Process for side lobe suppression and amplitude or phase monopulse radar device

• US 6,118,402 A
• Filed: 03/08/1999
• Issued: 09/12/2000
• Est. Priority Date: 03/09/1998
• Status: Expired due to Fees

• Current Assignee: Siemens Schweiz AG (Siemens AG)
• Original Assignee: Siemens Schweiz AG (Siemens AG)
• Inventors: Kupfer, Hanspeter
• Primary Examiner(s): Sotomayor, John B.
• Application Number:
  US09/264,001
• Time in Patent Office: 554 Days
• Field of Search: 342/80, 342/91, 342/94, 342/115, 342/135, 342/140, 342/141, 342/149, 342/152, 342/159, 342/162, 342/194, 342/195, 342/203
• US Class Current: 342/149
• CPC Class Codes: G01S 13/44 Monopulse radar, i.e. simultaneous lobing
• 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

Abstract

The process is used for suppressing the effect of signals that are received or sent via side lobes of an antenna (PA; HA) of an amplitude or phase monopulse radar device, in which for the purpose of position measurement of a first and, if need be, a second target (T1, T2) detected by the radar beam, three illumination functions Je(Lx), Jk(Lx) and Js(Lx) for the antenna (PA; HA) are provided for each measurement axis, as well as antenna functions Fe(X), Fk(X), and Fs(X) resulting from them. The first, second, and third illumination functions Je(Lx); Jk(Lx), and Js(Lx) are selected in this connection so that a quotient function Qe(X)=Fe(X)/Fs(X) or Qk(X)=Fk(X)/Fs(X), which is linearly or quadratically dependent on the target direction, is produced by normalizing the first and the second antenna functions Fe(X); Fk(X) with the third antenna function Fs(X). The power of this quotient is compared with at least one threshold value th_e or th_k that is selected in accordance with the magnitude of the main antenna lobe, and when the threshold value th_e or th_k is exceeded, the effect of the received signal is suppressed. In a preferred embodiment of the invention, the provision is made that the zero points of the antenna functions Fe(X), Fk(X), and Fs(X) are shifted slightly in relation to one another.

Claims

1. A method for suppressing the effect of signals that are received or sent via side lobes of an antenna of an amplitude or phase monopulse radar device, comprising:

providing three illumination functions for the antenna for each measurement axis, the three illumination functions provided for position measurement of targets, three antenna functions produced from the three illumination functions for the antenna;

producing a quotient between at least one of signals and signal powers that are at least one of received and sent via at least one of the first and the second antenna function of the three illumination functions for the antenna and at least one of the signal and its signal power that is at least one of received and sent via the third antenna function of the three illumination functions for the antenna;

comparing the quotient with a threshold value; and

determining whether the signal and its signal power were at least one of received and sent via a side lobe of the antenna.

2. The method according to claim 1 comprising:

normalizing the first and the second antenna function with the third antenna function;

producing quotient functions from the normalizing; and

comparing signal powers of the quotient functions at least one of individually and if necessary weighted with factors and summed, with at least one threshold value.

3. The method according to claim 1 comprising:

normalizing the powers of the signals of the first and second antenna function, which have if necessary, been weighted with the factors and vectorially added, with the power of the signals of the third antenna function;

producing a quotient power function from the second normalizing, the values of the quotient power function being compared with a threshold value;

sending first transmission signals that are transmitted by at least one of the first and the second antenna function to a receiving station chronologically separate from second transmission signals that are transmitted by the third antenna function;

producing in the receiving station a quotient from the powers of the first and second transmission signals;

comparing the quotient with a threshold value; and

suppressing the effects of the received signals if the threshold value is exceeded.

4. The method according to claim 1, the illumination functions being selected such that the zero points of the antenna functions, which result by Fourier transformation from the illumination functions, at least one of occur with at least almost the same target direction and not occur with the same target direction.

5. The method according to claim 4, the first illumination function being selected as the first differentiation of the third illumination function, the second illumination function being selected as the second differentiation of the third illumination function, after which, a shifting of the zero points of the first and the second illumination function being produced by a linear distortion in the abscissa that represents a function argument such that a progression of the first illumination function is expanded in comparison to the first illumination function and a progression of the second illumination function is compressed in comparison to the second illumination function, wherein the zero points of the first and second antenna functions are disposed at least one of lower and higher values than the corresponding zero points of the third antenna function.

6. The method according to claim 4, the first illumination function being selected as the first differentiation of the third illumination function, the second illumination function being selected as the second differentiation of the third illumination function, after which, a shifting of the zero points of the first and the second illumination function being produced by a linear distortion in the abscissa that represents a function argument such that a progression of the second illumination function is expanded in comparison to the second illumination function and a progression of the first illumination function is compressed in comparison to the first illumination function, wherein the zero points of the first and second antenna functions are disposed at least one of lower and higher values than the corresponding zero points of the third antenna function.

7. The method according to claim 1, comprising producing a reciprocal phase shifting of ±

90°

at least one of before the summation in the receiving instance and before the reciprocal superimposition in the sending instance, the reciprocal phase shifting being produced between the signals to be added that belong to the first and the second antenna function.

8. The method according to claim 1, the antenna functions being used for target measurement in accordance with the curvature process, the first antenna function being a slope function, the second antenna function being a curvature function, and the third antenna function being a sum function.

9. The method according to claim 1, comprising selecting the threshold value such that the effects of signals that are received from outside the main lobe are suppressed.

10. A radar device for at least one of amplitude and phase monopulse for carrying out the method according to claim 1 comprising:

an antenna, three illumination functions and antenna functions resulting from the three illumination functions being provided for each measurement axis of the antenna;

a division stage, the at least one of signals and signal powers that are at least one of received and sent via at least one of the first and the second antenna function being compared in the division stage with at least one of the signals and signal powers that are at least one of received and sent via the third antenna function; and

a comparator, the signal emitted by the division stage being supplied directly to the comparator via a quadrature stage, a weighting stage, and an addition stage, the comparator comparing the supplied signal with a threshold value, the comparator sending a signal based on the comparing, the effect of signals that are at least one of received and sent via side lobes being suppressed when the threshold value is exceeded.

11. The radar device according to claim 10, the signals of at least one of the first and the second antenna function being divisible by the signals of the third antenna function in a division stage, the resulting quotients each being supplied via a quadrature stage to a comparator in which they are compared with the threshold values.

12. The radar device according to claim 10, the signals of at least one of the first and the second antenna function being divisible by the signals of the third antenna function in a division stage, the resulting quotients each being supplied via a quadrature stage and a weighting stage to an addition stage, the addition stage being connected to a comparator in which the supplied signals are compared with the threshold value.

13. The radar device according to claim 10, the signals of the first and the second antenna function each being summed via a weighting stage and an addition stage and being supplied to a first quadrature stage, the signals of the third antenna function being supplied to a second quadrature stage, the output signals of the first quadrature stage being divisible in a division stage by the output signals of the second quadrature stage, the resulting quotient being compared with the threshold value in the comparator.

14. The radar system that has an amplitude or phase monopulse radar device according to claim 10, comprising:

a sending stage, the sending stage being a part of the amplitude or phase monopulse radar device, the sending stage being used for time-lagged emission of first and second transmission signals to the antenna;

a receiving station, the second transmission signals being transmittable to the receiving station by at least one of the first and the second antenna function, the first signals being transmittable to the receiving station by the third antenna function, a quotient being produced in the receiving station if need be after being temporarily stored in a memory module, the quotient being produced in a division stage from the powers of the first and second transmission signals, the quotient being compared with the threshold value in the comparator.

15. The radar device according to one of claim 10, the illumination functions being selected such that the zero points of the antenna functions that result by Fourier transformation from the illumination functions occur with at least the same target direction.

16. The radar device according to one of claim 10, the illumination functions being selected such that the zero points of the antenna functions that result by Fourier transformation from the illumination functions not occurring with the same target direction.