360.degree. Azimuth scanning antenna without rotating RF joints

• US 3,916,416 A
• Filed: 09/24/1974
• Issued: 10/28/1975
• Est. Priority Date: 09/24/1974
• Status: Expired due to Term

• Current Assignee: Bernard L. Lewis
• Original Assignee: Bernard L. Lewis
• Inventors: Lewis, Bernard L.
• Primary Examiner(s): Lieberman, Eli
• Application Number:
  US05/508,777
• Time in Patent Office: 399 Days
• Field of Search: 343/756,761,779,839,840,872
• US Class Current: 343/756
• CPC Class Codes: H01Q 19/195 wherein a reflecting surface acts also as a polarisation filter or a polarising device
• CPC Class Codes: H01Q 3/20 wherein the primary active element is fixed and the reflecting device is movable
• CPC Class Codes: H01Q 3/24 varying the orientation by switching energy from one active radiating element to another, e.g. for beam switching

Abstract

A 360* scanning radar antenna has a plurality of primary focusing-structures arranged in a circular fashion illuminating corresponding secondary focusing-structures which in turn are arranged about, and directed toward, a rotating multi-sided halfwave plane reflector. Radar energy is switched to radiate from a given primary focusing-structure during the time when the plane reflector is in position to reflect all of the energy collimated by the corresponding secondary focusing-structure. The secondary focusing-structure may be made to appear transparent to the beam reflected by the plane reflector.

Claims

1. A 360* scanning high-frequency antenna system comprising:

an antenna platform;

a supporting framework surrounding and attached to said platform;

tertiary reflecting means for reflecting electromagnetic energy;

rotating means attached between said tertiary reflecting means and said platform for rotating said tertiary reflecting means about an axis of rotation;

a plurality of high-frequency primary focusing-structures attached to said supporting framework and arranged in a generally circular fashion about said axis of rotation;

a plurality of secondary focusing-structures attached to said supporting framework and arranged in a generally circular fashion about said axis of rotation, each said secondary focusing-structure being associated with a corresponding one or said primary focusing-structures; and

, switching means for energizing selected primary-focusing structures when said tertiary reflecting means is positioned to reflect energy radiating from said selected primary focusingstructures as collimated by said corresponding secondary focusing-structure whereby said energy is reflected by said tertiary reflecting means.

2. The 360* scanning antenna system of claim 1, wherein:

said primary focusing-structures are adapted to radiate linearly polarized energy of predetermined orientation;

said secondary focusing-structures are made polarization sensitive so as to reflect energy polarized in one direction and to pass orthogonally polarized energy without attenuation;

said tertiary reflecting means is a reflector having a plurality of half-wave plane reflective surfaces constructed so that the direction of polarization energy incident on any of said half-wave reflective surfaces will be changed by 90* upon reflection, whereby energy from said primary focusing-structures polarized in one direction is collimated and reflected to said tertiary reflecting means by said secondary focusing structures and said reflected energy is rotated in polarization by 90* and reflected back through said secondary focusing-structures by said tertiary reflecting means.

3. The 360* scanning antenna system of claim 2 wherein the width of said tertiary reflecting means is 1/cos 45* times the width in the scan plane of one of said secondary focusing-structures.

4. The antenna system of claim 3 wherein said switching means energizes selected primary focusing-structures when said tertiary reflector forms an angle of not more than 45* to either side of the optical axis of said corresponding secondary focusing-structure.

5. The 360* scanning antenna system of claim 4 wherein a environment stable, electromagnetically transparent enclosure is attached to and encloses said supporting framework.

6. The 360* scanning antenna system of claim 5 wherein said enclosure is constructed of fiberglass.