Steerable offset antenna with fixed feed source

A method for transmitting an electromagnetic signal between a fixed feed source or image thereof and a target moving within an antenna coverage region, said electromagnetic signal having a gain varying with the position of said target within said coverage region according to a predetermined signal gain profile thereacross, said coverage region defining a region peripheral edge, said method comprising the steps of:

• positioning a reflector relative to said feed source or image thereof for reflecting said electromagnetic signal between said feed source or image thereof and said target, said reflector defining a reflector surface, said reflector surface defining a focal point, a reflector center point and a reflector normal axis substantially perpendicular to said reflector surface at said reflector center point, said reflector center point and said focal point being spaced relative to each other by a focal point-to-center point distance, said reflector center point and said feed source or image thereof being spaced relative to each other by a feed-to-center point distance along a feed axis, said feed-to-center point distance being substantially equal to said focal point-to-center point distance, said reflector normal axis and said feed axis defining a common offset plane;
• rotating said reflector about a rotation axis extending generally perpendicularly from said offset plane in a position generally adjacent said reflector center point so that said antenna provides a nominal signal gain profile over said coverage region, said reflector defining a reference position wherein said focal point substantially intersects said feed axis and corresponding to a nominal signal gain being substantially maximum with said electromagnetic signal substantially pointing at said region peripheral edge;
• and
• altering said nominal signal gain profile so that the latter matches said predetermined signal gain profile;
• whereby said reflector in combination with said gain altering means are rotatable about said rotation axis so as to steer said electromagnetic signal according to said predetermined signal gain profile at said target moving across said coverage region.

A steerable antenna for allowing transmission of an electromagnetic signal between a fixed feed source and a target moving within an antenna coverage region, said electromagnetic signal having a gain varying with the position of said target within said coverage region according to a predetermined signal gain profile thereacross, said coverage region defining a region peripheral edge, said antenna comprising:

• a reflector defining a reflector surface for reflecting said electromagnetic signal between said feed source and said target, said reflector surface defining a focal point, a reflector center point and a reflector normal axis substantially perpendicular to said reflector surface at said reflector center point, said reflector center point and said focal point being spaced relative to each other by a focal point-to-center point distance, said reflector center point and said feed source being spaced relative to each other by a feed-to-center point distance along a feed axis, said feed-to-center point distance being substantially equal to said focal point-to-center point distance, said reflector normal axis and said feed axis extending in a common offset plane;
• a first rotating means for rotating said reflector about a rotation axis extending generally perpendicularly from said offset plane in a position generally adjacent said reflector center point so that said antenna provides a nominal signal gain profile over said coverage region, said reflector rotating about said rotation axis between a first limit position wherein said reflector normal axis is substantially collinear with said feed axis and a second limit position wherein said focal point substantially intersects said feed axis and corresponding to a nominal signal gain being substantially maximum with said electromagnetic signal substantially pointing at said region peripheral edge;
• a gain altering means for altering said nominal signal gain profile so that the latter matches said predetermined signal gain profile;
• and
• a second rotating means for rotating said reflector about said feed axis, said reflector being rotatable between a first azimuth position and a second azimuth position, said second azimuth position is generally 360 degrees apart from said first azimuth position;
• whereby said reflector in combination with said gain altering means are rotatable about said rotation axis between said first and second limit positions and about said feed axis between said first and second azimuth positions so as to steer said electromagnetic signal according to said predetermined signal gain profile at said target moving across said coverage region, so that the reflected electromagnetic signal, when pointing at said target, defines a coverage region having a generally conical configuration.