Miniaturized low-profile horizontal omnidirectional ultra-wideband electromagnetic metasurface antenna

Abstract

This invention provides a miniaturized, low-profile, horizontally omnidirectional, ultra-wideband electromagnetic metasurface antenna, relating to the field of ultra-wideband antenna design technology. It includes a dielectric substrate, a metal ground plane, a metasurface patch, and a feeding structure. The metal ground plane is disposed on the bottom surface of the dielectric substrate; the metasurface patch is disposed on the top surface of the dielectric substrate and is configured with a centrally symmetrical structure; the feeding structure perpendicularly passes through the dielectric substrate, with its upper end connected to the metasurface patch and its lower end electrically connected to a coaxial feed connector. This invention achieves antenna miniaturization and stable horizontal omnidirectional radiation within the covered frequency band using a simple single-layer, low-profile structure.

Description

Technical Field

[0001] This invention relates to the field of ultra-wideband antenna design technology, and more specifically, to a miniaturized low-profile horizontal omnidirectional ultra-wideband electromagnetic metasurface antenna. Background Technology

[0002] With the rapid development of 5G mobile communication and IoT technologies, modern wireless communication systems have placed comprehensive performance requirements on antennas, including miniaturization, low profile, ultra-wideband, and stable omnidirectional radiation. Metasurface antennas, as an emerging solution, have become a research hotspot in this field due to their flexibility in controlling electromagnetic waves and their potential in achieving low profile and wideband performance. Especially on space-constrained platforms such as drones and portable terminals, there is an urgent need for antennas that can achieve ultra-wideband operation and maintain a good horizontal omnidirectional radiation pattern within an extremely thin structure to support multi-band, high-speed communication. However, existing ultra-wideband antennas often struggle to simultaneously achieve wide bandwidth and low profile performance when achieving omnidirectional radiation. Traditional omnidirectional antennas typically have a large profile height, while low-profile omnidirectional antennas implemented using microstrip or metasurface technologies often face bandwidth limitations. Furthermore, the multi-layered structures used to broaden the bandwidth are often complex to manufacture; and in the pursuit of extreme miniaturization of the antenna's lateral dimensions, interference from higher-order modes can easily lead to distortion of the horizontal omnidirectional radiation pattern at high frequencies, resulting in insufficient stability.

[0003] Therefore, how to achieve antenna miniaturization and stable horizontal omnidirectional radiation within the coverage band in a simple single-layer, low-profile structure remains a challenging technical problem in the field of antenna design. Summary of the Invention

[0004] The purpose of this invention is to provide a miniaturized, low-profile, horizontally omnidirectional, ultra-wideband electromagnetic metasurface antenna to improve the aforementioned problems. To achieve this objective, the technical solution adopted by this invention is as follows:

[0005] This application provides a miniaturized, low-profile, horizontally omnidirectional, ultra-wideband electromagnetic metasurface antenna, comprising: a dielectric substrate, a metal ground plane, a metasurface patch, and a feeding structure. The metal ground plane is disposed on the bottom surface of the dielectric substrate; the metasurface patch is disposed on the top surface of the dielectric substrate and is configured with a centrally symmetrical structure; the feeding structure passes vertically through the dielectric substrate, the upper end of the feeding structure is connected to the metasurface patch, and the lower end of the feeding structure is electrically connected to a coaxial feed connector.

[0006] Preferably, the dielectric substrate has a dielectric constant of 2.2 and a loss tangent of 0.005.

[0007] Preferably, the metasurface patch includes an innermost circular patch, a third ring surrounding the circular patch, and a fan-ring unit structure surrounding the third ring, with gaps provided between the circular patch, the continuous third ring, and the fan-ring unit structure.

[0008] Preferably, the third ring is provided with a plurality of metallized short-circuit vias and a spiral patch, the metallized short-circuit vias perpendicularly penetrating the dielectric substrate, and the top of the metallized short-circuit vias being connected to the third ring through the spiral patch.

[0009] Preferably, a plurality of butterfly-shaped gaps are evenly arranged along the circumference of the third ring. The butterfly-shaped gaps are configured as an axisymmetric structure, and their shape is two right triangles whose vertices are connected.

[0010] Preferably, the circular patch includes a first ring and a second ring, with a ring gap provided between the first ring and the second ring.

[0011] Preferably, the top of the power supply structure is connected to the first ring.

[0012] Preferably, the power supply structure is a conical stepped gradient structure, with its cross-sectional radius increasing continuously in a stepped manner from the lower end connecting the coaxial power supply connector to the upper end connecting the metasurface patch.

[0013] Preferably, the antenna operates in a frequency band of 2 GHz to 18 GHz, and the voltage standing wave ratio (VSWR) is less than 3 within the operating frequency band.

[0014] Preferably, the cross-sectional height of the antenna in the direction perpendicular to the metal ground plane is 0.077 times the wavelength corresponding to the lowest operating frequency, and its overall lateral dimension is 0.53 times the square of the wavelength corresponding to the lowest operating frequency.

[0015] The beneficial effects of this invention are as follows:

[0016] This invention fundamentally achieves low profile and planarization of the antenna by employing an integrated architecture of a single-layer dielectric substrate with a centrally symmetric metasurface patch and a bottom metal ground plane, facilitating fabrication and conformal integration. Building upon this, a peripheral composite inductive loading structure is introduced. By integrating metallized short-circuit vias and helical microstrip connectors around the metasurface, the equivalent electrical length of the antenna is significantly increased without increasing the physical size, thus achieving effective electrical miniaturization and overcoming the challenge of reducing the lateral dimensions of traditional omnidirectional antennas under low profile constraints. More importantly, by reconstructing the radiating patch and introducing specific types of gaps in key areas and adjusting the element spacing, this design cleverly suppresses high-order mode interference induced by miniaturization and broadband, thereby achieving stable and excellent horizontal omnidirectional radiation characteristics over the ultra-wideband range and solving the high-frequency pattern distortion problem commonly found in broadband low-profile antennas. Simultaneously, the unique conical stepped gradient feed structure and the synergistic design of the metasurface elements achieve smooth impedance matching and broadband coverage from the feed line to the radiator, ensuring efficient transmission of ultra-wideband signals. Ultimately, the organic combination of these technical means produced an unexpected synergistic effect, enabling the present invention to simultaneously and successfully solve several mutually restrictive technical challenges such as miniaturization, low profile, ultra-wideband and stable omnidirectional radiation within a single, compact physical structure, and achieve a significant improvement in overall performance.

[0017] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing embodiments of the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a top view schematic diagram of the miniaturized low-profile horizontal omnidirectional ultrawideband electromagnetic metasurface antenna structure described in an embodiment of the present invention;

[0020] Figure 2 This is a side view schematic diagram of the miniaturized low-profile horizontal omnidirectional ultrawideband electromagnetic metasurface antenna structure described in the embodiment of the present invention;

[0021] Figure 3This is a bottom view of the miniaturized low-profile horizontal omnidirectional ultrawideband electromagnetic metasurface antenna structure described in this embodiment of the invention.

[0022] Figure 4 for Figure 1 Enlarged view of point A in the middle;

[0023] Figure 5 This is a three-dimensional structural diagram of the power supply structure described in the embodiment of the present invention;

[0024] Figure 6 The 2GHz E-plane and H-plane radiation patterns of the miniaturized low-profile horizontal omnidirectional ultrawideband electromagnetic metasurface antenna structure described in this embodiment of the invention;

[0025] Figure 7 The 6GHz E-plane and H-plane radiation patterns of the miniaturized low-profile horizontal omnidirectional ultrawideband electromagnetic metasurface antenna structure described in this embodiment of the invention;

[0026] Figure 8 The E-plane and H-plane radiation patterns of the miniaturized low-profile horizontal omnidirectional ultrawideband electromagnetic metasurface antenna structure described in this embodiment of the invention are shown in the 10 GHz E-plane and H-plane.

[0027] Figure 9 The images show the 14GHz E-plane and H-plane radiation patterns of the miniaturized low-profile horizontal omnidirectional ultrawideband electromagnetic metasurface antenna structure described in this embodiment of the invention.

[0028] Figure 10 The images show the 18GHz E-plane and H-plane radiation patterns of the miniaturized low-profile horizontal omnidirectional ultrawideband electromagnetic metasurface antenna structure described in this embodiment of the invention.

[0029] In the figure: 1. Metal ground plane; 2. Dielectric substrate; 3. Power supply structure; 4. First ring; 5. Second ring; 6. Third ring; 7. Fan ring unit structure; 8. Metallized short-circuit via; 9. Spiral patch; 10. Butterfly slot. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0031] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this invention, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0032] Example 1:

[0033] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 , Figure 8 , Figure 9 and Figure 10 As shown, this embodiment provides a miniaturized low-profile horizontal omnidirectional ultrawideband electromagnetic metasurface antenna, including: a dielectric substrate 2, a metal ground plane 1, a metasurface patch, and a feeding structure 3. The metal ground plane 1 is disposed on the bottom surface of the dielectric substrate 2; the metasurface patch is disposed on the top surface of the dielectric substrate 2, and the metasurface patch is configured with a centrally symmetrical structure; the feeding structure 3 passes vertically through the dielectric substrate 2, the upper end of the feeding structure 3 is connected to the metasurface patch, and the lower end of the feeding structure 3 is electrically connected to the coaxial feed connector.

[0034] It is understood that this invention, by placing a metal ground plane 1 at the bottom of a substrate and printing a metasurface patch on the top, with the feed structure 3 vertically connecting them, naturally possesses low profile characteristics, making it easy to process and conformally integrate with modern mobile devices. The metasurface patch employs a centrosymmetric structure to geometrically ensure the rotational symmetry distribution of the excitation current, laying the physical foundation for achieving a stable horizontal omnidirectional radiation mode. This integrated design of "single-layer dielectric + symmetrical metasurface + vertical feed" fundamentally avoids the drawbacks of traditional implementations, such as high profile, complex processing, or difficult assembly, achieving a synergistic design of miniaturization, ultra-wideband, and omnidirectional radiation.

[0035] The dielectric substrate 2 has a dielectric constant of 2.2 and a loss tangent of 0.005.

[0036] It is understandable that this invention chooses a substrate with a dielectric constant of 2.2 as a balance between performance, cost, and process maturity. A relatively low dielectric constant helps reduce the confinement of electromagnetic waves by the medium, thereby lowering the antenna's quality factor. This is beneficial for extending the antenna's operating bandwidth, a fundamental requirement for achieving ultra-wideband (2-18 GHz) characteristics. Simultaneously, a dielectric constant of 2.2 is a typical value for commonly used PCB materials in RF circuits, readily available and easy to process. This invention sets the loss tangent to 0.005, indicating the selection of a low-loss dielectric material.

[0037] The metasurface patch includes an innermost circular patch, a third ring 6 surrounding the circular patch, and a fan-ring unit structure 7 surrounding the third ring 6. A gap is provided between the circular patch, the continuous third ring 6, and the fan-ring unit structure 7.

[0038] It is understood that this invention, through a three-layer layout of "circular patch - third ring 6 - fan-ring unit structure 7" with increasing dimensions from the inside out, can effectively excite multiple resonant modes operating at different frequencies within a limited lateral dimension. The gaps between the structural layers are not simple physical separations, but key coupling elements. The capacitive coupling effect generated by these gaps can bring the frequency points of the different resonant modes closer and effectively merge them, thereby forming a continuous and wide impedance bandwidth in the frequency domain. This is the structural basis for setting the antenna to operate in an ultra-wideband configuration from 2GHz to 18GHz. At the same time, this strictly rotationally symmetrical layout with the central patch as the core and the surrounding units geometrically ensures the symmetry of the excitation current distribution, providing fundamental support for obtaining a stable horizontal omnidirectional radiation pattern throughout the entire broadband band.

[0039] The third ring 6 is provided with a plurality of metallized short-circuit vias 8 and spiral patch 9. The metallized short-circuit vias 8 penetrate the dielectric substrate 2 vertically, and the top of the metallized short-circuit vias (8) is connected to the third ring (6) through the spiral patch (9).

[0040] It is understood that this invention constructs a highly efficient integrated loading network by connecting a spiral patch 9 on the third ring 6 to a metallized short-circuit via 8. The metallized short-circuit via 8 vertically penetrates the dielectric substrate 2 and connects to the bottom metal ground plane 1, equivalent to a parallel ground inductor. Simultaneously, the spiral patch 9 forms an extremely long, meandering current path in the plane, equivalent to a series distributed large inductor. The combined effect of these two inductance properties significantly increases the effective electrical length of the antenna without increasing its actual physical aperture. This design significantly lowers the low-frequency resonant point of the antenna, allowing it to maintain ultra-wideband performance (set to a low frequency starting at 2GHz) while employing a smaller lateral dimension, making it a key structure for achieving miniaturization.

[0041] Among them, a plurality of butterfly-shaped gaps 10 are evenly arranged along the circumference of the third ring 6. The butterfly-shaped gaps 10 are set as an axisymmetric structure, and their shape is two right triangles whose vertices are connected.

[0042] It is understood that when the antenna in this invention operates at higher frequencies, the miniaturized structures such as the peripheral metallized short-circuit vias can excite parasitic lateral currents, disrupting the rotational symmetry of the radiating structure, leading to distortion of the horizontal radiation pattern and deterioration of omnidirectional performance. The axisymmetric shape of the butterfly slot 10 (two right-angled triangles connected at their vertices) effectively cuts off and constrains these undesirable lateral current paths. By uniformly and periodically etching these slots, the symmetry of the high-frequency current distribution can be restored, thereby significantly suppressing higher-order mode interference and cross-polarization radiation, ensuring that the antenna outputs a stable omnidirectional beam from low to high frequencies (2-18 GHz). This is precisely the structural realization of "optimizing omnidirectional radiation characteristics" and "successfully suppressing interference from higher-order modes".

[0043] The circular patch includes a first ring 4 and a second ring 5, with a circular gap between the first ring 4 and the second ring 5.

[0044] It is understood that this invention aims to effectively enhance the energy coupling between the probe and the radiator by using a coupling annular slot etched on the top-layer central circular patch. This slot works in conjunction with the feed structure 3 (conical stepped gradient probe) to more finely adjust the equivalent impedance near the feed point. It particularly helps improve the impedance matching characteristics of the antenna in the low-frequency band, making the energy transfer from the feed line to the antenna radiator smoother near the starting frequency of the ultra-wideband (2-18 GHz), and is an important structure supporting the overall ultra-wideband performance.

[0045] The top of the power supply structure 3 is connected to the first ring 4.

[0046] It is understood that the connection point in this invention establishes the direct energy injection location. Connecting the top of the feed structure 3 to the central first ring 4 constitutes a standard center-feeding method. This geometrically centrally symmetrical feed point layout is most conducive to exciting the rotationally symmetrical fundamental mode of the metasurface patch, thereby ensuring the symmetry of the radiation current distribution from the source. This corresponds to the centrally symmetrical structure adopted by the entire metasurface patch and is one of the fundamental guarantees for obtaining a stable horizontal omnidirectional radiation pattern. At the same time, this connection point is also the physical interface for impedance transformation and energy transfer between the feed structure 3 (conical stepped gradient structure) and the radiator, jointly serving to achieve ultra-wideband impedance matching from 2GHz to 18GHz.

[0047] The power supply structure 3 is a conical stepped gradient structure, and its cross-sectional radius increases continuously in a stepped manner from the lower end connected to the coaxial power supply connector to the upper end connected to the metasurface patch.

[0048] It is understood that the structure of this invention acts as a built-in broadband impedance transformer. The lower end of the feed structure 3 is connected to a standard coaxial feed line, and the upper end is connected to the input port of the metasurface patch. By designing it as a cone with a continuously increasing cross-sectional radius, a smooth, gradual transition in characteristic impedance is achieved from the lower end to the upper end. This design effectively disperses the concentrated impedance jumps caused by abrupt changes in physical dimensions (such as the coaxial inner core being directly connected to a planar radiator), distributing the matching process over an extended, gradual region. It greatly reduces impedance discontinuities, thereby achieving good impedance matching over an extremely wide frequency range (2-18 GHz), ensuring efficient signal energy transmission, and initially suppressing parasitic modes that may be triggered by structural abrupt changes.

[0049] The antenna operates in a frequency band of 2 GHz to 18 GHz, and its voltage standing wave ratio (VSWR) is less than 3 within the operating frequency band.

[0050] It is understandable that these two indicators of the present invention directly and quantitatively verify the final effectiveness of the synergistic work of the aforementioned structural designs (such as graded feed optimization matching, composite loading to achieve miniaturization, etc.). Setting the frequency to 2GHz to 18GHz means that the antenna has an extremely high frequency ratio (up to 9:1), which meets the definition of ultra-wideband, enabling it to be compatible with and adapt to various wireless communication protocols and frequency bands from low to high frequencies, and possessing the potential to operate in complex electromagnetic environments. Simultaneously, maintaining a voltage standing wave ratio (VSWR) of less than 3 throughout the entire ultra-wideband indicates that good impedance matching has been achieved between the antenna and the feed system, with most of the input energy being effectively radiated rather than reflected back. This ensures the antenna's radiation efficiency and signal transmission quality throughout its operating range.

[0051] The antenna's cross-sectional height in the direction perpendicular to the metal ground plane 1 is 0.077 times the wavelength corresponding to the lowest operating frequency, and its overall lateral dimension is 0.53 times the square of the wavelength corresponding to the lowest operating frequency.

[0052] It is understood that the profile height of this invention is 0.077 times the wavelength corresponding to the lowest operating frequency, and the antenna is extremely thin in the direction perpendicular to the metal ground plane 1, which is a typical low-profile design. This fully meets the urgent needs of modern mobile communication devices, drones, and other platforms for low-profile antennas that are easy to conformally integrate. At the same time, the fact that "the overall lateral dimension is 0.53 times the square of the wavelength corresponding to the lowest operating frequency" indicates that the area occupied by the antenna on the plane is also controlled within a very compact range. The combination of these two factors means that while achieving ultra-wideband performance covering 2GHz to 18GHz and stable omnidirectional radiation, this antenna successfully overcomes the contradiction between bandwidth, size, and profile height in traditional antenna design, providing a feasible solution for deploying high-performance antennas in extremely space-constrained situations.

[0053] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0054] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A miniaturized, low-profile, horizontally omnidirectional, ultrawideband electromagnetic metasurface antenna, characterized in that, include: Dielectric substrate (2); Metal ground plane (1), the metal ground plane (1) is disposed on the bottom surface of the dielectric substrate (2); Metasurface patch, wherein the metasurface patch is disposed on the upper top surface of the dielectric substrate (2), and the metasurface patch is configured with a centrally symmetrical structure; The power supply structure (3) passes vertically through the dielectric substrate (2), the upper end of the power supply structure (3) is connected to the metasurface patch, and the lower end of the power supply structure (3) is electrically connected to the coaxial power supply connector.

2. The miniaturized low-profile horizontal omnidirectional ultrawideband electromagnetic metasurface antenna according to claim 1, characterized in that... The dielectric constant of the dielectric substrate (2) is 2.2 and the loss tangent is 0.

005.

3. The miniaturized low-profile horizontal omnidirectional ultrawideband electromagnetic metasurface antenna according to claim 1, characterized in that... The metasurface patch includes an innermost circular patch, a third ring (6) surrounding the circular patch, and a fan-ring unit structure (7) surrounding the third ring (6). A gap is provided between the circular patch, the continuous third ring (6), and the fan-ring unit structure (7).

4. The miniaturized low-profile horizontal omnidirectional ultrawideband electromagnetic metasurface antenna according to claim 3, characterized in that... The third ring (6) is provided with a plurality of metallized short-circuit vias (8) and spiral-shaped patches (9). The metallized short-circuit vias (8) penetrate the dielectric substrate (2) vertically, and the top of the metallized short-circuit vias (8) is connected to the third ring (6) through the spiral-shaped patches (9).

5. The miniaturized low-profile horizontal omnidirectional ultrawideband electromagnetic metasurface antenna according to claim 3, characterized in that... Multiple butterfly-shaped gaps (10) are evenly arranged along the circumference of the third ring (6). The butterfly-shaped gaps (10) are set as an axisymmetric structure, and their shape is two right triangles with their vertices connected.

6. The miniaturized low-profile horizontal omnidirectional ultrawideband electromagnetic metasurface antenna according to claim 3, characterized in that... The circular patch includes a first ring (4) and a second ring (5), and a ring gap is provided between the first ring (4) and the second ring (5).

7. The miniaturized low-profile horizontal omnidirectional ultrawideband electromagnetic metasurface antenna according to claim 6, characterized in that... The top of the power supply structure (3) is connected to the first ring (4).

8. The miniaturized low-profile horizontal omnidirectional ultrawideband electromagnetic metasurface antenna according to claim 1, characterized in that... The power supply structure (3) is a conical stepped gradual structure, and its cross-sectional radius increases continuously in a stepped manner from the lower end of the coaxial power supply connector to the upper end of the metasurface patch.

9. The miniaturized low-profile horizontal omnidirectional ultrawideband electromagnetic metasurface antenna according to claim 1, characterized in that... The antenna's operating frequency band is set to 2GHz to 18GHz, and the voltage standing wave ratio is less than 3 within the operating frequency band.

10. The miniaturized low-profile horizontal omnidirectional ultrawideband electromagnetic metasurface antenna according to claim 1, characterized in that... The antenna's cross-sectional height in the direction perpendicular to the metal ground plane (1) is 0.077 times the wavelength corresponding to the lowest operating frequency, and its overall lateral dimension is 0.53 times the square of the wavelength corresponding to the lowest operating frequency.

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