LOW ANGLE RADAR TRACKING SYSTEM

• US 3,854,135 A
• Filed: 11/09/1973
• Issued: 12/10/1974
• Est. Priority Date: 11/09/1973
• Status: Expired due to Term

• Current Assignee: Warren D. White
• Original Assignee: Warren D. White
• Inventors: White, Warren D.
• Primary Examiner(s): Tubbesing, T. H.
• Assistant Examiner(s): Montone, G. E.
• Application Number:
  US05/414,465
• Time in Patent Office: 396 Days
• Field of Search: 343/16M,16R,16LS,7TA,7A,17.1R,1SA
• US Class Current: 342/148
• CPC Class Codes: G01S 13/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S13/46
• CPC Class Codes: G01S 13/4409 HF sub-systems particularly adapted therefor, e.g. circuits for signal combination multi-lobing aerials or aerial systems H01Q25/00

Abstract

The elevation angle of a target which is at a low altitude over a reflecting surface is ascertained by receiving both direct and reflected radar signals on a pair of fixed directional beams which have patterns such that their ratio has even order symmetry about a horizontal axis. The ratio of the total signals received on these beams is indicative of this angle.

Claims

1. In a method for determining by radar the elevation angle of a target which is at a relatively low altitude so that both direct and reflected radar signals are returned to the radar site, the steps of receiving said direct and reflected radar signals On a pair of directional beams which have patterns and are orientated such that their ratio has even order symmetry with respect to a horizontal axis;

and determining the ratio of the signals received on said pair of directional beams, said ratio being indicative of said elevation angle.

2. In a method as defined in claim 1 wherein the ratio of said beam patterns has a parabolic shape.

3. In a method as defined in claim 2 wherein the square root of the ratio of the signals is determined.

4. In a method as defined in claim 1 wherein one of said directional beams is squinted upwardly with respect to said horizontal axis so as to discriminate in favor of the direct signal arriving at said radar site.

5. In a method for determining the elevation angle of a target which employs radar and wherein direct and reflected radar signals arrive back at the radar site, the steps of forming a pair of directional beams in space which have patterns that over their main beam areas have even order symmetry with respect to an axis;

orientating said directional beams such that this axis is horizontal;

receiving both the direct and reflected radar signals from said target on this pair of beams; and

measuring the ratio of the signals so received, said ratio being indicative of the elevation angle.

6. In a method as defined in claim 5 wherein each value of the ratio corresponds to only one positive value in the main beam region.

7. Apparatus for determining the elevation angle of a low altitude target which is above a reflecting surface so that radar signals striking said target produce direct and reflected radar signals back at the radar site, the combination of means for forming a pair of directional beams which have patterns such that over the main beam regions the ratio of these patterns has even order symmetry with respect to a horizontal direction;

means for receiving said direct and reflected radar signals on each beam; and

means for measuring the ratio of the signals so received, said ratio providing an indication of the elevation angle.

8. In an arrangement as defined in claim 7 wherein the ratio of said patterns has a parabolic shape;

and means for obtaining the square root of the ratio of the radar signals.