Multi-frequency microstrip antenna and preparation method thereof

Abstract

The invention provides a multi-frequency microstrip antenna and a preparation method, and relates to the technical field of antennae, the multi-frequency microstrip antenna comprises a metal floor, the metal floor is provided with an antenna substrate and at least two antenna radiation assemblies with different frequency bands, and the antenna substrate and the antenna radiation assemblies are embedded into the metal floor and are flush with the metal floor; the phase centers of the antenna radiation assemblies are the same, and the antenna radiation assembly of the higher frequency band is arranged on the inner ring of the antenna radiation assembly of the lower frequency band to form a double-layer concentric-square-shaped structure or a multi-layer concentric-square-shaped structure. According to the invention, low profile and lightweight design can be satisfied, scattering sources can be reduced, spatial domain pattern mutation and gain reduction are avoided, antenna RCS is effectively reduced, the phase centers of the antenna radiation assemblies are the same, the defect of poor stability of the phase centers is effectively solved, the isolation between the antenna radiation assemblies of different frequency bands is increased, coupling is reduced, and the antenna radiation efficiency is improved. The antenna gain is improved.

Description

Technical Field

[0001] The present invention relates to the field of antenna technology, and in particular to a multi-frequency microstrip antenna and a preparation method thereof. Background Art

[0002] The terminal antenna of the high-precision satellite navigation system needs to use a high-precision phase center antenna. The stability of the antenna phase center will significantly affect the positioning accuracy and working performance of the system. The actual project requires the antenna to be miniaturized, low-profile and lightweight, and there are restrictions on the size and height of the antenna. The antenna is becoming increasingly miniaturized, but the number of antenna bands and array elements is increasing. Microstrip antennas are mostly used in multi-band and multi-element combined antenna array designs because of their low profile, wide beam, and convenient combination design.

[0003] The size of the metal floor of the existing antenna array is much larger than the antenna radiation component, and the metal floor is lower than the antenna radiation component. The limited oversized metal floor will cause multiple reflections of the antenna radiation component and cause surface wave coupling, so that the antenna radiation pattern beam focuses to the vertex or has a null, the spatial radiation pattern suddenly changes, the gain decreases, and the phase center discreteness is increased; in addition, the metal floor usually adopts an irregular shape, which produces asymmetric edge scattering, the high-frequency array element radiation pattern becomes concave, and the gain, axial ratio, radiation pattern non-circularity and phase center stability indicators deteriorate.

[0004] In summary, the existing microstrip antennas have problems such as low antenna gain, pattern collapse, poor phase center stability and high radar cross section (RCS) due to the use of oversized irregular metal floors. Summary of the invention

[0005] The present invention provides a multi-frequency microstrip antenna and a preparation method thereof, which are used to solve the problems of low antenna gain, pattern collapse, poor phase center stability and high RCS caused by an oversized irregular metal floor.

[0006] The present invention provides a multi-frequency microstrip antenna, comprising a metal floor, an antenna substrate and at least two antenna radiating components of different frequency bands, wherein the antenna substrate and each of the antenna radiating components are embedded in the metal floor and are flush with the metal floor; the phase centers of each of the antenna radiating components are the same, and the antenna radiating components of the higher frequency band are arranged in the inner circle of the antenna radiating components of the lower frequency band to form a double-layered ring-shaped structure or a multi-layered ring-shaped structure.

[0007] As an embodiment, the antenna substrate and the metal surface of the antenna substrate have a diamond-shaped structure.

[0008] As an embodiment, each of the antenna radiating components includes an antenna radiating metal sheet and at least one feeding pole. The antenna radiating metal sheet is arranged on the inner circle of the metal surface of the antenna substrate. The feeding pole is arranged on the antenna radiating metal sheet near the phase center and passes through the metal surface and the metal back side of the antenna substrate.

[0009] As an embodiment, the number of the feeding poles is greater than or equal to 1, and there is a phase difference between adjacent feeding poles.

[0010] As an embodiment, each of the antenna radiation components further includes a short-circuit post, which is arranged around the outer ring of the antenna radiation metal sheet and passes through the metal surface and the metal back side of the antenna substrate.

[0011] As an embodiment, the spacing between adjacent antenna radiation metal sheets ranges from 1 mm to 6 mm.

[0012] As an embodiment, the shape and size of the antenna radiation metal sheet are determined based on the dielectric constant of the antenna substrate.

[0013] As an embodiment, the shape of the antenna radiation metal sheet is rectangular or circular.

[0014] As an embodiment, the phase center of each antenna radiating element is approximately located at the physical center of the metal floor.

[0015] The present invention also provides a method for preparing a multi-frequency microstrip antenna, comprising: According to preset design parameters, a metal floor, an antenna substrate, and antenna radiation components of at least two different frequency bands are prepared; Embed the antenna substrate and each of the antenna radiation components into the metal floor and make them flush with the metal floor; Among them, the phase centers of the antenna radiation components are the same, and the antenna radiation components of the higher frequency band are arranged in the inner circle of the antenna radiation components of the lower frequency band to form a double-layer U-shaped structure or a multi-layer U-shaped structure.

[0016] The multi-frequency microstrip antenna and preparation method provided by the present invention include a metal floor, an antenna substrate and at least two antenna radiating components of different frequency bands, the antenna substrate and each of the antenna radiating components are embedded in the metal floor and are flush with the metal floor; the phase centers of each of the antenna radiating components are the same, and the antenna radiating component of the higher frequency band is arranged in the inner circle of the antenna radiating component of the lower frequency band to form a double-layered ring-shaped structure or a multi-layered ring-shaped structure. The present invention embeds the antenna substrate and each antenna radiation component into the metal floor and makes it flush with the metal floor, which can not only meet the requirements of low-profile and lightweight design, but also reduce scattering sources, avoid sudden changes in the spatial radiation pattern and gain reduction, and effectively reduce the antenna RCS. The phase centers of each of the antenna radiation components are the same, which effectively solves the defect of poor phase center stability. The antenna radiation component of the higher frequency band is arranged in the inner circle of the antenna radiation component of the lower frequency band to form a double-layer ring-shaped structure or a multi-layer ring-shaped structure, which can increase the isolation between antenna radiation components of different frequency bands, so that the antenna radiation component of the lower frequency band becomes the ground end of the antenna radiation component of the higher frequency band, reducing coupling and improving antenna gain. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a schematic structural diagram of an embodiment of a multi-frequency microstrip antenna provided by the present invention.

[0019] Figure 2 It is one of the structural schematic diagrams of the antenna substrate and antenna radiation component provided by the present invention.

[0020] Figure 3 This is the second structural schematic diagram of the antenna substrate and antenna radiation component provided by the present invention.

[0021] Figure 4 This is the third structural schematic diagram of the antenna substrate and antenna radiation component provided by the present invention.

[0022] Figure 5 It is a schematic diagram of the shape of the antenna radiation metal sheet provided by the present invention.

[0023] Figure 6 It is a schematic flow chart of the method for preparing a multi-frequency microstrip antenna provided by the present invention.

[0024] In the figure: 100-metal floor, 200-antenna substrate, 210-metal surface, 220-metal back, 300-antenna radiation metal sheet, 310-high frequency antenna radiation metal sheet, 320-low frequency antenna radiation metal sheet, 400-feeding pole, 410-high frequency feeding pole, 420-low frequency feeding pole, 500-short-circuit pole, 510-high frequency short pole, 520-low frequency short pole. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] To address the defects of microstrip antennas, such as low antenna gain, pattern collapse, poor phase center stability, and high radar cross section (RCS), caused by the use of oversized irregular metal floors, the existing solutions and their defects are as follows: 1. Change the internal structure of the metal floor. This method increases the periodic defective ground structure (DGS) to cut off the surface current. However, due to the large structural size of the metal floor, the maximum size of the DGS is one-fourth of the wavelength of the antenna radiation component. It can be seen that this method can only improve the phase center stability index to a certain extent, but cannot improve the antenna gain. It is not suitable for compact antenna arrays and cannot meet the miniaturization design. The secondary resonance of the DGS will also cause the antenna RCS index to deteriorate.

[0027] 2. Add a circular metal pad of appropriate height and size between the antenna radiation component and the metal floor. This method increases the height of the antenna and cannot meet the low-profile design requirements. The added metal pad will affect the performance of array elements in other frequency bands, and the weight of the antenna will increase with the metal pad, making it impossible to achieve a lightweight design. The metal pad will also cause the antenna RCS index to deteriorate.

[0028] 3. Adding metal frames or chokes around the antenna radiation component can improve the phase center stability to a certain extent, but the added structure has a greater impact on the performance of array elements in other frequency bands. The choke structure requires a multi-layer circular ring structure to have a better phase stabilization effect, but the gain of the antenna radiation component will be reduced. The metal structure occupies more space in the antenna array and cannot be arranged in a compact antenna array. Moreover, the metal frame or choke is prone to interfere with the optimal layout position of other antenna radiation components. Adding vertical metal structures will form multiple strong scattering sources of mirror reflection, which will introduce structural scattering and lead to high RCS.

[0029] 4. The stacked design is adopted and placed at the geometric center of the metal floor, that is, the low-frequency radiation array is at the bottom and the high-frequency radiation array is at the top. Through the form of feed pin coupling or metallized isolation vias, the high phase center and high gain design of the multi-frequency antenna are realized. The size of the stacked array is smaller than the lower array, protruding from the installation cavity, and each step of the antenna contains a vertical prism. This structural mutation will form multiple strong scattering sources of mirror reflection, which will introduce structural scattering and lead to high RCS.

[0030] The above methods cannot meet the requirements of low-profile and miniaturized design of the whole equipment. The present invention provides a multi-frequency microstrip antenna and a preparation method. Under the requirements of low-profile and miniaturized design, the harmful scattering of oversized metal floors is reduced, the gain and phase center stability of the antenna radiation component are improved, and the RCS is reduced. A detailed description is given below in conjunction with the accompanying drawings.

[0031] Figure 1 FIG. 1 is a schematic diagram of a structure of an embodiment of a multi-frequency microstrip antenna provided by the present invention. Figure 1As shown, the present invention provides a multi-frequency microstrip antenna, including a metal floor 100, an antenna substrate 200 and at least two antenna radiating components of different frequency bands, the antenna substrate 200 and each of the antenna radiating components are embedded in the metal floor 100 and flush with the metal floor 100; the phase centers of each of the antenna radiating components are the same, and the antenna radiating components of the higher frequency band are arranged in the inner circle of the antenna radiating components of the lower frequency band to form a double-layer U-shaped structure or a multi-layer U-shaped structure. The double-layer U-shaped structure refers to a gap between the antenna radiating components of the higher frequency band and the antenna radiating components of the lower frequency band, forming a layer of U-shaped structure, and a gap between the antenna radiating components of the lower frequency band and the antenna substrate 200, forming a layer of U-shaped structure. The multi-layer U-shaped structure refers to the situation where the number of antenna radiating components is greater than or equal to 3, the antenna radiating components are nested according to the frequency bands, there are gaps between each other, and there is a gap between the antenna radiating components of the lowest frequency band and the antenna substrate 200, forming at least three layers of U-shaped structure. Taking the example of 3 antenna radiation components, the antenna radiation components include high-frequency band antenna radiation components, mid-frequency band antenna radiation components and low-frequency band antenna radiation components. According to the frequency band from high to low, the high-frequency band antenna radiation components, the mid-frequency band antenna radiation components and the low-frequency band antenna radiation components are nested and arranged in sequence from the inside to the outside. There is a gap between the high-frequency band antenna radiation components and the mid-frequency band antenna radiation components to form a first-layer U-shaped structure, there is a gap between the mid-frequency band antenna radiation components and the low-frequency band antenna radiation components to form a second-layer U-shaped structure, there is a gap between the low-frequency band antenna radiation components and the antenna substrate 200 to form a third-layer U-shaped structure, and the first-layer U-shaped structure, the second-layer U-shaped structure and the third-layer U-shaped structure constitute a multi-layer U-shaped structure.

[0032] Optionally, the installation gap between the metal floor and the antenna substrate is controlled between 0.05-1 mm to prevent the installation gap between the metal floor and the antenna substrate from being too large and affecting the RCS performance of the multi-frequency microstrip antenna.

[0033] The metal floor 100, as a reference plane for the antenna, can provide a stable electric and magnetic field distribution, help enhance the radiation pattern of the antenna, and make the antenna radiation more symmetrical. The metal floor 100 helps to reflect the electromagnetic waves radiated from the antenna and reduce the ground effect. Through reflection, the radiated power of the antenna can be concentrated in a useful direction, thereby increasing the gain of the antenna. The floor affects the input impedance of the antenna. A reasonable design can optimize the impedance matching between the antenna and the feeder, reduce reflection losses, and improve antenna efficiency. The metal floor 100 can effectively suppress the sidelobe radiation of the antenna and guide the energy to concentrate in the main radiation direction, thereby improving the directivity of the antenna. The metal floor 100 provides support for the microstrip antenna structure, making it more stable during production and installation. The metal floor 100 can also reduce the interference of the antenna from the surrounding environment or other electrical equipment, provide a certain shielding effect, and improve signal quality.

[0034] The frequency types of the antenna radiation component include but are not limited to B1, B2, B3, L, S, GPS, and the corresponding frequency ranges of B1, B2, B3, L, S, GPS are 1561.098MHz, 1207.14MHz, 1268.52MHz, 1618.34MHz, 2491.75MHz and 1575.42MHz, respectively. The present invention utilizes high dielectric constant materials to make the radiation metal sheet into different sizes and various shapes.

[0035] The present invention adopts a co-centered co-planar embedded design, embedding the antenna substrate 200 and each of the antenna radiation components into the metal floor 100 and flush with the metal floor 100, so that the phase center of each of the antenna radiation components is the same, and the antenna radiation component of the higher frequency band is arranged in the inner circle of the antenna radiation component of the lower frequency band to form a double-layer U-shaped structure or a multi-layer U-shaped structure, and each layer of the structure is a frequency band. By setting a double-layer U-shaped structure or a multi-layer U-shaped structure, the isolation between antenna radiation components of different frequency bands is increased, so that the antenna radiation component of the lower frequency band becomes the metal ground of the antenna radiation component of the higher frequency band, which can effectively reduce coupling and improve antenna gain. On the other hand, the antenna radiation component of the higher frequency band has a short wavelength and a small volume. Placing the antenna radiation component of the higher frequency band in the inner circle of the antenna radiation component of the lower frequency band is conducive to further reducing the size of the antenna.

[0036] It can be understood that the present invention embeds the antenna base 200 and each antenna radiating component into the metal floor 100 and makes it flush with the metal floor 100, which can not only meet the low-profile and lightweight design, but also reduce scattering sources, avoid sudden changes in the spatial radiation pattern and gain reduction, and effectively reduce the antenna RCS. The phase centers of each of the antenna radiating components are the same, which effectively solves the defect of poor phase center stability. The antenna radiating component of the higher frequency band is arranged in the inner circle of the antenna radiating component of the lower frequency band to form a double-layer ring-shaped structure or a multi-layer ring-shaped structure, which can increase the isolation between antenna radiating components of different frequency bands, so that the antenna radiating component of the lower frequency band becomes the ground end of the antenna radiating component of the higher frequency band, reducing coupling and improving antenna gain.

[0037] Based on the above embodiment, as an optional embodiment, the antenna substrate 200 is obtained based on a high dielectric constant material. The high dielectric constant material can be polytetrafluoroethylene (PTFE), a ceramic substrate, a polymer composite material, a high dielectric constant polyimide and other high dielectric constant materials. Specifically, PTFE is a low-loss polymer with a dielectric constant of about 2.1. Although its own dielectric constant is low, it is usually used in combination with other materials to meet specific design requirements. PTFE has excellent electrical insulation properties and stability and is suitable for high-frequency microstrip antennas. Ceramic substrates include barium titanate (BaTiO3) and aluminum oxide (Al2O3). The dielectric constant of barium titanate (BaTiO3) is usually between 100 and 200, which is very suitable for high-gain microstrip antennas. Aluminum oxide (Al2O3) is another commonly used ceramic material with a high dielectric constant (about 9) and good mechanical strength and high temperature performance. Polymer composites refer to some polymers that can be made into composite materials by doping high dielectric constant fillers (such as ceramic particles) to achieve a higher dielectric constant while maintaining lightness and easy processing. High dielectric constant polyimide (PI) refers to modified polyimide with high dielectric constant and excellent thermal and electrical properties, which is suitable for advanced microstrip antenna design. Other high dielectric constant materials refer to some specific synthetic materials and new materials (such as graphene-based materials).

[0038] It is understandable that using high dielectric constant materials to make the antenna substrate 200 can obtain a very small antenna and achieve miniaturization. High dielectric constant materials can provide better radiation characteristics and higher gain. High dielectric constant materials composed of combined materials can achieve wider bandwidth and better impedance matching characteristics.

[0039] Based on the above embodiment, as an optional embodiment, the phase center of each antenna radiation component is approximately located at the physical center of the metal floor 100. Optionally, when manufacturing a microstrip antenna, the physical center of the metal floor 100 can be first determined, and then the antenna radiation components of each frequency band are sequentially embedded with the physical center of the metal floor 100 as the center, which can effectively ensure the center consistency of the antenna.

[0040] It can be understood that the phase center of the co-centric multi-band antenna provided by the present invention is approximately located at the physical center of the antenna structure, the phase centers of multiple antennas of the multi-band antenna are more consistent, and the antenna can obtain better low elevation gain and non-circularity.

[0041] Figure 2 It is one of the structural schematic diagrams of the antenna substrate 200 and the antenna radiation component provided by the present invention. Figure 3 FIG. 2 is a second structural diagram of the antenna substrate 200 and the antenna radiation component provided by the present invention. Figure 2 and Figure 3 As shown, based on the above embodiment, as an optional embodiment, the antenna substrate 200 and the metal surface 210 of the antenna substrate 200 are in a rhombus structure, and the metal surface 210 of the antenna substrate 200 is connected to the ground. A smaller rhombus angle in the rhombus structure has an angle range of 50°-80° to effectively reduce the antenna RCS.

[0042] It is understandable that structure is an important factor affecting the RCS performance of the antenna. A structural feature may become a scattering source. Therefore, the structural features of the antenna should be reduced as much as possible, so reducing the number of scattering sources can effectively reduce the RCS of the target. The present invention makes the antenna base 200 and the metal surface 210 into a diamond structure, and the embedded installation design avoids the appearance of metal steps and vertical prisms, reduces structural mutations, maintains structural continuity, and effectively reduces the RCS of the antenna. In addition, the rhombus-shaped antenna base 200 and the metal surface 210 of the antenna base 200 can make the antenna base 200 better transition to the metal floor 100, reduce the high RCS of the connection gap between the antenna and the metal floor 100, and have no effect on the antenna performance.

[0043] Figure 4 This is a third structural diagram of the antenna substrate 200 and the antenna radiation component provided by the present invention, such as Figure 4 As shown, based on the above embodiments, as an optional embodiment, each of the antenna radiation components includes an antenna radiation metal sheet 300 and at least one feeding pole 400, the antenna radiation metal sheet 300 is arranged on the inner circle of the metal surface 210 of the antenna substrate 200, and the feeding pole 400 is arranged on the antenna radiation metal sheet 300 near the phase center and passes through the metal surface 210 and the metal back side 220 of the antenna substrate 200.

[0044] Optionally, the antenna provided by the present invention is printed from a plate with a uniform dielectric constant. The high-frequency array element has a short wavelength and a small volume. The antenna radiating metal sheet 300 in the middle area is a high-frequency array element, and the metal sheets around it away from the center are low-frequency array elements. The high-frequency and low-frequency array elements are relative, and the radiating metal sheets close to the center are all high-frequency array elements of the radiating metal sheets close to the outside, and vice versa.

[0045] Optionally, the feed post 400 is perpendicular to the metal surface 210 and the metal back side 220 of the antenna substrate 200, and the feed post 400 can effectively introduce the signal into the antenna to ensure high radiation efficiency, especially in applications requiring high gain. A properly designed feed post 400 can improve the impedance matching between the antenna and the feed line, reduce reflection losses, and thus improve overall performance. The flexible design of the feed post 400 allows the microstrip antenna to be used in a variety of frequencies and application scenarios, including portable devices, satellite communications, radar systems, and wireless communications. The present invention adopts a multi-feed post 400 design to facilitate the circular polarization design of the antenna.

[0046] On the basis of the above embodiment, as a preferred embodiment, the number of the feeding poles 400 is greater than or equal to 1, and the preferred number range is 1-6. The number of the feeding poles 400 is preferably 2, 4, and 6. There is a phase difference between adjacent feeding poles 400. The number of feeding poles 400 in the accompanying drawings is 4, and the number of feeding poles 400 is not limited to 4. When the number of feeding poles 400 is 4, the phase difference between the feeding poles 400 is 90 degrees, realizing the circular polarization design of the antenna.

[0047] Taking two groups of antenna radiation components as an example, the antenna radiation metal sheet 300 includes a high-frequency antenna radiation metal sheet 310 and a low-frequency antenna radiation metal sheet 320, and the feed column 400 includes a high-frequency feeding column 410 and a low-frequency feeding column 420. The high-frequency antenna radiation metal sheet 310 provided in the embodiment of the present invention is rhombus-shaped, and the high-frequency feeding column 410 is arranged at the center of the high-frequency antenna radiation metal sheet 310 according to the layout requirements of the circular polarization antenna. The outer circle of the low-frequency antenna radiation metal sheet 320 is rhombus-shaped, and the inner circle is provided with a rhombus-shaped opening. The high-frequency antenna radiation metal sheet 310 is arranged in the rhombus-shaped opening, and the low-frequency feeding column 420 is arranged at the inner circle of the low-frequency antenna radiation metal sheet 320 according to the layout requirements of the circular polarization antenna. The high-frequency antenna radiating metal sheet 310 and the high-frequency feeding post 410 constitute a high-frequency circularly polarized antenna, and the low-frequency antenna radiating metal sheet 320 and the low-frequency feeding post 420 constitute a low-frequency circularly polarized antenna. At the same time, the position of the low-frequency feeding post 420 corresponds to the high-frequency feeding post 410 to form a dual-band circularly polarized microstrip antenna.

[0048] Based on the above embodiments, as a preferred embodiment, each antenna radiation component further includes a short-circuit post 500, which is arranged around the outer ring of the antenna radiation metal sheet 300 and passes through the metal surface 210 and the metal back surface 220 of the antenna substrate 200. The short-circuit post 500 is made of metal material.

[0049] like Figure 1-Figure 4As shown, the number of short-circuit posts 500 provided in the embodiment of the present invention is relatively large. Taking two groups of antenna radiation components as an example for explanation, the short-circuit posts 500 include high-frequency short-circuit posts 510 and low-frequency short-circuit posts 520. The high-frequency short-circuit posts 510 are provided at the inner circle of the low-frequency antenna radiation metal sheet 320, and are closer to the high-frequency antenna radiation metal sheet 310 of the high-frequency antenna radiation component than the low-frequency feeding posts 420, forming an ideal electric wall, increasing the isolation between the high-frequency array element (high-frequency antenna radiation metal sheet 310) and the low-frequency array element (low-frequency antenna radiation metal sheet 320), reducing coupling, and improving antenna gain. The low-frequency short-circuit posts 520 are provided at the inner circle of the metal surface 210 of the antenna substrate 200, forming an ideal electric wall, increasing the isolation between the low-frequency array element (low-frequency antenna radiation metal sheet 320) and the metal surface 210 of the antenna substrate 200, reducing coupling, and improving antenna gain.

[0050] It can be understood that the present invention adds short-circuit posts 500 around the high-frequency antenna radiation element. The short-circuit posts 500 penetrate the metal surface 210 and the metal back surface 220 of the antenna substrate 200 to form an ideal electric wall, thereby increasing the isolation between the high-frequency element (high-frequency antenna radiation metal sheet 310) and the low-frequency element (low-frequency antenna radiation metal sheet 320), reducing coupling, and improving the antenna gain; the low-frequency element has a forced short-circuit point near the inner circle, which can change the impedance characteristics of the antenna port, realize impedance matching of long-distance feeding, reduce antenna mode scattering, and improve the RCS performance of the antenna.

[0051] Based on the above embodiment, as a preferred embodiment, the distance between adjacent antenna radiation metal sheets 300 is in the range of 1 mm to 6 mm. If the distance is too large, the RCS will be deteriorated; if the distance is too small, the antenna performance will be deteriorated.

[0052] It is understandable that the metal radiation sheet of the microstrip antenna generates a magnetic field between the metal ground to radiate energy outward. If the gap is too small, that is, the metal-free part of the substrate is too small, the energy cannot be radiated out, resulting in poor gain performance of the microstrip antenna. If the gap is too large, a strong reflection will be generated when the radar is irradiated, resulting in poor RCS. The present invention limits the spacing range of adjacent antenna radiation metal sheets 300 to 1mm-6mm, which can effectively balance the gain performance and RCS performance.

[0053] Figure 5 is a schematic diagram of the shape of the antenna radiation metal sheet 300 provided by the present invention, such as Figure 5 As shown, based on the above embodiments, as a preferred embodiment, the shape and size of the antenna radiation metal sheet 300 are determined based on the dielectric constant of the antenna substrate 200 .

[0054] The present invention is achieved by Figure 5The shape of the antenna radiating metal sheet 300 is illustrated by way of example. The shape of the antenna radiating metal sheet 300 is not limited. The shape of the antenna radiating metal sheet 300 can be varied and only needs to be designed in accordance with the dielectric constant of the substrate. It should be noted that in order to avoid asymmetric edge scattering caused by an irregular shape, the antenna radiating metal sheet 300 in the present invention adopts a symmetrical shape.

[0055] Preferably, the shape of the antenna radiation metal sheet 300 is rectangular or circular.

[0056] The following table is a performance comparison diagram of the existing laminated microstrip antenna and the multi-frequency microstrip antenna provided by the present invention.

[0057]

[0058] It can be seen from the above table that compared with the existing laminated microstrip antenna, the multi-frequency microstrip antenna provided by the present invention embeds the antenna substrate and each antenna radiation component into the metal floor and is flush with the metal floor. The antenna low elevation angle gain is improved by 1.67dB, the phase center stability is improved by 2.71mm, and the RCS value is improved by 7dB, and the performance in all aspects is improved.

[0059] In summary, the multi-frequency microstrip antenna provided by the present invention can meet the requirements of low profile and miniaturization design, which not only improves the gain, non-circularity of the radiation pattern, phase center stability and phase center consistency of the antenna, but also optimizes the antenna RCS to achieve high gain, high precision and low RCS requirements. The present invention can be laid out according to the height limit of the whole machine and the size and position of the array element layout, and has a high degree of design freedom.

[0060] The following is a description of a method for preparing a multi-frequency microstrip antenna provided by the present invention. The method for preparing the multi-frequency microstrip antenna described below and the multi-frequency microstrip antenna described above can be referred to each other.

[0061] Figure 6 FIG. 1 is a flow chart of a method for preparing a multi-frequency microstrip antenna provided by the present invention. Figure 6 As shown, the present invention also provides a method for preparing a multi-frequency microstrip antenna, comprising the following steps.

[0062] Step S1, according to preset design parameters, prepare a metal floor, an antenna substrate and at least two antenna radiation components of different frequency bands. The preset design parameters include the overall height limit of the antenna, the antenna frequency band, the size and position of the array element layout, and other parameters.

[0063] Optionally, before preparing the metal floor, the antenna substrate and at least two antenna radiation components of different frequency bands, the preset design parameters can be imported into the simulation software to determine whether the design parameters need to be adjusted in order to improve the preparation effect and reduce defective products.

[0064] Step S2, embedding the antenna substrate and each of the antenna radiation components into the metal floor and making them flush with the metal floor.

[0065] Among them, the phase centers of the antenna radiation components are the same, and the antenna radiation components of the higher frequency band are arranged in the inner circle of the antenna radiation components of the lower frequency band to form a double-layer U-shaped structure or a multi-layer U-shaped structure.

[0066] Optionally, in step S2, the installation gap between the metal floor and the antenna substrate needs to be controlled between 0.05-1 mm to prevent the installation gap between the metal floor and the antenna substrate from being too large and affecting the RCS performance of the multi-frequency microstrip antenna.

[0067] As an embodiment, the antenna substrate and the metal surface of the antenna substrate are in a diamond structure. Specifically, before step S1, the RCS performance requirements of the multi-frequency microstrip antenna are imported into the simulation software, so that the simulation software performs angle simulation analysis of the diamond structure according to the RCS performance requirements, and optimizes the angle of the diamond structure to achieve the best RCS performance.

[0068] As an embodiment, each of the antenna radiating components includes an antenna radiating metal sheet and at least one feeding pole. The antenna radiating metal sheet is arranged on the inner circle of the metal surface of the antenna substrate. The feeding pole is arranged on the antenna radiating metal sheet near the phase center and passes through the metal surface and the metal back side of the antenna substrate.

[0069] As an embodiment, the number of the feeding poles is greater than or equal to 1, preferably 2, 4, or 6, and there is a phase difference between adjacent feeding poles. If the number of the feeding poles is 4, the phase difference is 90 degrees.

[0070] As an embodiment, each of the antenna radiation components further includes a short-circuit post, which is arranged around the outer ring of the antenna radiation metal sheet and passes through the metal surface and the metal back side of the antenna substrate.

[0071] As an embodiment, the spacing between adjacent antenna radiation metal sheets ranges from 1 mm to 6 mm.

[0072] As an embodiment, the shape of the antenna radiation metal sheet is determined based on the dielectric constant of the antenna substrate.

[0073] As an embodiment, the phase center of each antenna radiating element is approximately located at the physical center of the metal floor.

[0074] In summary, the multi-frequency microstrip antenna manufactured using the multi-frequency microstrip antenna preparation method has the same technical effect as the multi-frequency microstrip antenna, which will not be described in detail.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-frequency microstrip antenna, comprising a metal floor, characterized in that: It also includes an antenna base and at least two antenna radiating components of different frequency bands, the antenna base and each of the antenna radiating components are embedded in the metal floor and are flush with the metal floor; the phase centers of each of the antenna radiating components are the same, and the antenna radiating component of the higher frequency band is arranged in the inner circle of the antenna radiating component of the lower frequency band to form a double-layer U-shaped structure or a multi-layer U-shaped structure.

2. The multi-frequency microstrip antenna according to claim 1, characterized in that: The antenna substrate and the metal surface of the antenna substrate are in a diamond structure.

3. The multi-frequency microstrip antenna according to claim 1 or 2, characterized in that: Each of the antenna radiating components includes an antenna radiating metal sheet and at least one feeding pole. The antenna radiating metal sheet is arranged on the inner circle of the metal surface of the antenna substrate. The feeding pole is arranged on the antenna radiating metal sheet near the phase center and passes through the metal surface and metal back side of the antenna substrate.

4. The multi-frequency microstrip antenna according to claim 3, characterized in that: The number of the feeding posts is greater than or equal to 1, and there is a phase difference between adjacent feeding posts.

5. The multi-frequency microstrip antenna according to claim 3, characterized in that: Each of the antenna radiation components also includes a short-circuit post, which is wound around the outer circle of the antenna radiation metal sheet and passes through the metal surface and the metal back side of the antenna substrate.

6. The multi-frequency microstrip antenna according to claim 3, characterized in that: The spacing between adjacent antenna radiation metal sheets ranges from 1 mm to 6 mm.

7. The multi-frequency microstrip antenna according to claim 3, characterized in that: The shape and size of the antenna radiation metal sheet are determined based on the dielectric constant of the antenna substrate.

8. The multi-frequency microstrip antenna according to claim 7, characterized in that: The shape of the antenna radiation metal sheet is rectangular or circular.

9. The multi-frequency microstrip antenna according to any one of claims 1-2 and 4-8, characterized in that: The phase center of each of the antenna radiating elements is approximately located at the physical center of the metal floor.

10. A method for preparing a multi-frequency microstrip antenna, characterized in that: include: According to preset design parameters, a metal floor, an antenna substrate, and antenna radiation components of at least two different frequency bands are prepared; Embed the antenna substrate and each of the antenna radiation components into the metal floor and make them flush with the metal floor; Among them, the phase centers of the antenna radiation components are the same, and the antenna radiation components of the higher frequency band are arranged in the inner circle of the antenna radiation components of the lower frequency band to form a double-layer U-shaped structure or a multi-layer U-shaped structure.

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