Antenna for multipath satellite communication links

Claim 2

An antenna system as set forth in claim 1, wherein said first angle is approximately 90°, and wherein said second angle is within a range of approximately 30° to approximately 60°.

Claim 3

An antenna system as claimed in claim 1 or 2, wherein said third angle is approximately 60°, and wherein N is equal to six.

Claim 4

An antenna system as set forth in claim 1 or 2, wherein said third angle is approximately 45°, and wherein N is equal to eight.

Claim 5

An antenna system as claimed in any one of claims 1 to 4, wherein there are a plurality of said antenna elements that are supported by each of said sub-structures, and wherein individual ones of said plurality of antenna elements are spaced apart by a distance that is a function of a wavelength of interest.

Claim 6

An antenna system as claimed in any one of the preceding claims, wherein there are a plurality of said antenna elements that are supported by each of said substructures, and wherein individual ones of said plurality of antenna elements are spaced apart by a distance within a range of approximately 0.5λ to approximately 0.8λ, wherein λ is a wavelength of interest.

Claim 7

An antenna system as claimed in any one of the preceding claims, and further comprising at least one reference antenna element that is oriented at said first angle with respect to said axis that is perpendicular to the surface of the earth.

Claim 8

An antenna system as claimed in any one of the preceding claims, wherein said first sub-structure has a generally planar, polygonal shape, and wherein individual ones of said second substructures each have an edge that is adjacent to one edge of said first sub-structure.

Claim 9

An antenna system as claimed in any one of the preceding claims, further comprising means for selectively outputting a signal received from at least one antenna element that is disposed upon one of said first substructure and said plurality N of second sub-structures.

Claim 10

An antenna system as claimed in any one of the preceding claims, further comprising means for selectively inputting a signal to at least one antenna element that is disposed upon one of said first sub-structure and said plurality N of second sub-structures.

Claim 11

An antenna system as claimed in any one of the preceding claims, wherein said first angle is approximately 90°, and wherein individual ones of said plurality N of second substructures are oriented so as to generally face north (N), northeast (NE), southeast (SE), south (S), southwest (SW) and northwest (NW), or subsets of these azimuthal orientations.

Claim 12

A communication system, comprising a constellation of low earth orbit satellites individual ones of which each comprise means for receiving a plurality of communication feeder links from at least one ground station and means for transmitting the received communication feeder links to a plurality of terrestrially located terminals and at least one ground station including means for transmitting said plurality of communication feeder links to at least one of said satellites and further comprising means for coupling said plurality of feeder links to a terrestrially located communications system, wherein each of the plurality of satellites is oriented, at any given time when in view of one of said terminals, at a particular elevation angle, characterized in that said terminal comprises, an antenna that is comprised of a first sub-structure having a major plane that is oriented at a first angle with respect to an axis that is perpendicular to the surface of the earth; a plurality N of second substructures individual ones of which have a local major plane that is disposed at a second angle to said major plane of said first sub-structure, each of said plurality N of sub-structures having an outwardly pointing normal from said local major plane that is oriented at a third angle around said axis from an outwardly pointing normal of an adjacent one of said sub-structures, said outwardly pointing normal of each of said plurality N of sub-structures being disposed so as to point away from said axis; and at least one antenna element supported by said first sub-structure and by each of said plurality N of second substructures, wherein antenna elements of said first sub-structure and at least some of said plurality N of second sub-structures enable a spread spectrum communication to occur between said terminal and at least one low earth orbit satellite over a range of elevation angles of said low earth orbit satellite.

Claim 13

A communication system as claimed in claim 12, wherein said antenna further comprises of at least one reference antenna element that is oriented at said first angle with respect to said axis that is perpendicular to the surface of the earth, and wherein said terminal further includes a multiple-finger spread spectrum receiver having inputs coupled to said plurality of antenna elements and to said at least one reference antenna element, said receiver including means for allocating one of said fingers for receiving said spread spectrum communication from said at least one low earth orbit satellite, and for allocating at least one other one of said fingers for receiving a synchronizing signal that is received through said at least one reference antenna element from at least one other of said low earth orbit satellites.

Claim 14

A communication system as claimed in claim 12 or 13, further comprising means for selecting as an output of said antenna an output of antenna elements associated with one of said first and second sub-structures, said selecting means being responsive to at least one of a predicted position of said at least one satellite and a received signal strength that is measured at said first and second sub-structures.

Claim 15

A communication system as claimed in claim 12 or 13, further comprising means for selecting as an output of said antenna an output of antenna elements associated with one of said first and second sub-structures, said selecting means being responsive at least to a track direction and to an elevation angle of said at least one satellite.

Claim 16

A communication system as claimed in any one of claims 12 to 15, further comprising means for selecting as an output of said antenna an output of antenna elements associated with one of said first and second sub-structures so as to switch the reception of said spread spectrum communication from said at least one low earth orbit satellite to said at least one other of said low earth orbit satellites.

Claim 17

A communication system as claimed in any one of claims 12 to 16, wherein said first angle is approximately 90°, and wherein individual ones of said plurality N of second substructures are oriented so as to face generally north (N), northeast (NE), southeast (SE), south (S), southwest (SW) and northwest (NW), or subsets of these azimuthal orientations.

Claim 18

A communication system as claimed in any one of claims 12 to 17, further comprising a communication system control means that is bidirectionally coupled to said at least one ground station through a data link.

Claim 19

A communication system as claimed in any one of claims 12 to 18, wherein said at least one ground station further comprises means for determining if said spread spectrum communication is to be operated in a diversity reception mode at the terminal and, if yes, for routing said spread spectrum communication simultaneously through a plurality of said low earth orbit satellites.

Claim 21

A method as claimed in claim 20, further comprising a step of, for a third range of elevation angles and azimuth angles, selecting a third portion of the antenna structure to receive the communication, the third portion being disposed at the first angle with respect to the axis that is normal to the surface of the earth.

Claim 22

A method as claimed in claim 20 or 21, wherein the first angle is within a range of approximately 30° to approximately 60°, and wherein the second angle is either within the range of approximately 30° to approximately 60° or is approximately 90°.

Claim 24

A method as claimed in claim 23, wherein the received communication is a spread spectrum communication, and wherein the steps of receiving and tracking include a step of locking to a synchronizing channel that is transmitted by the at least one other satellite.

Claim 28

A method as claimed in claim 27, further comprising a step of, for a third range of elevation angles, selecting a third portion of the antenna structure to transmit the communication, the third portion being disposed at the first angle with respect to the axis that is normal to the surface of the earth.

Claim 29

A method as claimed in claim 27 or 28, wherein the first angle is within a range of approximately 30° to approximately 60°, and wherein the second angle is either within the range of approximately 30° to approximately 60° or is approximately 90°.

Claim 33

A method as claimed in claim 32, wherein the first angle is within a range of approximately 30° to approximately 60°, and wherein the second angle is either within the range of approximately 30° to approximately 60° or is approximately 90°.

Claim 35

A method as claimed in claim 34, wherein the first angle is within a range of approximately 30° to approximately 60°, and wherein the second angle is either within the range of approximately 30° to approximately 60° or is approximately 90°.