Terminal antenna for communications systems
First Claim
1. An antenna for communication with at least two nodes comprising:
- an azimuth turntable mounted for rotational motion in either direction about a central axis;
an elevation table mounted upon said azimuth turntable for arcuate movement about a transverse axis which is perpendicular to said central axis, said upper surface of said table containing a plurality of antenna elements to form a phased array antenna in which the scan plane of said phased array lies in a plane which is substantially parallel to said transverse axis;
means for rotating said azimuth turntable about said central axis and arcuately moving said elevation table about said transverse axis until said phased array antenna elements mounted upon said elevation table are positioned so that two of said nodes with which said antenna is to communicate lie within the scan plane of said antenna elements; and
means for electronically scanning the beam of the phased array antenna elements mounted upon said elevation table to be selectively directed to either one or the other of said two nodes.
8 Assignments
0 Petitions
Accused Products
Abstract
An inexpensive high gain antenna for use on terminals communicating with low earth orbit (LEO) satellites which include an elevation table mounted for arcuate movement about a transverse axis on an azimuth turntable mounted for rotational movement about a central axis. A plurality of antenna elements forming a phased array antenna are mounted on the top of the elevation table and have a scan plane which is parallel to and extends through the transverse axis of the elevation table. The antenna may be both mechanically and electrically scanned and is used to perform handoffs from one LEO satellite to another by positioning the elevation table of the antenna with its boresight in a direction intermediate the two satellites and with the scan plane of the antenna passing through both satellites. At the moment of of handoff, the antenna beam is electronically scanned from one satellite to another without any loss in data communication during the process.
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Citations
31 Claims
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1. An antenna for communication with at least two nodes comprising:
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an azimuth turntable mounted for rotational motion in either direction about a central axis; an elevation table mounted upon said azimuth turntable for arcuate movement about a transverse axis which is perpendicular to said central axis, said upper surface of said table containing a plurality of antenna elements to form a phased array antenna in which the scan plane of said phased array lies in a plane which is substantially parallel to said transverse axis; means for rotating said azimuth turntable about said central axis and arcuately moving said elevation table about said transverse axis until said phased array antenna elements mounted upon said elevation table are positioned so that two of said nodes with which said antenna is to communicate lie within the scan plane of said antenna elements; and means for electronically scanning the beam of the phased array antenna elements mounted upon said elevation table to be selectively directed to either one or the other of said two nodes. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An antenna for communication with two low earth orbit satellites comprising:
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an azimuth turntable mounted for rotational motion in either direction about a central axis; an elevation table mounted upon said azimuth turntable for arcuate movement about a transverse axis which is perpendicular to said central axis, said upper surface of said table containing a plurality of antenna elements to form a phased array antenna in which the scan plane of said phased array lies in a plane which is substantially parallel to said transverse axis; two sets of feed networks to said antenna elements and two sets of scan electronics connected to said antenna elements to define two independent beams for said antenna; means for rotating said azimuth turntable about said central axis and arcuately moving said elevation table about said transverse axis until said phased array antenna elements mounted upon said elevation table are positioned so that said two satellites with which said antenna is to communicate lie within the scan plane of said antenna elements; and means for independently electronically scanning the each of said two independent beams of the phased array antenna elements mounted upon said elevation table to be directed toward each of said two satellites.
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8. A method of performing handoff of a communication signal between a first low earth orbit (LEO) satellite and a second LEO satellite with an antenna in which the beam thereof may be both physically scanned by moving the antenna and electronically scanned by changing the phase relationship between the antenna elements, said antenna having a scan plane directed outwardly from the surface thereof within which said antenna beam is electronically scannable, said method comprising:
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establishing communication with a first LEO satellite and tracking said satellite with the beam of said antenna as it moves in its orbit with either mechanical movement of the antenna or electronic scanning of the beam or a combination thereof; anticipating the location of said second satellite at the time of handoff; physically positioning the antenna prior to the said handoff so that both said first satellite and the anticipated location of the second satellite lie within the scan plane of the antenna; and electronically scanning the beam of the antenna from said first satellite to said second satellite at said time of handoff to de-establish communication with the first satellite and establish communication with the second satellite. - View Dependent Claims (9, 10, 11, 12, 13, 17, 18, 19)
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14. A system for performing handoff of a communication signal between a first low earth orbit (LEO) satellite and a second LEO satellite with an antenna in which the beam thereof may be both physically scanned by moving the antenna and electronically scanned by changing the phase relationship between the antenna elements, said antenna having a scan plane directed outwardly from the surface thereof within which said antenna beam is electronically scannable, said system comprising:
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means for establishing communication with a first LEO satellite and tracking said satellite with the beam of said antenna as it moves in its orbit with either mechanical movement of the antenna or electronic scanning of the beam or a combination thereof; means for anticipating the location of said second satellite at the time of handoff; means for physically positioning the antenna prior to said handoff so that both said first satellite and the anticipated location of the second satellite lie within the scan plane of the antenna; and means for electronically scanning the beam of the antenna from said first satellite to said second satellite at said time of handoff to de-establish communication with the first satellite and establish communication with the second satellite. - View Dependent Claims (15, 16)
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20. A method of performing of handoff of a terminal from one satellite to another by an antenna which is capable of being both mechanically and electronically scanned, said method comprising:
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tracking a first satellite with boresight pointing of the antenna by mechanical and or electronic scanning of the antenna to follow the satellite; receiving information from the satellite as to next handoff time and the position of a second satellite at that handoff time; calculating and predicting the position of the first satellite at said handoff time; calculating a first vector from the antenna to the first satellite at said handoff time; calculating a second vector from said antenna to said second satellite at said handoff time; mechanically positioning said antenna so that both of said calculated vectors lie upon the electronic scan plane of said antenna; scanning electronically from said first satellite to said second satellite at handoff time to establish communication with said second satellite; and beginning to track said second satellite with boresight pointing using mechanical scanning of said antenna. - View Dependent Claims (21, 22)
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23. A system for performing handoff of a terminal from one satellite to another by an antenna which is capable of being both mechanically and electronically scanned, comprising:
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means for tracking a first satellite with boresight pointing of the antenna by mechanical and or electronic scanning of the antenna to follow the satellite; means for receiving information from the satellite as to next handoff time and the position of a second satellite at that handoff time; means for calculating and predicting the position of the first satellite at said handoff time; means for calculating a first vector from the antenna to the first satellite at said handoff time; means for calculating a second vector from said antenna to said second satellite at said handoff time; means for mechanically positioning said antenna so that both of said calculated vectors lie upon the electronic scan plane of said antenna; means for scanning electronically from said first satellite to said second satellite at handoff time to establish communication with said second satellite; and means for beginning to track said second satellite with boresight pointing using mechanical scanning of said antenna. - View Dependent Claims (24, 25)
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26. A method for communicating with at least two communications nodes comprising:
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providing an azimuth turntable mounted for rotational motion in either direction about a central axis; providing an elevation table mounted upon said azimuth turntable for arcuate movement about a transverse axis which is perpendicular to said central axis, said upper surface of said table containing a plurality of antenna elements to form a phased array antenna in which the scan plane of said phased array lies in a plane which is substantially parallel to said transverse axis; rotating said azimuth turntable about said central axis and arcuately moving said elevation table about said transverse axis until said phased array antenna elements mounted upon said elevation table are positioned so that two of said nodes with which said antenna is to communicate lie within the scan plane of said antenna elements; and electronically scanning the beam of the phased array antenna elements mounted upon said elevation table to be selectively directed to either one or the other of said two nodes. - View Dependent Claims (27, 28, 29, 30, 31)
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Specification