A Doppler radar that provides navigation information for aircraft

Abstract

The present invention relates to a Doppler radar that provides navigation information for an aircraft. The radar comprises an antenna unit, a transceiver unit, and a processing and control unit. The antenna unit is a four-beam array antenna with a common aperture for transmission and reception, comprising a transmitting antenna and a receiving antenna. The transmitting antenna is configured to feed four-channel transmission signals output by the transceiver unit through four transmitting and feeding ports, respectively, and then radiate four radar beams in a centrally symmetrical X-shape. The receiving antenna is configured to receive echo signals from the four radar beams and feed them to the transceiver unit through four receiving and feeding ports for echo signal processing. The transceiver unit is configured to generate four-channel transmission signals and receive corresponding four-channel echo signals. The processing and control unit is configured to control the coordinated operation of the Doppler radar and calculate the aircraft's navigation information based on the Doppler frequency shifts of the transmission and echo signals. The present invention achieves antenna miniaturization and reduces coordinate errors or interference between transmission and reception.

Description

Technical Field

[0001] The present invention relates to the field of radar technology, and in particular to a Doppler radar that provides navigation information for an aircraft. Background Art

[0002] Doppler speed measurement radar can automatically, continuously and accurately measure the speed vector information of aircraft including manned aircraft and unmanned aircraft. Its operation is not restricted by geographical and meteorological conditions, and the speed measurement accuracy is exactly the same throughout the entire flight.

[0003] However, the single-beam Doppler radar antennas currently in use suffer from significant errors in measuring low speeds and drift angles. Furthermore, the antennas for multi-beam Doppler radars are large, making them difficult to miniaturize and unable to meet the technical requirements for Doppler radars providing navigation information for aircraft with limited antenna apertures. Summary of the Invention

[0004] In view of the above analysis, an embodiment of the present invention aims to provide a Doppler radar that provides navigation information for an aircraft, thereby solving the multi-beam pointing and miniaturization problems of the Doppler radar.

[0005] The technical solution provided by the present invention is:

[0006] The present invention discloses a Doppler radar that provides navigation information for an aircraft, comprising an antenna unit, a transceiver unit, and a processing control unit;

[0007] The antenna unit is a four-beam array antenna with a common aperture for transmission and reception, including a transmitting antenna and a receiving antenna. The transmitting antenna is used to feed the four-channel transmission signals output by the transceiver unit from four transmitting and feeding ports, and radiate four radar beams in a centrally symmetrical X shape outward; the receiving antenna is used to receive the echo signals of the four radar beams and feed them to the transceiver unit through four receiving and feeding ports for echo signal processing.

[0008] The transceiver unit is used to generate 4-channel transmission signals and receive corresponding 4-channel echo signals;

[0009] The processing control unit is used to control the coordinated work of the Doppler radar system and calculate the navigation information of the aircraft based on the Doppler frequency shift of the transmitted signal and the echo signal.

[0010] Furthermore, the transmitting antenna includes a first feeding waveguide, a second feeding waveguide and N radiating waveguides with the same structure;

[0011] The first feeding waveguide and the second feeding waveguide are rectangular waveguides with the same structure;

[0012] N radiating waveguides are arranged in parallel and evenly to form a radiating waveguide array;

[0013] The short side wall of the first feeding waveguide is connected to the waveguide port on one side of the radiating waveguide array; the short side wall of the second feeding waveguide is connected to the waveguide port on the other side of the radiating waveguide array;

[0014] The two-channel transmission signals fed into the two ports of the first transmitting and feeding waveguide are output to the transmitting and radiating waveguide array through the first transmitting and feeding waveguide, and then radiate two radar beams into space;

[0015] The two-channel transmission signals fed into the two ports of the second transmitting and feeding waveguide are output to the transmitting and radiating waveguide array through the first transmitting and feeding waveguide, and then radiate two radar beams into space;

[0016] The four radar beams have the same oblique angle relative to the radiation waveguide array surface and are in a centrally symmetrical X shape.

[0017] Furthermore, the radiating waveguide is a narrow-side slit radiating waveguide; a plurality of narrow-side slits of the same length and width with staggered inclination angles are provided on the narrow side of the waveguide, the intervals between every two adjacent narrow-side slits are the same, and the narrow-side slits are symmetrically distributed with respect to the center line of the radiating waveguide;

[0018] N narrow side cracks are formed on the short side walls of the waveguides connecting the first and second feeding waveguides and the radiating waveguide array, and electromagnetic signals are transmitted to the radiating waveguide array through the narrow side cracks.

[0019] Furthermore, the deflection angle of the radiating waveguide direction of each beam is The deflection angle of each beam in the vertical direction of the radiating waveguide Where λ is the wavelength of the signal in free space, g is the wavelength of the signal in the waveguide; d1 is the distance between the centers of two adjacent narrow side cracks on the radiating waveguide; d2 is the distance between the centers of two adjacent narrow side cracks on the feeding waveguide.

[0020] Furthermore, the amplitude distribution function of the coupling function of the narrow side crack of the radiating waveguide to the waveguide is Where E(x) is the amplitude distribution function, P(x) is the power passing through the waveguide, and x is the value normalized relative to half the length of the antenna; P(0) = P0; φ(+1)=[P(+1)-P0] / [P(+1)+P0].

[0021] Furthermore, the receiving antenna includes a first feeding waveguide, a second feeding waveguide and N radiating waveguides with the same structure;

[0022] The first receiving and feeding waveguide and the second receiving and feeding waveguide are rectangular waveguides with the same structure as the first transmitting and feeding waveguide or the second transmitting and feeding waveguide;

[0023] N radiating and receiving waveguides are arranged in parallel and evenly, forming a radiating and receiving waveguide array with the same spacing as the radiating and transmitting waveguide array;

[0024] The short side wall of the first feeding waveguide is connected to the waveguide port on one side of the receiving and radiating waveguide array; the short side wall of the second feeding waveguide is connected to the waveguide port on the other side of the receiving and radiating waveguide array.

[0025] Furthermore, the transmitting antenna and the receiving antenna are arranged in a staggered manner and are placed in different heights to achieve a common aperture for transmission and reception;

[0026] Specifically, the first transmitting waveguide and the second transmitting waveguide are located directly above the first receiving waveguide and the second receiving waveguide respectively; and the N transmitting waveguides and the N receiving waveguides are arranged in a staggered manner.

[0027] Furthermore, each port of the first transmitting and feeding waveguide, the second transmitting and feeding waveguide, the first receiving and feeding waveguide, and the second receiving and feeding waveguide comprises a waveguide isolator;

[0028] During transmission, when one of the four ports in the first and second transmission feeding waveguides is incident, the isolators at the three ports function as reverse load absorption.

[0029] During reception, when one of the four ports in the first and second feeding waveguides is used for output, the isolators at the other three ports function as reverse load absorbers.

[0030] Furthermore, the processing control unit controls the illumination order of the four beams to be random illumination, so as to overcome co-channel interference.

[0031] Furthermore, the processing control unit calculates the speed information in the navigation information of the aircraft according to the Doppler frequency shift of the transmission signal and the echo signal as follows:

[0032]

[0033] Where, f is the velocity component of the carrier coordinate system X, Y, and Z axes measured by the Doppler radar; d1 、f d2 、f d3 、f d4 are the Doppler shifts of the four beams respectively; γ0 is the angle between the center line of each beam and the X-axis of the aircraft carrier coordinate system; δ0 is the angle between the projection of the beam line on the corresponding plane and the Y-axis of the carrier coordinate system; λ is the wavelength of the radar transmission signal.

[0034] The present invention can achieve at least the following beneficial effects:

[0035] The Doppler radar antenna of the present invention realizes four-beam pointing, adopts the common aperture of the transmitting and receiving antennas to realize the miniaturization of the antenna, and enables the beam pointing angles of the transmitting and receiving antennas to be solved in the same coordinate system, thereby reducing coordinate error or mutual interference between transmitting and receiving, and realizing resistance to co-frequency interference.

[0036] In the present invention, the above-mentioned technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of the present invention will be described in the following description, and some advantages will become apparent from the description or be learned through practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0038] Figure 1 FIG1 is a block diagram of a Doppler radar according to an embodiment of the present invention;

[0039] Figure 2 1 is a top view of a four-beam array antenna in an embodiment of the present invention;

[0040] Figure 3 2 is a side view of a four-beam array antenna in an embodiment of the present invention;

[0041] Reference numerals: 1—radiating waveguide, 2—first transmitting and feeding waveguide, 3—second transmitting and feeding waveguide, 4—radiating and receiving waveguide, 5—first receiving and feeding waveguide, 6—second receiving and feeding waveguide, 7—transmitting and feeding port, 8—receiving and feeding port. DETAILED DESCRIPTION

[0042] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, and are not used to limit the scope of the present invention.

[0043] One embodiment of the present invention discloses a Doppler radar that provides navigation information for an aircraft, such as Figure 1 As shown, it includes an antenna unit, a transceiver unit and a processing control unit;

[0044] The antenna unit is a four-beam array antenna with a common aperture for transmission and reception, including a transmitting antenna and a receiving antenna. The transmitting antenna is used to feed the four-channel transmission signals output by the transceiver unit from four transmitting and feeding ports, and radiate four radar beams in a centrally symmetrical X shape outward; the receiving antenna is used to receive the echo signals of the four radar beams and feed them to the transceiver unit through four receiving and feeding ports for echo signal processing.

[0045] The transceiver unit is used to generate 4-channel transmission signals and receive 4-channel echo signals;

[0046] The processing control unit is used to control the coordinated work of the Doppler radar system and calculate the navigation information of the aircraft based on the Doppler frequency shift of the transmitted signal and the echo signal.

[0047] like Figure 2 and Figure 3 As shown, the transmitting antenna of the four-beam array antenna with a common aperture for transmitting and receiving includes a first transmitting and feeding waveguide, a second transmitting and feeding waveguide, and N transmitting and radiating waveguides with the same structure;

[0048] The first feeding waveguide and the second feeding waveguide are rectangular waveguides with the same structure;

[0049] N radiating waveguides are arranged in parallel and evenly to form a radiating waveguide array;

[0050] The short side wall of the first feeding waveguide is connected to the waveguide port on one side of the radiating waveguide array; the short side wall of the second feeding waveguide is connected to the waveguide port on the other side of the radiating waveguide array;

[0051] The two-channel transmission signals fed into the two ports (port 1 and port 2) of the first transmitting and feeding waveguide are output to the transmitting and radiating waveguide array through the first transmitting and feeding waveguide, and then radiate two radar beams into space;

[0052] The two-channel transmission signals fed into the two ports (port 3 and port 4) of the second transmitting and feeding waveguide are output to the transmitting and radiating waveguide array through the first transmitting and feeding waveguide, and then radiate two radar beams into space;

[0053] The four radar beams have the same oblique angle relative to the radiation waveguide array surface and are in a centrally symmetrical X shape.

[0054] The radiating waveguide in this embodiment differs from conventional traveling-wave antennas, which use a single-end power input and an absorbing load at the other end. In conventional traveling-wave antennas, if the spacing between the radiating slits is not an integer multiple of half the waveguide wavelength, a traveling wave state is established in the waveguide, and the main beam of the pattern tilts toward the waveguide axis. The shape of a traveling-wave antenna's pattern is related to the electric field amplitude distribution, which in turn depends on the degree of coupling between the slit and the waveguide. Therefore, conventional traveling-wave antennas use a unidirectional input. Based on parameters such as pattern sidelobes and gain, the coupling function between the slit and the waveguide is typically asymmetric to ensure the desired pattern shape.

[0055] The radiating waveguide in this embodiment utilizes bidirectional power input, meaning the load port of a conventional traveling-wave antenna also serves as a second input port for electromagnetic waves. Furthermore, the narrow slits on the radiating waveguide in this embodiment are symmetrically distributed about the centerline of the radiating waveguide, meaning they are also symmetrical when viewed from both ends. By setting the slit coupling function, the beam angles of the incident electromagnetic waves at both ends of the radiating waveguide are strictly consistent. The spacing between the narrow slits in the radiating waveguide determines the X-direction beam pointing angle of the radiating waveguide.

[0056] Therefore, in this embodiment, a narrow-side slit radiation waveguide is used as the radiation waveguide. Multiple narrow-side slits of the same length and width with staggered inclination angles are set on the narrow side of the waveguide. The interval between every two adjacent narrow-side slits is the same, and the narrow-side slits are symmetrically distributed with respect to the center line of the radiation waveguide. The spacing between the narrow-side slits of the radiation waveguide determines the X-beam pointing angle of the radiation pattern.

[0057] N narrow slits are defined on the short sidewalls of the waveguides that connect the first and second feeding waveguides to the radiating waveguide array. Electromagnetic signals are transmitted through these narrow slits to the radiating waveguide array. The spacing between the narrow slits in the feeding waveguides is identical to the spacing between the radiating waveguides in the radiating waveguide array. Therefore, the spacing of the narrow slits in the radiating waveguides determines the Y-axis beam pointing angle of the radiation pattern.

[0058] More specifically, the deflection angle of the radiating waveguide direction (direction pattern X) of each beam is The deflection angle of the radiating waveguide of each beam in the vertical direction (direction Y direction) Where λ is the wavelength of the signal radiated into free space, λ g is the wavelength of the signal in the waveguide; d1 is the distance between the centers of two adjacent narrow side cracks on the radiating waveguide; d2 is the distance between the centers of two adjacent narrow side cracks on the feeding waveguide.

[0059] The radar transmission signal is fed into the transmitting antenna from the two ports of the first transmitting and feeding waveguides and the two ports of the second transmitting and feeding waveguides, and radiated into the free space through the transmitting and radiating waveguide array, forming four X-shaped beams symmetrical with respect to the vertical line of the center of the radiating waveguide array surface. The beam pointing angles are strictly symmetrical, ensuring the subsequent calculation of the precise flight speed of the flying vehicle in three directions through the relationship between the Doppler frequency offset and the beam pointing angle.

[0060] Furthermore, in order to solve the symmetry of the antenna pattern, it is also necessary to ensure that the slot coupling function is an even function.

[0061] Unlike traditional traveling wave array designs, in order to ensure that the incoming waves in two directions of a single radiating waveguide have symmetrical radiation pattern characteristics, the radiating waveguide of this embodiment has the cracks symmetrically arranged at both ends. That is, the coupling function of the crack to the waveguide is an even function relative to the middle of the radiation aperture. At this time, the amplitude distribution function is no longer symmetrical (traditional traveling wave antennas are symmetrical).

[0062] Therefore, the amplitude distribution function of the coupling function of the narrow side crack of the radiating waveguide of this embodiment to the waveguide is:

[0063] Where E(x) is the amplitude distribution function, P(x) is the power passing through the waveguide, and x is the value normalized relative to half the length of the antenna; P(0) = P0;

[0064]

[0065]

[0066] φ(+1)=[P(+1)-P0] / [P(+1)+P0].

[0067] After obtaining the degree distribution function (amplitude characteristic), the pattern characteristic can be obtained, thereby fully solving the problem of the four-beam symmetry of the pattern.

[0068] Furthermore, the inclination angle and penetration depth of each slot in a narrow-side slotted single waveguide can be determined through the amplitude distribution function and the coupling function of the waveguide.

[0069] To achieve miniaturization of the antenna and enable the beam pointing angles of the transmitting and receiving antennas to be calculated in the same coordinate system, thereby reducing coordinate errors or mutual interference between transmission and reception, the antenna unit of this embodiment adopts a co-aperture design for transmission and reception.

[0070] A receiving antenna having the same aperture as the transmitting antenna, comprising a first feeding waveguide, a second feeding waveguide and N radiating waveguides having the same structure;

[0071] The first receiving and feeding waveguide and the second receiving and feeding waveguide are rectangular waveguides with the same structure as the first transmitting and feeding waveguide or the second transmitting and feeding waveguide;

[0072] N radiating and receiving waveguides are arranged in parallel and evenly to form a radiating and receiving waveguide array with the same spacing as the radiating and transmitting waveguide array;

[0073] The short side wall of the first feeding waveguide is connected to the waveguide port on one side of the receiving and radiating waveguide array; the short side wall of the second feeding waveguide is connected to the waveguide port on the other side of the receiving and radiating waveguide array.

[0074] The two-channel transmission signals fed into ports 1 and 2 of the first transmitting and feeding waveguide are output to the transmitting and radiating waveguide array through the first transmitting and feeding waveguide. The two radar beams are then radiated into space. After being reflected by the radiating and receiving waveguide array, the echo signals are fed out to the transceiver unit from ports 5 and 6 of the first receiving and feeding waveguide.

[0075] The two-channel transmission signals fed into ports 3 and 4 of the second transmitting and feeding waveguide are output to the transmitting and radiating waveguide array through the second transmitting and feeding waveguide. The two radar beams are then radiated into space. After being reflected by the radiating and receiving waveguide array, the reflected echo signals are fed out to the transceiver unit from ports 7 and 8 of the second receiving and feeding waveguide.

[0076] Since the structure of the receiving antenna is exactly the same as that of the transmitting antenna, the boom beam pointing angles of the four radar beams of the receiving antenna are strictly equal to the boom beam pointing angles of the four radar beams of the transmitting antenna, forming a centrally symmetrical X shape.

[0077] More preferably, since both the radiating waveguide array and the receiving radiating waveguide array are radiating waveguide arrays with narrow-side slots, in order to achieve beam pointing on the Y-axis, there is a certain spacing between the radiating waveguides, which is the distance d2 between the centers of two adjacent narrow-side slots on the transmitting and feeding waveguides.

[0078] Furthermore, in this embodiment, the interval d2 is larger than the narrow side width of the radiating waveguide. Therefore, the radiating waveguides and the radiating waveguides can be arranged in a staggered manner without blocking each other.

[0079] Therefore, the transmitting and receiving antennas of this embodiment are designed with a common aperture, and the transmitting antenna and the receiving antenna are arranged in a staggered layout to achieve an integrated design. At the same time, considering the influence of the feed network, the radiating waveguides of the transmitting and receiving antennas are arranged in a high-low arrangement in the vertical plane.

[0080] Specifically, in the vertical direction (Z direction of the radiation pattern), the first transmitting waveguide and the second transmitting waveguide are respectively located directly above the first receiving waveguide and the second receiving waveguide; in the horizontal direction (Y direction of the radiation pattern), the N transmitting waveguides and the N receiving waveguides are staggered.

[0081] The miniaturization and integration of the transmitting and receiving antennas are solved by staggered arrangement and high and low placement of the radiating waveguides of the transmitting and receiving antennas, so that the beam pointing angles of the transmitting and receiving antennas are within a reference coordinate system, and the problem of staggered feeding of the transmitting and receiving antennas is solved at the same time.

[0082] Each port of the first transmitting and feeding waveguide, the second transmitting and feeding waveguide, the first receiving and feeding waveguide, and the second receiving and feeding waveguide comprises a waveguide isolator;

[0083] During transmission, when one of the four ports in the first and second transmission feeding waveguides is incident, the isolators at the three ports function as reverse load absorption.

[0084] During reception, when one of the four ports in the first and second feeding waveguides is used for output, the isolators at the other three ports function as reverse load absorbers.

[0085] More specifically, this embodiment also provides a specific antenna unit structure, including: the antenna's structural dimensions do not exceed 400mm × 200mm × 30mm. The number N of transmitting and receiving waveguides is 11. Each transmitting and receiving waveguide has 36 narrow slots with staggered angles for radiating electromagnetic energy into space. The spacing between the radiating slots is 11 mm. The inner dimensions of the transmitting and receiving waveguides are 17mm × 4mm; the dimensions of the transmitting and receiving feed waveguides are 18.75mm × 4mm.

[0086] Furthermore, the processing control unit controls the illumination order of the four beams to be random illumination, so as to overcome co-channel interference.

[0087] Specifically, methods to overcome co-channel interference include:

[0088] 1) Numbering each beam of the Doppler radar; arranging the numbers to form a one-dimensional array as an illumination sequence set of each beam of the Doppler radar;

[0089] More specifically, the antenna beams are numbered 1, 2, 3, and 4;

[0090] Arrange the 4 numbers to form 24 combinations, forming a one-dimensional array with a length of 24, which is:

[0091] {3142,4312,3421,4321,2413,4213,2431,4231,2314,3214,2341,3241,1423,4123,1432,4132,1324,3124,1342,3142,1234,1243,2134,2143}.

[0092] The one-dimensional array is used as the illumination sequence set of each beam of the Doppler radar,

[0093] 2) Generate a corresponding random number in each data collection cycle;

[0094] The random number may be generated by a software random number generator or a hardware random number generator.

[0095] 3) Performing a modulo operation on the random number of the current data acquisition cycle and the length of the array; using the modulo value to index the value at the corresponding position in the array, and using the order of the numbers in the values as the beam irradiation order of the current cycle.

[0096] Specifically, the random number generated by the random number generator is modulo 24, and the remainder range is [0, 23]. Then, the remainder value is used to index the corresponding subscript of the sequence array to determine the beam irradiation order of the current cycle.

[0097] For example, if the generated random number is 0, the remainder is 0, and the first value in the array is 3142. The beam illumination order is 3-1-4-2. If the generated random number is 47, the remainder is 23, and the 24th value in the array is 2143. The beam illumination order is 2-1-4-3, and so on. This achieves random control of beam illumination. This overcomes the problem of co-channel interference caused by the fixed beam illumination order in each data acquisition cycle.

[0098] Furthermore, the processing control unit calculates the speed information in the navigation information of the aircraft according to the Doppler frequency shift of the transmission signal and the echo signal as follows:

[0099]

[0100] Where, f is the velocity component of the carrier coordinate system X, Y, and Z axes measured by the Doppler radar; d1 、f d2 、f d3 、f d4 are the Doppler shifts of the four beams respectively; γ0 is the angle between the center line of each beam and the X-axis of the aircraft carrier coordinate system; δ0 is the angle between the projection of the beam line on the corresponding plane and the Y-axis of the carrier coordinate system; λ is the wavelength of the radar transmission signal.

[0101] Therefore, as long as the instantaneous Doppler frequency values of the four beams are measured in real time, the components of the radar carrier velocity vector (i.e. the longitudinal velocity along the heading, the lateral velocity perpendicular to the heading, and the vertical velocity) can be calculated in real time according to the above formula for navigation.

[0102] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A Doppler radar for providing navigation information for an aircraft, characterized in that: including an antenna unit, a transceiver unit and a processing control unit; The antenna unit is a four-beam array antenna with a common aperture for transmission and reception, including a transmitting antenna and a receiving antenna. The transmitting antenna is used to feed the four-channel transmission signals output by the transceiver unit from four transmitting and feeding ports, and radiate four radar beams in a centrally symmetrical X shape outward; the receiving antenna is used to receive the echo signals of the four radar beams and feed them to the transceiver unit through four receiving and feeding ports for echo signal processing. The transceiver unit is used to generate 4-channel transmission signals and receive corresponding 4-channel echo signals; The processing control unit is used to control the coordinated operation of the Doppler radar system and calculate the navigation information of the aircraft based on the Doppler frequency shift of the transmitted signal and the echo signal; The transmitting antenna includes a first feeding waveguide, a second feeding waveguide and N radiating waveguides with the same structure; The first transmitting and feeding waveguide and the second transmitting and feeding waveguide are rectangular waveguides with the same structure; N radiating waveguides are arranged in parallel and evenly to form a radiating waveguide array; The short side wall of the first feeding waveguide is connected to the waveguide port on one side of the radiating waveguide array; the short side wall of the second feeding waveguide is connected to the waveguide port on the other side of the radiating waveguide array; The two-channel transmission signals fed into the two ports of the first transmitting and feeding waveguide are output to the transmitting and radiating waveguide array through the first transmitting and feeding waveguide, and then radiate two radar beams into space; The two-channel transmission signals fed into the two ports of the second transmitting and feeding waveguide are output to the transmitting and radiating waveguide array through the first transmitting and feeding waveguide, and then radiate two radar beams into space; The four radar beams have the same oblique angle relative to the radiation waveguide array surface and are in a centrally symmetrical X shape; The receiving antenna includes a first feeding waveguide, a second feeding waveguide and N radiating waveguides with the same structure; The first receiving and feeding waveguide and the second receiving and feeding waveguide are rectangular waveguides with the same structure as the first transmitting and feeding waveguide or the second transmitting and feeding waveguide; N radiating and receiving waveguides are arranged in parallel and evenly, forming a radiating and receiving waveguide array with the same spacing as the radiating and transmitting waveguide array; The short side wall of the first feeding waveguide is connected to the waveguide port on one side of the radiating waveguide array; the short side wall of the second feeding waveguide is connected to the waveguide port on the other side of the radiating waveguide array; Both the radiating waveguide array and the receiving waveguide array are radiating waveguide arrays with narrow side slots. There is a certain distance between the radiating waveguides. The distance is the distance d2 between the centers of two adjacent narrow side slots on the transmitting and feeding waveguides. The distance d2 is greater than the narrow side width of the radiating waveguide. The transmitting antenna and the receiving antenna are arranged in a staggered manner and are placed in a high and low position to achieve the same aperture for transmission and reception; The first transmitting waveguide and the second transmitting waveguide are located directly above the first receiving waveguide and the second receiving waveguide respectively; the N transmitting waveguides and the N receiving waveguides are arranged in a staggered manner; The processing control unit calculates the speed information in the navigation information of the aircraft according to the Doppler frequency shift of the transmission signal and the echo signal as follows: Where, f is the velocity component of the carrier coordinate system X, Y, and Z axes measured by the Doppler radar; d1 、f d2 、f d3 、f d4 are the Doppler shifts of the four beams respectively; γ0 is the angle between the center line of each beam and the X-axis of the aircraft carrier coordinate system; δ0 is the angle between the projection of the beam line on the corresponding plane and the Y-axis of the carrier coordinate system; λ is the wavelength of the radar transmission signal.

2. The Doppler radar according to claim 1, characterized in that The radiating waveguide is a narrow-side slit radiating waveguide; a plurality of narrow-side slits of the same length and width with staggered inclination angles are provided on the narrow side of the waveguide, the intervals between every two adjacent narrow-side slits are the same, and the narrow-side slits are symmetrically distributed with respect to the center line of the radiating waveguide; N narrow side cracks are formed on the short side walls of the waveguides connecting the first and second feeding waveguides and the radiating waveguide array, and electromagnetic signals are transmitted to the radiating waveguide array through the narrow side cracks.

3. The Doppler radar according to claim 2, characterized in that: The deflection angle of the radiating waveguide direction of each beam The deflection angle of the radiating waveguide of each beam in the vertical direction Where λ is the wavelength of the signal in free space, g is the wavelength of the signal in the waveguide; d1 is the distance between the centers of two adjacent narrow side cracks on the radiating waveguide; d2 is the distance between the centers of two adjacent narrow side cracks on the feeding waveguide.

4. The Doppler radar according to claim 2, characterized in that: The amplitude distribution function of the coupling function of the narrow side crack of the radiating waveguide to the waveguide is: Where E(x) is the amplitude distribution function, P(x) is the power passing through the waveguide, and x is the value normalized relative to half the length of the antenna; P(0) = P0; φ(+1)=[P(+1)-P0] / [P(+1)+P0].

5. The Doppler radar according to claim 1, characterized in that Each port of the first transmitting and feeding waveguide, the second transmitting and feeding waveguide, the first receiving and feeding waveguide, and the second receiving and feeding waveguide comprises a waveguide isolator; During transmission, when one of the four ports in the first and second transmission feeding waveguides is incident, the isolators at the three ports function as reverse load absorption. During reception, when one of the four ports in the first and second feeding waveguides is used for output, the isolators at the other three ports function as reverse load absorbers.

6. The Doppler radar according to claim 1, characterized in that The processing control unit controls the illumination order of the four beams to be random illumination, so as to overcome co-frequency interference.

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