Broadband vertical polarization directional antenna and airborne top-crossing blind compensation method

Abstract

The invention discloses a broadband vertical polarization directional antenna and an airborne overhead blind compensation method, and belongs to the field of communication antennas. The antenna comprises a spherical conformal metal floor which is conformally matched with the surface of an installation carrier; the single magnetic dipole units are arranged on the surface of the spherical metal floor and are arranged in an annular array; the single magnetic dipole unit comprises a metal reflection table top, a feed probe and a bent metal radiation arm; the metal reflection table top is embedded in the surface of the spherical metal floor; the bent metal radiation arm comprises a vertical feed section, a horizontal radiation section and a grounding section; the grounding section is connected with the metal reflection table top, the vertical feed section is parallel to the grounding section, and the horizontal radiation section is connected between the vertical feed section and the grounding section; and one end of the feed probe passes through the metal table top and is connected with the vertical feed section, and the other end of the feed probe is connected with the feed network.

Description

Technical Field

[0001] The present invention relates to the field of communication antennas, and in particular to a broadband vertically polarized directional antenna and an airborne overhead blind spot filling method. Background Art

[0002] With the rapid growth of aviation communications demand in recent years, airborne communication systems have faced significant technical challenges. Current aircraft antenna systems generally employ polarization isolation: the dorsal antenna is horizontally polarized, while the ventral antenna is vertically polarized to prevent polarization crosstalk with the dorsal antenna. However, this traditional solution has an inherent flaw: vertically polarized antennas create a natural radiation null at 0° on the Z axis (directly below the aircraft), creating a communication blind spot.

[0003] This technical bottleneck makes the vertical communication link with the belly antenna extremely susceptible to interruption during flight, such as during climbs and circling, and especially during takeoff and landing at low altitudes. Existing solutions primarily employ two approaches: increasing the number of auxiliary antennas, which significantly increases system weight and complexity; and increasing transmit power, which not only wastes energy but also potentially introduces electromagnetic compatibility issues. More seriously, none of these solutions fundamentally address the problem of vertically polarized antennas experiencing radiation nulls in the overhead region. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the present invention proposes a broadband vertically polarized directional antenna and an airborne over-the-top blind spot filling method.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A first aspect of the present invention relates to an antenna, comprising:

[0007] Spherical conformal metal floor, conformally matched to the surface of the mounting carrier;

[0008] and a plurality of single magnetic dipole units arranged in a ring array on the surface of the spherical metal floor;

[0009] The single magnetic dipole unit includes a metal reflection table, a feeding probe and a bent metal radiation arm;

[0010] The metal reflective table is embedded in the surface of the spherical metal floor;

[0011] The bent metal radiation arm includes a vertical feeding section, a horizontal radiation section and a grounding section;

[0012] The grounding section is connected to the metal reflective table, the vertical feeding section is parallel to the grounding section, and the horizontal radiating section is connected between the vertical feeding section and the grounding section;

[0013] One end of the feeding probe passes through the metal table and is connected to the vertical feeding section, and the other end is connected to the feeding network.

[0014] Optionally, the angle between the metal reflective table and the horizontal plane is 54 degrees.

[0015] Optionally, an opening or a groove is provided in the middle of the metal reflective table for accommodating the feeding probe.

[0016] Optionally, the bent metal radiation arm, the spherical conformal metal floor and the metal reflection table are all made of copper.

[0017] The coupled feed probe is a copper structure with overall dimensions of 8mm in length, 1.37mm in width, and 0.8mm in thickness. It maintains a spacing of 0.32mm with the vertical feed section of the bent metal radiation arm. By optimizing the geometric shape of the design, efficient electromagnetic coupling is achieved while ensuring impedance matching characteristics.

[0018] Optionally, the metal reflective table is parallel to the horizontal radiation section.

[0019] Optionally, the annularly arranged single magnetic dipole units include two groups of single magnetic dipole units arranged in circular arrays, wherein the number of single magnetic dipole units in the inner circle is 4, and the number of single magnetic dipole units in the outer circle is 8; the angle between the midpoint of the horizontal radiation segment of the inner circle and the center of the spherical conformal metal floor and the Z axis is 14 degrees; the angle between the midpoint of the horizontal radiation segment of the outer circle and the center of the spherical conformal metal floor and the Z axis is 28 degrees.

[0020] Optionally, the spacing between the single magnetic dipole units is half the wavelength corresponding to the operating frequency.

[0021] Optionally, there is a height difference between the horizontal radiation sections of the single magnetic dipole units in the inner ring and the outer ring.

[0022] A second aspect of the present invention relates to a broadband vertically polarized antenna blind spot control method, comprising the following steps:

[0023] By calculating the path difference between the inner and outer single magnetic dipole units of the antenna in the Z-axis direction, the required phase compensation value is determined accordingly. By adjusting the feeding network to apply a corresponding phase offset to each unit, the electromagnetic waves radiated by the two circles of units are superimposed in phase in space, thereby precisely concentrating the maximum vertical polarization gain in the +Z-axis direction.

[0024] Optionally, the phase difference caused by the path difference is The specific calculation formula is as follows:

[0025]

[0026] Where c is the speed of light, f is the frequency, and d is the path difference.

[0027] A third aspect of the present invention relates to an airborne communication system, comprising the above-mentioned antenna.

[0028] Beneficial effects of the present invention:

[0029] 1. The present invention effectively solves the radiation null problem of traditional vertically polarized antennas in the 0° direction of the Z axis in the C band (5.4-6.4GHz) through the innovative three-section bent metal radiation arm design of the single magnetic dipole antenna and the 54° inclined metal reflective table structure. The design achieves a high-gain vertically polarized beam coverage of 13.64dB in the overhead area, while maintaining excellent impedance matching characteristics (S11 <-10dB) throughout the entire operating frequency band (5.4GHz ~ 6.4GHz). In particular, the performance stability under broadband working conditions is ensured by optimizing the designed 54° reflective table tilt angle. This innovative structural design not only significantly improves the reliability of the airborne communication system, but also enhances the system's adaptability to different communication protocols through broadband characteristics, providing a reliable technical solution for the new generation of aviation communication systems.

[0030] 2. The conformal antenna array of the present invention adopts a spherical integrated design, which perfectly matches the aircraft fuselage through a precise 110mm radius hemispherical metal floor. Combined with a double-layer array arrangement (4 elements in the first circle and 8 elements in the second circle) and half-wavelength spacing control, it achieves excellent radiation performance while maintaining a compact structure.

[0031] 3. The unique phase compensation method of the present invention realizes the in-phase superposition of spatial radiation current by feeding the opposing units 180° apart and accurately calculates the path difference between the two circles of units and applies precise phase compensation, so that the main beam is accurately pointed in the +Z axis 0° direction, perfectly adapting to various flight attitudes of the aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention will be further described below with reference to the accompanying drawings.

[0033] Figure 1 (a) is a schematic diagram of the overall structure of a C-band airborne broadband vertically polarized blind spot-filling conformal antenna array in an embodiment of the present invention; (b) is a front view; (c) is an attached view;

[0034] Figure 2 A top view of the three-section bent metal radiation arm structure of the single magnetic dipole antenna unit of the present invention;

[0035] Figure 3 This is a side view of the first circle of single magnetic dipole antenna units and the metal reflective table of the present invention;

[0036] Figure 4 This is a side view of the second circle single magnetic dipole antenna unit and the metal reflective table of the present invention;

[0037] Figure 5 This is a schematic diagram of the positions of the first and second circles of the single magnetic dipole unit of the present invention;

[0038] Figure 6 This is a schematic diagram of the vertical polarization gain results of the horizontally placed antenna unit of the present invention.

[0039] Figure 7 Schematic diagram of the S-parameter test results of the antenna array of the present invention;

[0040] Figure 8 Schematic diagram of the antenna array isolation test results of the present invention;

[0041] Figure 9 Schematic diagram of the vertical polarization gain results of the antenna array of the present invention;

[0042] Figure 10 The maximum vertical polarization gain of the metal reflective table of the antenna array of the present invention is obtained at different tilt angles.

[0043] In the figure, 1: spherical conformal metal floor; 2: single magnetic dipole unit; 3: metal reflection table; 4: coupled feed probe. DETAILED DESCRIPTION

[0044] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only 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 making any creative efforts shall fall within the scope of protection of the present invention.

[0045] Some embodiments of the present invention disclose a broadband vertically polarized directional antenna and an airborne overhead blind spot compensation method. The antenna comprises a spherical conformal metal floor 1 and single magnetic dipole elements 2 arranged in a circular array on the spherical conformal metal floor 1. The spherical conformal metal floor 1 is mounted on a carrier, and its shape and curvature conform to the carrier.

[0046] Specifically, the carrier includes but is not limited to vehicles that can move on land, wearable devices or aircraft, etc. The spherical conformal metal floor 1 is made of a high-conductivity metal material, and the surface may be coated with an anti-oxidation coating.

[0047] In some specific embodiments of the present invention, using an aircraft as an example, the spherical conformal metal floor 1 employs a hemispherical structure with a radius of 110 mm, whose radius of curvature precisely matches the aircraft's fuselage skin. This hemispherical structure inherently possesses excellent geometric stability, achieving structural self-support through its complete surface continuity, maintaining shape integrity without the need for additional reinforcement.

[0048] The surface of the spherical conformal metal floor 1 is integrated with a metal reflective surface 3, and the connection between the metal reflective surface 3 and the spherical conformal metal floor 1 adopts a curved surface transition. The spherical conformal metal floor 1 is internally provided with a feed network system, which adopts a multi-layer wiring structure to achieve signal transmission.

[0049] The single magnetic dipole antenna array consists of multiple identical units, each unit includes a three-section bent metal radiation arm (vertical feeding section 7.6mm×34.38mm, horizontal radiation section 5.36mm×34.38mm, grounding section 10mm×34.38mm), a coaxial feeder and a rectangular coupled metal feeding probe 4 (8mm×1.37mm), and the radiation arm is made of high-conductivity metal material copper.

[0050] In some specific embodiments of the present invention, the array adopts a double-layer concentric circle arrangement, with 4 units evenly distributed in the first circle array and 8 units evenly distributed in the second circle array. To meet the half-wavelength arrangement spacing and optimize the radiation performance, the first circle units are spaced 90° apart relative to the Z axis, and the second circle units are spaced 45° apart relative to the Z axis. At the same time, the first circle units are rotated 14° as a whole relative to the spherical conformal metal floor 1, and the second circle units are rotated 28° as a whole. This special arrangement design effectively reduces the coupling between units and achieves the maximum gain synthesis effect.

[0051] The first ring of units forms an angle of ∠a = 14° relative to the center of the spherical conformal metal floor 1, while the second ring of units forms an angle of ∠b = 28° relative to the center of the spherical conformal metal floor 1, forming a specific spatial phase relationship. More specifically, ∠a is the angle between the Z-axis and the line connecting the midpoint of the first ring's horizontal radiating segment and the center of the spherical conformal metal floor 1; ∠b is the angle between the Z-axis and the line connecting the midpoint of the second ring's horizontal radiating segment and the center of the spherical conformal metal floor 1.

[0052] The metal reflective surface 3 is made of the same copper material as the spherical conformal metal floor 1, with overall dimensions of 40 mm in length, 20 mm in width, and 1.5 mm in thickness. The plane of the metal reflective surface 3 is parallel to the second metal radiation arm of the single magnetic dipole unit 2.

[0053] The single magnetic dipole unit 2 is arranged as a whole perpendicular to the metal reflection table 3, and the metal reflection table 3 is inclined at 54°±0.5° relative to the horizontal ground. This angle is verified by full-wave electromagnetic simulation to be the optimal direction angle with the maximum vertical polarization gain.

[0054] After update: The single magnetic dipole unit 2 is arranged as a whole perpendicular to the reflection table, and the metal reflection table 3 is inclined relative to the horizontal ground at ∠c=54°±0.5°. This angle has been verified by full-wave electromagnetic simulation to be the optimal direction angle with the maximum vertical polarization gain.

[0055] A circular opening is provided in the center of the reflection table, which is used to accommodate the coupled feeding probe and is connected through the internal feeding network.

[0056] In some embodiments of the present invention, in order to maximize the benefits of the above-mentioned antenna structure, a feeding phase and phase compensation control method is provided, which specifically includes the following steps:

[0057] For the conformal array arrangement structure, the feeding phase difference between the diagonally positioned units is precisely controlled to be 180°, so that the spatial current flow direction of each unit remains in phase; the phase compensation method uses wave path difference calculation and feeding network adjustment to ensure that the electromagnetic waves are superimposed in phase in space, thereby precisely pointing the main beam radiation direction to the +Z axis 0° direction.

[0058] For the double-layer arrangement structure of the conformal array, the path difference between the four units in the first circle and the eight units in the second circle in the Z-axis direction is accurately calculated, and the required phase compensation value is determined accordingly. The method applies a corresponding phase offset to each unit by adjusting the feeding network, so that the electromagnetic waves radiated by the two circles of units are superimposed in phase in space, thereby precisely concentrating the maximum vertical polarization gain in the +Z-axis direction.

[0059] In particular, the array of single magnetic dipole elements occupies a limited space at the top of the sphere, 25mm in height (corresponding to the crown height). This highly compact design offers multiple technical advantages: From a spatial perspective, the top 25mm is dedicated to addressing the nulling of vertically polarized signals within the Z-axis range of 0°±15°, leaving approximately 85mm of free space for integrating other functional antenna arrays. This vertical spatial partitioning design achieves two core functions: the top blind spot array precisely fills the blind spot of traditional vertically polarized antennas through an innovative three-segment magnetic dipole structure and a 54° tilted metal reflective table. The lower space accommodates forward and side scanning arrays, collaborating with the top system to build a complete airspace coverage network. Importantly, this compact 25mm height arrangement leaves ample room for system expansion, while the lower space of the sphere maintains its conformal surface properties, providing ample design margin for future system expansion. This compact layout design not only ensures the high-performance radiation characteristics of the blind spot array, but also fully considers the scalability of the overall system, enabling the antenna system to perfectly adapt to the aircraft's complex aerodynamic shape and limited space constraints.

[0060] In some embodiments of the present invention, the specific size design of the antenna array is disclosed, such as Figure 2 、 3 As shown in Figures 4 and 5, each single magnetic dipole unit utilizes an innovative three-segment bent metal radiating arm structure design. The vertical feed segment is l8 = 7.6 mm long and l2 = 34.38 mm wide; the horizontal radiating segment is w2 = 5.36 mm long and l2 = 34.38 mm wide; and the ground segment is l7 = 10 mm long and l2 = 34.38 mm wide. The three-segment radiating arm is integrally formed through precision machining, with each segment maintaining consistent width. The unit is equipped with a rectangular coupling feed probe, which measures l4 = 8 mm long and w3 = 1.37 mm wide. It maintains a precise spacing of l3 = 0.32 mm from the vertical feed segment. This spacing parameter has been optimized through electromagnetic field simulation to achieve optimal impedance matching characteristics. This unique three-segment structural design, through electromagnetic coupling between the vertical feed segment and the coupling probe, directional radiation from the horizontal radiating segment, and a current loop in the ground segment, together form a complete radiation system, effectively solving the radiation null problem of traditional vertically polarized antennas in the overhead area.

[0061] The present invention adopts an innovative double-layer concentric circle array arrangement scheme, such as Figure 1(c) As shown in the top view, the first circle array is composed of four evenly distributed single magnetic dipole units, with strict 90° azimuth spacing between each unit; the second circle array consists of eight units, with precise 45° angular spacing between units. This unique arrangement was obtained through mathematical optimization calculations, in which the first circle units are rotated 14° (∠a) relative to the spherical conformal metal floor 1, and the second circle units are rotated 28° (∠b) relative to the spherical conformal metal floor, forming a specific spatial phase relationship. Full-wave electromagnetic simulation verification shows that this arrangement achieves an optimal unit spacing of 26.8mm (approximately 0.5λ) at an operating frequency of 5.6GHz. This key parameter design not only meets the array radiation performance requirements but also ensures structural compactness.

[0062] like Figure 8 As shown, this precise geometric arrangement keeps the isolation between radiating elements on the same layer below -15dB, while the isolation between elements on different layers is below -25dB, significantly improving the array's overall radiation efficiency. Measured data shows that this arrangement achieves a vertical polarization gain of 13.64dB at 0° on the Z axis, while maintaining a 7dB gain beamwidth of 32°, perfectly meeting the technical requirements for overhead coverage of airborne communication systems.

[0063] like Figure 2 As shown, this mesa is made of the same copper material as the spherical conformal metal floor 1, with a length l1 = 40 mm and a width w1 = 20 mm. Due to the special features of the spherical conformal metal floor 1, the length of the metal reflective mesa 3 remains constant at l1 = 40 mm. Specifically, the first circle of metal reflective mesa has a width w4 = 19.70 mm, and the distance from the edge of the mesa to the conformal floor is l9 = 18 mm. The second circle of metal reflective mesa has a width w1 = 20 mm, and the distance from the edge of the mesa to the spherical conformal metal floor 1 is l6 = 12.25 mm.

[0064] The parallelism control of the metal reflective table 3 and the horizontal radiation section of the single magnetic dipole ensures that the two maintain a strict parallel relationship. Figure 6 and Figure 10 As shown in the vertical polarization gain results for a horizontally positioned single magnetic dipole antenna unit, the maximum vertical polarization gain is achieved at 54°. Therefore, the metal reflector 3 is installed at a 54° angle relative to the horizontal ground. This angle has been verified by full-wave electromagnetic simulations as the optimal orientation for maximum vertical polarization gain. The central circular opening accommodates the coupled feed probe.

[0065] The antenna unit feeding phase setting of the present invention adopts the spatial current in-phase superposition and wave path difference compensation mechanism to achieve precise beamforming through precise electromagnetic field calculation. As shown in Table 2, the system implements differentiated phase compensation based on the geometric characteristics of the double-layer array: First, for each circle of opposing units (such as the 0° and 180° units in the first circle), by precisely controlling their feeding phase difference to 180°, the spatial current of the units is superimposed in phase, ensuring that the radiation beam of each unit can be accurately pointed to the 0° direction of the Z axis; secondly, due to the height difference of 110 between the first circle (4 units) and the second circle (8 units), according to the electromagnetic wave propagation theory, the phase difference caused by the wave path difference is The specific calculation formula is as follows:

[0066]

[0067] Where c is the speed of light, f is the frequency, which is 5.6GHz here, and the path difference d=l10=12.2mm. After calculation, the phase difference It is 82°.

[0068] Specifically, l10 is the vertical height difference between the horizontal radiation section of the first circle single magnetic dipole antenna unit and the horizontal radiation section of the second circle single magnetic dipole antenna unit (also the path difference of the vertical radiation of the first and second circle antenna arrays), and is therefore equivalent to d in the above formula, that is, the path difference.

[0069] like Figure 9 The radiation pattern test results shown in the figure demonstrate a vertical polarization gain of 13.64 dB at 0° on the Z axis, and a 7dB gain beamwidth of 32°. These performance indicators fully meet the requirements of airborne communication systems, ensuring the stability of the communication link, especially when the aircraft is flying overhead from a ground monitoring station.

[0070] All dimensions of this embodiment are shown in Table 1.

[0071] Table 1

[0072]

[0073] Table 2

[0074]

[0075]

[0076] Among them, the phase The corresponding position of Figure 1 (c) shown.

[0077] In summary, the antenna structure provided by the embodiments of the present invention successfully overcomes the inherent defects of vertically polarized antennas through spherical conformal design and a precise phase compensation mechanism. In particular, the present invention utilizes a collaborative design of tilted single magnetic dipole units and a metal reflective table. While maintaining vertical polarization characteristics, it effectively fills the radiation null at 0° along the Z axis through precise path difference compensation. This conformal array structure not only solves the communication coverage problem in the blind spots above the aircraft, but also adapts to various complex flight conditions, providing a reliable technical solution for the next generation of aviation communication systems.

[0078] Based on the antenna structure provided in the embodiment of the present invention and without departing from the purpose of the present invention, those skilled in the art are capable of optimizing the design of some of the above-mentioned design parameters according to different scenarios and requirements, without being limited to the size parameters provided in Table 1.

[0079] In addition, although the usage scenarios provided in the embodiments of the present invention take aircraft communications as an example, those skilled in the art should understand that the antenna structure of the present invention can also be applied in other scenarios, such as drones or other aircraft or flying vehicles.

[0080] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0081] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the invention as claimed.

Claims

1. An antenna, characterized in that: include: Spherical conformal metal floor, conformally matched to the surface of the mounting carrier; and a plurality of single magnetic dipole units arranged in a ring array on the surface of the spherical metal floor; The single magnetic dipole unit includes a metal reflection table, a feeding probe and a bent metal radiation arm; The metal reflective table is embedded in the surface of the spherical metal floor; The bent metal radiation arm includes a vertical feeding section, a horizontal radiation section and a grounding section; The grounding section is connected to the metal reflective table, the vertical feeding section is parallel to the grounding section, and the horizontal radiating section is connected between the vertical feeding section and the grounding section; One end of the feeding probe passes through the metal table and is connected to the vertical feeding section, and the other end is connected to the feeding network.

2. The antenna according to claim 1, wherein The angle between the metal reflective table and the horizontal plane is 54 degrees.

3. The antenna according to claim 1, wherein An opening or a groove is provided in the middle of the metal reflection table for accommodating the feeding probe.

4. The antenna according to claim 1, wherein The bent metal radiation arm, the spherical conformal metal floor and the metal reflection table are all made of copper.

5. The antenna according to claim 1, wherein The annularly arranged single magnetic dipole units include two groups of single magnetic dipole units arranged in circular arrays, wherein the number of single magnetic dipole units in the inner circle group is 4, and the number of single magnetic dipole units in the outer circle group is 8; the angle between the midpoint of the horizontal radiation segment of the inner circle and the center of the spherical conformal metal floor and the Z axis is 14 degrees; the angle between the midpoint of the horizontal radiation segment of the outer circle and the center of the spherical conformal metal floor and the Z axis is 28 degrees.

6. The antenna according to claim 5, characterized in that The spacing between the single magnetic dipole units is half the wavelength corresponding to the operating frequency.

7. The antenna according to claim 5, characterized in that There is a height difference between the horizontal radiation sections of the single magnetic dipole units of the inner circle and the outer circle.

8. A broadband vertical polarization antenna blind spot control method, comprising the following steps: By calculating the path difference between the inner and outer single magnetic dipole units of the antenna described in any one of claims 5 to 7 in the Z-axis direction, and determining the required phase compensation value accordingly; by adjusting the feeding network to apply a corresponding phase offset to each unit, the electromagnetic waves radiated by the two circles of units are superimposed in phase in space, thereby accurately concentrating the maximum vertical polarization gain in the +Z-axis direction.

9. The broadband vertical polarization antenna blind spot control method according to claim 8, characterized in that: The phase difference caused by the path difference is The specific calculation formula is as follows: Where c is the speed of light, f is the frequency, and d is the path difference.

10. An airborne communication system comprising the antenna according to any one of claims 1 to 7.

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