center of said antenna; and control means for controlling the reactance states of said non-parasitic reactance element so as to thereby control the location of the phase center of said antenna.

Claim 17

Dependent Claim 82 words

Apparatus comprising: an antenna having a directional amplitude pattern; non-parasitic reactance element electromagnetically interactive with said antenna and positioned proximal said antenna but offset therefrom in a direction transverse to said directional amplitude pattern, said element being switchable between first and second reactance states differently effecting the location of the phase center of said antenna; and control means for controlling the reactance states of said non-parasitic reactance element so as to thereby control the location of the phase center of said antenna.

Claim 18

Dependent Claim 47 words

Apparatus as set forth in claim 13, wherein said non-parasitic reactance element comprises at least one dipole having two dipole arms joined through a circuit switchable between a high impedance state and a low impedance state, the state of said circuit being controlled by said control means.

Claim 19

Dependent Claim 32 words

Apparatus as set forth in claim 14, wherein the length of said dipole, measured along said dipole arms, is less than 0.35 times the wavelength of the operating frequency of said antenna.

Claim 20

Dependent Claim 67 words

Apparatus as set forth in claim 14, wherein said circuit comprises at least one unidirectional current conducting means electrically joining said dipole arms together, and wherein said control means includes means for applying a forward or reverse bias across said unidirectional current conducting means so as to controllably switch said unidirectional current conducting means into either a low impedance, conductive state, or a high impedance, non-conductive state.

Claim 21

Dependent Claim 57 words

Apparatus as set forth in claim 13, wherein said antenna comprises a pair of orthogonal dipoles having substantially coincident centers, and wherein said non-parasitic reactance element is one of a plurality of similar non-parasitic reactance elements positioned circumferentially about said pair in a plane oriented parallel to the plane in which said pair of othogonal dipoles lie.

Claim 22

Dependent Claim 41 words

Apparatus as set forth in claim 17, wherein said control means comprises means for controlling the reactance states of said plurality of non-parasitic reactance element so as to cause the phase center of said antenna to move in a predetermined manner.

Claim 23

Dependent Claim 41 words

Apparatus as set forth in claim 18 wherein said means for controlling the reactance states of said plurality of non-parasitic reactance elements comprises means for controlling said elements such that the phase center of said antenna effectively rotates around said antenna.

Claim 24

Dependent Claim 50 words

Apparatus as set forth in claim 17, wherein each of said plurality of non-parasitic reactance elements comprises a pair of orthogonal dipoles having substantially coincident centers, each dipole having two dipole arms and means responsive to said control means for controllably shorting or not shorting said two dipole arms together.

Claim 25

Dependent Claim 118 words

Apparatus comprising electromagnetic energy directing means for focusing electromagnetic energy at a vertex, a feed antenna having a directional amplitude pattern, said feed antenna being disposed at said vertex and pointed so that said energy directing means is disposed within said pattern, non-parasitic reactance means for electromagnetically interacting with said feed antenna to shift its phase center by an amount dependent upon the reactance of said reactance means, said reactance means having a controllable reactance, and control means for controlling the reactance of said reactance means so as to shift the position of said phase center in a known manner, whereby a signal received by said feed antenna is modulated in accordance with said controlled phase center shifting.

Claim 26

Dependent Claim 118 words

Apparatus comprising electromagnetic energy directing means for focusing electromagnetic energy at a vertex, a feed antenna having a directional amplitude pattern, said feed antenna being disposed at said vertex and pointed so that said energy directing means is disposed within said pattern, non-parasitic reactance means for electromagnetically interacting with said feed antenna to shift its phase center by an amount dependent upon the reactance of said reactance means, said reactance means having a controllable reactance, and control means for controlling the reactance of said reactance means so as to shift the position of said phase center in a known manner, whereby a signal received by said feed antenna is modulated in accordance with said controlled phase center shifting.

Claim 27

Dependent Claim 30 words

Apparatus as set forth in claim 21, wherein said non-parasitic reactance means is positioned proximal said feed antenna but offset therefrom in a direction transverse to said directional amplitude pattern.

Claim 28

Dependent Claim 36 words

Apparatus as set forth in claim 21, and further comprising a plurality of other non-parasitic reactance means positioned circumferentially about said feed antenna, wherein said control means comprises means for controlling all of said reactance means.

Claim 29

Dependent Claim 33 words

Apparatus as set forth in claim 23, wherein said control means comprises means for controlling said plurality of reactance means so as to cause said phase center to rotate around said feed antenna.

Claim 30

Dependent Claim 95 words

Apparatus comprising: a horn antenna comprising an open-ended waveguide having a directional amplitude pattern and a phase center situated inside the open end of said waveguide; non-parasitic reactance means for influencing the position of said phase center in accordance with the reactance of said reactance means, said means comprising an elongated conductive member extending from a wall of said waveguide toward said phase center in a direction transverse to said directional amplituide pattern; and means for controlling the reactance of said reactance means and thereby the location of the phase center of said horn antenna.

Claim 31

Dependent Claim 95 words

Apparatus comprising: a horn antenna comprising an open-ended waveguide having a directional amplitude pattern and a phase center situated inside the open end of said waveguide; non-parasitic reactance means for influencing the position of said phase center in accordance with the reactance of said reactance means, said means comprising an elongated conductive member extending from a wall of said waveguide toward said phase center in a direction transverse to said directional amplituide pattern; and means for controlling the reactance of said reactance means and thereby the location of the phase center of said horn antenna.

Claim 32

Dependent Claim 33 words

Apparatus as set forth in claim 25, wherein said means for controlling the reactance of said reactance means comprises means for controllably shorting said elongated conductive member to said wall of said waveguide.

Claim 33

Dependent Claim 30 words

Apparatus as set forth in claim 25, wherein there are plural said elongated conductive members extending from said wall, said plural conductive members being disposed substantially parallel to one another.

Claim 34

Dependent Claim 37 words

Apparatus as set forth in claim 27, wherein said means for controlling the reactance of said reactance means comprises means for providing a single control signal for commonly controlling the reactance of all said plural elongated members.

Claim 35

Dependent Claim 31 words

Apparatus as set forth in claim 27, wherein said means for controlling the reactance of said reactance means comprises means for controllably shorting said plural elongated members to said side wall.

Claim 36

Dependent Claim 31 words

Apparatus as set forth in claim 25 and further comprising a plurality of like non-parasitic reactance means positioned about said phase center in a plane transverse to said directional amplitude pattern.

Claim 37

Dependent Claim 57 words

Apparatus as set forth in claim 30, wherein each of said plurality of like non-parasitic reactance means comprises an elongated conductive member extending from an associated side wall of said waveguide, and wherein said reactance control means comprises means for controllably connecting one or more of said reactance means to the associated side wall of said waveguide.

Claim 38

Dependent Claim 50 words

Apparatus as set forth in claim 25, and further comprising a second elongated conductive member extending from a side wall of said waveguide in a direction substantially perpendicular to the direction in which the first said elongated conductive member extends whereby said elongated members effect orthogonal polarizations of electromagnetic energy.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1986-06-06	1986-12-06	1987-06-07	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1990-06-06	1990-12-06	1991-06-07	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1994-06-06	1994-12-06	1995-06-07	$7700.00	Window Closed / Lapsed

Antenna having electrically positionable phase center

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