A broadband filtering electrically small dipole antenna based on evanescent wave coupling

Abstract

The application discloses a kind of broadband filtering electric small dipole antennas based on evanescent wave coupling, belong to filtering antenna technical field, including dipole unit, evanescent wave coupling unit and feed structure, dipole unit is set to evanescent wave coupling unit side, feed structure is set on dipole unit, there is air gap between dipole unit and evanescent wave coupling unit, dipole unit includes driven dipole unit and parasitic dipole unit, evanescent wave coupling unit includes rectangular waveguide and capacitive metasurface, rectangular waveguide left and right two sides are open, driven dipole unit and parasitic dipole unit are placed in the open face one end of rectangular waveguide, capacitive metasurface is placed in the open face other end of rectangular waveguide.The application uses the above-mentioned one kind of broadband filtering electric small dipole antennas based on evanescent wave coupling, while keeping miniaturization design, can realize wideband filtering and good omni-directional radiation performance.

Description

Technical Field

[0001] This invention relates to the field of filtered antenna technology, and in particular to a broadband filtered electric small dipole antenna based on evanescent wave coupling. Background Technology

[0002] In modern wireless communication systems, spectrum resources are becoming increasingly scarce, placing demands on antennas not only for efficient signal transmission and reception but also for in-band signal selectivity and out-of-band interference suppression. Filtered antennas, as key components integrating signal transmission and reception with interference filtering, can achieve frequency selection at the antenna end, thereby reducing reliance on traditional external filters. They have significant engineering application value, especially in high-density, complex electromagnetic environments, where their application prospects are very broad.

[0003] However, existing omnidirectional filtering dipole antennas inherently present a trade-off between miniaturization and broadband performance. On the one hand, to achieve electrically miniaturized design, the dipole size is constrained by physical limits, resulting in a high antenna quality factor and limited bandwidth. On the other hand, to obtain broadband filtering characteristics, it is usually necessary to add parasitic elements or introduce complex coupling structures, which not only increases the antenna size but may also affect its omnidirectional radiation characteristics. Therefore, traditional omnidirectional filtering dipole antennas struggle to achieve a balance between miniaturization, broadband filtering, and excellent omnidirectional radiation performance, limiting their widespread adoption and application in modern radio frequency systems, especially in space-constrained and highly integrated applications. Summary of the Invention

[0004] The purpose of this invention is to provide a broadband filtering electric dipole antenna based on evanescent wave coupling, which can achieve broadband filtering and good omnidirectional radiation performance while maintaining a miniaturized design.

[0005] To achieve the above objectives, the present invention provides a broadband filtered electrically small dipole antenna based on evanescent wave coupling, comprising a dipole element, an evanescent wave coupling element, and a feeding structure. The dipole element is disposed on one side of the evanescent wave coupling element, and the feeding structure is disposed on the dipole element. An air gap exists between the dipole element and the evanescent wave coupling element. The dipole element includes a driving dipole element and a parasitic dipole element. The evanescent wave coupling element includes a rectangular waveguide and a capacitive metasurface. The rectangular waveguide is open on both sides. The driving dipole element and the parasitic dipole element are placed at one end of the open surface of the rectangular waveguide, and the capacitive metasurface is placed at the other end of the open surface of the rectangular waveguide.

[0006] Preferably, the driving dipole unit and the parasitic dipole unit are connected through a dielectric substrate, the driving dipole unit is attached to the top layer of the dielectric substrate, the parasitic dipole unit is attached to the bottom layer of the dielectric substrate, and a gap is opened in the center of the driving dipole unit for the input of power supply energy.

[0007] Preferably, both the driving dipole unit and the parasitic dipole unit are Egyptian axe-electric small antenna structures, with the size of the parasitic dipole unit being smaller than that of the driving dipole unit.

[0008] Preferably, the driving dipole unit includes a driving dipole arm and driving dipole curved arms symmetrically arranged on the driving dipole arm, and longitudinal matching branches are symmetrically loaded on the driving dipole arm.

[0009] Preferably, the parasitic dipole unit includes a parasitic dipole arm and parasitic dipole curved arms symmetrically arranged on both sides of the parasitic dipole arm, wherein the curvature of the driving dipole curved arm is greater than the curvature of the parasitic dipole curved arm, and the width of the driving dipole curved arm is greater than the width of the parasitic dipole curved arm.

[0010] Preferably, the rectangular waveguide is located in the radiation direction of the driving dipole unit and the parasitic dipole unit, and is closer to the parasitic dipole unit. The four sides of the rectangular waveguide are composed of four metal plates.

[0011] Preferably, the capacitive metasurface includes a metal patch and a high dielectric constant substrate. The metal patch is attached to the high dielectric constant substrate, and one side of the metal patch is bonded to one open end of a rectangular waveguide. The metal patch is composed of multiple metal sheet units, which are arranged in an array, with gaps between adjacent metal sheet units.

[0012] Preferably, the length and width dimensions of the rectangular waveguide are the same as those of the high dielectric constant substrate of the capacitive metasurface, and the depth of the rectangular waveguide along the propagation direction is greater than the thickness of the dielectric substrate of the capacitive metasurface.

[0013] Preferably, the overall size of the antenna is within the range of electrical small size ka < 1.

[0014] Therefore, the broadband filtered electrically small dipole antenna based on evanescent wave coupling described above has the following beneficial effects: (1) The overall antenna structure design maintains the small electrical characteristics within the range of electrical small (ka<1). By utilizing the spatial coupling of dipoles with rectangular waveguides and capacitive metasurfaces, the physical size of the antenna is effectively compressed, achieving high integration, which is suitable for space-constrained application scenarios. (2) On the one hand, the parasitic dipole unit and the driving dipole unit adopt near-field resonance parasitic technology, which breaks through the limitations of small electrical strength and wide bandwidth. On the other hand, the structure of the dipole antenna provides the basic omnidirectional radiation characteristics for the overall radiation performance of the antenna, so that the antenna can achieve omnidirectional radiation on the radiation H-plane while significantly expanding the working bandwidth. (3) On the high-frequency side, the coupling between the driving dipole unit and the parasitic dipole unit forms a filter zero in the high-frequency region, thereby improving frequency selectivity; on the low-frequency side, the evanescent mode coupling between the rectangular waveguide and the capacitive metasurface achieves effective suppression of signals outside the low-frequency band and significantly improves the low-frequency roll-off coefficient. The high-frequency zero and the low-frequency roll-off work together to give the antenna excellent frequency selectivity, thereby achieving high-performance filtering effect.

[0015] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of an embodiment of a broadband filtered electrically small dipole antenna based on evanescent wave coupling according to the present invention; Figure 2 This is a view along the x-direction of a broadband filtered electric small dipole antenna based on evanescent wave coupling according to the present invention. Figure 3 This is a diagram of the electrically small driven dipole element of a broadband filtered electrically small dipole antenna based on evanescent wave coupling according to the present invention. Figure 4 This is a diagram of the electrically small parasitic dipole element of a broadband filtered electrically small dipole antenna based on evanescent wave coupling according to the present invention. Figure 5 This is a diagram of the evanescent wave coupling element of a broadband filtered electrically small dipole antenna based on evanescent wave coupling according to the present invention. Figure 6 The return loss and achievable gain curves of a broadband filtered electrically small dipole antenna based on evanescent wave coupling according to the present invention are shown in the figure. Figure 7 The E-plane and H-plane radiation patterns of a broadband filtered electrically small dipole antenna based on evanescent wave coupling at 2.5 GHz are shown in the present invention. Figure 8 The diagram shows the overall efficiency curve of a broadband filtered electric small dipole antenna based on evanescent wave coupling according to the present invention. Figure Labels 1. Dipole unit; 11. Driving dipole unit; 111. Matching stub; 112. Driving dipole bent arm; 113. Driving dipole arm; 12. Parasitic dipole unit; 121. Parasitic dipole bent arm; 122. Parasitic dipole arm; 13. Dielectric substrate; 2. Evanescent wave coupling unit; 21. Rectangular waveguide; 22. Capacitive metasurface; 221. Metal patch; 2211. Metal sheet unit; 2212. Gap; 222. High dielectric constant substrate; 3. Feed structure. Detailed Implementation

[0017] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0018] 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. 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.

[0019] Example like Figure 1-5 As shown, this invention provides a broadband filtered electrically small dipole antenna based on evanescent wave coupling, comprising a dipole element 1, an evanescent wave coupling element 2, and a feeding structure 3. The dipole element is disposed on one side of the evanescent wave coupling element 2, and the feeding structure 3 is disposed on the dipole element. There is a certain distance between the dipole element and the evanescent wave coupling element 2. h 2 The air gap 2212 is used for space energy coupling, and the size of the overall antenna structure is always within the electrically small (ka<1) size range.

[0020] The dipole unit includes a driving dipole unit 11 and a parasitic dipole unit 12. The driving dipole unit 11 and the parasitic dipole unit 12 are connected through a dielectric substrate “Rogers RT / duroid 5880 (tm)”. The driving dipole unit 11 is attached to the top layer of the dielectric substrate 13, and the parasitic dipole unit 12 is attached to the bottom layer of the dielectric substrate 13. A gap with a width of gap is opened in the center of the driving dipole unit 11 for loading a microstrip balun or other feeding structure 3. The parasitic dipole unit 12 and the driving dipole unit 11 adopt near-field resonance parasitic technology.

[0021] Both the driving dipole unit 11 and the parasitic dipole unit 12 are typical "Egyptian axe" electrically small structures, with the size of the parasitic dipole unit 12 being smaller than that of the driving dipole unit 11. The sizes of the driving dipole unit 11 and the parasitic dipole unit 12 are within the electrically small range (ka < 1).

[0022] The driving dipole unit 11 includes a driving dipole arm 113 and driving dipole curved arms 112 symmetrically arranged on the driving dipole arm 113. Longitudinal matching stubs 111 are symmetrically loaded on the driving dipole arm 113. The length of the driving dipole arm 113 is 2* R 1, width is w 1. The maximum bending arc of the driving dipole bending arm 112 is: α1, width is The length and width of the matched branch 111 are respectively and The electric field of the driving dipole unit 11 is ka = 0.78 (calculated at the lowest frequency when the driving dipole unit operates alone).

[0023] The parasitic dipole unit 12 includes a parasitic dipole arm 122 and parasitic dipole curved arms 121 symmetrically arranged on both sides of the parasitic dipole arm 122. The length of the parasitic dipole arm 122 is 2* R 3, width is w 2. The maximum bending arc of the parasitic dipole curved arm 121 is α 2, width is The outermost wall radius of parasitic dipole unit 12 is R 4 The curvature of the driving dipole bending arm 112 is greater than that of the parasitic dipole bending arm 121, and the width of the driving dipole bending arm 112 is greater than that of the parasitic dipole bending arm 121.

[0024] The dielectric substrate “Rogers RT / duroid 5880 (tm)” has a thickness of It has a flat cylindrical structure with a radius slightly larger than the outermost radius of the driving dipole unit 11. R 2.

[0025] The evanescent wave coupling unit 2 includes a rectangular waveguide 21 and a capacitive metasurface 22. The rectangular waveguide 21 is open on both the left and right sides. The driving dipole unit 11 and the parasitic dipole unit 12 are placed at one end of the open side of the rectangular waveguide 21, and the capacitive metasurface 22 is placed at the other end of the open side of the rectangular waveguide 21. Specifically, the rectangular waveguide 21 is located in the radiation direction of the driving dipole unit 11 and the parasitic dipole unit 12, and is closer to the parasitic dipole unit 12. The four sides of the rectangular waveguide 21 are composed of four metal plates.

[0026] The capacitive metasurface 22 includes a metal patch 221 and a high-dielectric-constant substrate “Rogers RT / duroid 6010 / 6010LM (tm)”. The metal patch 221 is attached to the high-dielectric-constant substrate 222, and the thickness of the high-dielectric-constant substrate 222 is [missing information]. The length and width are A×B. One side of the metal patch 221 is attached to one open end of the rectangular waveguide 21. The metal patch 221 is composed of multiple metal sheet units 2211, which are arranged in an array. The length and width of each metal sheet unit 2211 are... There is a gap 2212 between adjacent metal sheet units 2211, wherein the gap 2212 between laterally adjacent metal sheet units 2211 is... g1. The gap 2212 between adjacent horizontal metal sheet units 2211 is... g 2.

[0027] The length and width dimensions of the rectangular waveguide 21 are the same as those of the high dielectric constant substrate 222 of the capacitive metasurface 22, and the depth of the rectangular waveguide 21 along the propagation direction is greater than the thickness of the dielectric substrate of the capacitive metasurface 22.

[0028] In this embodiment, the rectangular waveguide 21 used has a cutoff frequency of 4.69 GHz and dimensions of [missing information]. A × B × C The rectangular waveguide 21 and the capacitive metasurface 22 form an evanescent wave coupling effect under the radiation feeding of the dipole unit 1, thereby improving the low-frequency gain roll-off.

[0029] The optimal dimensions of the antenna parameters of this invention, obtained through simulation optimization, are shown in Table 1. Table 1 Optimal Dimensions for Each Parameter

[0030] Based on the optimal dimensions for each parameter in Table 1, the performance of the designed antenna was simulated, and the simulation results are as follows: Impedance bandwidth and achievable gain, such as Figure 6 As shown, the antenna satisfies |S| within the frequency range of 2-2.92 GHz. 11 It has a matching performance of ≤-10dB, a relative bandwidth of 37.4%, a peak gain of 2.38dBi, good out-of-band rejection performance at low frequencies, and introduces a radiation null at high frequencies. Radiation pattern performance such as Figure 7 As shown, the E-plane radiation pattern exhibits a figure-eight pattern, and the H-plane radiation pattern demonstrates that the antenna has good omnidirectional radiation performance. Overall efficiency performance such as Figure 8 As shown, the overall in-band efficiency of the antenna is greater than 90%.

[0031] Therefore, the present invention employs a broadband filtering electrically small dipole antenna based on evanescent wave coupling, which achieves broadband filtering and good omnidirectional radiation performance while maintaining a miniaturized design, making it suitable for the needs of modern wireless communication systems for compact, high-performance filtering antennas.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A broadband filtering electrically small dipole antenna based on evanescent wave coupling, characterized by: It includes a dipole unit, an evanescent wave coupling unit, and a feeding structure. The dipole unit is disposed on one side of the evanescent wave coupling unit, and the feeding structure is disposed on the dipole unit. There is an air gap between the dipole unit and the evanescent wave coupling unit. The dipole unit includes a driving dipole unit and a parasitic dipole unit. The evanescent wave coupling unit includes a rectangular waveguide and a capacitive metasurface. The rectangular waveguide is open on both the left and right sides. The driving dipole unit and the parasitic dipole unit are placed at one end of the open surface of the rectangular waveguide, and the capacitive metasurface is placed at the other end of the open surface of the rectangular waveguide.

2. A broad band filtering electrically small dipole antenna based on evanescent wave coupling according to claim 1, characterized in that: The driving dipole unit and the parasitic dipole unit are connected through a dielectric substrate. The driving dipole unit is attached to the top layer of the dielectric substrate, and the parasitic dipole unit is attached to the bottom layer of the dielectric substrate. A gap is opened in the center of the driving dipole unit for the input of power supply.

3. A broad band filtering electrically small dipole antenna based on evanescent wave coupling according to claim 1, characterized in that: Both the driving dipole element and the parasitic dipole element are Egyptian axe-electric small antenna structures, with the parasitic dipole element being smaller than the driving dipole element.

4. A broad-band filtering electrically small dipole antenna based on evanescent- wave coupling according to claim 3, characterized in that: The driving dipole unit includes a driving dipole arm and a driving dipole curved arm symmetrically arranged on the driving dipole arm, and longitudinal matching branches are symmetrically loaded on the driving dipole arm.

5. A broad-band filtering electrically small dipole antenna based on evanescent- wave coupling according to claim 4, characterized in that: The parasitic dipole unit includes a parasitic dipole arm and parasitic dipole curved arms symmetrically arranged on both sides of the parasitic dipole arm. The curvature of the driving dipole curved arm is greater than the curvature of the parasitic dipole curved arm, and the width of the driving dipole curved arm is greater than the width of the parasitic dipole curved arm.

6. A broad-band filtering electrically small dipole antenna based on evanescent- wave coupling according to claim 1, characterized in that: The rectangular waveguide is located in the radiation direction of the driving dipole unit and the parasitic dipole unit, and is closer to the parasitic dipole unit. The four sides of the rectangular waveguide are composed of four metal plates.

7. A broad-band filtering electrically small dipole antenna based on evanescent- wave coupling according to claim 1, characterized in that: The capacitive metasurface includes a metal patch and a high dielectric constant substrate. One side of the metal patch is bonded to one open end of a rectangular waveguide. The metal patch is composed of multiple metal sheet units, which are arranged in an array with gaps between adjacent metal sheet units.

8. A broad-band filtering electrically small dipole antenna based on evanescent- wave coupling according to claim 7, characterized in that: The rectangular waveguide has the same length and width dimensions as the high dielectric constant substrate of the capacitive metasurface, and the depth of the rectangular waveguide along the propagation direction is greater than the thickness of the dielectric substrate of the capacitive metasurface.

9. A broad-band filtering electrically small dipole antenna based on evanescent- wave coupling according to claim 7, characterized in that: The overall size of the antenna is within the electrical small kA < 1 size range.

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