Method of performing beam compression process on antenna pattern of radar

• US 5,418,539 A
• Filed: 08/22/1994
• Issued: 05/23/1995
• Est. Priority Date: 09/13/1993
• Status: Expired due to Fees

• Current Assignee: National Space Development Agency of Japan
• Original Assignee: National Space Development Agency of Japan
• Inventors: Sezai, Toshihiro
• Primary Examiner(s): Blum, Theodore M.
• Application Number:
  US08/297,721
• Time in Patent Office: 274 Days
• Field of Search: 342/372, 342/378, 342/380, 342/383, 342/157
• US Class Current: 342/378
• 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 21/296 Multiplicative arrays

Abstract

An antenna system comprises a main antenna for use of transmission and reception and a pair of sub-antennas use of only reception. The antenna beam of the system is scanned in the direction of a beam width to be compressed. Both received signals of the main antenna and the sub-antennas are fed to a signal processing circuit. The signal processing circuit converts these received signals to power signals and then performs signal processing on them. In this signal processing, the power signal received by the main antenna is output as a final output signal only if both double differential coefficients of the received signals received by the main antenna and the sub-antennas are equal to or less than corresponding predefined positive real number values, and if the phase difference between the power signal received by the main antenna and the power signal received by the sub-antennas is equal to or less than 90°, thereby producing the output signal representing faithfully the distribution of scattering objects without distortion.

Claims

1. A method of compressing the beam width of the antenna pattern of a radar system, comprising the steps of:

providing an antenna system comprising a main antenna for transmitting and receiving radio waves and one or more pairs of dedicated receiving sub-antennas which are disposed at both sides adjacent to said main antenna in the direction of the beam width to be compressed of said main antenna such that the directions of the beam axes of said sub-antennas coincide with the direction of the beam axis of said main antenna;

scanning the antenna beam of said antenna system in the direction of said beam width to be compressed, and receiving by the main antenna and sub-antennas the radio wave which was transmitted by the main antenna and reflected by scattering objects and has finally come back;

converting the respective received signals received by the main antenna and the sub-antennas to power signals;

performing double differential processing with respect to the scanning angle on the received power signals received by the main antenna and the sub-antennas, respectively, thereby producing double differential coefficients of the received power signals associated with the main antenna and the sub-antennas, respectively;

calculating the phase difference between the received power signal received by the main antenna and the received power signal received by the sub-antennas; and

outputting the received power signal received by the main antenna as a final output signal only if the conditions that both said double differential coefficients of the received power signals associated with the main antenna and the sub-antennas be equal to or less than predefined corresponding positive real number values and that said phase difference be equal to or less than 90°

are satisfied, and outputting a zero signal as the final output signal if said conditions are not satisfied.

2. A method of compressing the beam width of the antenna pattern of a radar system, according to claim 1, wherein said condition that said phase difference be equal to or less than 90°

is such as that said phase difference be equal to or less than a predefined angle less than 90°

.

3. A method of compressing the beam width of the antenna pattern of a radar system, according to claim 1, wherein:

said step of providing an antenna system includes the step of disposing plural pairs of the sub-antennas; and

said step of converting the received signals to power signals includes the steps of adding received signals received by the pairs of sub-antennas together, and converting the sum of the received signals received by the pairs of sub-antennas to a power signal.

4. A method of compressing the beam width of the antenna pattern of a radar system, according to claim 2, wherein:

said step of providing an antenna system includes the step of disposing plural pairs of the sub-antennas; and

said step of converting the received signals to power signals includes the steps of adding received signals received by the pairs of sub-antennas together, and converting the sum of the received signals received by the pairs of sub-antennas to a power signal.