Arc conformal array antenna based on array signal reconstruction and adaptive array signal reconstruction method

Abstract

The invention relates to an array signal reconstruction-based arc conformal array antenna, which comprises a central array element and six inclined array elements which are arranged along the circumference, the inclined array elements are all inclined outwards by 30 degrees, the central array element is kept horizontal, and the inclined array elements are arranged along the circumference. According to the arc conformal array antenna, the passive gain of part of arrays to a low-elevation satellite can be improved. The invention also relates to a self-adaptive array signal reconstruction method of the arc conformal array antenna based on array signal reconstruction. The method comprises the following steps: S1, acquiring a satellite angle; s2, reconstructing an array signal; according to the method, the maximum SNR criterion is adopted, inertial navigation attitude information, satellite ephemeris, reconstruction zeroing or beam forming constraint conditions are combined, the average signal-to-noise ratio of input signals is increased, and the purpose of optimizing the anti-interference performance is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of satellite navigation signal anti-interference, relates to an anti-interference antenna, and in particular to an arc conformal array antenna based on array signal reconstruction and an adaptive array signal reconstruction method. Background Art

[0002] With the increase of scientific exploration, resource development, commercial transportation and other activities in polar regions, high-precision and highly reliable polar navigation technology is indispensable. The global navigation satellite system has a wide range of application scenarios and can provide all-weather, high-precision location and time services. With the development and improvement of the Beidou navigation satellite system, the number of visible satellites around the world has increased significantly. Even in the polar regions, public data show that the number of Beidou satellites that can be effectively observed is an average of 9-10. However, the satellite navigation system also faces some inherent problems in polar region applications. On the one hand, due to the limited inclination of the satellite orbit (the inclination of the GPS, Galileo, and BD system orbits is about 55°), the observable satellite elevation angle is generally low, resulting in a small gain provided by the receiving antenna; at the same time, the signal propagation path is long and the signal energy loss is large, resulting in different degrees of attenuation of the satellite signal carrier-to-noise ratio, thereby affecting the positioning performance of the receiving system. On the other hand, in a confrontational environment, high-power suppression interference will cause the received signal carrier-to-noise ratio to decrease. When the noise or interference signal strength exceeds a certain threshold, it will directly cause the satellite signal to lose lock and be difficult to locate.

[0003] In order to further improve satellite navigation capabilities, it is crucial to conduct research on polar anti-interference algorithms in response to the special confrontation environment in the polar regions. Traditional planar array antennas have low gain for low-elevation angle signals and high gain for high-elevation angle interference. In polar regions, the signal-to-noise ratio will decrease, and the anti-interference capability will decrease. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a circular conformal array antenna based on array signal reconstruction and an adaptive array signal reconstruction method. According to the actual anti-interference performance requirements, a circular conformal array structure design and an adaptive beam reconstruction algorithm are proposed based on the traditional planar array antenna.

[0005] The present invention solves the technical problem by the following technical solutions:

[0006] A circular arc conformal array antenna based on array signal reconstruction comprises a central array element and tilted array elements arranged along a circumference, wherein the number of the tilted array elements is 6, the tilted array elements are all tilted outward by 30 degrees, and the central array element remains horizontal.

[0007] An adaptive array signal reconstruction method for a circular arc conformal array antenna based on array signal reconstruction, the method is applied to the circular arc conformal array antenna, and is used for anti-interference processing of signals after frequency conversion by the circular arc conformal array antenna; the steps of the method are:

[0008] S1. Satellite angle acquisition: According to the satellite positioning results and satellite ephemeris data, the azimuth of each satellite is acquired, and the angle information is output to the array signal reconstruction module;

[0009] S2, array signal reconstruction: The array signal reconstruction module divides the space into 6 quadrants. After receiving the angle information of each satellite, it makes a difference judgment between the satellite angle and the center angle of each quadrant. If the angle difference is less than 30°, the 3 array elements on the quadrant side and the 4-way signal of the center array element are selected as the output signal, and the output signal is output to the signal adaptive filtering processing module;

[0010] S3. Signal adaptive filtering processing: The signal adaptive filtering processing module receives 4-way array element signals, uses spatial domain / space-time / space-frequency adaptive filtering algorithm to perform adaptive filtering calculation, and outputs the filtered signal.

[0011] Moreover, the signal processing of the circular arc conformal array antenna includes a data sampling module, a data selection module, a signal adaptive filtering processing module and a satellite capture module;

[0012] The data sampling module collects the signals after the frequency down-conversion of the 7-way array elements of the circular arc conformal array through ADC sampling, waits for the satellite information judgment module to make a judgment result, and then selectively outputs the signals of each array element to the signal adaptive filtering processing module;

[0013] The data selection module determines in real time whether the satellite angle information is currently obtained. If the satellite angle information is obtained, the adaptive array signal reconstruction method is used to reconstruct the array signal, and the reconstructed 4-way signal is output to the signal adaptive filtering processing module; if the satellite angle information is not obtained, the 7-element signal is output to the signal adaptive filtering processing module;

[0014] The signal adaptive filtering processing module performs spatial / spatial-temporal / spatial-frequency adaptive filtering on the received 7-channel array element signals or 4-channel reconstructed signals to filter out signal interference, and outputs the filtered signals to the satellite acquisition module;

[0015] The satellite capture module receives the filtered signal, captures satellite information in the signal, and outputs the captured satellite angle information to the data selection module.

[0016] The advantages and beneficial effects of the present invention are:

[0017] 1. The circular conformal array antenna design of the present invention can improve the passive gain of some arrays for low-elevation satellites. Based on this, research on coordinate transformation and modeling technology based on circular conformal arrays can be carried out to optimize circular array element adjustment calibration and corresponding adaptive algorithm parameters.

[0018] 2. The adaptive array signal reconstruction method of the circular arc conformal array antenna of the present invention adopts the maximum SNR criterion, combines the inertial navigation attitude information and the satellite ephemeris, reconstructs the nulling or beamforming constraints, improves the average signal-to-noise ratio of the input signal, and achieves the purpose of optimizing the anti-interference performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a design idea diagram of the circular arc conformal array antenna based on array signal reconstruction of the present invention;

[0020] Figure 2 The satellite signal gain diagram of the present invention;

[0021] Figure 3 A schematic diagram of a circular arc conformal array of the present invention;

[0022] Figure 4 It is a schematic diagram of array signal reconstruction of the present invention;

[0023] Figure 5 is a signal processing flow chart of the present invention;

[0024] Figure 6 It is the conventional beam pattern of a traditional planar array;

[0025] Figure 7 The beam pattern is reconstructed for the circular array of the present invention. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below through specific examples. The following examples are only illustrative and not restrictive, and the protection scope of the present invention cannot be limited thereto.

[0027] like Figure 1 As shown, the present invention proposes a circular arc conformal array antenna based on array signal reconstruction and an adaptive array signal reconstruction method thereof.

[0028] The circular conformal array design improves the passive gain of some arrays for low-elevation-angle satellites, and carries out research on coordinate transformation and modeling technology based on the circular conformal array to optimize the circular array element adjustment calibration and corresponding adaptive algorithm parameters.

[0029] The array signal reconstruction design adopts the maximum SNR criterion, combines the inertial navigation attitude information and satellite ephemeris, reconstructs the zeroing or beamforming constraints, improves the average signal-to-noise ratio of the input signal, and achieves the purpose of optimizing the anti-interference performance.

[0030] A circular arc conformal array antenna based on array signal reconstruction, the innovation of which lies in: comprising a central array element and tilted array elements arranged along a circle, the number of the tilted array elements is 6, the tilted array elements are all tilted outward by 30°, and the central array element remains horizontal.

[0031] In a conformal array, we first assume that each array element is an ideal point source, then the array pattern is determined only by the array factor and has nothing to do with the unit pattern. First, for a single array element in the array, the normal of each array element aperture usually corresponds to the maximum gain point in the antenna pattern, such as Figure 2 As shown in FIG. 1 , in the antenna pattern design, the maximum difference in gain from low elevation angle to high elevation angle is generally 5dB-10dB. Based on the above analysis, the present invention considers using a circular arc non-planar array, such as Figure 3 As shown, the overall array configuration still uses a 7-element circular array, but the 6 arrays on the circumference are tilted outward by 30°, so that the maximum gain point of each element tends to the low elevation angle area. In this way, there will always be some elements that can provide more ideal gain for low elevation angle signals incident at different azimuths. The central element remains horizontal as a reference element to ensure that all incoming signals can be received.

[0032] The signal power gain is related to the pitch angle of the signal relative to each array element. The signal power gain can be calculated by combining the relationship between the pitch angle and the satellite signal gain. In the arc conformal array structure, the pitch angle of each signal relative to each array is different, and coordinate conversion calculation is required in the simulation design.

[0033] The incident angle of the signal in the global coordinate system (X, Y, Z) is a known quantity, the azimuth angle φ of each side array element de It is known that in order to obtain the received signal representation of each array element, the local coordinate system (X de ,Y de ,Z de ). According to the relationship between the local coordinate system and the global coordinate system of the array element, the signal incident angle The incident angle converted to the local coordinate system of each element By observing the antenna array structure, it is found that the global coordinate system needs to be rotated along the Z axis φ to transform the local coordinate system. de Angle, and then rotate a certain angle along the X axis to get it.

[0034] The rectangular coordinate system (X, Y, Z) rotates around the Z axis by φ de Then it is transformed into another rectangular coordinate system (X', Y', Z'). The conversion formula is as follows:

[0035]

[0036] The rectangular coordinate system (X', Y', Z') is transformed into another rectangular coordinate system (X de ,Y de ,Z de ), the conversion formula is as follows:

[0037]

[0038] Taking the actual data of the polar region in a typical low-elevation signal and high-elevation interference environment as an example, the satellite signal elevation angle is no higher than 45°, and the interference signal elevation angle can reach more than 60°. According to the above coordinate conversion calculation formula, it can be calculated that relative to the array element facing the signal, the signal elevation angle can be increased by 30°, the adjacent array element signal elevation angle can be increased by more than 20°, and the average gain can reach more than 5dB.

[0039] An adaptive array signal reconstruction method for a circular arc conformal array antenna based on array signal reconstruction, the innovation of which lies in: the method is applied to the circular arc conformal array antenna, and is used for anti-interference processing of the signal after the frequency conversion of the circular arc conformal array antenna; the steps of the method are:

[0040] After the satellite navigation receiving system is positioned, the azimuth and elevation angles of each satellite relative to the array antenna can be calculated based on the ephemeris and array element coordinates. For the 7-element circular array, this scheme divides the space into 6 quadrants, reconstructs the array signal based on the quadrant where the satellite signal is coming from, selects the array elements close to the signal coming from to form a 4-element array model to participate in the weight update process of beamforming, and performs corresponding weighted processing to suppress interference.

[0041] like Figure 4 As shown in the figure, the central array element is numbered as element 1, and the other 6 array elements are equally divided on the circumference at intervals of 60°. Taking quadrant 1 as an example, the north direction is defined as the azimuth angle of 0°, and the central angle of quadrant 1 is is 30°, and the azimuth angle of a satellite signal is if

[0042]

[0043] Then reconstruct the array signal, input the sampling signals corresponding to array element 1, array element 2, array element 3, and array element 4 to calculate the anti-interference weight vector. Since the satellite signal falls into this quadrant, the orientation of the above four array elements can provide a higher receiving gain, and the three array elements on the back do not participate in the anti-interference processing process because the received signal is significantly weakened. Similarly, quadrant 2 corresponds to array element 1, array element 2, array element 3, and array element 7, and the other quadrants are analogous, and will not be repeated.

[0044] In general, it is assumed that the gain that the non-planar array element can provide to the satellite signal is G a , the conventional planar array gain is Gb As long as you meet

[0045] G a +10lg(4)>G b +10lg(7)

[0046] Then it can be guaranteed that the proposed solution can bring performance improvement. The above formula can be simplified to:

[0047] G a -G b >10lg(7)-10lg(4)≈2.43dB

[0048] Based on the analysis of arc conformal array design, it can be known that the difference in signal receiving gain from the normal direction of the array element to the horizontal direction (low elevation angle) can usually reach 5dB-10dB. Therefore, this solution tilts the array element, which is usually easier to meet the above condition.

[0049] like Figure 5 As shown, the signal processing of the circular arc conformal array antenna of the present invention includes a data sampling module, a data selection module, a signal adaptive filtering processing module and a satellite capture module;

[0050] The data sampling module collects the signals after the frequency down-conversion of the 7-way array elements of the circular arc conformal array through ADC sampling, waits for the satellite information judgment module to make a judgment result, and then selectively outputs the signals of each array element to the signal adaptive filtering processing module;

[0051] The data selection module determines in real time whether the satellite angle information is currently obtained. If the satellite angle information is obtained, the adaptive array signal reconstruction method is used to reconstruct the array signal, and the reconstructed 4-way signal is output to the signal adaptive filtering processing module; if the satellite angle information is not obtained, the 7-element signal is output to the signal adaptive filtering processing module;

[0052] The signal adaptive filtering processing module performs spatial / spatial-temporal / spatial-frequency adaptive filtering on the received 7-channel array element signals or 4-channel reconstructed signals to filter out signal interference, and outputs the filtered signals to the satellite acquisition module;

[0053] The satellite capture module receives the filtered signal, captures satellite information in the signal, and outputs the captured satellite angle information to the data selection module.

[0054] The present invention compares the improved circular array reconstructed beam with the conventional planar array conventional beam. Figure 6 is the conventional beam pattern of a traditional planar array. Figure 7 The circular array reconstructed beam pattern of the present invention shows that the satellite signal carrier-to-noise ratio of the present invention is improved by 2-3 dB.

[0055] Although the embodiments and drawings of the present invention are disclosed for illustrative purposes, those skilled in the art will appreciate that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A circular arc conformal array antenna based on array signal reconstruction, characterized in that: It includes a central array element and inclined array elements arranged along a circumference, the number of the inclined array elements is 6, the inclined array elements are all inclined outwards by 30 degrees, and the central array element remains horizontal.

2. An adaptive array signal reconstruction method for circular arc conformal array antenna based on array signal reconstruction, characterized in that: The method is applied to the circular arc conformal array antenna according to claim 1, and is used for anti-interference processing of signals after frequency conversion by the circular arc conformal array antenna; the steps of the method are: S1. Satellite angle acquisition: According to the satellite positioning results and satellite ephemeris data, the azimuth of each satellite is acquired, and the angle information is output to the array signal reconstruction module; S2, array signal reconstruction: The array signal reconstruction module divides the space into 6 quadrants. After receiving the angle information of each satellite, it makes a difference judgment between the satellite angle and the center angle of each quadrant. If the angle difference is less than 30°, the 3 array elements on the quadrant side and the 4-way signal of the center array element are selected as the output signal, and the output signal is output to the signal adaptive filtering processing module; S3. Signal adaptive filtering processing: The signal adaptive filtering processing module receives 4-way array element signals, uses spatial domain / space-time / space-frequency adaptive filtering algorithm to perform adaptive filtering calculation, and outputs the filtered signal.

3. The adaptive array signal reconstruction method of circular arc conformal array antenna based on array signal reconstruction according to claim 2, characterized in that: The signal processing of the circular arc conformal array antenna includes a data sampling module, a data selection module, a signal adaptive filtering processing module and a satellite capture module; The data sampling module collects the signals after the frequency down-conversion of the 7-way array elements of the circular arc conformal array through ADC sampling, waits for the satellite information judgment module to make a judgment result, and then selectively outputs the signals of each array element to the signal adaptive filtering processing module; The data selection module determines in real time whether the satellite angle information is currently obtained. If the satellite angle information is obtained, the adaptive array signal reconstruction method is used to reconstruct the array signal, and the reconstructed 4-way signal is output to the signal adaptive filtering processing module; If the satellite angle information is not obtained, the 7-element signal is output to the signal adaptive filtering processing module; The signal adaptive filtering processing module performs spatial / spatial-temporal / spatial-frequency adaptive filtering on the received 7-channel array element signals or 4-channel reconstructed signals to filter out signal interference, and outputs the filtered signals to the satellite acquisition module; The satellite capture module receives the filtered signal, captures satellite information in the signal, and outputs the captured satellite angle information to the data selection module.

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