Method of performing beam compression process on antenna pattern of radar

• US 5,432,519 A
• Filed: 03/14/1994
• Issued: 07/11/1995
• Est. Priority Date: 04/22/1993
• Status: Expired due to Term

• Current Assignee: National Space Development Agency of Japan
• Original Assignee: National Space Development Agency of Japan
• Inventors: Sezai, Toshihiro
• Primary Examiner(s): Hellner, Mark
• Application Number:
  US08/209,901
• Time in Patent Office: 484 Days
• Field of Search: 342/427, 342/373, 342/149
• US Class Current: 342/149
• 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
• CPC Class Codes: G01S 13/87 Combinations of radar systems, e.g. primary radar and secondary radar
• CPC Class Codes: G01S 7/2813 Means providing a modification of the radiation pattern for cancelling noise, clutter or interfering signals, e.g. side lobe suppression, side lobe blanking, null-steering arrays specially adapted to secondary radar systems G01S13/762; aerials or aerials systems H01Q21/29, H01Q25/00
• CPC Class Codes: H01Q 25/02 providing sum and difference patterns H01Q25/04 takes precedence

Abstract

An antenna system comprising two similar radiation antenna elements with a single monopulse feed system is scanned while transmitting in-phase radio waves from the two elements. Reflected radio waves are received by the two elements and fed to a hybrid circuit which in turn produces a sum signal Σ and a difference signal Δ. After detection is performed by a detector, a signal processing unit subtracts the difference signal Δ from the sum signal Σ. In this processing step, the output signal produced by the above subtraction process is actually output only if the receiving pattern waveform associated with the sum signal Σ has an upwardly convex form, that is, its double differential coefficient is negative and further if the receiving pattern waveform associated with the difference signal Δ has a downwardly convex form, that is, its double differential coefficient is positive, whereby an antenna pattern with beam compression is provided.

Claims

1. A method for compressing the beam width of the antenna pattern of a radar system including a radar antenna system having two radiating antenna elements of a single monopulse power feed system, comprising the steps of:

scanning said antenna system while transmitting radio waves from said two elements of the antenna system in such a manner that both the radio waves transmitted from the respective elements are in the same phase;

receiving by the antenna system the radio waves which were transmitted from said antenna system and reflected back by scattering objects to said antenna system;

producing both a sum signal and a difference signal of the received signals of said two elements of the antenna system; and

performing signal processing comprising the steps of subtracting said difference signal from said sum signal and providing the resulting signal as a final antenna output signal, wherein said signal processing step further comprises the step of providing said final antenna output signal only if a double differential coefficient of a receiving pattern waveform associated with said sum signal is negative and further if a double differential coefficient of a receiving pattern waveform associated with said difference signal is positive whereas providing a zero output signal if the above conditions are not satisfied.