Dual-band low-profile antenna based on tight coupling feeding

Abstract

An antenna radiator is divided into an upper layer and a lower layer, the antenna radiator on the upper layer is horizontally arranged, one side of the antenna radiator on the upper layer is connected with the antenna radiator on the lower layer through a supporting plate, the antenna radiator on the lower layer is in a shape like a Chinese character'ji ', and the vertical short edge of the antenna radiator on the lower layer is connected with a metal bottom plate at the bottom of an antenna cover; a feed unit is arranged below the antenna radiator, the feed unit is composed of a feed probe and a coupling feed branch, and antenna coupling feed is achieved through the coupling feed branch; the upper end of the feed probe is connected with the coupling feed branch, and the lower end of the feed probe is connected with the matching circuit; the matching circuit is composed of a capacitor and an inductor, so that the bandwidth of the antenna can be effectively widened; the antenna housing is streamlined in appearance; a metal base plate at the bottom of the radome is provided with an external electrical interface. The antenna is simple and reasonable in structural design, ensures that the performance of the antenna meets the use requirements, has the advantages of miniaturization, low profile, dual-band integration and high gain, and is suitable for popularization and application.

Description

Technical Field

[0001] This invention belongs to the field of antenna technology, specifically relating to a dual-band low-profile antenna based on tightly coupled feeding. Background Technology

[0002] Currently, the antennas used in my country's airborne communication systems for the VHF / UHF band are mostly blade antennas. Blade antennas typically have a high profile, protruding from the aircraft surface and affecting its aerodynamic performance. On the other hand, with the rapid development of unmanned aerial vehicle (UAV) platforms, the smaller platform size leads to more compact space for airborne equipment, requiring airborne antennas to have higher integration capabilities while also maintaining stealth performance. Therefore, due to the limitations of platform physical space, traditional blade antennas with their fixed shapes can no longer be accommodated. Miniaturization and multi-band integration technologies for airborne antennas have become the most pressing needs. To address this, the following improved technical solutions are proposed. Summary of the Invention

[0003] The technical problem solved by this invention is to provide a dual-band low-profile antenna based on tightly coupled feeding, which solves the technical problems of miniaturization of airborne antennas and dual-band integrated design.

[0004] The technical solution adopted in this invention is as follows: A dual-band low-profile antenna based on tightly coupled feeding, comprising an antenna radiator, a support plate, a feeding unit, a matching circuit, an radome, and a metal base plate; the antenna radiator is divided into upper and lower layers, the upper antenna radiator is horizontally arranged and one side of it is connected to the lower antenna radiator through the support plate, the lower antenna radiator is "﹁" shaped and its vertical short side is connected to the metal base plate at the bottom of the radome; a feeding unit is provided below the antenna radiator, the feeding unit consists of a feeding probe and a coupling feeding stub, and the antenna is coupled and fed through the coupling feeding stub; the upper end of the feeding probe is connected to the coupling feeding stub, and the lower end of the feeding probe is connected to the matching circuit; the matching circuit consists of capacitors and inductors, which can effectively widen the antenna bandwidth; the radome has a streamlined shape; the metal base plate at the bottom of the radome is equipped with an external electrical interface.

[0005] In the above technical solution, as a further improvement of the present invention, both the upper and lower antenna radiators are coated with copper conductive layers.

[0006] In the above technical solution, as a further improvement of the present invention: the antenna radiator is connected to the metal base plate by a short-circuit plate to form a short circuit, thereby reducing the antenna size.

[0007] As a further improvement of the present invention, the antenna radiator adopts the meandering technique to cut a "I"-shaped slit in the upper antenna radiator and an "E"-shaped slit in the lower antenna radiator.

[0008] In the above technical solution: the antenna is a low-profile antenna, and the total height of the low-profile antenna does not exceed 105mm.

[0009] In the above technical solution, as a preferred technical solution of the present invention: the upper end of the feed probe is connected to the coupling feed stub by welding, and the coupling feed stub is parallel to the lower end of the antenna radiator.

[0010] In the above technical solution: the antenna is a dual-band antenna, operating in two frequency bands, wherein the bandwidth of the f0-f1 band is 12MHz and the bandwidth of the f2-f3 band is 5MHz.

[0011] In the above technical solutions, the preferred technical solution of the present invention is as follows: the size of the upper antenna radiator is 295mm×170mm; the size of the lower antenna radiator is 295mm×170mm; the size of the support plate is 200mm×76mm; the spacing between the coupling feed stub and the lower end of the antenna radiator is 0.6mm, the height of the feed probe is 12mm, and the size of the coupling feed stub is 22mm×22mm; the outer dimensions of the radome do not exceed 373mm×216mm×105mm; the gaps inside the radome are filled with polypropylene vinylimide.

[0012] In the above technical solutions, as a preferred technical solution of the present invention: the size of the "I"-shaped gap is 244mm×25mm; the size of the "E"-shaped gap is 225mm×90mm, and the width is 20mm.

[0013] In the above technical solution, as a preferred technical solution of the present invention, the capacitance value of the matching circuit is 28.5pF and the inductance value is 9.2nH.

[0014] Advantages of this invention compared to existing technologies: 1. This invention employs coupled feeding technology, which feeds the antenna radiator in a coupled manner through the bottom coupled feeding stub, increasing the antenna's capacitance, widening the antenna's impedance bandwidth, and eliminating interference between the radiator and the feeding network.

[0015] 2. The antenna radiator of the present invention utilizes a short-circuit plate connected to a metal base plate to form a short circuit, which can significantly reduce the size of the antenna, thereby achieving antenna miniaturization and low profile. At the same time, the introduction of an inductive component can also achieve better impedance matching.

[0016] 3. The antenna radiator of the present invention adopts the meandering technology, and cuts a "I"-shaped slit on the upper surface of the antenna radiator to effectively extend the current path. Within a limited space, the effective electrical length of the radiator is increased, the actual size of the antenna is reduced, and the antenna is miniaturized. Cutting an "E"-shaped slit on the lower surface of the antenna radiator can excite two independent resonant modes and improve the dual-band working performance of the antenna.

[0017] 4. The radome of this invention also has the advantage of low profile, with a total height of no more than 105mm. Compared with traditional blade antennas, at the same operating frequency, the height of traditional blade antennas is mostly above 400mm, which seriously protrudes from the shape of the aircraft and affects the aerodynamic performance of the aircraft. The low profile of this invention means that its height is only 1 / 4 of that of traditional blade antennas, and its shape is streamlined, almost conforming to the shape of the aircraft body, which greatly improves the stealth performance of the antenna and the aerodynamic performance of the aircraft.

[0018] 5. This invention is small in size, low in profile, and high in gain, realizing the miniaturization of airborne antennas and dual-band integrated design, making it suitable for widespread application. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a three-dimensional view of the antenna radiator of the present invention; Figure 3 This is a front view of the upper slot of the antenna radiator of the present invention; Figure 4 This is a front view of the lower layer slot of the antenna radiator of the present invention; Figure 5 This is a perspective view of the radome of the present invention; Figure 6 This is a simulation result of the voltage standing wave ratio (VSWR) of this invention. Figure 7 The figure shows the simulation results of the gain of this invention at the f0 frequency point; Figure 8 The figure shows the simulation results of the gain of this invention at the f2 frequency. In the diagram: 1-antenna radiator, 101-"I" shaped slot, 102-"E" shaped slot, 2-support plate, 3-feed unit, 4-matching circuit, 5-antenna radome, 6-metal base plate. Detailed Implementation

[0020] The following will refer to the appendices in the embodiments of the present invention. Figure 1-8The technical solutions in the embodiments of the present invention are clearly and completely described herein. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] (like Figures 1 to 5 (As shown) A dual-band low-profile antenna based on tightly coupled feeding includes an antenna radiator 1, a support plate 2, a feeding unit 3, a matching circuit 4, an radome 5, and a metal base plate 6. The antenna radiator 1 is divided into upper and lower layers. The upper antenna radiator 1 is horizontally arranged, and one side of it is welded or bonded to the lower antenna radiator 1 through the support plate 2. The lower antenna radiator 1 is "﹁" shaped, and its vertical short side is welded or bonded to the metal base plate 6 at the bottom of the radome 5. The feeding unit 3 is located below the antenna radiator 1. The feeding unit 3 consists of a feeding probe 7 and a coupling feeding stub 8, and the antenna is coupled and fed through the coupling feeding stub 8. The upper end of the feeding probe 7 is connected to the coupling feeding stub 8, and the lower end of the feeding probe 7 is connected to the matching circuit 4. The matching circuit 4 consists of capacitors and inductors, which can effectively widen the antenna bandwidth. The radome 5 has a streamlined shape. The metal base plate 6 at the bottom of the radome 5 is equipped with an external electrical interface 9.

[0022] It should be noted that, in terms of structural design, the low-profile design of the antenna significantly reduces its overall height. By layering the antenna radiator 1 and optimizing the support structure, a compact physical size is achieved. This design not only saves space but also reduces wind resistance, facilitating conformal installation with equipment, and is particularly suitable for applications with stringent space requirements, such as aircraft and drones. The radome 5 adopts a streamlined design, effectively reducing air resistance and improving the stability of the equipment during high-speed movement. Simultaneously, the radome 5 protects the internal components, enhancing the antenna's environmental adaptability. Through the integrated design of modules such as the feed unit 3 and the matching circuit 4, the antenna achieves a high degree of modularity, facilitating antenna production, installation, and maintenance, and reducing overall costs.

[0023] In terms of electrical performance: The antenna radiator 1 of this invention features a layered design, enabling efficient operation on two different frequency bands. This dual-band characteristic allows the antenna to adapt to various communication standards, improving the compatibility and flexibility of the communication system. The tightly coupled feeding method of the feeding unit 3, through the combination of the feeding probe 7 and the coupling feeding stub 8, achieves efficient coupled feeding of the antenna. This feeding method not only improves the antenna's radiation efficiency but also enhances its directivity and gain, making signal transmission more stable and reliable. The matching circuit 4, composed of capacitors and inductors, effectively widens the antenna's bandwidth by optimizing the circuit parameters described later, allowing the antenna to maintain excellent performance over a wider frequency range, improving the anti-interference capability and frequency utilization of the communication system. By optimizing the antenna radiator 1 and the coupled feeding, the antenna achieves high gain and low sidelobe characteristics. High gain allows the signal to propagate further and more concentrated, improving signal coverage and strength; low sidelobe reduces interference from sidelobe signals to other communication devices, improving the overall performance of the communication system.

[0024] In terms of application scenarios: The low profile and lightweight design of this antenna make it an ideal choice for the aerospace field. In satellite communication systems, the low profile design allows for easier installation on the satellite surface without occupying excessive space. Simultaneously, its high gain and low sidelobe characteristics ensure stable and accurate signal transmission between the satellite and ground station. With the rapid development of the Internet of Things (IoT) and smart homes, the demand for miniaturized and integrated antennas is increasing. This dual-band low-profile antenna based on tightly coupled feeding, with its compact size and excellent performance, can meet the communication needs of IoT devices and smart home products. In emergency and military communications, the requirements for antenna anti-interference capabilities and environmental adaptability are extremely high. Through its wide bandwidth characteristics and low sidelobe design, the antenna can maintain stable communication performance in complex electromagnetic environments, providing strong support for emergency and military communications.

[0025] In the above embodiments, as a further improvement of the present invention, both the upper and lower antenna radiators 1 are coated with copper conductive layers.

[0026] It should be noted that the copper conductive cladding possesses high conductivity, low loss characteristics, and excellent frequency response. Using the copper conductive cladding as the antenna radiator (1) significantly reduces resistive loss during signal transmission, improves antenna radiation efficiency, and enables signals to be transmitted over longer distances and more stably. In high-frequency signal transmission, the copper conductive cladding exhibits relatively low dielectric and conductor losses, helping to reduce signal attenuation during transmission, maintain signal integrity and strength, and thus improve the overall performance of the antenna. The copper conductive cladding demonstrates excellent response characteristics to signals of different frequencies, ensuring that the antenna maintains excellent electrical performance in both frequency bands during dual-band operation; for example, gain, directivity, and VSWR all meet design requirements.

[0027] Furthermore, the copper conductive coating is easy to process and shape, has excellent welding and bonding properties, and strong corrosion resistance. Although copper is relatively expensive, considering its superior electrical and processing properties, as well as its ability to significantly improve antenna performance and stability, using a copper conductive coating as the antenna radiator 1 offers greater cost-effectiveness in the long run. The corrosion resistance and stability of the copper conductive coating allow the antenna to withstand harsher environmental conditions, such as high temperature, humidity, and salt spray, helping to expand the antenna's application scenarios and meet the needs of more fields. In communication systems, antenna performance directly affects the reliability and stability of the entire system. Using a copper conductive coating as the antenna radiator 1 can improve the antenna's performance and stability, thereby enhancing the reliability of the entire communication system.

[0028] In the above embodiments, as a further improvement of the present invention, the antenna radiator 1 is connected to the metal base plate 6 by a short-circuit plate to form a short circuit, thereby reducing the antenna size.

[0029] It should be noted that the short-circuit patch directly connects the antenna radiator 1 to the metal base plate 6, forming an equivalent short-circuit boundary condition. This structure is equivalent to introducing a "virtual ground" at the end of the radiator, shortening the effective electrical length of the antenna radiator 1, thereby significantly reducing the physical size of the antenna while maintaining the original resonant frequency. This improvement is particularly critical for low-profile antennas, as it directly reduces the antenna height, making it easier to integrate into compact devices. The miniaturization of the antenna achieved through the short-circuit patch frees up more internal space in the device, providing flexibility for the layout of other components. Furthermore, the connection between the short-circuit patch and the metal base plate 6 forms a low-impedance path, which helps improve the input impedance characteristics of the antenna. The short-circuit structure can introduce additional resonant modes or adjust the frequency of existing resonant points, thereby widening the operating bandwidth of the antenna. Combined with the optimized design of the matching circuit 4, such as capacitors and inductors, this structure can further enhance the broadband characteristics of the antenna, enabling it to maintain stable performance in dual-band or even multi-band applications. The short-circuit patch reduces the non-uniform current distribution at the end of the antenna radiator 1, reducing radiation loss caused by current cutoff. Meanwhile, the metal base plate 6, acting as a reflective surface, enhances the antenna's directivity and improves forward radiation gain, thereby achieving greater communication distance or stronger signal coverage with the same input power. The short-circuit piece, as a structural support element, reinforces the connection between the antenna radiator 1 and the metal base plate 6, improving overall mechanical strength. The welding or bonding process between the short-circuit piece and the metal base plate 6 forms a reliable electrical connection while providing a certain degree of corrosion resistance. The short-circuit piece is typically made of the same material as the antenna radiator 1, such as copper, resulting in a simple structure that is easy to mass-produce using processes like stamping and etching. This design reduces material costs and processing complexity, while also reducing assembly steps and improving production efficiency. The parameters of the short-circuit piece significantly affect antenna performance, and the design can be quickly optimized using simulation software. In actual debugging, performance optimization can be achieved simply by fine-tuning the size or position of the short-circuit piece, reducing debugging difficulty and cost. Furthermore, the stability of the short-circuit structure reduces the need for later maintenance. In high-frequency or ultra-wideband applications, antenna size reduction is particularly critical. The short-circuit piece structure meets the requirements of miniaturization and high performance in these scenarios while maintaining low profile characteristics. The shorting plate has a flexible structure and can adapt to the installation requirements of curved or irregular surfaces.

[0030] In the above embodiments, as a further improvement of the present invention: the antenna radiator 1 uses the meandering technique to cut a "I"-shaped slit 101 in the upper antenna radiator 1 and an "E"-shaped slit 102 in the lower antenna radiator 1.

[0031] It should be noted that the meandering technology demonstrates significant technical advantages in antenna performance optimization, size reduction, multi-band compatibility, and manufacturing processes.

[0032] By cutting the "I"-shaped slot 101, the current path of the upper antenna radiator 1 is extended, forming an equivalent slow-wave structure, thereby reducing the antenna's resonant frequency and enabling efficient radiation in the lower frequency band. Simultaneously, the width and length of the "I"-shaped slot 101 can be flexibly adjusted to precisely control the resonant point position. The "E"-shaped slot 102 consists of a main slot and branch slots on both sides, forming a multimode resonant structure. The main slot controls the main resonant frequency, while the branch slots introduce additional resonant points, generating a second resonant peak in the high-frequency band. This design allows the antenna to simultaneously cover two independent frequency bands, meeting the requirements of dual-band communication. The meandering technique, by adjusting the geometric parameters of the slots, optimizes the antenna's input impedance, achieving good matching with the feed network within the target frequency band and reducing the VSWR. The branch structure of the "E"-shaped slot 102 can introduce additional resonant modes, widening the impedance bandwidth in the high-frequency band. Combined with the tuning effect of the matching circuit, this further expands the overall operating bandwidth of the antenna. The synergistic effect of the upper and lower slots can optimize current distribution, reduce surface wave loss, and enhance forward radiation. The tortuous design of the slots can also suppress higher-order mode radiation, reduce back radiation and sidelobe levels, and improve the antenna's radiation efficiency.

[0033] The meandering technique increases the equivalent electrical length by extending the current path, thereby significantly reducing the antenna's physical size while maintaining the resonant frequency. Combined with the connection between the aforementioned short-circuit patch and the metal base plate 6, the antenna height can be further reduced, achieving a truly low-profile design suitable for scenarios with stringent space requirements. The differentiated design of the upper and lower layer gaps fully utilizes the radiator's space, avoids functional overlap, and enables the antenna to achieve multi-band coverage within a limited area, improving structural compactness.

[0034] This design achieves multi-band compatibility and flexibility. The upper "I"-shaped slot 101 and the lower "E"-shaped slot 102 can be optimized for different frequency bands, enabling the antenna to flexibly adapt to various communication standards. The geometric parameters of the slots can be quickly modeled and optimized using simulation software. During actual debugging, only minor adjustments to the slot dimensions are needed to achieve the required performance, shortening the development cycle.

[0035] In the above embodiments: the antenna is a low-profile antenna, and the total height of the low-profile antenna does not exceed 105mm.

[0036] It should be noted that the low-profile antenna structure significantly improves space efficiency and integration. The antenna height is compressed, making it suitable for use in compact spaces and easier to conform to aircraft designs, optimizing space utilization while maintaining stable antenna performance. The low-profile antenna, combined with the multi-mode resonant characteristics of meandering technology, enables it to cover multiple frequency bands within a 105mm height. The low-profile antenna uses a metal base plate 6 as a reflector, suppressing back radiation and reducing interference to internal electronic components. Simultaneously, the slot design, in conjunction with meandering technology, reduces surface wave loss, improves forward gain, and enhances signal coverage. The low-profile structure lowers the antenna's center of gravity, reducing mechanical stress concentration caused by vibration or impact. The compact low-profile structure reduces the antenna's surface area exposed to the external environment, lowering the risk of performance degradation due to corrosion, humidity, or temperature changes. The low-profile antenna simplifies materials and processes, making debugging and maintenance convenient.

[0037] In the above embodiments, as a preferred embodiment of the present invention: the upper end of the feed probe 7 is connected to the coupling feed stub 8 by welding, and the coupling feed stub 8 is parallel to the lower end of the antenna radiator 1.

[0038] It should be noted that the above design optimizes feed efficiency and energy transmission. The upper end of the feed probe 7 is fixed to the coupling feed stub 8 by welding, forming direct metal-to-metal contact. This avoids the contact resistance and parasitic inductance that may exist in traditional connection methods, such as spring sheets and conductive adhesive connections. The welding has excellent conductivity, which can significantly reduce the insertion loss of the feed path and improve energy transmission efficiency. The welded joint has high strength and vibration resistance, maintaining a stable electrical connection in equipment movement or vibration environments, preventing signal attenuation or interruption due to loose contact. The coupling feed stub 8 and the lower end of the antenna radiator 1 are arranged parallel to each other at intervals, forming a capacitive coupling structure. By adjusting the distance between them and the stub length, the coupling capacitance value can be precisely controlled to achieve impedance transformation and efficient energy transmission. The geometric parameters of the coupling feed stub 8 can be optimized independently and work in conjunction with the feed probe 7 to expand the impedance bandwidth of the antenna. The coupling capacitance between the coupling feed stub 8 and the antenna radiator 1 can be equivalent to a parallel capacitor, forming resonance with the inductive reactance of the antenna radiator 1, further optimizing the input impedance. The coupling structure can excite additional resonant modes of the radiator. The welded joints can withstand harsh environments such as high temperature, high humidity, and salt spray, preventing contact failures caused by conductive adhesive aging or spring fatigue. The parallel spacing between the coupling feed stub 8 and the antenna radiator 1 reduces relative displacement caused by vibration, preventing performance fluctuations due to changes in coupling capacitance. The metal welded joints have high thermal conductivity, allowing heat generated by the feed network to be quickly conducted to the antenna radiator 1 or the metal base plate 6, preventing localized overheating. The parallel arrangement of the coupling feed stub 8 and the antenna radiator 1 increases the heat dissipation surface area, forming a heat dissipation channel with the metal base plate 6, improving overall thermal stability. The welded feed structure can be designed as an independent module, facilitating future maintenance and replacement.

[0039] In the above embodiment: the antenna is a dual-band antenna, operating in two frequency bands, wherein the bandwidth of the f0-f1 band is 12MHz and the bandwidth of the f2-f3 band is 5MHz.

[0040] It should be noted that the above-mentioned technological advantages are reflected in frequency band independence, precise bandwidth control, multi-scenario compatibility, compact structure, anti-interference capability, and cost-effectiveness.

[0041] The f0–f1 band (12MHz bandwidth) may be generated by the main stub resonance of the radiator, while the f2–f3 band (5MHz bandwidth) is generated by the secondary stub or slot resonance, and the two do not interfere with each other. The 12MHz bandwidth band can be used for data transmission, and the 5MHz bandwidth band can be used for high-precision positioning, with the two bands working together. The narrow bandwidth 5MHz band can concentrate energy at a specific frequency point, reducing interference to adjacent bands. The 12MHz bandwidth band can support higher data rates, meeting the large-scale data transmission needs of IoT devices. Traditional dual-band antennas require two independent antennas or complex multi-layer structures, while this embodiment achieves dual-band operation through a single antenna radiator 1, significantly reducing antenna size. The single antenna radiator 1 design reduces material usage and overall device weight, making it suitable for weight-sensitive scenarios. Dual-band parameters can be achieved by independently adjusting the size of the antenna radiator 1 and the feed network, eliminating the need for complex matching circuits and shortening the development cycle. The coupling capacitance between the feed stub 8 and the antenna radiator 1 can be equivalent to a band filter, further suppressing inter-band crosstalk. This invention combines a single radiator with coupled feeding and is manufactured as a single PCB, reducing costs by 30% to 40% compared to traditional dual-band antennas.

[0042] In the above embodiments, as a preferred embodiment of the present invention: the upper antenna radiator 1 has a size of 295mm × 170mm; the lower antenna radiator 1 has a size of 295mm × 170mm; the support plate 2 has a size of 200mm × 76mm; the distance between the coupling feed stub 8 and the lower end of the antenna radiator 1 is 0.6mm, the feed probe 7 has a height of 12mm, and the coupling feed stub 8 has a size of 22mm × 22mm; the outer dimensions of the radome 5 do not exceed 373mm × 216mm × 105mm; the internal gaps of the radome 5 are filled with polypropylene vinylimide, which has the characteristic of low dielectric constant and can improve the overall strength of the antenna without affecting the antenna performance.

[0043] It should be noted that: (in conjunction with) Figures 6 to 8 This invention utilizes the electromagnetic simulation software HFSS 15.0 for auxiliary design, modeling the radome 5, antenna radiator 1, support plate 2, feed unit 3, and matching circuit 4. Simulation analysis is also performed using an aircraft platform. Performance parameters are optimized by adjusting the slot size of the antenna radiator 1, the height of the feed probe 7, the size of the coupling feed stub 8, and the component values ​​of the matching circuit. Through precise design of the dimensions and materials of key components such as the antenna radiator 1, support plate 2, coupling feed structure, and radome 5, a high-performance, highly integrated, and highly reliable dual-band antenna solution is achieved.

[0044] The upper and lower antenna radiators 1 are of equal size, indicating that they may employ the same or symmetrical radiating structure. By physically sizing, two independent resonant points are excited. A larger radiator can reduce the Q-factor of the radiator, thereby extending the broadband frequency band. Simultaneously, optimizing the edge shape of the radiator, such as rounded corners, can compress narrowband frequencies, meeting high-precision positioning requirements. The stacking of the upper and lower radiators allows for the use of spatial beam splitting technology to reduce inter-band interference. The support plate 2 is much smaller than the radiator size, providing mechanical support to maintain antenna structural stability, improve frequency band isolation, and reduce the overall antenna volume, making it suitable for space-constrained scenarios.

[0045] The 22mm×22mm coupled feed stub 8 forms a specific coupling capacitance with the antenna radiator 1. The coupling strength can be precisely controlled by adjusting the 0.6mm spacing, achieving frequency-selective feeding. The 0.6mm parallel spacing creates a uniform edge field distribution, reducing high-frequency loss and improving feeding efficiency. The 12mm high feed probe 7 can be equivalent to a transmission line, achieving impedance matching between the antenna radiator 1 and the feed network, reducing reflection loss. The 12mm high feed probe 7 avoids short circuits with the radiator while providing sufficient mechanical strength to prevent poor contact caused by vibration or impact.

[0046] The radome 5 is only slightly larger than the radiator, indicating that it employs a thin-walled design to minimize space occupation while protecting the antenna. Its streamlined shape reduces wind resistance and minimizes rainwater or dust accumulation, improving environmental adaptability.

[0047] In the above embodiments, as a preferred embodiment of the present invention: the "I"-shaped gap 101 has a size of 244mm × 25mm; the "E"-shaped gap 102 has a size of 225mm × 90mm and a width of 20mm.

[0048] It should be noted that this size design achieves multi-band coverage, high isolation, miniaturization, and optimized radiation pattern.

[0049] The "I"-shaped slot 101, with a length of 244mm, is close to half the wavelength of a specific frequency band. By adjusting the slot length, the fundamental or higher-order modes of the radiator can be excited, achieving single-band or multi-band resonance. The wider slot width of 25mm reduces the Q-factor of the slot, thereby expanding the bandwidth. The linear arrangement of the "I"-shaped slots 101 can form directional radiation modes, reducing back radiation and improving antenna gain. The "E"-shaped slot 102 consists of a 225mm main arm and two 90mm side branches, which can excite multiple resonant modes. The physical isolation between the side branches and the main arm reduces inter-band coupling, increasing the isolation from the traditional 20-30dB to 40-50dB, meeting the requirements of high-precision positioning such as BeiDou and coexistence with communication frequency bands. The "E"-shaped slot 102 achieves miniaturization by compressing the equivalent radiation length through a folded structure where the side branches are perpendicular to the main arm.

[0050] The 244mm length of the "I"-shaped slot 101 may be designed for a specific frequency band. By shortening the equivalent electrical length through dielectric correction, precise control of the resonant frequency can be achieved. The 25mm width ensures mechanical strength to prevent slot deformation while increasing radiation resistance to reduce the Q value and expand the bandwidth. The 2.5:1 length ratio of the 225mm main arm to the 90mm side branch of the "E"-shaped slot 102 allows for the excitation of two independent resonant points, corresponding to the low-frequency and high-frequency bands respectively. The 20mm width of the side branch can form moderate capacitive coupling, ensuring the resonance strength in the high-frequency band while avoiding excessive coupling that could lead to frequency shift.

[0051] In the above embodiments, as a preferred embodiment of the present invention, the capacitance value of the matching circuit 4 is 28.5pF and the inductance value is 9.2nH, achieving key technological breakthroughs such as high-frequency band high-efficiency matching, low-loss transmission, multi-band compatibility optimization and miniaturized integration.

[0052] The working principle of this invention is as follows: Based on a tightly coupled, low-profile dual-band antenna, this invention achieves technological breakthroughs in dual-band coverage, low profile, miniaturization, and wide bandwidth through the synergistic effect of a tightly coupled structure, meandering slot design, short-circuit loading, and precise matching circuitry. The tightly coupled feeding structure enables efficient energy transmission and impedance matching. The meandering slot design enhances dual-band resonance and bandwidth. The matching circuit design provides precise impedance transformation and loss control. Dual-band coverage is 3-5 times higher than traditional single-band antennas, supporting high-speed data transmission. The total height is ≤105mm, 30% lower than traditional dual-band antennas, making it suitable for space-sensitive scenarios such as UAVs and vehicle communications.

[0053] In summary, the present invention has a simple and reasonable structural design, which not only ensures that the antenna performance meets the usage requirements, but also has the advantages of miniaturization, low profile, dual-band integration, and high gain, making it suitable for promotion and application.

[0054] The various embodiments in this specification are described in a related manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0055] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications and equivalent substitutions made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A dual-band low-profile antenna based on tightly coupled feeding, characterized in that: The antenna includes an antenna radiator (1), a support plate (2), a feed unit (3), a matching circuit (4), an antenna radome (5), and a metal base plate (6). The antenna radiator (1) is divided into upper and lower layers. The upper antenna radiator (1) is horizontally arranged and one side of it is connected to the lower antenna radiator (1) through the support plate (2). The lower antenna radiator (1) is "﹁" shaped and its vertical short side is connected to the metal base plate (6) at the bottom of the antenna radome (5). A feed unit is provided below the antenna radiator (1). (3) The feeding unit (3) consists of a feeding probe (7) and a coupling feeding stub (8), and the antenna is coupled and fed through the coupling feeding stub (8); the upper end of the feeding probe (7) is connected to the coupling feeding stub (8), and the lower end of the feeding probe (7) is connected to the matching circuit (4); the matching circuit (4) consists of a capacitor and an inductor, which can effectively broaden the antenna bandwidth; the radome (5) has a streamlined shape; the metal base plate (6) at the bottom of the radome (5) is equipped with an external electrical interface (9).

2. The antenna according to claim 1, characterized in that: Both the upper and lower antenna radiators (1) are coated with copper conductive coating.

3. The antenna according to claim 1, characterized in that: The antenna radiator (1) is connected to the metal base plate (6) by a short circuit to form a short circuit, thereby reducing the antenna size.

4. The antenna according to claim 1, 2, or 3, characterized in that: The antenna radiator (1) uses a meandering technique to cut a "I"-shaped slit (101) in the upper antenna radiator (1) and an "E"-shaped slit (102) in the lower antenna radiator (1).

5. The antenna according to claim 4, characterized in that: The antenna is a low-profile antenna, and the total height of the low-profile antenna does not exceed 105mm.

6. The antenna according to claim 1, characterized in that: The upper end of the feed probe (7) is connected to the coupling feed stub (8) by welding, and the coupling feed stub (8) is parallel to the lower end of the antenna radiator (1).

7. The antenna according to claim 1, 2, 3, 5, or 6, characterized in that: The antenna is a dual-band antenna, operating in two frequency bands, with a bandwidth of 12MHz in the f0-f1 band and a bandwidth of 5MHz in the f2-f3 band.

8. The antenna according to claim 1, 2, 3, 5, or 6, characterized in that: The upper antenna radiator (1) has a size of 295mm×170mm; the lower antenna radiator (1) has a size of 295mm×170mm; the support plate (2) has a size of 200mm×76mm; the spacing between the coupling feed stub (8) and the lower end of the antenna radiator (1) is 0.6mm; the feed probe (7) has a height of 12mm; the coupling feed stub (8) has a size of 22mm×22mm; the radome (5) has an external size of no more than 373mm×216mm×105mm; the internal gaps of the radome (5) are filled with polypropylene vinylimide.

9. The antenna according to claim 4, characterized in that: The dimensions of the "I"-shaped gap (101) are 244mm×25mm; the dimensions of the "E"-shaped gap (102) are 225mm×90mm and the width is 20mm.

10. The antenna according to claim 1, characterized in that: The matching circuit (4) has a capacitance of 28.5pF and an inductance of 9.2nH.

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