Variable beamwidth antenna

An antenna comprising:

• a parabolic cylindrical main reflector having a first focal axis;
• a cylindrical sub-reflecor having a second focal axis;
• said main reflector and sub-reflector being positioned with said first and second axes orthogonally and a point source of said second axis being an image of a line source on said first axis;
• a feed for transducing waves of electromagnetic energy positioned on said second axis to form a pattern that irradiates said sub-reflector and is reflected between said sub-reflector and main reflector to illuminate said main reflector;
• and
• means for controlling the size of the surface area of at least one of said reflectors, wherein at least one of said main reflector and said sub-reflector includes a telescoping section and a fixed section, said telescoping secton adapted to slide contiguously to said fixed portion whereby bidirectional zooming of a beam is provided.

An antenna comprising:

• a parabolic cylinder main reflector having a first focal axis;
• a parabolic cylinder sub-reflector having a second focal axis, said reflector and sub-reflector positioned with their axes orthogonally, said sub-reflector intersecting said first axis and said main reflector intersecting said second axis;
• a feed for transducing electromagnectic waves positioned tangentially to said main reflector along said second axis and irradiating said sub-reflector;
• and
• means for adjusting the size of the surface area of at least one of said reflector and said sub-reflector.

A reflector for an antenna system, said reflector comprising:

• a first parabolic cylinder having a first focal axis;
• a second parabolic cylinder having a second focal axis;
• said first and second parabolic cylinders positioned with said first and second axes orthogonally;
• said first parabolic cylinder being truncated by a plane tangent to said second parabolic cylinder and parallel to said first focal axis;
• and
• means for adjusting the size of the suurface area of at least one of said first and second parabolic cylinders.

An antenna comprising:

• a parabolic cylinder main reflector having a first focal axis;
• a parabolic cylinder sub-reflector having a second focal axis, said reflector and sub-reflector positioned with their axes orthogonally, said sub-reflector intersecting said first axis and said main reflector intersecting said second axis;
• a feed for transducing electromagnetic waves positioned tangentially to said main reflector along said second axis and irradiating said sub-reflector;
• and
• means for adjusting the axial length of at least one of said cylinders parallel to the focal axis thereof.