Method for sidelobe clutter suppression of airborne weather radar

Abstract

The present application provides a kind of sidelobe clutter suppression method of airborne weather radar, comprising: step one, using phased array antenna, form wide antenna pattern and narrow antenna pattern, and make wide antenna pattern and narrow antenna pattern can be switched in time;Step two, according to the flight height of aircraft, the atmospheric environment of flight and ground environment determine the scanning angle of wide beam and narrow beam;Wherein, narrow beam carries out weather detection, wide beam carries out topographic mapping;Step three, according to scanning pattern, electromagnetic wave is emitted, and the echo of wide beam and narrow beam is received;Step four, calculate the echo power difference of wide beam and narrow beam of each distance unit, when the echo power difference of wide beam and narrow beam satisfies the set condition, then deduct the echo of narrow beam distance unit;Step five, after completing a antenna line scanning by repeating step three and step four, the echo of narrow beam is converted into weather reflectivity and quantified and sent to display, and the echo of wide beam is converted into ground reflectivity and quantified and sent to display.

Description

Technical Field

[0001] This invention relates to the field of radar technology, and specifically to a method for suppressing sidelobe clutter in airborne weather radar. Background Technology

[0002] When an aircraft flies at a low altitude or in an area with high backscattering, such as a city, sidelobe clutter may appear on the radar screen. Sidelobe clutter typically includes altitude clutter and other sidelobe clutter. Altitude clutter is caused by the antenna sidelobes pointing vertically below the aircraft, and it is usually an arc-shaped echo. Its location is related to the aircraft's altitude. The location of altitude clutter can be estimated based on the aircraft's altitude and the ground level. Other sidelobe clutter may be caused by the beam sidelobes directly hitting areas with high reflectivity on the ground or by secondary reflection within the radome. Therefore, it is very difficult to accurately determine its specific location. Currently, airborne weather radar products do not have sidelobe suppression capabilities, and the appearance of sidelobe clutter can easily be confused with weather echoes, causing interference to the pilot. Summary of the Invention

[0003] In view of this, embodiments of this specification provide a method for suppressing sidelobe clutter of airborne weather radar, so as to reduce the impact of sidelobe clutter on flight.

[0004] This specification provides the following technical solution in its embodiments: a method for suppressing sidelobe clutter in airborne weather radar, comprising the following steps: Step 1: Using a phased array antenna to form a wide antenna pattern and a narrow antenna pattern, and enabling time-division switching between the wide and narrow antenna patterns; Step 2: Determining the scanning angles of the wide and narrow beams based on the aircraft's flight altitude, the atmospheric environment, and the ground environment; wherein, the narrow beam is used for meteorological detection, and the wide beam is used for terrain mapping; Step 3: Transmitting electromagnetic waves according to the scanning pattern and receiving the echoes of the wide and narrow beams; Step 4: Calculating the echo power difference between the wide and narrow beams for each range cell; when the power difference between the wide and narrow beam echoes meets a set condition, the narrow beam echo for that range cell is deducted; Step 5: Repeating steps 3 and 4 to complete one antenna line scan, converting the narrow beam echo into meteorological reflectivity and quantizing it for display, and converting the wide beam echo into ground reflectivity and quantizing it for display.

[0005] Furthermore, step two specifically involves: using the formula and Determine the scanning angles for wide and narrow beams, where, For flight altitude, At atmospheric zero degrees, For average height, To display the measurement range.

[0006] Further, step three specifically involves: using dual-beam coordinated azimuth scanning. At each azimuth line, a narrow-beam electromagnetic wave is first transmitted, and the received echo sample is denoted as S0(nr). Then, a wide-beam electromagnetic wave is transmitted, and the received echo sample is denoted as S1(nr), where nr is the range gate number.

[0007] Further, step four includes: comparing the range gate data of S0(nr) and S1(nr) one by one, and identifying sidelobe clutter based on the power difference between S0(nr) and S1(nr).

[0008] Furthermore, step four specifically involves:

[0009] Step 4.1, using the formula Calculate the angle of the nth distance gate relative to the aircraft;

[0010] Step 4.2, using the formula Calculate the theoretical echo difference between the main lobe echo and the side lobe echo in both wide and narrow beams;

[0011] Step 4.3, using the formula Calculate the actual echo difference between the main lobe echo and the side lobe echo in both wide and narrow beams.

[0012] Step 4.4: When both conditions are met simultaneously and When this occurs, it is identified as a sidelobe echo.

[0013] Compared with the prior art, the beneficial effects that can be achieved by the above-mentioned at least one technical solution adopted in the embodiments of this specification include at least the following: combining airborne weather radar meteorological detection with terrain detection, which not only ensures the perception of the weather and terrain situation in a large area in front of the aircraft, but also achieves the suppression of sidelobe clutter, which can further improve flight safety and reduce unnecessary yaw. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a flowchart illustrating an embodiment of the present invention;

[0016] Figure 2 These are the wide and narrow antenna radiation patterns in this embodiment of the invention;

[0017] Figure 3 This is a weather display diagram before sidelobe suppression according to an embodiment of the present invention;

[0018] Figure 4 This is a meteorological display diagram after sidelobe suppression according to an embodiment of the present invention;

[0019] Figure 5 This is a ground display diagram according to an embodiment of the present invention. Detailed Implementation

[0020] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0021] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] like Figures 1 to 5 As shown, this embodiment of the invention provides a method for suppressing sidelobe clutter in airborne weather radar, comprising:

[0023] 1. A phased array antenna was used, and the phase and power of the TR component were adjusted to form both wide and narrow beams. The narrow beam pattern has a main beam width of 3dB Bw0, a main lobe gain of Fm0, and an average sidelobe gain of Fs0; the wide beam pattern has a main beam width of 3dB Bw1 and a main lobe gain of Fm1.

[0024] The narrow beam is a pencil beam, while the wide beam can adopt any beam shape that meets the following conditions, such as cosecting beams: the wide beamwidth is not less than 40 degrees (3dB); the main lobe gain Fm1 of the wide beam is at least 3dB less than the main lobe gain Fm0 of the narrow beam; and the main lobe gain Fm1 of the wide beam is at least 10dB greater than the average sidelobe gain Fs0 of the narrow beam.

[0025] 2. Determine the elevation angles of the narrow and wide beam antennas based on the aircraft's altitude and the terrain's altitude. The elevation angle of the narrow beam antenna is E0, and the elevation angle of the wide beam antenna is E1. The calculation method is as follows:

[0026] ;

[0027] ;

[0028] in, For flight altitude, At atmospheric zero degrees, For average height, To display the measurement range.

[0029] 3. Dual-beam coordinated azimuth scanning, from -AZ to +AZ. At each azimuth line, a narrow-beam electromagnetic wave is first transmitted, and the received echo sample is denoted as S0( Then, a wide-beam electromagnetic wave is transmitted, and the received echo sample is recorded as S1( ), Number the distance gate. =1: Weather detection results are as follows: Figure 3 .

[0030] 4. Compare the distance gate data of S0 and S1 one by one, and denot the distance of the nr-th distance gate as... Sidelobe clutter is identified based on the power difference between S0 and S1.

[0031] 1) Calculate the angle of the nth distance gate relative to the aircraft:

[0032] ;

[0033] 2) Calculate the main lobe echo of wide and narrow beams Compared with the theoretical value of side lobe echo :

[0034] ;

[0035] 3) Calculate the actual echo difference:

[0036] ;

[0037] 4) Side lobe recognition:

[0038] if ;

[0039] and ;

[0040] Where TI and T2 are error tolerance values, generally not greater than 6dB, then the nr-th distance gate echo is determined to be a sidelobe echo. Set to 0 to subtract the sidelobe clutter echo.

[0041] 5. Perform meteorological and topographic mapping processing on S0 and S1 respectively. After completing an antenna azimuth scan, quantize and display the data to achieve meteorological detection and topographic mapping image display, such as... Figure 4 and Figure 5 .

[0042] This invention addresses the difficulties in identifying sidelobe clutter in airborne weather radar and the lack of sidelobe clutter suppression capabilities in airborne weather radar products. It proposes a sidelobe clutter suppression method for airborne weather radar, utilizing the beamforming capability of a phased array antenna and employing combined wide and narrow beam detection to suppress sidelobe clutter. Simultaneously, it enables the display of weather and terrain information, reducing false alarms caused by sidelobe clutter and improving the weather and terrain perception detection efficiency of airborne weather radar. This further enhances flight safety and has promising market application prospects in both military and civilian airborne weather radar fields.

[0043] The above description is merely a specific embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, any substitution of equivalent components or equivalent changes and modifications made within the scope of protection of this patent should still fall within the scope of this patent. Furthermore, the technical features, technical features and technical solutions, and technical solutions in this invention can be freely combined and used.

Claims

1. A method for suppressing sidelobe clutter in airborne weather radar, characterized in that, Includes the following steps: Step 1: Use a phased array antenna to form a wide antenna pattern and a narrow antenna pattern, and enable time-division switching between the wide antenna pattern and the narrow antenna pattern; Step 2: Determine the scanning angles of the wide beam and narrow beam based on the aircraft's flight altitude and the atmospheric and ground environment; the narrow beam is used for meteorological detection, and the wide beam is used for terrain mapping. Step 3: Transmit electromagnetic waves according to the scanning pattern and receive echo samples S1(nr) of the wide beam and S0(nr) of the narrow beam. Step 4: Calculate the echo power difference between the wide beam and the narrow beam for each range cell. If the echo power difference between the wide beam and the narrow beam meets the set conditions, then deduct the echo of the narrow beam for that range cell. Step 5: Repeat steps 3 and 4 to complete one antenna line scan, convert the narrow beam echo into meteorological reflectivity and quantize it for display, and convert the wide beam echo into ground reflectivity and quantize it for display. Step four includes: comparing the distance gate data of S0(nr) and S1(nr) one by one, and identifying sidelobe clutter based on the power difference between S0(nr) and S1(nr); Step four specifically involves: Step 4.1, using the formula Calculate the angle of the nth distance gate relative to the aircraft; Step 4.2, using the formula Calculate the theoretical value of the main lobe echo for both wide and narrow beams. Compared with the theoretical value of side lobe echo ; Step 4.3, using the formula Calculate the actual echo difference between the main lobe echo and the side lobe echo in both wide and narrow beams; Step 4.4: When both conditions are met simultaneously and When this occurs, it is identified as a sidelobe echo; Where E0 is the elevation angle of the narrow-beam antenna, E1 is the elevation angle of the wide-beam antenna, Fm0 is the main lobe gain of the narrow-beam antenna, Fm1 is the main lobe gain of the wide-beam antenna, and Fs0 is the average sidelobe gain of the narrow-beam antenna. Let be the angle of the nth distance gate relative to the aircraft.

2. The airborne weather radar sidelobe clutter suppression method according to claim 1, characterized in that, Step two specifically involves: using the formula and Determine the elevation angle E0 of the narrow-beam antenna and the elevation angle E1 of the wide-beam antenna, where, For flight altitude, At atmospheric zero degrees, For average height, To display the measurement range, Bw1 represents the 3dB width of the main beam of the wide beam pattern.

3. The airborne weather radar sidelobe clutter suppression method according to claim 2, characterized in that, Step three specifically involves: using dual-beam coordination for azimuth scanning. At each azimuth line, a narrow-beam electromagnetic wave is first transmitted, and the received narrow-beam echo sample is denoted as S0(nr). Then, a wide-beam electromagnetic wave is transmitted, and the received wide-beam echo sample is denoted as S1(nr), where nr is the range gate number.

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