Antenna arrangements for suppressing selected sidelobes

An antenna arrangement for suppressing selected sidelobes, the antenna comprising:

• a main focusing reflector (10);
• and
• a first feed arrangement (14) disposed to permit radiation of a first beam of electromagnetic energy therefrom in a particular direction along a feed axis of the antenna arrangement such that a central ray of the first beam impinges a particular point (P) on the main focusing reflector
• characterized in that
• the antenna arrangement further comprises:
• a second and a third feed arrangement (20, 21) disposed on opposite sides of, and a predetermined equal distance from the first feed arrangement and in a plane corresponding to the plane of the selected sidelobes to be suppressed, the second and third feed arrangement being capable of radiating a second and a third beam, respectively, of electromagnetic energy, comprising the same signal as transmitted in the first beam, in a direction to cause a central ray of the second and third beams to impinge the same particular point (P) on the main reflector as the central ray of the first beam;
• and
• means (24, 26) connected to the second and third feed arrangement for adjusting the amplitude and phase of a signal passing therethrough to cause the combined resultant E-field distribution of the second and third beams at the edge of the reflector in the plane of the feed arrangements to have an amplitude which is substantially equal and opposite to an E-field distribution of the first beam for reducing selected far sidelobes.