Conformal embedded omnidirectional HF antenna based on inversion design and design method thereof

Abstract

The invention belongs to the technical field of communication antennas, and provides a conformal embedded omnidirectional HF antenna based on inversion design and a design method thereof.The antenna comprises an embedded cavity platform, a radiation structure and a feed and support structure, and the feed and support structure is located between the radiation structure and the bottom face of a cavity; the feeding and supporting structure comprises a metal disc cone, a short-circuit probe and a coaxial feeder line, the metal disc cone is a hollow truncated cone, the axis of the metal disc cone coincides with the axis of the embedded cavity platform, and the bottom of the metal disc cone is connected with the bottom of a cavity of the embedded cavity platform; the upper surface of the short-circuit probe is connected to the lower surface of the radiation structure, and the lower surface of the short-circuit probe is connected with the bottom of the cavity of the embedded cavity platform; the coaxial feeder is connected into the cavity from the center position of the bottom of the cavity of the embedded cavity platform, an outer conductor of the coaxial feeder is connected with the metal disc cone, and an inner conductor of the coaxial feeder is connected to the radiation structure. According to the antenna, the far-field performance index requirement is met, and meanwhile the space is remarkably saved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of communication antennas, and relates to a communication antenna of a stealth aircraft and a design method thereof, in particular to a conformal embedded omnidirectional VHF and UHF antenna based on inversion design and a design method thereof. BACKGROUND

[0002] In modern aviation technology, the design of airborne platform antennas is of great importance, as it directly affects the communication, navigation and overall operational performance of the aircraft. These antennas must meet complex high-performance requirements in extremely limited space, while also adapting to the stable operation of the aircraft in high-speed and variable environments. Embedded conformal antennas become the key to solving this problem due to their unique design advantages. Such antennas can be integrated with the aircraft's shape, not only significantly saving space, but also not affecting the appearance of the aircraft's wings due to their perfect fit with the aircraft's surface, thus maintaining the original aerodynamic characteristics of the aircraft. In addition, a regular hexagonal prism is a typical structure of the aircraft's surface, and designing the antenna embedded cavity as a regular hexagonal prism will restore the real installation environment to the greatest extent, making it easier to achieve close conformity with the aircraft.

[0003] On the other hand, VHF / UHF band electromagnetic waves not only meet the long-distance communication requirements, but also have excellent penetration ability, which makes them play a key role in ensuring the communication stability of the aircraft in complex environments, and thus are widely used in the aviation field. The omnidirectional vertically polarized antenna is the focus of application in this frequency band, and such an antenna can uniformly transmit and receive signals in all directions, and is particularly suitable for applications that require highly reliable communication, such as air traffic control and aviation rescue operations. Such an antenna system can support wide-area network coverage, enabling the aircraft to maintain continuous contact with the command center and other flying units, and maintaining the stability of communication even in extreme conditions.

[0004] Currently, there is no VHF / UHF antenna that can realize the design of an antenna embedded cavity. SUMMARY

[0005] To solve the above problems, the present application provides a conformal embedded omnidirectional HF antenna based on inversion design and a design method thereof, which can adapt well to the installation environment while its radiation pattern can fully meet the far-field performance requirements proposed in the first step. The subsequent optimization work mainly focuses on adjusting the size parameters to achieve impedance matching of the antenna in a specific frequency band.

[0006] The technical solution of the present application is as follows: The application discloses a conformal embedded omnidirectional HF antenna based on inversion design, which comprises an embedded cavity platform, a radiation structure, a feeding and supporting structure, the embedded cavity platform is a structure conforming to the fuselage and having a regular hexagonal cross section, an aperture surface is formed at the upper end of the embedded cavity platform, the upper surface of the radiation structure is in the same horizontal plane as the aperture surface of the embedded cavity platform, and the feeding and supporting structure is located in the space between the radiation structure and the bottom of the cavity; the feeding and supporting structure comprises a metal disc cone, a short-circuit probe and a coaxial feeding line, the metal disc cone is a hollow truncated cone, the axis of the metal disc cone is coincident with the axis of the embedded cavity platform, and the bottom of the metal disc cone is connected with the bottom of the cavity of the embedded cavity platform; the upper surface of the short-circuit probe is connected to the lower surface of the radiation structure, and the lower surface of the short-circuit probe is connected with the bottom of the cavity of the embedded cavity platform; the coaxial feeding line is connected to the inside of the cavity from the central position of the bottom of the cavity of the embedded cavity platform, the outer conductor of the coaxial feeding line is connected with the metal disc cone, and the inner conductor of the coaxial feeding line is connected to the radiation structure.

[0007] Further, the aperture surface of the embedded cavity platform is a regular hexagon, and the radiation structure comprises a metal prismatic disc, the metal prismatic disc is a regular hexagon in plan view.

[0008] Further, the center of each of the six sides of the metal prismatic disc is provided with a curved flow slot with the same width w1 and the same length L4.

[0009] Further, the distance L2 from the center of the metal prismatic disc to each side length is 0.23 to 0.25 times the free space wavelength corresponding to the highest frequency in the working bandwidth.

[0010] Further, the short-circuit probe has six roots, the six short-circuit probes are in a central symmetric structure relative to the center of the radiation structure and are distributed on the six corners of the regular hexagon of the metal prismatic disc.

[0011] Further, the diameter d3 of each short-circuit probe is 0.018 to 0.022 times the length h2 of each short-circuit probe is 0.09 to 0.011 times the horizontal distance between each short-circuit probe and the center of the disc cone is 0.21 to 0.025 times . the free space wavelength corresponding to the highest frequency in the working bandwidth Further, the inscribed circle radius L1 of the embedded cavity platform is 0.27 to 0.29 times the depth h1 of the embedded cavity platform is 0.09 to 0.11 times the side thickness d1 of the embedded cavity platform is 0.1 to 0.12 times the bottom thickness d2 of the embedded cavity platform is 0.48 to 0.52 times​​ To simulate the real fuselage structure; For the highest frequency in the operating bandwidth corresponding to the free space wavelength.

[0012] A design method of a conformal embedded omnidirectional HF antenna based on inversion design, for designing a conformal embedded omnidirectional HF antenna based on inversion design as described above, comprising the following steps: S1, taking gain, beam width, sidelobe level and other far field indicators as optimization targets, performing far field reconstruction; S2, transforming the far field data obtained in S1 to complete aperture field inversion; S3, based on the shape of the antenna installation space, performing surface equivalent magnetic current inversion of the aperture surface; S4, completing the matching of the inherent mode of the embedded cavity; S5, based on the cavity field distribution matched with the far field indicator requirements, constructing an antenna structure capable of supporting the far field distribution in the cavity to complete antenna structure synthesis.

[0013] Further, in S1, the far field pattern is expanded using spherical harmonic functions as basis functions; the expansion coefficients of the spherical harmonic functions at different frequencies are determined using an optimization algorithm, and the least square solution is taken at multiple frequencies to obtain the far field pattern reconstruction; In S2, the inverse Fourier transform of the far field data of S1 can obtain the near field spectrum, and the Fourier transform of the near field spectrum can derive the field distribution at any position, including the aperture near field; In S3, the installation space of the UHF antenna is a cylindrical cavity, and the equivalent magnetic current on the aperture surface is expanded by real value basis functions; the expansion coefficients of the equivalent magnetic current on the aperture surface are solved by combining the boundary conditions of Maxwell's equations, the aperture near field data solved in S2, and the orthogonal characteristics of Bessel functions.

[0014] Further, in S4, the cylindrical cavity set in S3 is abstracted in physical sense as a cylindrical cavity with electric walls on the side surface and the upper and lower surfaces, and there is a certain magnetic current excitation on the top surface, taking the top surface as the starting point of the longitudinal coordinate to obtain the transverse component of the eigenmode electric field of the cylindrical cavity; the total electromagnetic field in the cavity is represented as a linear combination of each eigenmode to obtain the inherent field distribution in the cavity; the mode expansion coefficients are solved by using the boundary conditions constructed by the ideal electric wall and the equivalent magnetic current; In S5, the antenna structure is constructed by the field distribution in the cavity.

[0015] The beneficial effects of the present application are: 1. The antenna of the present application has high conformality with the fuselage, significantly saves space while achieving the requirements of far field performance indicators, and realizes perfect fit with the fuselage.

[0016] 2、The antenna of the present application adopts a typical structure of a regular hexagonal prism as an embedded cavity, and has a small electric size, so that the antenna can be widely applied to various aircrafts.

[0017] 3、The antenna of the present application has good omnidirectional radiation characteristics, and the gain is higher than that of a conventional omnidirectional antenna, further ensuring stable and smooth communication. 4、The antenna configuration obtained by the antenna design method of the present application can fully meet the proposed far-field performance index requirements while realizing good adaptation to the installation environment, and the subsequent optimization work mainly focuses on the adjustment of size parameters to realize impedance matching of the antenna in a specific frequency band, so that the designed antenna can fully meet the index requirements in theory. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is a structure schematic diagram of a conformal embedded omnidirectional VHF / UHF antenna based on the inversion design method of the present application. Figure 2 It is a size parameter of a conformal embedded omnidirectional VHF / UHF antenna based on the inversion design method of the present application. Figure 1 .

[0019] Figure 3 It is a size parameter of a conformal embedded omnidirectional VHF / UHF antenna based on the inversion design method of the present application. Figure 2 ; Figure 4 It is a structure composition diagram of a conformal embedded omnidirectional VHF / UHF antenna based on the inversion design method of the present application. Figure 5 It is a top view of a conformal embedded omnidirectional VHF / UHF antenna based on the inversion design method of the present application. Figure 6 It is a front view of a conformal embedded omnidirectional VHF / UHF antenna based on the inversion design method of the present application. Figure 7 It is a bottom view of a conformal embedded omnidirectional VHF / UHF antenna based on the inversion design method of the present application. Figure 8 It is a standing wave ratio (VSWR) of a conformal embedded omnidirectional VHF / UHF antenna based on the inversion design method of the present application. Figure 9 It is an elevation plane two-dimensional pattern at a center frequency point of a conformal embedded omnidirectional VHF / UHF antenna based on the inversion design method of the present application. Figure 10 It is an azimuth plane two-dimensional pattern at a center frequency point of a conformal embedded omnidirectional VHF / UHF antenna based on the inversion design method of the present application.

[0020] Wherein, 1 is an inner cavity platform, 2 is a radiation structure, 3 is a feeding and supporting structure, 101 is an inner cavity, 201 is a metal disc, 202, 203, 204, 205, 206, 207 are six meandering seams respectively, 301 is a metal disc cone, 302, 303, 304, 305, 306, 307 are six short-circuit probes respectively, and 308 is a coaxial feeding line. DETAILED DESCRIPTION

[0021] This part is an embodiment of the present application, which is used to explain and illustrate the technical solutions of the present application. The embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0022] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship as the orientation or positional relationship given to the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or the case must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" and the like are only for the purpose of description and cannot be understood as indicating or implying relative importance or implying the number of the indicated technical features. Therefore, the features defined with "first", "second" and the like can explicitly or implicitly include more features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0023] In the description of the present application, it should be noted that unless otherwise specified and limited, the terms "mounting", "connecting", "connection" should be interpreted broadly, for example, it can be fixed connection, or detachable connection or integrated connection; it can be mechanical connection, or point connection; it can be direct connection, or indirect connection through intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood through specific circumstances.

[0024] Embodiment 1: A conformal embedded omnidirectional HF antenna based on inversion design, comprising an embedded cavity platform 1, a radiation structure 2, and a feeding and supporting structure 3, the embedded cavity platform 1 is a structure conforming to the fuselage and having a cross section of a regular hexagon, the upper end of the embedded cavity platform 1 is open to form an aperture plane, the upper surface of the radiation structure 2 is in the same horizontal plane as the aperture plane of the embedded cavity platform 1, and the feeding and supporting structure 3 is located in the space between the radiation structure 2 and the bottom of the cavity; the feeding and supporting structure 3 comprises a metal disc cone 301, a short-circuit probe, and a coaxial feeding line 308, the metal disc cone 301 is a hollow truncated cone, the axis of the metal disc cone 301 coincides with the axis of the embedded cavity platform 1, and the bottom of the metal disc cone 301 is connected to the bottom of the cavity of the embedded cavity platform 1; the upper surface of the short-circuit probe is connected to the lower surface of the radiation structure 301, and the lower surface of the short-circuit probe is connected to the bottom of the cavity of the embedded cavity platform 1; the coaxial feeding line 308 is connected to the inside of the cavity from the center of the bottom of the cavity of the embedded cavity platform 1, the outer conductor of the coaxial feeding line 308 is connected to the metal disc cone 301, and the inner conductor of the coaxial feeding line 308 is connected to the radiation structure 2.

[0025] The aperture plane of the embedded cavity platform 1 is a regular hexagon, and the radiation structure 2 comprises a metal prismatic disc 201, which is a regular hexagon when viewed from above.

[0026] The center of each side of the metal prismatic disc 201 is provided with a curved slot with the same width w1 and the same length L4.

[0027] The distance L2 from the center of the metal prismatic disc 201 to each side is 0.23 to 0.25 times the thickness d3 of the metal prismatic disc 201 is 0.018 to 0.022 times . the free space wavelength corresponding to the highest frequency in the working bandwidth.

[0028] The short-circuit probe has six probes, which are arranged in a central symmetric structure with respect to the center of the radiation structure 2 and are distributed on the six corners of the regular hexagon of the metal prismatic disc 201.

[0029] The diameter d3 of each short-circuit probe is 0.018 to 0.022 times the length h2 of each short-circuit probe is 0.09 to 0.011 times the horizontal distance between each short-circuit probe and the center of the disc cone is 0.21 to 0.025 times . the free space wavelength corresponding to the highest frequency in the working bandwidth the inscribed circle radius L1 of the embedded cavity platform 1 is 0.27 to 0.29 times the depth h1 of the embedded cavity platform 1 is 0.09 to 0.11 times the side thickness d1 of the embedded cavity platform 1 is 0.1 to 0.12 times The bottom surface thickness d2 of the inner-embedded cavity platform 1 is 0.48 to 0.52 times To simulate the real fuselage structure; The free space wavelength corresponding to the highest frequency in the working bandwidth.

[0030] A design method of a conformal inner-embedded omnidirectional HF antenna based on inversion design, for designing a conformal inner-embedded omnidirectional HF antenna based on inversion design as described above, comprising the following steps: S1, taking gain, beam width, sidelobe level and other far field indicators as optimization targets, performing far field reconstruction; S2, transforming the far field data obtained in S1 to complete aperture field inversion; S3, based on the shape of the antenna installation space, performing surface equivalent magnetic current inversion of the aperture surface; S4, completing inner-embedded cavity inherent mode matching; S5, based on the cavity field distribution matched with the far field indicator requirements, constructing an antenna structure capable of supporting the far field distribution in the cavity to complete antenna structure synthesis.

[0031] In S1, the far field pattern is expanded with spherical harmonic functions as basis functions; the expansion coefficients of the spherical harmonic functions at different frequencies are determined by using an optimization algorithm, and the least square solution is taken at multiple frequencies to obtain the far field pattern reconstruction; In S2, the inverse Fourier transform of the far field data of S1 can obtain the near field spectrum, and the Fourier transform of the near field spectrum can derive the field distribution at any position, including the aperture near field; In S3, the installation space of the UHF antenna is a cylindrical cavity, and the equivalent magnetic current on the aperture surface is expanded by real-valued basis functions; then, the expansion coefficients of the equivalent magnetic current on the exit aperture surface are solved by using the boundary conditions of Maxwell's equations, the aperture near field data solved in S2, and the orthogonal characteristics of Bessel functions.

[0032] In S4, the cylindrical cavity set in S3 is abstracted in physical sense as a cylindrical cavity with electric walls on the side surface and the upper and lower surfaces, and there is a certain magnetic current excitation on the top surface, taking the top surface as the starting point of the longitudinal coordinate to obtain the transverse component of the eigenmode electric field of the cylindrical cavity; then, the total electromagnetic field in the cavity is represented as a linear combination of each eigenmode to obtain the inherent field distribution in the cavity; the mode expansion coefficients are solved by using the boundary conditions constructed by the ideal electric wall and the equivalent magnetic current; In S5, the antenna structure is constructed by the field distribution in the cavity.

[0033] Embodiment 2: The body conformal embedded antenna is installed in a section of a regular hexagon embedded cavity, and sequentially includes a radiation structure, a feed and support structure from top to bottom. The antenna is installed in an embedded way, and an installation environment is a full metal embedded cavity to imitate an aircraft body. The conformal embedded omnidirectional VHF / UHF antenna based on an inversion design method has high gain and good omnidirectional radiation characteristics.

[0034] The body conformal embedded antenna is installed in a section of a regular hexagon embedded cavity, and sequentially includes a radiation structure, a feed and support structure from top to bottom. The antenna is installed in an embedded way, and an installation environment is a full metal embedded cavity to imitate an aircraft body. The conformal embedded omnidirectional VHF / UHF antenna based on an inversion design method has high gain and good omnidirectional radiation characteristics.

[0035] As a preferred solution, the embedded cavity section is a regular hexagon, the inscribed circle radius is L1=0.28 ( The embedded cavity depth is h=0.1 .

[0036] As a preferred solution, the embedded cavity side wall thickness is d1=0.11 , and the bottom thickness is d2=5mm.

[0037] As a preferred solution, the antenna radiation structure is a regular hexagonal disc, the section inscribed circle radius is L2=0.24 , and the thickness is d4=3mm.

[0038] As a preferred solution, the upper surface of the metal disc cone has a diameter d6 = 0.01 , the lower surface has a diameter d5 = 0.43 , and the height is h3 = 0.09 .

[0039] As a preferred solution, each short-circuit probe has a diameter d3 = 0.02 , and a length h2 = 0.1 .

[0040] As a preferred solution, the horizontal distance between each short-circuit probe and the center of the disc cone is L4 = 0.23 .

[0041] As a preferred solution, the outer conductor of the coaxial line has a diameter d7 = 6.9 mm, and the inner conductor has a diameter d8 = 3 mm.

[0042] Invention principle: The design of the present antenna innovatively adopts an antenna inversion design method, taking the far-field performance index requirement as the starting point, and gradually progressing to the antenna structure. The specific design process is as follows.

[0043] First step: far-field reconstruction Taking gain, beam width, and sidelobe level as optimization targets, the present design aims to design a very high frequency omnidirectional antenna that meets the requirements of airborne. Therefore, the far-field performance index adopted is: beam width: 60°-90° in elevation, 0°-360° in azimuth; gain: >1 dB; installation environment: regular hexagonal metal embedded cavity; working frequency band: VHF / UHF.

[0044] Taking spherical harmonic function as the base function, the far-field pattern is expanded as follows: (1) where the spherical harmonic function (2) is a normalized associated Legendre function. The index .

[0045] The expansion coefficients of the spherical harmonic function at different frequency points are determined by using an optimization algorithm , and the least square solution is taken at multiple frequency points, so as to obtain the far-field directional diagram reconstruction.

[0046] Second step: aperture field inversion The inverse Fourier transform of the far-field data obtained in the first step can obtain the near-field spectrum .

[0047] ​ (3) Fourier transforming the near-field spectrum of (3) gives the field distribution at any position, including the aperture near-field (4) It is worth noting that the above integral involves an oscillatory kernel and the integration region is infinite, which brings challenges to numerical computation. Stationary phase method can be used to accelerate the evaluation of its result, which replaces the highly oscillatory integral kernel with a Taylor series expansion around several stationary points of the phase term.

[0048] Third step: aperture equivalent magnetic current inversion Suppose the installation space of the UHF antenna is a cylindrical cavity, so the equivalent magnetic current on the aperture can be expanded by real-valued basis functions as: (5) where is the first-order Bessel function, and is the mth zero point of it.

[0049] Using the boundary conditions of Maxwell equations and the aperture near-field data solved in the second step, we can get equation (6) (6) Combined with the orthogonal property of Bessel functions: (7) we can solve the expansion coefficients of the equivalent magnetic current on the aperture.

[0050] Fourth step: intrinsic mode matching of the embedded cavity In the third step, the embedded cavity of the antenna installation is regarded as a metal cylindrical cavity, which can be abstracted as a cylindrical cavity with both sides and upper and lower surfaces as electric walls, and has a certain magnetic current excitation on the top surface. If the top surface is taken as the starting point of the longitudinal coordinate, the transverse component of the eigenmode electric field of the cylindrical cavity (the transverse component of TE / TM is isomorphic) is: (8) where , is the nth root of the mth Bessel function .

[0051] The total electromagnetic field in the cavity caused by radiation can be represented as a linear combination of each eigenmode : (9) ​​From the above formula, it can be seen that the intrinsic field distribution in the cavity is solved, that is, the mode coefficient of each eigenmode is solved .

[0052] The boundary conditions constructed by ideal electric walls and equivalent magnetic currents are as follows: (10) (11) The mode expansion coefficient can be obtained as follows: (12) Fifth step: antenna structure synthesis In the first four steps, the field distribution in the cavity that matches the far-field index requirements has been obtained. Next, if an antenna structure that can support the above field distribution is constructed in the cavity, it means that the far-field pattern generated by the antenna structure also meets the far-field index requirements, and the final design goal is achieved. Antenna structure synthesis should follow the following two principles: Principle one: mode field distribution shape preserving principle.

[0053] The conductor is as far as possible to be set at a position perpendicular to the electric field, and is often set at a position where the electric field is strong; The slot structure is as far as possible to be set at a position where the magnetic field is strong, and is often set at a position where the magnetic field is strong; The conductor is set at a position where the electric field vector direction changes significantly.

[0054] Principle two: signal transmission advantage principle.

[0055] High excitation efficiency. Electric excitation: linear structure probe type excitation is set at a position parallel to the electric field where the electric field is the strongest; magnetic excitation: electric small ring type excitation is set at a position parallel to the magnetic field where the magnetic field is the strongest.

[0056] Low transmission loss and reflection loss. In the antenna matching design, the antenna radio frequency matching scheme is preferred, and then the network matching scheme is considered.

[0057] The antenna configuration obtained based on the above design method can fully meet the far-field performance index requirements proposed in the first step while realizing good adaptation to the installation environment. The subsequent optimization work mainly focuses on the adjustment of the size parameters to realize impedance matching of the antenna in a specific frequency band.

[0058] Example 3: The embodiment provides a conformal embedded omnidirectional VHF / UHF antenna based on an inversion design method, which comprises an embedded cavity platform, a radiation structure, a feed and a support structure. The antenna adopts an antenna inversion design method, combines antenna installation environment requirements, and gradually recursively reaches the antenna structure from the far field performance index requirements. After subsequent optimization, the obtained antenna is well adapted to the installation environment, and the directivity diagram can fully meet the far field performance index requirements, has high gain, and has excellent omnidirectional radiation characteristics.

[0059] The embedded antenna is surrounded by the embedded cavity platform 1 around the fuselage, the upper surface of the radiation structure 2 is in the same horizontal plane as the aperture surface of the embedded cavity 1, and the feed and support structure 3 is located in the space between the radiation structure 2 and the bottom surface of the cavity. The base of the embedded cavity 1 is a regular hexagon, the top plane is removed, the side and bottom surfaces are retained, and a cavity structure with an open upper end is formed. The radiation structure 2 is composed of a metal regular hexagonal disc 201, the upper surface of which is a regular hexagon and is coplanar with the aperture surface of the embedded cavity 1. In order to further reduce the working frequency of the antenna, six curved flow seams 202, 203, 204, 205, 206 are arranged at the center of each side of the hexagon to realize miniaturization design. The feed and support structure 3 comprises a metal disc cone 301, six metal short-circuit probes 302, 303, 304, 305, 306, 307 and a coaxial feed line 308. The metal disc cone 301 is a hollow truncated cone, the disc cone axis is coincident with the embedded cavity axis, and the bottom is connected with the embedded cavity bottom. The upper surfaces of the short-circuit probes 302, 303, 304, 305, 306, 307 are connected to the lower surface of the radiation structure 301, and the lower surfaces are connected with the embedded cavity bottom. The six probes are centrally symmetric with respect to the center of the radiation structure, and are distributed on the six corners of the regular hexagon. The coaxial feed line 308 is connected to the inside of the cavity from the center of the cavity bottom, the outer conductor is connected with the metal disc cone, and the inner conductor is connected to the regular hexagonal disc.

[0060] In the embodiment, the cross section of the embedded cavity is a regular hexagon, the inscribed circle radius is L1=0.28 , the embedded cavity depth is h=0.1 .

[0061] In the embodiment, the embedded cavity side wall thickness is d1=0.11 , and the bottom thickness is d2=5mm.

[0062] In the embodiment, the antenna radiation structure is a regular hexagonal disc, the cross section inscribed circle radius is L2=0.24 , and the thickness is d4=3mm.

[0063] In the embodiment, the upper surface diameter of the metal disc cone is d6=0.01​ the lower surface diameter is d5=0.43 the height is h3=0.09 .

[0064] In an embodiment, each shorting probe has a diameter d3=0.02 a length h2=0.1 .

[0065] In an embodiment, each shorting probe has a horizontal distance from the center of the disc cone L4=0.23 .

[0066] In an embodiment, the coaxial outer conductor has a diameter d7=6.9 mm and the inner conductor has a diameter d8=3 mm.

[0067] Figure 8 The VSWR (Voltage Standing Wave Ratio) of the conformal embedded omnidirectional VHF / UHF antenna based on the inversion design method is less than 3 in the whole frequency band, and the relative bandwidth is 49%. The VSWR of the antenna is less than 3 in the whole frequency band, and the energy utilization rate is high.

[0068] Figure 9 The elevation plane pattern at the center frequency is provided, and the maximum gain of the antenna is 4.2 dB, but the beam width is upturned, which is caused by the secondary reflection of the finite metal floor. In actual application, the size of the fuselage is much larger than the size of the antenna, so the size of the floor can be regarded as infinite. Therefore, the beam upturning problem will not occur in actual application.

[0069] Figure 10 The azimuth plane pattern at the center frequency is provided. As can be seen from the figure, the minimum gain of the antenna is greater than -2 dB, and the non-circularity is less than 0.5 dB, and the overall has excellent omnidirectional radiation characteristics.

[0070] The above is only a specific embodiment of the present application, which is described in detail, and the part not described in detail is a conventional technology. However, the protection scope of the present application is not limited to this, any changes or replacements that can be easily thought of by those skilled in the art within the technical range disclosed by the present application should be covered in the protection scope of the present application. The protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A conformal embedded omnidirectional HF antenna based on inversion design, characterized in that, It includes an internal cavity platform (1), a radiation structure (2), and a power supply and support structure (3). The internal cavity platform (1) is a structure conformal to the fuselage with a regular hexagonal cross section. The upper opening of the internal cavity platform (1) forms a diameter surface. The upper surface of the radiation structure (2) is in the same horizontal plane as the diameter surface of the internal cavity platform (1). The power supply and support structure (3) is located in the space between the radiation structure (2) and the bottom surface of the cavity. The power supply and support structure (3) includes a metal disc cone (301), a short-circuit probe, and a coaxial power supply line (308). The metal disc cone (301) is a hollow truncated cone. The axis of the metal disc cone (301) coincides with the axis of the embedded cavity platform (1). The bottom of the metal disc cone (301) is connected to the bottom of the cavity of the embedded cavity platform (1). The upper surface of the short-circuit probe is connected to the lower surface of the radiation structure (301). The lower surface of the short-circuit probe is connected to the bottom of the cavity of the embedded cavity platform (1). The coaxial power supply line (308) is connected to the cavity from the center of the bottom of the cavity of the embedded cavity platform (1). The outer conductor of the coaxial power supply line (308) is connected to the metal disc cone (301). The inner conductor of the coaxial power supply line (308) is connected to the radiation structure (2).

2. The conformal embedded omnidirectional HF antenna based on inversion design according to claim 1, characterized in that, The aperture of the embedded cavity platform (1) is a regular hexagon, and the radial structure (2) includes a metal prism (201), which is a regular hexagon when viewed from above.

3. A conformal embedded omnidirectional HF antenna based on inversion design according to claim 2, characterized in that, The center of each of the six sides of the metal prism (201) has a curved slit of the same width and length.

4. A conformal embedded omnidirectional HF antenna based on inversion design according to claim 2, characterized in that, The distance L2 from the center of the hexagon of the metal prism (201) to each side length is 0.23 to 0.25 times. The thickness d3 of the metal prism (201) is 0.018 to 0.022 times. , It is the free-space wavelength corresponding to the highest frequency within the operating bandwidth.

5. A conformal embedded omnidirectional HF antenna based on inversion design according to claim 2, characterized in that, There are six short-circuit probes. The six short-circuit probes are centrally symmetrical about the center of the radiation structure (2) and are distributed on the six corners of the regular hexagon of the metal regular hexagonal disk (201).

6. A conformal embedded omnidirectional HF antenna based on inversion design according to claim 5, characterized in that, The diameter d3 of each short-circuit probe is 0.018 to 0.022 times. The length h2 of each short-circuit probe is 0.09 to 0.011 times. The horizontal distance between each short-circuit probe and the center of the cone is 0.21 to 0.025 times. , It is the free-space wavelength corresponding to the highest frequency within the operating bandwidth.

7. A conformal embedded omnidirectional HF antenna based on inversion design according to claim 2, characterized in that, The radius L1 of the inscribed circle of the embedded cavity platform (1) is 0.27 to 0.29 times. Depth h1 is 0.09 to 0.11 times. The side thickness d1 of the embedded cavity platform (1) is 0.1 to 0.12 times. The bottom thickness d2 of the embedded cavity platform (1) is 0.48 to 0.52 times. To simulate the actual fuselage structure; It is the free-space wavelength corresponding to the highest frequency within the operating bandwidth.

8. A design method for a conformal embedded omnidirectional HF antenna based on inversion design, used to design a conformal embedded omnidirectional HF antenna based on inversion design as described in any one of claims 1-7, characterized in that, Includes the following steps: S1 uses far-field parameters such as gain, beamwidth, and sidelobe level as optimization targets for far-field reconstruction. S2 transforms the far-field data obtained from S1 to complete the aperture field inversion. S3, based on the shape of the antenna installation space, perform surface equivalent magnetofluid inversion of the aperture surface; S4, complete the inherent pattern matching of the embedded cavity; S5, based on the intracavity field distribution that matches the far-field performance requirements, constructs an antenna structure within the cavity that can support the far-field distribution, thus completing the antenna structure synthesis.

9. The design method of a conformal embedded omnidirectional HF antenna based on inversion design according to claim 8, characterized in that, In S1, the far-field pattern is expanded using the spherical harmonic function as the basis function; the expansion coefficients of the spherical harmonic function at different frequencies are determined by an optimization algorithm, and the least squares solution is taken at multiple frequencies to obtain the far-field pattern reconstruction. In S2, the inverse Fourier transform of the far-field data of S1 can be used to obtain the near-field spectrum. Then, the Fourier transform of the near-field spectrum can be used to derive the field distribution at any location, including the near-field of the aperture. In S3, the installation space of the UHF antenna is assumed to be a cylindrical cavity. The equivalent magnetic flux on the aperture surface is expanded using real-valued basis functions. Then, using the boundary conditions of Maxwell's equations and the near-field data obtained from S2, combined with the orthogonality of the Bessel function, the expansion coefficients of the equivalent magnetic flux on the aperture surface are solved.

10. The design method of a conformal embedded omnidirectional HF antenna based on inversion design according to claim 9, characterized in that, In S4, the cylindrical cavity set in S3 is physically abstracted as a cylindrical cavity with electric walls on the sides and top and bottom surfaces, and a definite magnetocurrent excitation on the top surface. Taking the top surface as the starting point of the vertical axis, the transverse component of the eigenmode electric field of the cylindrical cavity is obtained. Then, the total electromagnetic field in the cavity is expressed as a linear combination of each eigenmode to obtain the inherent field distribution in the cavity. The mode expansion coefficients are obtained by using the boundary conditions constructed with ideal electric walls and equivalent magnetic currents. In S5, the antenna structure is constructed by the field distribution within the cavity.

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