Conically scanning antenna system for tracking radars

Claim 2

An antenna system comprising: a main reflector with a paraboloidal concave surface centered on a principal axis; feed means on said principal axis for emitting linearly polarized outgoing waves with an electric-field vector oriented in a predetermined first direction transverse to said principal axis and for receiving linearly polarized incoming waves with an electric-field vector oriented in a second direction orthogonal to said first direction; a first auxiliary reflector confronting said paraboloidal surface and said feed means with a hyperboloidally curved first convex surface centered on said principal axis, said first auxiliary reflector being substantially transparent to said incoming waves but reflecting said outgoing waves from said feed means onto said paraboloidal surface for transmission in the direction of said principal axis; a second auxiliarly reflector confronting said paraboloidal surface and said feed means with a hyperboloidally curved solid second convex surface centered on an axis inclined to said principal axis at an acute angle, said first auxiliary reflector lying between said main reflector and said second auxiliary reflector whereby incoming waves reflected from said paraboloidal surface toward said second auxiliary reflector and redirected by the latter toward said feed means pass twice through said first auxiliary reflector; and drive means coupled with said second auxiliary reflector for rotating same about said principal axis, thereby subjecting said incoming waves to a conical scan.

Claim 3

An antenna system as defined in claim 1 wherein said second convex surface has a focal point in a plane transverse to said principal axis passing through a common focus of said first convex surface and said paraboloidal surface.

Claim 4

An antenna system as defined in claim 2 wherein said second convex surface has an apex on said principal axis and another focal point in another plane transverse to said principal axis passing through a second focus of said first convex surface.

Claim 5

An antenna system as defined in claim 3 wherein said feed means has a phase center coinciding with said second focus.

Claim 6

In a tracking radar, in combination: transmission means generating linearly polarized outgoing waves; a horn centered on a principal axis, said horn having an input guide coupled to said transmission means for axially emitting said outgoing waves with an electric-field vector oriented in a predetermined first direction transverse to said principal axis and further having an output guide for conveying incoming waves echoed by outlying targets with an electric-field vector oriented in a second direction orthogonal to said first direction; receiving means coupled with said output guide; a main reflector with a paraboloidal concave surface centered on said principal axis; a first auxiliary reflector confronting said paraboloidal surface and said horn with a hyperboloidally curved first convex surface centered on said principal axis, said first auxiliary reflector being substantially transparent to said incoming waves but reflecting said outgoing waves from said horn onto said paraboloidal surface for transmission in the direction of said principal axis; a second auxiliary reflector confronting said paraboloidal surface and said horn with a hyperboloidally curved solid second convex surface centered on an axis inclined to said principal axis at a acute angle, said first auxiliary reflector lying between said main reflector and said second auxiliary reflector whereby incoming waves reflected from said paraboloidal surface toward said second auxiliary reflector and redirected by the latter toward said horn pass twice through said first auxiliary reflector, said reflectors forming an antenna system; and drive means coupled with said second auxiliary reflector for rotating same about said principal axis, thereby subjecting said incoming waves to a conical scan.

Claim 7

In a tracking radar, in combination: transmission means generating linearly polarized outgoing waves; a horn centered on a principal axis, said horn having an input guide coupled to said transmission means for axially emitting said outgoing waves with an electric-field vector oriented in a predetermined first direction transverse to said principal axis and further having an output guide for conveying incoming waves echoed by outlying targets with an electric-field vector oriented in a second direction orthogonal to said first direction; receiving means coupled with said output guide; a main reflector with a paraboloidal concave surface centered on said principal axis; a first auxiliary reflector confronting said paraboloidal surface and said horn with a hyperboloidally curved first convex surface centered on said principal axis, said first auxiliary reflector being substantially transparent to said incoming waves but reflecting said outgoing waves from said horn onto said paraboloidal surface for transmission in the direction of said principal axis; a second auxiliary reflector confronting said paraboloidal surface and said horn with a hyperboloidally curved solid second convex surface centered on an axis inclined to said principal axis at a acute angle, said first auxiliary reflector lying between said main reflector and said second auxiliary reflector whereby incoming waves reflected from said paraboloidal surface toward said second auxiliary reflector and redirected by the latter toward said horn pass twice through said first auxiliary reflector, said reflectors forming an antenna system; and drive means coupled with said second auxiliary reflector for rotating same about said principal axis, thereby subjecting said incoming waves to a conical scan.

Claim 8

An antenna system as defined in claim 1, 2, 3, 4 or 5 wherein said first auxiliary reflector has a grid structure with wires generally parallel to said first direction.