Compact three-frequency-band hemispherical wave beam combined antenna

Abstract

The invention discloses a compact three-frequency-band hemispherical beam combined antenna, which comprises a metal base, an azimuth turntable and UHF (Ultra High Frequency), L and S-frequency-band antennas. The UHF antenna is installed on the rotary table at an inclination angle of 35 degrees, and hemisphere coverage is achieved through rotation. The L antenna and the S antenna are installed on the two sides above the UHF antenna through a glass fiber support, and a low-profile microstrip antenna form and a four-arm spiral antenna form are adopted respectively. Through the UHF antenna 45-degree polarization design, the high-frequency antenna feeding point bias and the feeder common ground structure, mutual coupling between frequency bands is effectively inhibited. The overall size of the antenna is about phi 250 mm * H350 mm, the three frequency bands all have good hemispherical wave beams, low standing-wave ratios and optimal circular polarization performance, the antenna is suitable for mobile satellite communication equipment, and the integration level and the multifunctionality are improved.

Description

Technical Field

[0001] This invention relates to the field of satellite communication technology, and in particular to a compact tri-band hemispherical beam combination antenna. Background Technology

[0002] With the rapid development of satellite communication technology, the application scenarios of antennas are constantly expanding. In satellite communication operations, the stability of the communication link is particularly important. For antennas, it is required that they can provide wide-angle coverage, and ideally, they should be able to cover the entire upper half of space to meet the needs of wider and more flexible deployment locations. Antennas with this beamforming characteristic are also called hemispherical beam antennas.

[0003] Electromagnetic waves with frequencies ranging from 300MHz to 3000MHz are generally referred to as Ultra High Frequency (UHF). This frequency band is characterized by low propagation loss and long propagation distance, and therefore it has been widely used in terrestrial and satellite communications since its inception. With the launch of my country's Tiantong-1 satellite, a large number of S-band satellite communication devices have emerged, and dual-mode combined satellite communication antennas integrating UHF and S-band frequencies have also been developed. Currently, my country's low-Earth orbit satellite internet constellation is also under continuous development and deployment, and L-band satellite communication will soon be put into application.

[0004] Against this backdrop, the trend towards multi-functional integration in various satellite communication devices is evident. Antennas that could only operate in one frequency band are no longer sufficient to meet the needs of these devices, creating a pressing demand for antennas capable of operating in multiple modes. Currently, the main approaches to address this need include ultra-wideband notch antennas, fractal antennas, reconfigurable antennas, and multimode combined antennas. The concept of reconfigurable antennas, being relatively recent, remains largely in the research stage and has limited practical application. Fractal and ultra-wideband antennas are generally suitable for higher frequency bands and are primarily in microstrip form. Combined antennas have fewer limitations in terms of operating frequency and antenna form, resulting in a wider range of applications. A combined antenna essentially involves physically combining multiple antenna types, fed through one or more ports. For multi-port fed combined antennas, the challenges lie in isolation and the mutual influence of radiation patterns. For single-port fed combined antennas, the key challenge is impedance matching. Summary of the Invention

[0005] This invention proposes a compact multi-port combined antenna that can operate simultaneously in the UHF, S, and L frequency bands. Through antenna type selection, layout design, and special structural design, the antennas in each frequency band can radiate efficiently and meet the hemispherical beam coverage requirements.

[0006] To achieve the above objectives, the solution adopted by the present invention is as follows: A compact tri-band hemispherical beam combination antenna includes a metal base, a turntable, a UHF band antenna, an L-band antenna, and an S-band antenna; The turntable is mounted on a metal base, and the UHF band antenna is mounted on the upper surface of the turntable by a diagonal support. The angle between the UHF band antenna and the upper surface of the turntable is 35°. On the metal base, two opposing fiberglass antenna supports are provided on both sides of the turntable. The height of the two fiberglass antenna supports is higher than that of the UHF band antenna, and the two supports overlap the crossbeam. The L-band antenna and the S-band antenna are respectively installed at both ends of the crossbeam, and the feed lines of both the L-band antenna and the S-band antenna extend downward along the fiberglass antenna support.

[0007] Furthermore, the UHF band antenna includes an upper radiator (1-1), a lower radiator (1-2), and a nylon support (1-3); both the upper radiator (1-1) and the lower radiator are covered on the outer surface of the nylon support (1-3); The nylon support (1-3) is a hollow hemispherical structure. The upper radiator (1-1) covers the top of the hollow hemispherical structure and is composed of four upper radiating patches. The four upper radiating patches are arranged in a circumferential array, and the upper radiating patches facing each other are connected by corresponding solder pads. The lower radiator (1-2) consists of four lower radiating patches, which correspond one-to-one with the four upper radiating patches. The lower radiating patches are located below the corresponding upper radiating patches. The bottom edge of the lower radiating patch is attached to the bottom edge of the hollow hemispherical structure, and there is a gap between the top edge of the lower radiating patch and the bottom edge of the upper radiating patch. The bottom of the nylon support (1-3) is provided with a grounding plate (1-7), and the lower radiator is short-circuited to the grounding plate (1-7) through a short-circuit pin (1-4); Each solder pad is connected to the corresponding RF connector (1-10) via the corresponding feed cable (1-8); the RF connector (1-10) is connected to the circular polarizer (1-11) via the impedance matching device (1-12).

[0008] Furthermore, the upper radiating patch is a triangular aluminum plate, the lower radiating patch is a trapezoidal aluminum plate, there is a gap between each adjacent radiating patch, and each lower radiating patch is connected to the ground plate (1-7) by two short-circuit pins (1-4).

[0009] Furthermore, the L-band antenna is a low-profile microstrip antenna, and the S-band antenna is a four-arm helical antenna that combines wide beamwidth and low height.

[0010] Furthermore, the L-band antenna and S-band antenna are supported above the UHF band antenna using a fiberglass support; the fiberglass support 7 has a shape that is wider at the top, wider at the bottom, and narrower in the middle.

[0011] Furthermore, the RF connectors of L-band antenna 2 and S-band antenna 4 are oriented downwards, and their RF connectors are offset from their own physical centers, far away from each other, and far away from the center feed point of UHF band antenna 1, in order to reduce the impact on the VSWR of UHF band antenna 1.

[0012] Furthermore, the L-band antenna feed line 3 and the S-band antenna feed line 5 extend downward along the inner wall of the fiberglass support 7, and at the position where they reach the metal base 8, the outer shielding layer and the metal base 8 are short-circuited to achieve a stable common ground effect.

[0013] Furthermore, the L-band antenna includes a radiating layer, a feeding layer, and an L-band RF socket arranged sequentially from top to bottom.

[0014] Furthermore, the S-band antenna includes a feed network (18), a spiral pattern printed circuit board (19), a polytetrafluoroethylene (PTFE) support (20), and an RF socket (21); the PTFE support (20) is located on the upper surface of the feed network (18) to form a closed space, the spiral pattern printed circuit board (19) is located in the closed space, and the RF socket is installed at the bottom of the feed network.

[0015] The beneficial effects of the above-described solution in this invention are as follows: This invention designs a compact three-band hemispherical beamforming antenna. Through optimal antenna configuration selection, polarization isolation, antenna placement, and special structural design, it cleverly combines three frequency bands into a compact unit, ensuring good performance in each band, including radiation efficiency, coverage, and circular polarization ratio, thereby guaranteeing stable communication links. The overall dimensions of the antenna are only 250mm in diameter and 350mm in height, making it suitable for use in terrestrial or mobile satellite communication equipment, improving the integration and multi-functional application capabilities of the equipment. Attached Figure Description

[0016] Figure 1 This is a side view structural diagram of an embodiment of the present invention; Figure 2 This is a top view of the structure according to an embodiment of the present invention; Figure 3 This is a side view of the glass fiber support 7 according to an embodiment of the present invention; Figure 4 This is a top view of the glass fiber support 7 according to an embodiment of the present invention; Figure 5 This is a side view of the L-band antenna 2 according to an embodiment of the present invention; Figure 6 This is a top view of the L-band antenna 2 according to an embodiment of the present invention; Figure 7This is a side view of the S-band antenna 4 according to an embodiment of the present invention; Figure 8 This is a top view of the S-band antenna 4 according to an embodiment of the present invention; Figure 9 This is the spiral pattern printed circuit board pattern of the S-band antenna 4 according to an embodiment of the present invention; Figure 10 This is a schematic diagram of the UHF band structure according to an embodiment of the present invention; Figure 11 This is a schematic diagram of the UHF band structure according to an embodiment of the present invention; Figure 12 This is the normalized gain pattern of the UHF band according to an embodiment of the present invention; Figure 13 This is the S-band normalized gain pattern according to an embodiment of the present invention; Figure 14 This is the L-band normalized gain pattern according to an embodiment of the present invention; Figure 15 This is the UHF band VSWR curve according to an embodiment of the present invention; Figure 16 This is the S-band VSWR curve of an embodiment of the present invention; Figure 17 This is the L-band VSWR curve of an embodiment of the present invention; Figure 18 This is the UHF band axial ratio curve according to an embodiment of the present invention; Figure 19 This is the S-band axial ratio curve of an embodiment of the present invention; Figure 20 This is the L-band axial ratio curve of an embodiment of the present invention. Detailed Implementation

[0017] To illustrate the structure and features of the present invention in detail, the technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0018] This invention provides a satellite communication antenna solution, specifically a compact combined antenna capable of operating simultaneously in three commonly used satellite communication frequency bands: UHF, L, and S. Its core objective is to achieve high-performance integration of three independent frequency band antennas within an extremely limited space (approximately 250mm in diameter and 350mm in height), ensuring that each frequency band effectively covers the upper half of space (hemispherical beam) while maintaining good circular polarization characteristics. This meets the urgent needs of modern terrestrial and mobile satellite communication equipment for multifunctionality, high integration, and reliability.

[0019] I. Overall System Architecture and Mechanical Layout The overall system architecture of this invention is shown in the appendix. Figure 1 (Side view) and appendix Figure 2 As shown in the top view, it is a multi-layered, three-dimensional integrated mechanical and electromagnetic complex, mainly comprising the following core components: Basic support platform: Metal base 8: Serves as the structural foundation and electromagnetic reference ground for the entire antenna system. It is usually made of highly conductive metal materials such as aluminum alloy, providing a stable mounting surface for all components and serving as the common ground reference for the entire system.

[0020] Orientation turntable 6: Fixedly installed at the center or a specific position of the metal base 8. It is a mechanical device (such as a gimbal) that can achieve 360° continuous or step rotation, and its rotation axis is perpendicular to the plane of the base.

[0021] Low-frequency antenna subsystem (UHF band): UHF band antenna 1: This is the largest physical antenna in the system, responsible for operating in the UHF band with a center frequency of around 380MHz.

[0022] Installation method: The antenna is not installed vertically, but is connected to the upper surface of the azimuth turntable 6 via a rigid diagonal support 9. The key installation parameter is that the physical axis (or main radiation direction) of the UHF antenna 1 forms a fixed 35° angle with the upper surface of the turntable (i.e., the horizontal plane). This tilted installation is one of the keys to achieving compactness.

[0023] Functionality: The UHF antenna itself has a wide beamwidth, but its fixed tilt angle causes its beam center to point 35° off-center (vertically upward). Driven by an azimuth turntable 6, it rotates continuously in the horizontal direction, causing its beam to perform a conical scan in space, thus synthesizing a signal coverage area covering the entire upper hemisphere. This achieves a hemispherical beam coverage scheme of "mechanical scanning + fixed tilt angle." This avoids designing an ultra-large UHF antenna to directly achieve a hemispherical beam, significantly reducing the overall height.

[0024] High-frequency antenna support structure and subsystems (L-band and S-band): Fiberglass antenna support 7: This is the key support structure of the invention. Two identical supports are symmetrically and uprightly mounted on the metal base 8, located on either side of the turntable 6. The support is made of fiberglass (a high-strength, low-loss non-metallic composite material), and its unique structural design is shown in the attached figure. Figure 3 and attached Figure 4 As shown, it presents a dumbbell-shaped or I-shaped profile that is wider at the top and bottom and narrower in the middle. This design achieves multiple purposes: High-strength support: The wide top and bottom provide a solid connection surface with the beams and base, ensuring structural rigidity.

[0025] To allow for rotation: The narrow waist section provides necessary physical space for the UHF antenna 1, which is installed at an angle below, to rotate and prevent collisions and interference.

[0026] Low electromagnetic influence: The non-conductive properties of glass fiber make it have minimal impact on the antenna's radiation field, avoiding beam distortion or performance degradation that may be caused by metal supports.

[0027] Top beam: The tops of the two fiberglass supports 7 are connected together by an internal or external beam structure to form a stable portal frame.

[0028] L-band antenna 2 and S-band antenna 4: These two high-frequency antennas are installed at the left and right ends of this crossbeam, respectively. Therefore, they are supported high and suspended above UHF antenna 1. This three-dimensional layout makes full use of vertical space and is the core layout strategy for achieving compact integration.

[0029] II. Detailed Design and Technical Characteristics of Antennas in Each Frequency Band UHF band antenna 1: Miniaturized tilted circularly polarized dipole array Structural Analysis: As described in the invention summary and specific embodiments, this antenna is a meticulously designed miniaturized cross-shaped dipole variant. Its core is a hollow hemispherical dielectric support body 1-3 made of nylon. Four sets of radiating elements are evenly distributed along the circumference (at 90° intervals) on the outer surface of the support body.

[0030] Radiation unit composition: Each unit consists of a triangular aluminum upper radiating patch (belonging to the upper radiator 1-1) and a trapezoidal aluminum lower radiating patch (belonging to the lower radiator 1-2). The upper and lower patches are staggered vertically, leaving an excitation gap in between. The upper radiating patches of two directly opposite units (180° apart) are electrically connected by solder pads to form a pair of equivalent oscillator arms.

[0031] Grounding and Feeding: A metal ground plane 1-7 is fixed to the bottom of the hemispherical support. Each trapezoidal lower radiating patch is securely short-circuited to the ground plane below it by two shorting pins 1-4, which helps to extend the antenna bandwidth and optimize impedance. The excitation of each radiating element is led to the RF connector 1-10 via an independent feed cable 1-8.

[0032] Circular polarization generation and decoupling design: The signal is processed externally through impedance matching 1-12 and circular polarizer 1-11 (such as a 3dB bridge) to provide excitation currents with equal amplitude and 90° phase difference to two pairs of orthogonal oscillator arms, thereby radiating circularly polarized waves.

[0033] When the antenna is installed at a 35° tilt angle, the plane containing each pair of vibrating arms makes a 45° angle with the horizontal ground (base plane). This means that regardless of how the azimuth turntable rotates the UHF antenna, the instantaneous linear polarization direction of its radiation field always maintains an angle of approximately 45° with the feed line direction (approximately vertical) of the fixed L / S band antenna above. This polarization mismatch effectively reduces energy exchange between the UHF antenna and the system above through near-field coupling, and is a core measure to improve system isolation, especially protecting the UHF antenna's own standing wave ratio (VSWR) from severe impact.

[0034] L-band Tian2: Low-profile circularly polarized microstrip patch antenna Structure and principle: such as Figure 5 and Figure 6 As shown, this antenna employs a classic circularly polarized microstrip patch antenna design. It utilizes a two-layer board structure: the top radiating printed circuit board 14 has etched metal patches (typically chamfered square or circular patches) that generate radiation; the bottom feeding printed circuit board 15 contains the feeding network (such as a single-point fed coupling slot or microstrip line). The two layers are separated by an air dielectric or a low-dielectric-constant support, forming an "air cavity," which helps improve antenna efficiency and bandwidth. The overall antenna profile is extremely low, with a total thickness controlled to approximately 18 mm.

[0035] The antenna is mounted horizontally at the left end of the support beam. Its RF socket 16 is mounted at the bottom and faces downwards. An important detail is that the socket is intentionally positioned off-center from the geometric center of the antenna radiating patch (off-center to the left in this embodiment). This "off-feed" design keeps the feed point of the L-band antenna (a potential source of strong interference) as far away as possible horizontally from the central feed area of ​​the UHF antenna 1 directly below, further weakening the near-field coupling path.

[0036] S-band Antenna 4: Compact Quadruple Spiral Antenna Structure and principle: such as Figures 7 to 9 As shown, this antenna is a four-arm helical antenna, known for its wide beam and good circular polarization performance within a limited height.

[0037] Core component: Spiral pattern printed circuit board 19 is a radiator. It is made of a flexible polytetrafluoroethylene board with an extremely thin (0.1mm) and low dielectric constant (2.2) material. A specific spiral microstrip pattern is etched on it and then rolled into a cylinder with a diameter of about 22mm.

[0038] Packaging and Feeding: The helical radiator is housed in a sealed space consisting of a feed network plate 18 (as a base plate) and a PTFE support 20 (as a housing), providing protection. The bottom feed network is a five-port microstrip circuit: one input port connects to the RF socket 21, and four output ports are rotationally symmetrically connected to the four arms of the helix, providing precise 0°, 90°, 180°, and 270° phase sequences to excite circularly polarized waves. The overall antenna height is approximately 80 mm (in this embodiment), making it very compact.

[0039] Installation details: Symmetrical to the L-band antenna, the S-band antenna is installed at the right end of the crossbeam, with its RF socket 21 also facing downwards and positioned slightly to the right. The purpose is the same as that of the L-band antenna: to increase the horizontal distance from the center area of ​​the UHF antenna.

[0040] III. System-level Integration and Electromagnetic Compatibility Design Feeder system and common grounding: The feed lines (3, 5) of the L-band and S-band antennas are led out from their respective antennas and laid down in an orderly manner along the inner sidewall of the fiberglass support 7. The cable binding holes 13 on the support are used to fix the cables to ensure neatness and reliability.

[0041] When the two coaxial feeders extend to the mounting height of the metal base 8, an important electromagnetic compatibility (EMC) operation is performed: a low-impedance, reliable short-circuit connection is established between the feeder outer conductors (shielding layer) and the metal base 8 (e.g., via grounding clamps or direct soldering). This operation ensures a stable equipotential connection, i.e., "common ground," between the L and S band subsystems and the metal base. This helps to: discharge any accumulated static electricity or common-mode current; provide a clear and consistent return path for high-frequency signals; and significantly reduce inter-band interference formed through ground loops, improving overall system stability.

[0042] External port configuration: The feed line of UHF antenna 1 extends downward from the center of its bottom.

[0043] Ultimately, the feed lines from the UHF, L, and S antennas converge and connect to their respective external interfaces. Therefore, this combined antenna presents three independent RF ports, each corresponding to a different operating frequency band, allowing users to connect it to different satellite communication transceivers as needed.

[0044] In this embodiment, Figure 12 , Figure 13 , Figure 14 The simulated normalized gain radiation pattern of this embodiment of the invention shows that the radiation patterns of the three frequency band antennas are regular in shape, with obvious directional radiation characteristics, exhibiting a hemispherical beam pattern, and a front-to-back ratio of more than 15dB. Figure 15 , Figure 16 , Figure 17 The figure shows the simulated VSWR curves of this invention. As can be seen from the figure, the VSWR performance of the three frequency bands is good, and the antenna has high radiation efficiency. Figure 18 , Figure 19 , Figure 20 The simulated axial ratio curves of this invention are shown in the figure. As can be seen from the figure, the circular polarization performance of the three frequency bands is good, and the axial ratio value at large angles is also low. From the above results, it can be seen that the three-band combined antenna of this invention has high engineering application value as a hemispherical beam antenna.

[0045] The above description is merely a preferred embodiment of the present invention, intended to further illustrate the invention, and not to limit it. Any simple substitutions made based on the content disclosed in the above text and drawings are within the scope of protection of this patent.

Claims

1. A compact tri-band hemispherical beamforming antenna, characterized in that, Includes a metal base, turntable, UHF band antenna, L-band antenna, and S-band antenna; The turntable is mounted on a metal base, and the UHF band antenna is mounted on the upper surface of the turntable by a diagonal support. The angle between the UHF band antenna and the upper surface of the turntable is 35°. On the metal base, two opposing fiberglass antenna supports are provided on both sides of the turntable. The height of the two fiberglass antenna supports is higher than that of the UHF band antenna, and the two supports overlap the crossbeam. The L-band antenna and the S-band antenna are respectively installed at both ends of the crossbeam, and the feed lines of both the L-band antenna and the S-band antenna extend downward along the fiberglass antenna support.

2. The compact tri-band hemispherical beamforming antenna according to claim 1, characterized in that, The UHF band antenna includes an upper radiator (1-1), a lower radiator (1-2), and a nylon support (1-3); the upper radiator (1-1) and the lower radiator are both covered on the outer surface of the nylon support (1-3); The nylon support (1-3) is a hollow hemispherical structure. The upper radiator (1-1) covers the top of the hollow hemispherical structure and is composed of four upper radiating patches. The four upper radiating patches are arranged in a circumferential array, and the upper radiating patches facing each other are connected by corresponding solder pads. The lower radiator (1-2) consists of four lower radiating patches, which correspond one-to-one with the four upper radiating patches. The lower radiating patches are located below the corresponding upper radiating patches. The bottom edge of the lower radiating patch is attached to the bottom edge of the hollow hemispherical structure, and there is a gap between the top edge of the lower radiating patch and the bottom edge of the upper radiating patch. The bottom of the nylon support (1-3) is provided with a grounding plate (1-7), and the lower radiator is short-circuited to the grounding plate (1-7) through a short-circuit pin (1-4); Each solder pad is connected to the corresponding RF connector (1-10) via the corresponding feed cable (1-8); the RF connector (1-10) is connected to the circular polarizer (1-11) via the impedance matching device (1-12).

3. A compact three-band hemispherical beamforming antenna according to claim 2, characterized in that, The upper radiating patch is a triangular aluminum plate, and the lower radiating patch is a trapezoidal aluminum plate. There is a gap between each adjacent radiating patch. Each lower radiating patch is connected to the ground plate (1-7) by two short-circuit pins (1-4).

4. A compact tri-band hemispherical beamforming antenna according to claim 1, characterized in that, The L-band antenna is a low-profile microstrip antenna, and the S-band antenna is a quad-arm helical antenna that combines wide beamwidth and low height.

5. A compact tri-band hemispherical beamforming antenna according to claim 1, characterized in that, The L-band and S-band antennas are supported above the UHF band antenna using a fiberglass support frame; the fiberglass support frame 7 has a shape that is wider at the top, wider at the bottom, and narrower in the middle.

6. A compact tri-band hemispherical beamforming antenna according to claim 1, characterized in that, The RF connectors of L-band antenna 2 and S-band antenna 4 face downwards, and their RF connectors are offset from their own physical centers, far away from each other, and far away from the center feed point of UHF band antenna 1, in order to reduce the impact on the VSWR of UHF band antenna 1.

7. A compact tri-band hemispherical beamforming antenna according to claim 1, characterized in that, The L-band antenna feed line 3 and the S-band antenna feed line 5 extend downwards along the inner wall of the fiberglass support 7. At the position where they reach the metal base 8, the outer shielding layer and the metal base 8 are short-circuited to achieve a stable common ground effect.

8. A compact tri-band hemispherical beamforming antenna according to claim 4, characterized in that, The L-band antenna includes a radiating layer, a feeding layer, and an L-band RF socket arranged from top to bottom.

9. A compact tri-band hemispherical beamforming antenna according to claim 4, characterized in that, The S-band antenna includes a feed network (18), a spiral pattern printed circuit board (19), a polytetrafluoroethylene (PTFE) support (20), and an RF socket (21). The PTFE support (20) is located on the upper surface of the feed network (18) to form a closed space, the spiral pattern printed circuit board (19) is located in the closed space, and the RF socket is installed at the bottom of the feed network.

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