Satellite-borne flexible coverage multi-beam antenna and design method thereof

Abstract

The invention discloses a satellite-borne flexible coverage multi-beam antenna and a design method thereof, and the antenna is composed of a reflector and a feed source array. A beam synthesis mode of synthesizing each beam by a full-scale feed source is adopted, antenna parameter configuration is optimized, and a feed source array excitation coefficient is reconstructed to carry out beam flexible coverage design, so that the problems that a traditional satellite-borne passive antenna does not have a beam on-orbit reconfigurable capability, the number of direct radiation array antennas is large, and a system is complex are solved; in-orbit flexibility and variability of antenna coverage size, coverage shape, coverage position, beam scale and the like in a service area are met, and an antenna design theoretical method and key technical support are provided for high-flux flexible load satellites in the future.

Description

TECHNICAL FIELD

[0001] The application relates to a spaceborne flexible coverage multi-beam antenna and a design method thereof, and belongs to the technical field of spaceborne high-throughput multi-beam antennas. BACKGROUND

[0002] With the continuous improvement of capacity performance and design life, the functional requirements of the satellite market at home and abroad are gradually changing. New communication satellites require higher flexibility of the load. The use requirements of users usually change in the entire life cycle of satellite services, such as the geographical distribution change of user hotspot areas and the urgent demand for on-orbit flexible coverage of user beams.

[0003] The spaceborne flexible coverage multi-beam antenna mainly synthesizes each beam through the whole longitudinal defocusing feed array, optimizes the configuration parameters of the reflector antenna, and optimizes the amplitude and phase distribution of the feed excitation coefficient, so that the coverage size, coverage shape, coverage position and beam scale of the antenna beam are flexible and variable on orbit. At present, the number of direct radiation array antennas of the active antenna is large, and the system is complex, which is at a disadvantage in engineering realization and engineering cost. In addition, the traditional spaceborne passive antenna does not have the capability of on-orbit reconfigurable beam, and cannot meet the demand of on-orbit flexible coverage of the multi-beam antenna of the communication satellite. SUMMARY

[0004] The technical problem to be solved by the application is to overcome the shortcomings of the prior art, and to provide a spaceborne flexible coverage multi-beam antenna and a design method thereof, so as to solve the problem that the traditional spaceborne passive antenna does not have the capability of on-orbit reconfigurable beam, and the number of direct radiation array antennas is large, the system is complex, the engineering realization is difficult, and the cost is high, so that the coverage size, coverage shape, coverage position and beam scale of the antenna beam cannot be reconfigured on orbit.

[0005] The application solves the above technical problems by adopting the following solution: a spaceborne flexible coverage multi-beam antenna, which comprises a reflector and a feed array.

[0006] The reflector is a standard offset parabolic reflector, the feed array is located on the line connecting the center position of the reflector and the focal point of the parabolic reflector, and maintains a certain distance from the focal point of the parabolic reflector, which is recorded as the feed array front push distance d. After the radio frequency signal is output from the feed array and reflected by the reflector, the antenna secondary sub-beam is output, and the antenna secondary sub-beam pattern is widened to a gate shape.

[0007] Preferably, the feed array comprises a horizontal beam forming network, a vertical beam forming network and M feed units, each feed unit comprises a light wall shaped horn and an orthogonal mode coupler; the antenna secondary sub-beam is N pairs, each pair comprises one antenna secondary horizontal polarization sub-beam and one antenna secondary vertical polarization sub-beam; M and N are greater than or equal to 1.

[0008] Light-wall shaped horn for radiating radio frequency signals;

[0009] Orthogonal mode coupler for splitting the radio frequency signals outputted by the light-wall shaped horn into two paths, one path for vertical polarization signals and the other path for horizontal polarization signals;

[0010] Horizontal beam forming network for taking the amplitude and phase of the M horizontal polarization signals as horizontal excitation coefficients, and for controlling the gain and pointing of the N antenna secondary horizontal polarization sub-beams by adjusting the horizontal excitation coefficients;

[0011] Vertical beam forming network for taking the amplitude and phase of the M vertical polarization signals as vertical excitation coefficients, and for controlling the gain and pointing of the N antenna secondary vertical polarization sub-beams by adjusting the vertical excitation coefficients;

[0012] The antenna secondary horizontal polarization sub-beams and the antenna secondary vertical polarization sub-beams corresponding to the radio frequency signals outputted by the same light-wall shaped horn have the same coverage range and pointing.

[0013] Preferably, the orthogonal mode coupler is a non-symmetrical four-arm orthogonal mode coupling structure, which is beneficial to minimizing the physical envelope of the device.

[0014] Preferably, the light-wall shaped horn is arranged in a triangular grid.

[0015] Preferably, the aperture envelope D f of the feed unit satisfies the design requirement of no grating lobe in the coverage area of the antenna synthesized beam:

[0016]

[0017] wherein M is the ratio of the corresponding antenna beam gain under the two conditions of the focal point and the overall feed array, θ max is the maximum scanning angle of the antenna, θ lab is the grating lobe position angle under the maximum scanning angle of the antenna, and λ is the working wavelength.

[0018] Another technical solution of the present application is a design method of a satellite-borne flexible coverage multi-beam antenna, which comprises the following steps:

[0019] S1. According to the arrangement mode of the light-wall shaped horn in the antenna and the coverage requirement of the antenna, the aperture envelope D f of the feed array is determined, so that the aperture envelope D f of the feed unit satisfies the design requirement of no grating lobe in the coverage area of the antenna synthesized beam;

[0020] S2. The feed array feed distance d is adjusted, so that the secondary sub-beam pattern is widened into a door shape, and the coverage area of the secondary sub-beam is widened to the coverage area of the antenna.

[0021] S3、in the feed array aperture envelope D f Under the condition that there is no grating lobe in the coverage area of the synthesized beam of the antenna, the aperture efficiency, cross-polarization level, return loss, and longitudinal length of the horn are optimized.

[0022] S4、in the feed array aperture envelope D f Under the condition that there is no grating lobe in the coverage area of the synthesized beam of the antenna, the polarization isolation degree and return loss of the port of the quadrature coupler are optimized to realize dual linear polarization in the frequency band.

[0023] S5、the horizontal excitation coefficient and the vertical excitation coefficient of the horizontal beam forming network and the vertical beam forming network are optimized to realize the control of the coverage area gain and shape of the antenna secondary horizontal polarization sub-beam and the antenna secondary vertical polarization sub-beam.

[0024] Preferably, the horizontal excitation coefficient and the vertical excitation coefficient of the vertical beam forming network or the horizontal beam forming network are optimized in the following steps:

[0025] S5.1、the amplitudes α1…α M of all the horizontal polarization signals or vertical polarization signals participating in beam synthesis in the coverage area are combined to form an optimization variable X1, X1=(α1…α M ) T , and the phases β1…β M are combined to form an optimization variable X2, X2=(β1…β M ) T , and X1 and X2 are combined to form an optimization variable X, X=[X1,X2].

[0026] S5.2、an observation variable Y is constructed, Y=(Y1…Y N ) T , wherein Y j ,j=1~N is the minimum gain in the coverage area of the jth antenna secondary horizontal polarization sub-beam or antenna secondary vertical polarization sub-beam;

[0027] S5.3、according to the optimization variable X and the observation variable Y, a target function F(X,Y) is constructed; the target function F(X,Y) represents the gap between the minimum gain in the coverage area of the antenna secondary horizontal polarization sub-beam or antenna secondary vertical polarization sub-beam and the preset gain;

[0028] S5.4、the target function F(X,Y) is optimized by a global optimization algorithm, and if the target function F(X,Y) is less than a threshold, the optimization is ended, and the optimized horizontal excitation coefficient or vertical excitation coefficient is obtained.

[0029] Preferably, the target function F(X,Y) is as follows:

[0030] F(X,Y) = [F1(X,Y1), F1(X,Y2),..., F1(X,Y n ),..., F1(X,Y N )] T

[0031] +...+[F p (X,Y1), F p (X,Y2),..., F p (X,Y n ),..., F p (X,Y N )] T

[0032] +...+[F P (X,Y1), F P (X,Y2),..., F P (X,Y n ),..., F P (X,Y N )] T

[0033] Fp(X,Y n ) = a n [G(Y n )-G p (X,Y n )]

[0034] wherein a n is a gain weight coefficient of the observation site; G(Y n ) is a gain value required by the design of the nth observation site; G p (X,Y n ) is a gain value of the nth observation site at the pth frequency point calculated under the condition that the optimization variable is X; F1(X,Y1), F1(X,Y n ), F1(X,Y N ) are respectively the redundancy values of the gain of the 1st, nth and Nth observation sites at the 1st frequency point under the condition that the optimization variable is X; F p (X,Y1), F p (X,Y n ), F p (X,Y N ) are respectively the redundancy values of the 1st, nth and Nth observation sites at the pth frequency point under the condition that the optimization variable is X; F P (X,Y1), F P (X,Y n ), F P (X,Y N) are respectively the redundancy values of the first, the n th and the N th observation station of the P th frequency point when the optimization variable is X; N is the total number of the observation stations taken, 1<=n<=N, P is the total number of the frequency points taken in the frequency band, 1<=p<=P.

[0035] Preferably, the design method of the spaceborne flexible coverage multi-beam antenna further comprises the following steps:

[0036] According to the horizontal excitation coefficient and the vertical excitation coefficient obtained in step 5.4, the size of the antenna secondary sub-beam coverage area is reduced or enlarged by adjusting the distance of the feed array deviating from the focal plane along the line connecting the center of the reflector and the focal point.

[0037] Preferably, the design method of the spaceborne flexible coverage multi-beam antenna further comprises the following steps:

[0038] According to the horizontal excitation coefficient and the vertical excitation coefficient obtained in step 5.4, the antenna coverage area is translated by adjusting the pointing of the reflector.

[0039] Compared with the prior art, the beneficial technical effects of the present application are:

[0040] The spaceborne flexible coverage multi-beam antenna provided by the present application solves the problem of flexible coverage of the multi-beam antenna of the feed array and the reflector, adopts the method of synthesizing each beam by full-scale feed based on the design concept of the overall longitudinal defocusing of the feed array, constructs the target optimization model by the performance index requirements in the coverage area such as gain, obtains the extraction of the optimal excitation coefficient of the horizontal beam forming network and the vertical beam forming network, and simultaneously realizes the flexible variation of the size, shape and number of beams of the antenna coverage area by optimizing the antenna parameter configuration (the position parameters of the reflector and the feed array, the position parameters of the reflector, etc.), reconstructing the excitation coefficient of the horizontal beam forming network and the vertical beam forming network and other strategies, thereby improving the utilization efficiency of the antenna. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 FIG. 1 is a structural schematic diagram of the antenna of the embodiment of the present application;

[0042] Figure 2 FIG. 2 is a design flow block diagram of the antenna of the embodiment of the present application;

[0043] Figure 3 FIG. 3 is a structural schematic diagram of the flexible coverage multi-beam antenna of the embodiment of the present application;

[0044] Figure 4 FIG. 4 is a schematic diagram of the beam arrangement of the embodiment of the present application;

[0045] Figure 5 FIG. 5 is a schematic diagram of the antenna secondary sub-beam pattern of the embodiment of the present application with the change of the feed array pre-push distance d;

[0046] Figure 6 for the antenna sub-beam pattern of the embodiment of the application;

[0047] Figure 7 for the antenna sub-beam pattern of the embodiment of the application;

[0048] Figure 8 for the antenna sub-beam pattern of the embodiment of the application;

[0049] Fig. 9(a) is the reduction and enlargement of the antenna coverage area of the embodiment of the application;

[0050] Fig. 9(b) is the translation of the antenna coverage area of the embodiment of the application;

[0051] Fig. 9(c) is the shape and number of the antenna coverage area of the embodiment of the application. DETAILED DESCRIPTION

[0052] The application will be described in detail below in combination with the drawings and embodiments.

[0053] The application discloses a satellite-borne flexible coverage multi-beam antenna and a design method thereof. The satellite-borne flexible coverage multi-beam antenna is aimed at the problems that the number of direct radiation array antennas of an active antenna is large, the system is complex, there is no advantage in engineering realization and engineering cost, and the traditional satellite-borne passive antenna does not have the capability of on-orbit reconfiguration of beams and cannot meet the demand of on-orbit flexible coverage of communication multi-beam antennas. The satellite-borne flexible coverage multi-beam antenna is realized by a multi-feed synthesis beam mode of a whole longitudinal defocusing feed array, the configuration parameters of the feed array and the reflector are selected, and the amplitude and phase distribution of the excitation coefficient of the corresponding beam forming network are optimized, so that the antenna coverage size, the coverage shape, the coverage position and the beam scale of the service area are on-orbit flexible and variable.

[0054] As shown in Fig. 1, the satellite-borne flexible coverage multi-beam antenna provided by the application comprises a reflector and a feed array. Figure 1

[0055] The reflector is a standard offset parabolic reflector, the antenna adopts a single offset design form, and the feed array is located on the defocusing plane of the reflector (offset from the focal plane). Specifically, the feed array is located on the line connecting the center position of the reflector and the focal point of the parabolic reflector and keeps a certain distance from the focal point of the parabolic reflector, which is recorded as the feed array front push distance d. After the radio frequency signal is output from the feed array and reflected by the reflector, the antenna secondary sub-beam is output, and the antenna secondary sub-beam pattern is widened into a door shape.

[0056] Figure 1 In the embodiment, the configurable parameters comprise: the aperture D of the reflector, the focal length F of the reflector, the offset distance H of the reflector, the arrangement of the feed array and the feed array front push distance d. r ​​

[0057] Preferably, the feed array comprises a horizontal beam forming network, a vertical beam forming network, M feed units, each feed unit comprising a light-wall shaped horn and an asymmetric four-arm quadrature mode coupler; the antenna secondary sub-beams are N pairs, which are N antenna secondary horizontal polarization sub-beams and N antenna secondary vertical polarization sub-beams respectively; M, N are greater than or equal to 1;

[0058] The light-wall shaped horn is used for radiating an antenna signal.

[0059] The quadrature mode coupler divides the radio frequency signal output by the light-wall shaped horn into two paths, one path being a vertical polarization signal and the other path being a horizontal polarization signal.

[0060] The horizontal beam forming network takes the amplitude and phase of the M horizontal polarization signals as horizontal excitation coefficients, controls the gain and pointing of the N antenna secondary horizontal polarization sub-beams by adjusting the horizontal excitation coefficients.

[0061] The vertical beam forming network takes the amplitude and phase of the M vertical polarization signals as vertical excitation coefficients, controls the gain and pointing of the N antenna secondary vertical polarization sub-beams by adjusting the vertical excitation coefficients.

[0062] The coverage range and pointing of the antenna secondary horizontal polarization sub-beam and the antenna secondary vertical polarization sub-beam corresponding to the radio frequency signal output by the same light-wall shaped horn are the same.

[0063] The horizontal beam forming network and the vertical beam forming network can be an analog beam forming network or a digital beam forming network.

[0064] The above-described spaceborne flexible coverage multi-beam antenna is a spaceborne full-scale feed synthesis multi-beam antenna, and all radio frequency signals can participate in the synthesis of the antenna secondary horizontal polarization sub-beam.

[0065] Preferably, the quadrature mode coupler is an asymmetric four-arm quadrature mode coupling structure, which is conducive to minimizing the physical envelope of the device.

[0066] Preferably, the light-wall shaped horn is arranged in a triangular grid.

[0067] Preferably, the aperture envelope D of the feed unit is f The design requirement of no grating lobe in the coverage area of the synthesized antenna beam is met.

[0068]

[0069] wherein M is the ratio of the corresponding antenna beam gain of the feed array under the two conditions of the focal point and the overall pre- and post-boost, θ max is the maximum scanning angle of the antenna, and θ labλ represents the grating lobe position angle at the maximum scanning angle of the antenna, and λ is the operating wavelength.

[0070] like Figure 2 As shown, the design method for the above-mentioned spaceborne flexible coverage multi-beam antenna includes the following steps:

[0071] S1. Determine the feed array aperture envelope D based on the arrangement of the shaped-wall horns in the antenna and the antenna coverage requirements. f This makes the feed element aperture envelope D f The antenna synthesized beam must be free of grating lobes within its coverage area.

[0072] S2. Adjust the feed array forward distance d so that the secondary sub-beam pattern is broadened into a gate shape, exhibiting flat-top characteristics, and the coverage area of ​​the secondary sub-beam is broadened to the coverage area of ​​the antenna.

[0073] like Figure 6 As shown, the calculation conditions that the performance parameters of the antenna secondary sub-beams must meet are as follows:

[0074] (a) The sub-beamwidth meets the coverage requirements in the mission specifications.

[0075] (b) The sub-beam pattern exhibits good flat-top characteristics.

[0076] S3, within the feed array aperture envelope D f Under the condition that there are no grating lobes in the coverage area of ​​the antenna synthesized beam, optimize the aperture efficiency, cross-polarization level, return loss, and longitudinal length of the horn in the optical wall shaping.

[0077] S4, Feed array aperture envelope D f Under the condition that there are no grating lobes in the coverage area of ​​the antenna synthesized beam, optimize the port polarization isolation and return loss of the orthogonal mode coupler to achieve bilinear polarization in the frequency band;

[0078] S5. Optimize the horizontal and vertical excitation coefficients of the horizontal and vertical beamforming networks to control the gain and shape of the coverage area of ​​the antenna secondary horizontally polarized sub-beam and the antenna secondary vertically polarized sub-beam.

[0079] Preferably, the optimization steps for the horizontal and vertical excitation coefficients of the vertical beamforming network or the horizontal beamforming network are as follows:

[0080] S5.1, the amplitudes α1…α of all horizontally polarized or vertically polarized signals participating in beamforming within the coverage area. M The combination constitutes the optimization variable X1, X1 = (α1…α M ) T Phase β1…β MThe combination constitutes an optimization variable X2, X2=(β1…β M ) T The combination of X1 and X2 constitutes an optimization variable X, X=[X1,X2].

[0081] S5.2, constructing an observation variable Y, Y=(Y1…Y N ) T Y j j=1~N is the minimum gain in the coverage range of the jth antenna secondary horizontal polarization sub-beam or antenna secondary vertical polarization sub-beam;

[0082] S5.3, constructing a target function F(X,Y) according to the optimization variable X and the observation variable Y; the target function F(X,Y) represents the gap between the minimum gain in the coverage range of the antenna secondary horizontal polarization sub-beam or the antenna secondary vertical polarization sub-beam and the preset gain;

[0083] S5.4, optimizing the target function F(X,Y) by a global optimization algorithm, if the target function F(X,Y) is less than a threshold, ending the optimization, and obtaining the optimized horizontal excitation coefficient or vertical excitation coefficient.

[0084] The global optimization algorithm can be a genetic algorithm, a particle swarm algorithm, etc.

[0085] Preferably, the target function F(X,Y) is:

[0086] F(X,Y)=[F1(X,Y1),F1(X,Y2),…,F1(X,Y n ),…,F1(X,Y N )] T

[0087] +…+[F p (X,Y1),F p (X,Y2),…,F p (X,Y n ),…,F p (X,Y N )] T

[0088] +…+[F P (X,Y1),F P (X,Y2),…,F P (X,Y n ),…,F P (X,Y N )] T

[0089] Fp(X,Y n )=a n [G(Yn )-G p (X,Y n )]

[0090] wherein a n is the gain weight coefficient of the observation site; G(Y n ) is the gain value required by the design of the nth observation site; G p (X,Y n ) is the gain value of the nth observation site at the pth frequency point calculated when the optimization variable is X; F1(X,Y1), F1(X,Y n ), and F1(X,Y N ) are the redundancy values of the gain of the 1st, nth, and Nth observation sites at the 1st frequency point when the optimization variable is X, respectively; F p (X,Y1), F p (X,Y n ), and F p (X,Y N ) are the redundancy values of the 1st, nth, and Nth observation sites at the pth frequency point when the optimization variable is X, respectively; F P (X,Y1), F P (X,Y n ), and F P (X,Y N ) are the redundancy values of the 1st, nth, and Nth observation sites at the Pth frequency point when the optimization variable is X, respectively; N is the total number of the observation sites taken, 1≦n≦N, P is the total number of the frequency points taken in the frequency band, 1≦p≦P.

[0091] If the optimization result cannot meet the preset requirement, the weight coefficient of the optimization objective function is adjusted, and further iteration optimization is performed, and if necessary, the antenna parameter configuration is adjusted, and optimization is performed again.

[0092] According to the obtained excitation coefficients of the corresponding beam forming network, and simultaneously, the antenna parameter configuration is optimized, such as adjusting the relative distance of the reflector and the feed array, the deflection angle of the reflector, and the like, the on-orbit reconfiguration of the antenna coverage can be realized. For example:

[0093] (1) According to the obtained horizontal excitation coefficients and vertical excitation coefficients, and simultaneously, along the line connecting the center of the reflector and the focal point, the size of the antenna secondary sub-beam coverage area is reduced and enlarged by adjusting the distance of the feed array deviating from the focal plane.

[0094] (2) According to the obtained horizontal excitation coefficients and vertical excitation coefficients, and simultaneously, the antenna coverage area is translated by adjusting the pointing direction of the reflector.

[0095] As shown in the accompanying drawings Figure 3As shown, the spaceborne flexible coverage multi-beam antenna according to the application comprises a reflector and a feed array. The reflector is a standard parabolic reflector in a single offset form; the feed array is longitudinally offset as a whole and is composed of a honeycomb arrangement of feed units and has a tangential outer envelope, and each feed unit is composed of a horn with light-wall shaping and a dual-orthogonal-mode coupler, and a beam forming network realizes the excitation coefficients required by the antenna synthesized beams.

[0096] The specific optimization design steps are as follows:

[0097] (S1) determining the beam arrangement mode according to the design index requirements.

[0098] As shown in the accompanying drawings, Figure 4 according to the required beam coverage range and beam width, a service area is covered by a plurality of beams formed by a plurality of radio frequency signals, the positions of the beams are determined, the beam forming mode of the full-scale feed for each beam is determined, and the number of secondary sub-beams is b.

[0099] (S2) optimizing the antenna configuration parameters

[0100] According to the design requirement of no grating lobe in the coverage area of the antenna synthesized beams, in the parameter configuration of the antenna, the aperture envelope D f of the feed unit is controlled within 51.0 mm, if it is too small, the dual-linear polarization coupler cannot realize the factor due to the interference of the physical envelope of the device, if it is too large, on the one hand, the weight and volume of the feed array are doubled, and on the other hand, it does not meet the design requirement of no grating lobe in the array synthesized beams.

[0101] The aperture envelope D f of the feed unit is determined, and then the configuration parameters of the antenna, including the aperture D, the focal length F and the offset distance H, are optimized, the feed array front push distance d is adjusted, so that the beam width of the secondary sub-beam meets the beam width requirement of the sub-beam in the task index requirement, as shown in the accompanying drawings, Figure 5 with the change of the front push distance d, the flat-top characteristics of the sub-beam pattern are different, the larger the d is, the wider the sub-beam width is, and the larger the corresponding beam coverage area size is.

[0102] (S3) designing the feed unit according to the aperture envelope D f of the feed unit determined in step (S2)

[0103] The aperture envelope D f of the feed unit is determined, and then the horn with light-wall shaping is selected as the radiating unit, the aperture efficiency, cross-polarization level, return loss and longitudinal length of the feed horn in the working frequency band are taken as the optimization targets, and the desired performance of the feed horn is realized through the shape optimization of the feed; the dual-linear polarization coupler is selected to have an orthogonal mode coupling structure, the dual-linear polarization is realized under the requirement of the envelope D f , and the port return loss, isolation and circular polarization performance meet the requirements of the feed performance.

[0104] (S4) Calculate the performance of the antenna secondary sub-beam

[0105] After the feed unit design is completed, the feed unit is designed to feed the array radiation pattern in the array composed of the feed unit as the input condition, according to the feed array arrangement determined by step (S1) sub-beam arrangement, according to the feed array push distance d determined in step (S2), combined with the parameter configuration of the reflector, the radiation pattern characteristics of the antenna secondary sub-beam are calculated, the flat head characteristics of the sub-beam pattern, which is beneficial to the performance optimization of the synthesized beam, as shown in the accompanying Figure 7 .

[0106] According to the technical index requirement, the method of using full-scale feed to synthesize each beam is determined, the aperture envelope D f of the feed unit is 51.0mm, the parameter configuration of the optimized design reflector aperture D r is selected as 2.4m, the focal length F is selected as 5.6m, and the offset distance H is selected as 4.1m.

[0107] The flexible coverage multi-beam antenna design described in this paper is based on the design concept of the overall longitudinal defocusing of the feed array, the method of using full-scale feed to synthesize each beam is adopted, through the construction of multi-objective optimization model for various performance indicators in the service area such as gain, the global optimization algorithm is used to obtain the optimal excitation coefficient of the beam forming network, the Figure 4 phase excitation distribution of the optimized center beam 31st beam is shown in the accompanying Figure 7 , and the corresponding 31st synthesized beam energy field distribution is shown in the accompanying Figure 8 .

[0108] At the same time, based on the optimization of the structure configuration of the feed array and the reflector (the position parameters of the reflector and the feed array, the position parameters of the reflector, etc.), the reconstruction of the excitation coefficient of the beam forming network, etc., the size, shape and number of beams of the antenna coverage area are realized, as shown in the accompanying Figures 9(a) to 9(c) .

[0109] Here, it should be noted that the contents not described in detail in this specification are realized by the skilled person in the art through the description in this specification and the prior art, therefore, no further description is made.

[0110] The above description is only the preferred embodiment of the present application, and is not used to limit the protection scope of the present application. For those skilled in the art, without creative labor, some modifications and replacements can be made to the present application, all of which should be covered in the protection scope of the present application.

Claims

1. A space-borne flexible coverage multi-beam antenna, characterized in that The antenna comprises a reflector and a feed array; the reflector is a standard offset parabolic reflector, the feed array is located on the line connecting the center of the reflector and the focal point of the parabolic reflector, and maintains a certain distance from the focal point of the parabolic reflector, which is recorded as the feed array front push distance d; after the radio frequency signals are output from the feed array and reflected by the reflector, the antenna secondary sub-beams are output, and the antenna secondary sub-beam pattern is widened into a door shape.

2. The space-borne flexible coverage multi-beam antenna according to claim 1, characterized in that The feed array comprises a horizontal beam forming network, a vertical beam forming network and M feed units, each feed unit comprises a light-wall shaped horn and an orthogonal mode coupler; the antenna secondary sub-beams are N pairs, each pair comprises one antenna secondary horizontal polarization sub-beam and one antenna secondary vertical polarization sub-beam; M and N are greater than or equal to 1; The light-wall shaped horn is used for radiating radio frequency signals. The orthogonal mode coupler divides the radio frequency signals output by the light-wall shaped horn into two paths, one path is a vertical polarization signal, and the other path is a horizontal polarization signal. The horizontal beam forming network takes the amplitude and phase of the M horizontal polarization signals as horizontal excitation coefficients, controls the gain and pointing direction of the N antenna secondary horizontal polarization sub-beams by adjusting the horizontal excitation coefficients. The vertical beam forming network takes the amplitude and phase of the M vertical polarization signals as vertical excitation coefficients, controls the gain and pointing direction of the N antenna secondary vertical polarization sub-beams by adjusting the vertical excitation coefficients. The coverage range and pointing direction of the antenna secondary horizontal polarization sub-beam and the antenna secondary vertical polarization sub-beam corresponding to the radio frequency signals output from the same light-wall shaped horn are the same.

3. The space-borne flexible coverage multi-beam antenna according to claim 1, c h a r a c t e r i z e d b y The orthogonal mode coupler is an asymmetric four-arm orthogonal mode coupling structure.

4. The space-borne flexible coverage multi-beam antenna according to claim 1, c h a r a c t e r i z e d b y The light-wall shaped horn is arranged in a triangular grid.

5. The space-borne flexible coverage multi-beam antenna according to claim 4, characterized in that, Aperture envelope D of the feed unit f Satisfy the design requirements of no grating lobe in the coverage area where the antenna synthesized beam is located: M = L / d Wherein, M is the ratio of the corresponding antenna beam gain under the two cases of the feed array located at the focal point and the overall forward and backward, θ max is the maximum scanning angle of the antenna, θ lab is the grating lobe position angle under the maximum scanning angle of the antenna, and λ is the working wavelength.

6. The method for designing a space-borne flexible coverage multi-beam antenna of claim 2, wherein The method comprises the following steps: S1, according to the arrangement mode of the light-wall shaped horn in the antenna and the antenna coverage requirement, determine the feed array aperture envelope D f So that the feed unit aperture envelope D f Satisfy the antenna synthesis beam in the coverage area without grating lobe; S2, adjusting the feed array front push distance d, so that the secondary sub-beam pattern is widened into a door shape, and the coverage area of the secondary sub-beam is widened to the coverage area of the antenna; S3, in the feed array aperture envelope D f Under the condition that there is no grating lobe in the coverage area of the antenna synthesized beam, the aperture efficiency, cross-polarization level, return loss, and longitudinal length of the horn are optimized. S4, feed array aperture envelope D f Under the condition that there is no grating lobe in the coverage area of the antenna synthesized beam, the polarization isolation degree and return loss of the orthogonal mode coupler port are optimized to realize dual linear polarization in the frequency band. S5, optimizing the horizontal excitation coefficients and the vertical excitation coefficients of the horizontal beam forming network and the vertical beam forming network to realize the control of the coverage area gain and shape of the antenna secondary horizontal polarization sub-beam and the antenna secondary vertical polarization sub-beam.

7. The method of claim 6, wherein, The horizontal excitation coefficient and the vertical excitation coefficient optimization step of the vertical beam forming network or the horizontal beam forming network is: S5.1, combine the amplitudes α1...α M to form the optimization variable X1, X1 = (α1...α M T , combine the phases β1...β M to form the optimization variable X2, X2 = (β1...β M T combine X1 and X2 to form the optimization variable X, X = [X1, X2].​​ S5.2, construct observation variable Y, Y = (Y1...Y N ) T wherein Y j j = 1 ~ N is the minimum gain of the jth antenna secondary horizontal polarization sub-beam or antenna secondary vertical polarization sub-beam covered range; S5.3, constructing a target function F(X, Y) according to the optimization variable X and the observation variable Y; the target function F(X, Y) represents the difference between the minimum gain in the coverage range of the antenna secondary horizontal polarization sub-beam or the antenna secondary vertical polarization sub-beam and the preset gain; S5.4, optimizing the target function F(X, Y) by using a global optimization algorithm, and if the target function F(X, Y) is less than a threshold, the optimization is ended, and the optimized horizontal excitation coefficient or the vertical excitation coefficient is obtained.

8. The method of claim 7, wherein, The target function F(X, Y) is: F(X,Y) = [F1(X,Y1), F1(X,Y2),..., F1(X,Y n ),..., F1(X,Y N )] T +...+[F p (X,Y1), F p (X,Y2),..., F p (X,Y n ),..., F p (X,Y N )] T +...+[F P (X,Y1), F P (X,Y2),..., F P (X,Y n ),..., F P (X,Y N )] T Fp(X,Y n ) = a n [G(Y n )-G p (X,Y n )] wherein a n is the gain weight coefficient of the observation site; G(Y n ) is the gain value required by the design of the nth observation site; G p (X, Y n ) is the gain value of the nth observation site at the pth frequency point calculated when the optimization variable is X; F1(X, Y1), F1(X, Y n ), and F1(X, Y N ) are the redundancy values of the 1st, nth, and Nth observation sites at the 1st frequency point when the optimization variable is X, respectively; F p (X, Y1), F p (X, Y n ), and F p (X, Y N ) are the redundancy values of the 1st, nth, and Nth observation sites at the pth frequency point when the optimization variable is X, respectively; F P (X, Y1), F P (X, Y n ), and F P (X, Y N ) are the redundancy values of the 1st, nth, and Nth observation sites at the Pth frequency point when the optimization variable is X, respectively; N is the total number of observation sites taken, 1≦n≦N, and P is the total number of frequency points taken within the frequency band, 1≦p≦P.

9. The method of claim 7, wherein Further comprising: According to the horizontal excitation coefficients and the vertical excitation coefficients obtained in step 5.4, the size of the coverage area of the antenna secondary sub-beam is reduced or enlarged by adjusting the distance between the feed array and the focal plane along the line connecting the center of the reflector and the focal point.

10. The method of claim 7, wherein Further comprising: According to the horizontal and vertical excitation coefficients obtained in step 5.4, the coverage area of the antenna is translated by adjusting the pointing of the reflector.

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