High gain, low side lobe dual reflector microwave antenna

• US 6,697,027 B2
• Filed: 08/23/2002
• Issued: 02/24/2004
• Est. Priority Date: 08/23/2001
• Status: Expired due to Fees

• Current Assignee: Optim Microwave Inc.
• Original Assignee: Optim Microwave Inc.
• Inventors: Mahon, John P.
• Primary Examiner(s): LE, HOANGANH T
• Application Number:
  US10/227,214
• Publication Number:
  US 20030038753A1
• Time in Patent Office: 550 Days
• Field of Search: H01/Q 1.300, 343/781.CA, 343/781.P, 343/781.R, 343/782, 343/840, 343/786, 343/785
• US Class Current: 343/781.0CA
• CPC Class Codes: H01Q 13/06 Waveguide mouths horns H01Q13/02
• CPC Class Codes: H01Q 19/08 for modifying the radiation pattern of a radiating horn in which it is located corrugated horns H01Q13/0208; producing a circular polarisation H01Q13/0241
• CPC Class Codes: H01Q 19/19 comprising one main concave reflecting surface associated with an auxiliary reflecting surface

Abstract

A significant problem in rotationally symmetric dual reflector systems is the blockage caused by the sub-reflector. This blockage produces lower gain and higher side lobes. The invention disclosed herein can be used to minimize or eliminate the blockage effects. In its simplest form, the invention is to place a hole in the sub-reflector. This allows radiation to by-pass the main reflector and replaces the radiation which is blocked by the sub-reflector. In general this radiation and the radiation which progresses on the standard path, which includes the main reflector, will not be in a useful phase and amplitude relationship. However by appropriate design of the inner and outer sub-reflector surfaces, the main reflector surface, the feed aperture, the dielectric support and the possible use of a dielectric rod, the phase and amplitude relationships can be controlled. The invention also applies to cylindrical dual reflector systems which are symmetric about a plane.

Claims

1. An antenna for transmission and reception of electromagnetic waves, the antenna comprising:

a main reflector having an outer surface;

a sub-reflector spaced from said main reflector and having an inner surface facing the outer surface of said main reflector and said sub-reflector having an outer surface facing away from the main reflector; and

an opening in the sub-reflector allowing radiation to pass therethrough and thereby bypass the main reflector.

2. The antenna of claim 1 wherein said antenna further comprises:

a waveguide associated with said opening and which allows the radiation to pass through said opening while controlling the phase and amplitude of the radiation passing through the opening.

3. The antenna of claim 2 further characterized in that said waveguide is loaded with a dielectric material which reduces the effective path difference between the radiation passing through the opening and the radiation which is received at the main reflector.

4. The antenna of claim 3 further characterized in that said dielectric material extends outside the opening in the sub-reflector and forms a dielectric waveguide.

5. The antenna of claim 1 further characterized in that the outer surface of said sub-reflector is arranged to control the pattern of the radiation which can pass through the opening.

6. The antenna of claim 1 further characterized in that the outer surface of said sub-reflector has a shape which approximates that of a horn antenna which aids in the control of the radiation passing through said opening.

7. The antenna of claim 1 further characterized in that the feed aperture is shaped.

8. The antenna of claim 7 further characterized in that at least one choke is disposed at said feed aperture.