Shrouded offset parabolic reflector antenna

Claim 2

A reflector antenna, comprising: a feed; an offset reflector for said feed; and shroud means partially encompassing said reflector for preventing spillover radiation from said feed along only a limited sector of the boundary of said reflector less than the entire boundary thereof, said shroud means comprises a hollow cylinder truncated at one end spaced from said reflector and along a plane at a skew angle relative to the plane containing the boundary of said reflector and secured adjacent its other said end to the periphery of said reflector such that the walls of said cylinder extend continuously from said reflector to said open end.

Claim 3

The reflector antenna of claim 1, wherein: said shroud means is at least partly absorbent to radiation emanating from said feed.

Claim 4

The reflector antenna of claim 1, whereiN: said shroud means is at least partly reflective to radiation emanating from said feed.

Claim 5

The reflector antenna of claim 1, wherein: said cylinder is composed of sheet metal.

Claim 6

The reflector antenna of claim 4, wherein: said cylinder is lined along at least part of its interior surface with material absorbent to radiation emanating from said feed.

Claim 7

The reflector antenna of claim 1, wherein: said cylinder is composed of sheet material absorbent to radiation emanating from said feed.

Claim 8

A reflector antenna, comprising: a horn; a feed line for said horn; a parabolic reflector positioned for illumination by energy radiated from said horn and having an axis tilted relative to the axis of said horn, for highly directive reflection of said energy without aperture blockage by said horn; and shroud means partly encompassing said reflector along the periphery thereof to block energy radiated from said horn that would otherwise spill over the edge of said reflector, only along a portion of the edge less than the entirety thereof, said shroud means comprises a sheet of material forming a cylinder having a free end cut off along a plane at a skew angle to the encompassing said periphery such that the walls of said cylinder extend continuously from said reflector to said free end.

Claim 9

A reflector antenna, comprising: a horn; a feed line for said horn; a parabolic reflector positioned for illumination by energy radiated from said horn and having an axis tilted relative to the axis of said horn, for highly directive reflection of said energy without aperture blockage by said horn; and shroud means partly encompassing said reflector along the periphery thereof to block energy radiated from said horn that would otherwise spill over the edge of said reflector, only along a portion of the edge less than the entirety thereof, said shroud means comprises a sheet of material forming a cylinder having a free end cut off along a plane at a skew angle to the encompassing said periphery such that the walls of said cylinder extend continuously from said reflector to said free end.

Claim 10

The reflector antenna of claim 7, wherein: the interior surface of said cylinder is reflective to energy radiated from said horn.

Claim 11

The reflector antenna of claim 7, wherein: the interior of said cylinder is absorbent to energy radiated from said horn.

Claim 12

A reflector antenna comprising: a feed; a parabolic reflector positioned for illumination by energy radiated from said feed and having an axis tilted relative to the axis of said feed, for highly directive reflection of said energy without aperture blockage by said horn; and shroud means partly encompassing said reflector along the periphery thereof to block energy radiated from said feed that would otherwise spill over the edge of said reflector, only along a portion of the edge less than the entirety thereof, said shroud means comprising a substantially continuous wall which is circular in cross section with one end thereof having a diameter essentially corresponding with that of said reflector and positioned adjacent thereto so as to essentially encompass the periphery of said reflector and having an open end spaced from said reflector, said open end being truncated along a plane at a skew angle relative to the plane containing the periphery of said reflector so that the length of said wall from said one end to said open end uniformly increases in both a clockwise direction and a counterclockwise direction from a first peripheral open end edge point spaced proximate to said reflector to substantially a second peripheral open end edge point, located 180* from said first point, and which is spaced substantially away from said reflector relative to that of said first point; said feed being positioned relative to said shroud means so as to be located proximate to said second peripheral open end edge point so that spillover radiation from said feed in a direction away from said reflector axis is blocked by the elongated inner wall proximate to said second edge point of said shroud means whereas at least a portion of the spillover radiation in the direction of said reflector axis is not blocked by the shorter inner wall proximate to the first edge point of said shroud means.

Claim 13

A reflector antenna comprising: a feed; a parabolic reflector positioned for illumination by energy radiated from said feed and having an axis tilted relative to the axis of said feed, for highly directive reflection of said energy without aperture blockage by said horn; and shroud means partly encompassing said reflector along the periphery thereof to block energy radiated from said feed that would otherwise spill over the edge of said reflector, only along a portion of the edge less than the entirety thereof, said shroud means comprising a substantially continuous wall which is circular in cross section with one end thereof having a diameter essentially corresponding with that of said reflector and positioned adjacent thereto so as to essentially encompass the periphery of said reflector and having an open end spaced from said reflector, said open end being truncated along a plane at a skew angle relative to the plane containing the periphery of said reflector so that the length of said wall from said one end to said open end uniformly increases in both a clockwise direction and a counterclockwise direction from a first peripheral open end edge point spaced proximate to said reflector to substantially a second peripheral open end edge point, located 180* from said first point, and which is spaced substantially away from said reflector relative to that of said first point; said feed being positioned relative to said shroud means so as to be located proximate to said second peripheral open end edge point so that spillover radiation from said feed in a direction away from said reflector axis is blocked by the elongated inner wall proximate to said second edge point of said shroud means whereas at least a portion of the spillover radiation in the direction of said reflector axis is not blocked by the shorter inner wall proximate to the first edge point of said shroud means.

Claim 14

A reflector antenna as set forth in claim 10, wherein said continuous wall is of cylindrical configuration.