A spaceborne dual-band co-aperture antenna array based on metal structure

Abstract

The present invention provides a satellite-borne dual-band common-surface antenna array based on a metal structure. The antenna array is a metal structure and is divided into two parts. One part is a hollow frame structure, which adopts a Vivaldi structure antenna form. Through the design of structural folding, structural hollowing, coupling between units, etc., the antenna has good electrical performance in the P band; the other part is embedded between the P-band antenna units and is located at the bottom of the overall structure. It serves as a metal floor of the P band and can also realize the slot radiation waveguide of the X-band electrical performance. The present invention also designs the dual-band antenna arrays into a dual-polarization form, in order to avoid polarization rotation caused by multipath reflection when electromagnetic waves penetrate dense plants, thereby generating polarization mismatch.

Description

Technical Field

[0001] The invention belongs to the field of electromagnetic field antennas, and in particular relates to a satellite-borne dual-band common aperture antenna array based on a metal structure. Background Art

[0002] The antenna array of the present invention is applied to a satellite platform, and its application is to accurately detect forest biomass. Forest biomass refers to the total weight of all living organisms accumulated over a long period of time per unit area of ​​a forest, and is an important indicator for measuring forest productivity. Its detection is a basic method for studying the material cycle of a forest ecosystem. However, a forest is composed of a large number of dense plants, and the method of using optical imaging analysis is extremely difficult and lacks accuracy. Therefore, it is necessary to adopt a detection method that can penetrate dense plants, namely electromagnetic wave detection. By using X-band and P-band, two electromagnetic waves with different penetration capabilities for interference detection, relevant information on the height of different areas of forest biomass can be obtained.

[0003] Since the frequency span between the P-band and the X-band is large, the wavelength difference exceeds 20 times the frequency range. When designing an antenna array, it is impossible to use a broadband antenna structure to achieve the working performance of the two frequency bands while ensuring the reasonable spacing between the two frequency band units. In principle, one antenna array form can meet this ultra-wide span multi-band performance, that is, the co-aperture antenna array, that is, to achieve dual-frequency or multi-frequency electrical performance through two or more structures under the same caliber. The following describes these three related studies:

[0004] Yihong Su et al. designed antennas that work at 3.5 GHz and 28 GHz respectively. The antenna with a frequency of 3.5 GHz is a printed monopole antenna. On the back of the printed monopole structure, multiple slot antenna units are designed through the SIW (coplanar integrated waveguide) structure to achieve operation in the 28 GHz frequency band. The operating frequency span of this scheme is 28 GHz / 3.5 GHz = 8.0, that is, 8.0 octaves. The structural model and operating frequency band are given below.

[0005] He Huang and others have developed an antenna array that can work at 0.7GHz in the low frequency band and 2.7GHz in the high frequency band. Among them, the antenna unit working in the 2.7GHz high frequency band is designed by using a printed cross-dipole structure; the antenna unit working in the 0.7GHz low frequency band is designed by using a slot coupling structure; and the dual-band co-port surface design is realized through spatial arrangement at different heights. The operating frequency span of this scheme is 2.7GHz / 0.7GHz=3.9, that is, 3.9 octaves. The structural model and operating frequency band are given below.

[0006] Meng Wei et al. designed a co-aperture antenna array for X-band and Ka-band through a compact nested arrangement. The X-band is realized by a microstrip structure, and the Ka-band is realized by a slot coupling structure. The operating frequency span of this scheme is 36GHz / 8.6GHz=4.2, that is, 4.2 octaves. The structural model and operating frequency band are given below.

[0007] It can be seen from the above existing technologies that the frequency spans in the existing technologies are 3.9, 4.2 and 8.0 octaves respectively. To achieve the common aperture design of the P-band and X-band, 9.6GHz / 0.4GHz=24.0, that is, 24.0 octaves is required. In current domestic and foreign research, there are few designs related to 24 octaves, and even fewer designs for the common aperture of the P-band and X-band. The main reason is that the physical structure dimensions between the two frequency bands under the same aperture are quite different, which will affect the electrical performance between the frequency bands, and it is difficult to design the two frequency bands in a balanced manner. Summary of the invention

[0008] In order to solve the above technical problems, the present invention adopts the principle of a common-aperture antenna array and provides a satellite-borne dual-band common-aperture antenna array based on a metal structure, which realizes a 24-fold common-aperture antenna array. Among them, the P-band adopts a hollow metal frame design, and in principle adopts the Vivaldi antenna form; the X-band adopts a miniaturized metal waveguide slot form. Not only that, the present invention also designs the dual-band antenna array into a dual-polarization form, in order to avoid polarization rotation caused by multi-path reflection when electromagnetic waves penetrate dense plants, thereby causing polarization mismatch.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is:

[0010] A satellite-borne dual-band common-surface antenna array based on a metal structure, the antenna array consists of a P-band antenna unit and a slot radiation waveguide; the P-band antenna unit is formed by bending the top structure of a planar Vivaldi structure, and making a symmetrical structure design, retaining the original exponential gradient form of the planar Vivaldi structure, and hollowing out its top structure and side support structure; the P-band antenna unit consists of a feeding structure and a radiating structure, the P-band antenna unit is excited by a P-band 50-ohm coaxial connector, the 50-ohm coaxial connector is installed on the lower floor structure, the outer conductor is connected to the floor, the inner conductor is physically connected to the Vivaldi structure, and is transmitted to the radiating structure through a slot line structure; the radiating structure includes a Vivaldi structure and a top fan-shaped hollow structure; after the top fan-shaped structure adopts a hollow design, only the outer frame metal part remains in the structure; a rectangular hollow structure is set on the Vivaldi structure perpendicular to the floor surface, and the position and size of the rectangular hollow structure are adjusted to obtain an optimized hollow size. ; The slot radiation waveguide is realized by an X-band antenna unit, and the X-band antenna unit includes 8 H-polarized waveguide slots and 8 V-polarized waveguide slots, and the structural section of the H-polarized waveguide slot is higher than the structural section of the V-polarized waveguide slot; the H-polarized waveguide slot includes a first waveguide cavity and a first waveguide ridge, and the antenna impedance is better matched by optimizing different size parameters of the first waveguide ridge, and the first waveguide ridge is a multi-stage transformation shape; the V-polarized waveguide slot includes a second waveguide cavity and a second waveguide ridge, and the second waveguide The guide ridge is a metal structure located in the second waveguide cavity, directly connected to the lower surface of the second waveguide cavity, the inner core of the X-band coaxial connector passes through but does not contact the second waveguide ridge, and is physically connected to the upper surface of the second waveguide cavity; a plurality of the X-band antenna units form an X-band subarray, and the X-band antenna subarray adopts an alternating arrangement of slot waveguide antennas with different polarizations in each column; the X-band antenna unit is placed at the bottom of the space between the P-band antenna units so that its top coincides with the floor of the P-band antenna array; the antenna arrays are all metal structures.

[0011] Furthermore, the P-band feeding structure is implemented by a coaxial-to-slotline structure, and a multi-stage arrangement is adopted. The X-band feeding structure is implemented by a coaxial-to-waveguide structure.

[0012] Beneficial effects:

[0013] (1) Material selection:

[0014] The antenna is the payload of the satellite platform. In order to cope with the complex space environment and increase the working life of the antenna, the present invention adopts an all-metal aluminum alloy structure design. The antenna forms in other documents generally adopt medium printed antennas such as microstrip patches, SIW coplanar integrated waveguides, and microstrip slot couplings. Even if some designs in the prior art are based on metal structures, their feeding parts still use microstrip lines for transmission. In the existing schemes, it is difficult to find a co-port surface design of a full metal structure. The reason is that metal materials have interference and shielding effects on electromagnetic fields. When designing the co-port surface, the frequency band structure with a large frequency difference also has huge differences in the physical section, resulting in the structural size of the low-frequency band being too large relative to the low-frequency size, which seriously affects the working performance of the low-frequency band antenna. Therefore, there are few reports on the co-port surface research of metal structure antennas.

[0015] (2)P-band hollow low profile design:

[0016] In order to reduce the influence of the low-frequency P-band structure height on the working performance of the high-frequency X-band, the P-band of the present invention is designed as a butterfly-shaped hollow Vivaldi form. The innovative design reduces the antenna profile while greatly reducing the electromagnetic interference caused by the low-profile design to the high-frequency X-band. The weight of the antenna is also reduced, thereby realizing a lightweight design of the antenna.

[0017] (3) X-band array design location:

[0018] In the co-surface design, the electrical performance between frequency bands restrains and restricts each other. Therefore, it is also crucial to reduce the impact of the X-band structure on the electrical performance of the P-band. In the present invention, the X-band is embedded in the floor of the P-band structure, so that the metal structure at the top of the X-band structure is equivalent to the ideal floor of the P-band (when the structural gap is less than 1 / 10 wavelength, the structure can be equivalent to the ideal floor of the corresponding frequency band). This design minimizes the impact of the X-band structure on the electrical performance of the P-band, and even makes it negligible. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the overall layout and a partially enlarged schematic diagram of a satellite-borne dual-band common-aperture antenna array based on a metal structure of the present invention;

[0020] Figure 2a , Figure 2b , Figure 2c , Figure 2d The design process diagram for the P-band antenna unit, where: Figure 2a Schematic diagram of typical Vivaldi radiation structure size and main electric field vectors. Figure 2b Schematic diagram of antenna dimensions and main electric field vectors designed for low profile. Figure 2c Schematic diagram of antenna dimensions and main electric field vectors for low-profile hollow design. Figure 2d A schematic diagram of the structures of the P-band antenna unit;

[0021] Figure 3 This is the structural model diagram of the P-band antenna array;

[0022] Figure 4 is the unit structure size in the P-band array;

[0023] Figure 5a , Figure 5b It is the structure and parameter diagram of X-band antenna; Among them, Figure 5a It is a schematic diagram of the structure of the X-band antenna; Figure 5b Provide a schematic diagram of the various structures of the X-band antenna;

[0024] Figure 6 This is a structural model diagram of the X-band antenna array;

[0025] Figure 7 It is the active standing wave coefficient ratio and gain curve;

[0026] Figure 8a , Figure 8b are the P-band H-plane and E-plane radiation patterns, where: Figure 8a is the H-plane direction diagram, Figure 8b is the E-plane directional diagram;

[0027] Figure 9a , Figure 9b is the scanning pattern of the H plane and E plane at the center frequency of the P band, where: Figure 9a is the H-plane scanning pattern, Figure 9b It is the E-plane scanning pattern;

[0028] Fig.10a , Fig.10b is the active standing wave ratio of H-polarization and V-polarization ports and array gain curve, where Fig.10a is the H polarization result, Fig.10b is the V polarization result;

[0029] Fig.11a , Fig.11b , Fig.11c , Fig.11d are the H-plane and E-plane directional diagrams of X-band H polarization and V polarization, where: Fig.11a is the H-plane pattern of H polarization, Fig.11b is the E-plane radiation pattern of H polarization, Fig.11c is the H-plane pattern of V polarization, Fig.11d is the E-plane pattern of V polarization;

[0030] Fig.12a , Figure 12b , Fig.12c , Fig.12dis the scanning pattern of the H-plane and E-plane of the X-band H-polarization and V-polarization, where Fig.12a is the H-plane scanning pattern of H polarization, Figure 12b is the E-plane scanning pattern of H polarization, Fig.12c is the H-plane scanning pattern of V polarization, Fig.12d It is the E-plane scanning pattern of V polarization. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0032] The overall structure of a satellite-borne dual-band common-aperture antenna array based on a metal structure of the present invention is as follows Figure 1 As shown, the antenna arrays are all metal structures and are divided into two parts. One part is a hollow frame structure, which adopts the antenna form of the Vivaldi structure. Through the design of structural folding, structural hollowing, coupling between units, etc., the antenna has good electrical performance in the P band; the other part is embedded between the P-band antenna units and is located at the bottom of the overall structure. It acts as a metal floor for the P band and can also realize the slot radiation waveguide with X-band electrical performance.

[0033] like Figure 2a , Figure 2b , Figure 2c , Figure 2d , Figure 3 , Figure 4As shown, the P-band antenna unit is composed of a feeding structure 1 and a radiating structure 2. The P-band antenna is excited by a 50-ohm coaxial connector 3 of the P-band, and the 50-ohm coaxial connector 3 of the P-band is installed on the lower floor structure 4. The P-band excitation signal is transmitted to the radiating structure 2 through the slot line structure, and a matching cavity 5 and a matching slot line 6 are loaded at both ends of the transmission line of the slot line structure to achieve good impedance matching of the coaxial to slot line structure. The radiating structure 2 of the P-band antenna unit adopts a Vivaldi structure 7 plus a top fan-shaped hollow structure 8. After the top fan-shaped hollow structure 8 adopts a hollow design, only the outer frame metal part 9 is left in the structure. While ensuring the electrical performance, the weight of the antenna top structure is greatly reduced, and the radiation shielding of the X-band antenna is also reduced. Another rectangular hollow structure 10 is designed on the Vivaldi structure 7 which is perpendicular to the lower floor structure 4. By adjusting the position and size of the rectangular hollow structure 10, an optimized hollow size is obtained so that the impedance performance meets the design requirements and the weight is greatly reduced. At the same time, the rectangular hollow structure further reduces the influence of the P-band on the X-band radiation performance.

[0034] like Figure 5a , Figure 5b, the slot radiation waveguide 11 is realized by an X-band antenna unit, and the X-band antenna unit includes 8 H-polarized waveguide slots 12 and 8 V-polarized waveguide slots 13. The structural cross-section of the H-polarized waveguide slot 12 is higher than the structural cross-section of the V-polarized waveguide slot 13. The structure of the H-polarized waveguide slot 12 includes two parts. The first part is a first waveguide cavity 14 including a slotted H-direction radiation slot, and its function is to effectively radiate the electromagnetic waves in the waveguide through the slot. The second part is the first waveguide ridge 15, which is a metal structure located in the first waveguide cavity 14 and is directly connected to the coaxial core, so that the electric field of the X-band coaxial connector 16 is transmitted to the first waveguide cavity 14. By optimizing the different size parameters of the first waveguide ridge 15, the antenna impedance is better matched and the electromagnetic wave transmission efficiency is improved. In the present invention, the first waveguide ridge 15 is designed to be a multi-stage transformation shape, which is equivalent to extending the path length of the electric field transmission in the waveguide, performing impedance matching of a lower frequency band in a smaller space, and completing the miniaturization design of the waveguide; the structure of the V-polarized waveguide slot 13 also includes two parts, the first part is a second waveguide cavity 17 including a V-polarized radiation slot slot, and its function is to effectively radiate the electromagnetic waves in the waveguide through the slot. The second part is the second waveguide ridge 18, which is a metal structure located in the second waveguide cavity 17 and is directly connected to the bottom surface structure of the second waveguide cavity 17, and the inner core of the 50-ohm coaxial connector 19 of the X-band passes through but does not contact the second waveguide ridge 18, and is physically connected to it on the upper layer of the waveguide. Through this structure, the electric field is transmitted to the second waveguide cavity 17, and by optimizing the different size parameters of the second waveguide ridge 18, the antenna impedance is better matched, and the electromagnetic wave transmission efficiency is improved. In the present invention, the design of the second waveguide ridge 18 is equivalent to extending the path length of the electric field transmission in the waveguide, performing impedance matching of a lower frequency band in a smaller space, and completing the miniaturization design of the waveguide. A plurality of the X-band antenna units form an X-band subarray, and the X-band subarray adopts an alternating arrangement of slot waveguide antennas with different polarizations in each column.

[0035] The following describes the physical structure and simulation test results of the P-band and X-band antennas respectively.

[0036] (1) P-band antenna unit design:

[0037] The structural design process of the P-band antenna unit is as follows Figure 2a , Figure 2b , Figure 2c , Figure 2d As shown, Figure 2a It is the original planar Vivaldi structure, also known as tapered slot antenna (TSA), with a profile height of generally 0.50λ0, where λ0 is the wavelength of the operating frequency in free space; Figure 2bThe top structure of the flat Vivaldi is bent 90 degrees at a height of 145mm, so that the bent structure is perpendicular to the supporting structure. For the symmetry of the electric field, the bent structure is designed to be axisymmetric along the fold line, and the original exponential gradient parameters are retained. That is, the fold line at a height of 145mm is used as the symmetry axis, and the bent structure is designed to be axisymmetrically replicated. The purpose is to reduce the structural height to about 0.15λ0 while maintaining the original impedance characteristics; Figure 2c As shown in the figure, the top structure and side support structure are hollowed out to extend the current path. Figure 2a , Figure 2b , Figure 2c , Figure 2d As shown in the figure, the hollowing design is as follows: ① The bending structure is hollowed out as a whole, and only the outer frame of the bending structure remains after hollowing out. ② The lower part of the supporting structure is hollowed out in a rectangular shape. In the figure, E is the direction of the electric field vector. Specifically, in the radiation structure, only about 4mm of metal ribs are retained as weighing supports, and all other structures are hollowed out. In the supporting structure, while ensuring the supporting function, the impedance characteristics must be kept stable, and as many supporting structures as possible must be hollowed out. The above designs can further reduce the profile and reduce the impact of the P-band antenna on the radiation performance of the X-band antenna. Through the above treatment, the antenna profile size can be reduced to the range of 0.12λ0.

[0038] Another thing that needs to be explained is the antenna feeding structure. The antenna is fed in the form of a coaxial slot line structure, and the feeding structure is also specially designed. A multi-stage matching design is used in the structure to ensure the stability of the antenna impedance characteristics within the target bandwidth.

[0039] like Figure 3 As shown, after the antenna unit is designed with a low profile as described above, the overall profile height is further reduced by a tightly coupled array. The array spacing is uniformly arranged in two dimensions with a size of 0.43λ0, and the electrical performance of dual-line polarization is achieved by a cross-array. In addition, the dual polarization of the P-band antenna array is achieved by forming dual-line polarization radiation through the cross-arrangement of the units. It should be noted that in order not to affect the feeding structure of the antenna unit, the intersection of the designed cross-arrangement array is located at both ends of the antenna unit, rather than the central feeding position. The designed coupling structure is based on this cross-cross structure. While retaining the original exponential gradient form, the end of the antenna's radiation structure is adjusted using a short gap as a tight coupling parameter. In this way, the capacitance parameter is mainly introduced between the antenna units, and the profile height is further reduced to the range of 0.09λ0. Figure 3 The structural model diagram of the designed P-band antenna array and the main dimensions of the array are given. The overall size of the P-band antenna array is 1354.0×1354.0mm2 The spacing between two-dimensional array units is 323.0 mm, and the maximum size of the X-band sub-array structure that can be placed between units is 314.0 × 314.0 mm. 2 . Figure 4 The final structural model and structural size parameters of the optimized unit in the P-band array are given.

[0040] (2) X-band antenna design:

[0041] like Figure 5a As shown in the figure, since the X-band antenna also requires dual-polarization performance, the designed antenna unit consists of 8 H-polarized and 8 V-polarized waveguide slots. The H-polarized structure has a higher cross-section than the V-polarized structure. The two polarization structures are fed by two independent excitation sources to facilitate installation between the P-band units. The structural size parameters are also shown in Figure 5b Given in.

[0042] After the X-band unit design is given, Figure 6 As shown in the figure, the structural model of the X-band antenna subarray is given. The X-band subarray adopts an alternating arrangement of slot waveguide antennas with different polarizations in each column. The size of the dual-polarization slots is 16×16. This structure is installed between the P-band antenna units. It can be seen that the size of the entire subarray is 314.0×314.0mm 2 , which coincides with the reserved installation dimensions of the P-band antenna structure design.

[0043] Due to the consideration of the electrical performance of the P-band antenna structure, the top of the X-band antenna cannot be designed to be the same height as the top of the P-band radiation structure, or higher than its height. Therefore, it can only be placed at the bottom of the space between the P-band antenna units so that its top coincides with the floor of the P-band antenna array. The X-band is designed at the bottom of the P-band antenna structure. In this case, in order to solve the problem of poor X-band scanning capability, the most direct solution is to hollow out the P-band. While designing the hollowing out of the P-band support structure, its impact on the X-band radiation characteristics can be well reduced; and while designing the hollowing out of the P-band radiation structure, its impact on the X-band impedance characteristics can be reduced.

[0044] (3) P-band and X-band co-interface design:

[0045] The overall array of the PX band is as follows Figure 1As shown in the figure, the P-band array scale of dual-polarization is 3×4 element array, and there are half unit structures on all sides as tight coupling structures to ensure good impedance matching performance of the units at the edge of the array. The X-band has a total of 3×3 sub-arrays, and the total gap scale is 48×48. In addition, during the prototype processing stage, due to the good consistency of the electrical performance of each sub-array, only one P-band sub-array and one X-band sub-array were verified.

[0046] (4) Performance analysis results:

[0047] After simulating and analyzing the performance of different antenna parameters, it is planned to use physical processing and testing to analyze and verify the accuracy and reliability of the final simulation model performance. The impedance characteristics are tested and verified by a vector network analyzer, and the radiation characteristics are tested and verified by a planar near-field test system.

[0048] (4.1) P band results:

[0049] Since the geometric structures of H and V polarizations in the P band are the same and their spatial placement is symmetrical, in order to make the results concise and clear, only the results of a single polarization are given, namely the active standing wave parameters of the H-polarized antenna, the in-band gain, and the E-plane and H-plane planar radiation patterns.

[0050] The voltage standing wave ratio VSWR and gain Gain results of the simulation and test of the antenna in the non-scanning state are both Figure 7 In the scanning state, only the simulated plane radiation pattern of the upper and lower sidebands and the center frequency is given, such as Figure 9a , Figure 9b shown.

[0051] like Figure 7 As shown, the antenna has 12 ports in the H polarization of the P band, and each port has an active standing wave ratio. It can be seen that the overall peak value is less than 2.0, and the low-frequency band performance (0.4-0.45GHz) of the port standing wave at the unit position in the array is better than the standing wave performance of the port located at the edge of the array. This should be caused by the inconsistency of the structural coupling parameters introduced by the unit in the array and the unit at the edge of the array. The simulation results of the gain of the P-band antenna in the non-scanning state are consistent with the measured results, and the gain range in the entire bandwidth is 14.7~19.6dBi.

[0052] like Figure 8a , Figure 8bThe simulation results of the P-band antenna in the non-scanning state are consistent with the measured results, and the maximum in-band sidelobe level is 14.3dBi. At 0.40GHz, 0.55GHz and 0.70GHz, the half-power beamwidths of the H-plane and E-plane are (30°, 22° and 16°) and (42°, 28° and 20°), respectively. In the H-plane, E-plane and D-plane radiation patterns, the cross-polarization levels are less than 30.0dB, 35.0dB and 24.1dB, respectively. In addition, Figure 9a , Figure 9b The P band can be scanned in the range of 0 to ±30 degrees, and the far-field radiation pattern has good performance. The sidelobe level is a maximum of 9.7dBi at ±30 degrees.

[0053] (4.2) X-band results:

[0054] Due to the different geometric structures of the two polarizations in the X-band, the results of the horizontally polarized and vertically polarized ports are given separately.

[0055] like Fig.10a , Fig.10b As shown in the figure, the medium voltage standing wave coefficient is less than or equal to 2.0. Because the edge structure of the vertical polarization H slot is close to the P-band floor, its port standing wave results are slightly different from those of other ports. The horizontal polarization slot structure is not affected by this difference, and its results are consistent. The simulation and test gains of the two polarizations are consistent, both increasing with frequency in the range of 29.1 to 30.2 dBi.

[0056] The X-band simulation test pattern results are also Fig.11a , Fig.11b , Fig.11c , Fig.11d The results are given in the table, and they are very consistent. In the non-scanning state, the sidelobe level of H polarization in the X-band is less than 13.5dBi on average, and the sidelobe level of V polarization is less than 13.2dBi on average. The cross-polarization level of H polarization is less than -35dB on the H plane and less than -35dB on the E plane; the cross-polarization level of V polarization is less than -33dB on the H plane and less than -32dB on the E plane.

[0057] like Fig.12a , Figure 12b , Fig.12c , Fig.12d As shown, in the scanning state, the X-band antenna subarray can scan in the range of 0 to ±30 degrees, and the far-field radiation pattern has good performance. At ±30 degrees, the maximum sidelobe level is 13.0dBi for H polarization and 13.3dBi for V polarization.

[0058] The present invention designs a novel Vivaldi hollow metal structure, realizes the size of low profile (0.09λ0) in P band, and adopts the co-aperture design with miniaturized slot waveguide array, realizes the impedance characteristics of ultra-wide frequency span P band (0.4-0.7GHz) and X band (9.3-9.9GHz), and the radiation performance of ±30 degree scanning angle. The feasibility of the present invention is verified by processing and testing the physical prototype. The test results show that the antenna array of the present invention has good impedance characteristics, radiation characteristics and scanning capabilities, and can be used in forest biomass measurement.

[0059] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A satellite-borne dual-band common-aperture antenna array based on a metal structure, characterized in that: The antenna array is composed of a P-band antenna unit and a slot radiation waveguide; the P-band antenna unit is formed by bending the top structure of the planar Vivaldi structure, and making a symmetrical structure design, retaining the original exponential gradient form of the planar Vivaldi structure, and hollowing out the top structure and the side support structure; The P-band antenna unit is composed of a feeding structure and a radiating structure. The P-band antenna unit is excited by a 50-ohm coaxial connector of the P-band. The 50-ohm coaxial connector is installed on the lower floor structure. The outer conductor is connected to the floor, and the inner conductor is physically connected to the Vivaldi structure, and is transmitted to the radiating structure through the slot line structure. The radiating structure includes a Vivaldi structure and a top fan-shaped hollow structure. After the top fan-shaped hollow structure adopts a hollow design, only the metal part of the outer frame remains in the structure. A rectangular hollow structure is set on the Vivaldi structure perpendicular to the floor surface, and the position and size of the rectangular hollow structure are adjusted to obtain the optimized hollow size. The slot radiation waveguide is realized by an X-band antenna unit. The X-band antenna unit includes 8 H-polarized waveguide slots and 8 V-polarized waveguide slots. The structural section of the H-polarized waveguide slot is The surface of the waveguide slot with a V polarization is higher than that of the V polarization; the first waveguide cavity and the first waveguide ridge of the H polarization waveguide slot are optimized, and the antenna impedance is well matched by optimizing different size parameters of the first waveguide ridge, and the first waveguide ridge is a multi-stage transformation shape; the waveguide slot with a V polarization includes a second waveguide cavity and a second waveguide ridge, and the second waveguide ridge is a metal structure located in the second waveguide cavity and is directly connected to the lower surface of the second waveguide cavity. The inner core of the X-band coaxial connector passes through but does not contact the second waveguide ridge and is physically connected to the upper surface of the second waveguide cavity; a plurality of the X-band antenna units form an X-band subarray, and the X-band antenna subarray adopts an alternating arrangement of slot waveguide antennas with different polarizations in each column; the X-band antenna unit is placed at the bottom of the space between the P-band antenna units so that its top coincides with the floor of the P-band antenna array; the antenna arrays are all metal structures.

2. The satellite-borne dual-band common-aperture antenna array based on a metal structure according to claim 1, characterized in that: The feeding structure of the P-band antenna unit is realized by a coaxial-to-slot-line structure, and a multi-stage setting is adopted. The feeding structure of the X-band antenna unit is realized by a coaxial-to-waveguide structure.

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