Anti-interference high-selectivity omnidirectional planar filtering antenna, filtering processing method and application

Abstract

The invention relates to an anti-interference high-selectivity omnidirectional planar filtering antenna, a filtering processing method and application, and the planar filtering antenna comprises a metal radiation layer, a first dielectric substrate, a first coupling layer, a second dielectric substrate and a second coupling layer which are sequentially stacked. The second dielectric substrate is provided with a plurality of metalized through holes which are distributed in an annular array mode and define a substrate integrated cavity with the first coupling layer and the second coupling layer, the metalized through holes divide the second coupling layer into an inner side patch and an outer side ring piece, and the inner side patch is evenly provided with a plurality of resonance grooves; and a feed probe penetrating and extending to the second dielectric substrate is arranged at the center of the bottom of the metal radiation layer. According to the invention, the substrate integrated waveguide technology is adopted, the substrate integrated cavity is formed, and a high-selectivity filtering effect is realized by utilizing the characteristic of high Q value, so that the interference of out-of-band signals is effectively inhibited, and the advantages of the patch antenna and the substrate integrated cavity are effectively combined.

Description

Technical Field

[0001] This invention relates to the field of antenna technology, and in particular to an anti-interference, highly selective omnidirectional planar filter antenna, a filtering method, and its application. Background Technology

[0002] With the rapid development of technologies such as 5G communication, the Internet of Things (IoT), and smart cities, mobile communication systems are facing unprecedentedly diverse service demands. Emerging application scenarios such as high-definition video transmission, industrial automation control, and vehicle-to-everything (V2X) networks place higher demands on the coverage, signal stability, and anti-interference performance of wireless devices. Against this backdrop, high-performance anti-interference antennas with both omnidirectional radiation and in-band and out-of-band filtering characteristics for smart meter communication have become a research hotspot. Omnidirectional antennas, with their 360-degree uniform coverage, can effectively solve the signal fluctuation problem caused by azimuth changes during user movement. Filtennas, by integrating the filtering circuit with the radiating element, can not only suppress out-of-band interference and reduce system noise, but also significantly reduce the insertion loss, size redundancy, and port coupling problems associated with traditional discrete filters. This innovative structure has significant engineering value for building high-density, low-latency communication base stations. While the design methods for unidirectional filtering antennas are relatively mature in existing research, most are difficult to directly apply to the design of omnidirectional filtering antennas. Therefore, designing an omnidirectional planar filtering antenna that combines structural and performance advantages remains a challenge.

[0003] Current mainstream research on omnidirectional filtering antennas mainly focuses on structures such as dielectric resonator antennas (DRA), monopole antennas, and patch antennas. Dielectric resonator antennas have an inherent advantage in broadband performance due to the high dielectric constant of their dielectric materials; however, traditional DRAs often require cylindrical or ring structures to achieve omnidirectional radiation, resulting in a profile height generally exceeding 0.15λ0 (λ0 is the wavelength of the dielectric at the center frequency), which is particularly prominent in the miniaturization trend of 5G millimeter-wave devices. Monopole antennas, with their inherent vertically polarized omnidirectional radiation characteristics, have an inherent advantage in low-profile design, but their frequency selectivity and out-of-band suppression levels still need improvement. Planar patch antennas, as the most mature form of microwave antenna, show unique potential in integrating filtering functions; however, traditional λ / 2 patch antennas are limited by their narrowband characteristics, with a typical bandwidth of only 3-5%. Although some studies have achieved bandwidth expansion and introduced filtering response through methods such as numerous slots, loading short-circuit pins, and defective structures, this obviously leads to a significant increase in structural complexity. Furthermore, the substrate integrated cavity employs a printed circuit board (PCB) fabrication technology similar to that of patch resonators, eliminating the need for the precision machining required for traditional waveguides, significantly reducing manufacturing costs. It combines the advantages of PCBs with low loss and high radiation efficiency. Therefore, researching how to combine the advantages of patch antennas and substrate integrated cavities is a practically feasible direction. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide an anti-interference, highly selective omnidirectional planar filter antenna, a filtering method and application, which has the advantages of strong anti-interference capability and excellent radiation and filtering performance.

[0005] To achieve the above and other related objectives, the present invention adopts the following technical solution:

[0006] According to a first aspect of the present invention, an anti-interference high-selectivity omnidirectional planar filter antenna is provided, comprising a metal radiating layer, a first dielectric substrate, a first coupling layer, a second dielectric substrate, and a second coupling layer arranged in sequence.

[0007] The second dielectric substrate has a plurality of metallized vias arranged in a ring array to form a substrate integrated cavity with the first coupling layer and the second coupling layer. The metallized vias divide the second coupling layer into an inner patch and an outer ring. The inner patch is uniformly provided with a plurality of resonant grooves.

[0008] A feed probe extending through to the second dielectric substrate is provided at the bottom center of the metal radiating layer. During the feeding process, the feed probe forms the substrate integrated cavity operating in TM01 mode and generates a first in-band resonant point and a lower sideband gain radiation zero point. The feed probe is also used to capacitively couple and excite the first coupling layer to form a TM02 resonant mode, and excite the outer ring to make the outer ring operate in half-TM02 mode and form a second in-band resonant point.

[0009] Furthermore, the outer ring can form a coupling effect with the first coupling layer to form an upper sideband gain radiation zero, and the operating excitation of the lower sideband gain radiation zero and the upper sideband gain radiation zero are both cross-coupled.

[0010] As a preferred embodiment of the invention, a via larger than the feed probe is formed on the metal radiating surface, and the feed probe passes through the via.

[0011] As a preferred embodiment of the invention, the first coupling layer is provided with a feed hole corresponding to the via, the feed probe passes through the feed hole, and a feed ring groove with a radius larger than the radius of the feed hole is provided outside the feed hole.

[0012] In a preferred embodiment of the invention, the length and width dimensions of the metal radiating layer, the first dielectric substrate, and the second dielectric substrate are all equal, and the length dimension L and the width dimension W both satisfy the following condition: 0.93λ c ≤L≤1.17λc 0.93λ c ≤W≤1.17λ c , where λ c The center frequency is the wavelength of the medium.

[0013] In a preferred embodiment of the invention, the first coupling layer and the second coupling layer are circles with the same radius, and the radii R3 of the first coupling layer and the radii R4 of the second coupling layer satisfy the following condition: 0.35λ c ≤R3= R4≤0.45λ c .

[0014] As a preferred embodiment of the invention, the resonant groove is an arc-shaped groove, and several of the resonant grooves are centrally symmetrical. Adjusting the size of the resonant groove can adjust the resonant frequency of the substrate integrated cavity in TM01 mode and the zero point of the lower sideband gain radiation.

[0015] As a preferred embodiment of the invention, the inner radius a and outer radius c of the arc-shaped groove respectively satisfy the following conditions: 0.12λ c ≤a≤0.19λ c 0.16λ c ≤c≤0.23λ c .

[0016] As a preferred embodiment of the invention, the inner arc length b1 and outer arc length b2 of the arc-shaped groove respectively satisfy the following conditions: 0.11λ c ≤b1≤0.21λ c 0.15λ c ≤b2≤0.25λ c .

[0017] The present invention discloses a second aspect of a filtering method for an anti-interference high-selectivity omnidirectional planar filter antenna as described in the first aspect, comprising:

[0018] During the feeding process, the feeding probe forms a substrate integrated cavity operating in TM01 mode between the first coupling layer, the metallized via, and the second coupling layer, and generates a first in-band resonant point and a lower sideband gain radiation zero point.

[0019] The feed probe capacitively excites the first coupling layer to form a TM02 resonant mode, and excites the outer ring to make the outer ring work in half-TM02 mode and form a second in-band resonant point.

[0020] The outer ring plate forms a coupling effect with the first coupling layer to form an upper sideband gain radiation zero. The operating excitation of both the lower sideband gain radiation zero and the upper sideband gain radiation zero is cross-coupled.

[0021] The third aspect of the present invention discloses the application of the anti-interference high-selectivity omnidirectional planar filter antenna as described in the first aspect in smart meter communication.

[0022] As described above, the present invention has the following beneficial effects:

[0023] This invention discloses an anti-interference, high-selectivity omnidirectional planar filter antenna, a filtering method, and its application. The omnidirectional planar filter antenna comprises a metal radiating layer, a first dielectric substrate, a first coupling layer, a second dielectric substrate, and a second coupling layer arranged in sequence. The metal radiating layer, the first coupling layer, and the second coupling layer are PCB board structures, requiring only simple processing to achieve good radiation and filtering performance. Utilizing the characteristics of the planar patch antenna's inherent resonant mode, combined with the loading of a substrate integrated cavity, a good filtering effect is achieved without introducing additional filtering circuitry. Compared to other designs with complex parasitic structures or feeding networks, this invention has significant processing advantages, lower costs, and only requires feeding through a simple feeding probe. The feeding structure is simple, occupies little space, and does not introduce additional losses. Furthermore, compared to ordinary patch antenna designs, this invention employs substrate integrated waveguide technology to form a substrate integrated cavity, utilizing its high Q value to achieve a highly selective filtering effect, thereby effectively suppressing out-of-band signal interference. This effectively combines the advantages of patch antennas and substrate integrated cavities. Attached Figure Description

[0024] Figure 1 The diagram shown is an exploded view of the anti-interference high-selectivity omnidirectional planar filter antenna in an embodiment of the present invention.

[0025] Figure 2 The image shown is a top view of the anti-interference high-selectivity omnidirectional planar filter antenna in an embodiment of the present invention.

[0026] Figure 3 The image shown is a top view of the first dielectric substrate and the first coupling layer in an embodiment of the present invention.

[0027] Figure 4 The image shown is a simulation diagram of the S-parameter curve of an anti-interference high-selectivity omnidirectional planar filter antenna, which is a specific example in an embodiment of the present invention.

[0028] Figure 5 The figure shown is a simulation diagram of the gain curve of an anti-interference high-selectivity omnidirectional planar filter antenna, which is a specific example in an embodiment of the present invention.

[0029] Figure 6 The image shown is a simulation diagram of the radiation efficiency curve of an anti-interference high-selectivity omnidirectional planar filter antenna, which is a specific example in an embodiment of the present invention.

[0030] Figure 7The image shown is a simulated radiation pattern at 3.5 GHz of an anti-interference high-selectivity omnidirectional planar filter antenna, which is a specific example in an embodiment of the present invention.

[0031] The numbers and letters in the diagram represent the names of the corresponding components:

[0032] 1. First dielectric substrate; 2. Second dielectric substrate; 3. Second coupling layer; 4. First coupling layer; 5. Metall radiating layer; 6. Feed probe; 7. Resonant groove; 8. Feed hole; 9. Feed ring groove; 10. Via; 11. Metallized through hole; 12. Inner patch; 13. Outer ring. Detailed Implementation

[0033] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0034] Please see Figures 1 to 3 The first aspect of this invention provides an anti-interference, high-selectivity omnidirectional planar filter antenna, with reference to... Figure 1 The coordinate direction shown includes a metal radiating layer 5, a first dielectric substrate 1, a first coupling layer 4, a second dielectric substrate 2, and a second coupling layer 3 arranged sequentially from bottom to top; the second dielectric substrate 2 is provided with a plurality of metallized vias 11 arranged in a ring array to form a substrate integrated cavity with the first coupling layer 4 and the second coupling layer 3, and the metallized vias 11 divide the second coupling layer 3 into an inner patch 12 and an outer ring 13, and a plurality of resonant grooves 7 are uniformly arranged on the inner patch 12; a feed probe 6 extending through to the second dielectric substrate 2 is provided at the bottom center of the metal radiating layer 5.

[0035] In this process, the feeding probe 6 forms a substrate integrated cavity operating in TM01 mode and generates a first in-band resonant point and a lower sideband gain radiation zero. The feeding probe 6 is also used to capacitively couple the first coupling layer 4 to form a TM02 resonant mode and to excite the outer ring 13 so that the outer ring 13 operates in half-TM02 mode and forms a second in-band resonant point. The outer ring 13 can form a coupling effect with the first coupling layer 4 to form an upper sideband gain radiation zero. The operating excitation of the lower sideband gain radiation zero and the upper sideband gain radiation zero is cross-coupled.

[0036] Specifically, TM stands for Toroidal Mode, which is a topological mode of the radiation pattern that describes the shape of the antenna's energy coverage on the horizontal plane (azimuth plane). TM01 mode refers to a single-ring mode or holographic mode, in which the radiated energy on the horizontal plane forms a uniform ring, with signal strength being basically consistent in all horizontal directions from 0° to 360°. TM02 mode refers to a dual-ring mode or dual-beam mode, in which the radiated energy in the horizontal direction forms two symmetrical lobes, resembling a figure-eight or bow, with the strongest signal in the two main directions of the lobes and a very weak signal in the vertical direction (null point). Half-TM02 mode refers to the original dual-beam state of TM02 mode, in which one lobe is suppressed or eliminated through physical blocking, wall / corner mounting, or the use of reflectors, so that only the remaining lobe is used for directional coverage.

[0037] It is understood that the centers of the metal radiating layer 5, the first dielectric substrate 1, the first coupling layer 4, the second dielectric substrate 2, and the second coupling layer 3 are located on the same axis. The feed probe 6 enters upward from the center of the metal radiating layer and extends to the second dielectric substrate 2. A via 10 with a size larger than the feed probe 6 is formed on the metal radiating surface. The feed probe 6 passes through the via 10 and does not contact the edge of the via 10. The via 10 is provided to prevent short circuits. Of course, corresponding holes need to be provided on the first dielectric substrate 1, the first coupling layer 4, and the second dielectric substrate 2 for the feed probe 6 to pass through.

[0038] In this embodiment, a feed hole 8 corresponding to the via 10 is provided on the first coupling layer 4. The feed probe 6 passes through the feed hole 8, and a feed ring groove 9 with a radius larger than the radius of the feed hole 8 is provided outside the feed hole 8. The feed ring groove 9 is used to realize the capacitive coupling excitation of the first coupling layer 4.

[0039] The length and width dimensions of the metal radiating layer 5, the first dielectric substrate 1, and the second dielectric substrate 2 are all equal. The length dimension L and the width dimension W both satisfy the following conditions: 0.93λc≤L≤1.17λc, 0.93λc≤W≤1.17λc, where λc is the wavelength of the center frequency dielectric. The first coupling layer 4 and the second coupling layer 3 are circles with the same radius. The radius R3 of the first coupling layer 4 and the radius R4 of the second coupling layer 3 satisfy the following condition: 0.35λc≤R3= R4≤0.45λc.

[0040] Preferably, the resonant slot 7 is an arc-shaped slot, and several resonant slots 7 are centrally symmetrical. Adjusting the size of the resonant slot 7 can adjust the resonant frequency and the lower sideband gain radiation zero point of the substrate integrated cavity in TM01 mode. In this embodiment, four resonant slots 7 are provided in a centrally symmetrical distribution. In other embodiments, more or fewer resonant slots 7 can be provided, such as 2-6.

[0041] The inner radius a and outer radius c of the arc groove satisfy the following conditions: 0.12λc≤a≤0.19λc, 0.16λc≤c≤0.23λc; the inner arc length b1 and outer arc length b2 of the arc groove satisfy the following conditions: 0.11λc≤b1≤0.21λc, 0.15λc≤b2≤0.25λc.

[0042] During operation, the metallized via 11 of the substrate integrated cavity is located at the weakest electric field position in the TM02 resonant mode formed by the first coupling layer 4, while the four resonant slots 7 are located on the inner side close to the metallized via 11. Combined with the combined boundary formed by the metallized via 11, the cylindrical substrate integrated cavity is directly fed through the feed probe 6 to obtain a first in-band resonant point and a lower sideband gain radiation zero point. By changing the size of the resonant slots 7, the resonant frequency and lower sideband gain radiation zero point of the substrate integrated cavity in the TM01 mode can be adjusted to meet the application requirements of different scenarios. The first coupling layer 4 is excited by the feed probe 6, and the capacitive coupling excitation of the first coupling layer 4 is achieved through the feed ring slot 9 on the first coupling layer 4, thereby obtaining an additional TM02 resonant mode in the band.

[0043] Furthermore, the feed probe 6 excites the outer ring plate 13 in the second coupling layer 3 through the first coupling layer 4 and the metallized via 11, causing the outer ring plate 13 to operate in half-TM02 mode and form a second in-band resonant point. Simultaneously, the outer ring plate 13 forms a coupling effect with the first coupling layer 4, creating an upper sideband gain radiation zero. The operating excitation of both the lower and upper sideband gain radiation zeros is cross-coupled. Taking the upper sideband gain radiation zero as an example, the outer ring plate 13 is loaded on the main coupling path of "feed-first coupling layer 4-free space," and a cross-coupled path of "feed-outer ring plate 13-free space" is added. There is a phase difference between these two paths. When the radiation generated by the two paths satisfies equal amplitude and out of phase, a gain radiation zero is generated.

[0044] The omnidirectional planar filter antenna of the present invention comprises a metal radiating layer 5, a first dielectric substrate 1, a first coupling layer 4, a second dielectric substrate 2, and a second coupling layer 3 arranged in sequence. The metal radiating layer 5, the first coupling layer 4, and the second coupling layer 3 are PCB board structures, which only require simple processing to achieve good radiation and filtering performance. Utilizing the characteristics of the resonant mode of the planar patch antenna itself, combined with the loading of the substrate integrated cavity, a good filtering effect is achieved without the need to introduce additional filtering circuits. Compared with other designs that load complex parasitic structures or feeding networks, it has significant processing advantages, lower cost, and only requires feeding through a simple feeding probe 6. With its simple structure and small footprint, this invention does not introduce additional losses. Furthermore, compared to ordinary patch antenna designs, this invention employs substrate integrated waveguide technology. By forming a substrate integrated cavity, its high Q value enables highly selective filtering, effectively suppressing out-of-band signal interference. This achieves an effective combination of the advantages of patch antennas and substrate integrated cavities. Additionally, by etching four centrally symmetrical resonant slots 7 in the second coupling layer 3, the resonant frequency and gain radiation null frequency of the substrate integrated cavity are significantly reduced. This combines the resonant frequency of the substrate integrated cavity with the resonant frequency of the first coupling layer 4, broadening the bandwidth and moving the gain radiation null to the lower edge of the passband.

[0045] A second aspect of the present invention provides a filtering method for an anti-interference high-selectivity omnidirectional planar filter antenna as described in the first aspect, comprising:

[0046] During the feeding process, the feed probe 6 forms a substrate integrated cavity operating in TM01 mode between the first coupling layer 4, the metallized via 11 and the second coupling layer 3, and generates a first in-band resonant point and a lower sideband gain radiation zero point. Under the direct excitation of the feed probe 6, the substrate integrated cavity operates in TM01 mode with the same omnidirectional radiation characteristics, and the excitation method is simpler.

[0047] S200, the feed probe 6 capacitively couples and excites the first coupling layer 4 to form a TM02 resonant mode, and excites the outer ring plate 13 to make the outer ring plate 13 work in half-TM02 mode and form a second in-band resonant point. Under the excitation of the feed probe 6, the first coupling layer 4 works in the TM02 mode with omnidirectional radiation characteristics. By placing a closed substrate integrated cavity in the electric field minimum region of the TM02 mode of the first coupling layer 4, a new resonant point and gain radiation zero point are introduced without affecting the resonant mode of the first coupling layer 4. At the same time, the feed probe 6 excites the outer ring plate 13 through the first coupling layer 4 and the metallized via 11 to obtain the outer ring plate 13 working in half-TM02 mode, and a new resonant point is generated in the band, further widening the bandwidth.

[0048] S300, the outer ring 13 and the first coupling layer 4 form a coupling effect to form an upper sideband gain radiation null. The working excitation of the lower sideband gain radiation null and the upper sideband gain radiation null is cross-coupled, and a new gain radiation null is generated in the upper sideband. Through the two gain radiation nulls of the upper and lower sidebands, the planar filter antenna has bandpass filtering characteristics.

[0049] The third aspect of the present invention provides the application of the anti-interference high-selectivity omnidirectional planar filter antenna as in the first aspect in smart meter communication. By replacing the existing communication antenna in the smart meter with the planar filter antenna of the present invention, the anti-interference performance can be effectively improved, and it has a wide impedance bandwidth, low omnidirectional non-circularity and excellent frequency selectivity.

[0050] The following is a detailed description of the interference-resistant, high-selectivity omnidirectional planar filter antenna of the present invention using a specific example, such as... Figure 1-7 As shown.

[0051] The interference-resistant, high-selectivity omnidirectional planar filter antenna in this embodiment includes a metal radiating layer 5, a first dielectric substrate 1, a first coupling layer 4, a second dielectric substrate 2, and a second coupling layer 3 stacked sequentially from bottom to top. The first dielectric substrate 1 has a thickness of 3 mm and is of Rogers 5880 type. The second dielectric substrate 2 has a thickness of 1.575 mm and is of Rogers 5880 type. The metal radiating layer 5 covers the lower surface of the first dielectric substrate 1. The first coupling layer 4 is located between the first dielectric substrate 1 and the second coupling layer 3. The second coupling layer 3 is located on the upper surface of the second dielectric substrate 2. The metal radiating layer 5, the first dielectric substrate 1, and the second dielectric substrate 2 are squares with equal length and width dimensions. The first coupling layer 4 and the second coupling layer 3 are circles with equal radii.

[0052] like Figure 2 As shown, a metal radiating layer 5 with a length L and a width W of 90 mm is covered on the lower surface of the first dielectric substrate 1. A via 10 with a radius of 2.175 mm is opened at the center of the metal radiating layer 5. A first coupling layer 4 with a radius R3 of 33 mm is opened on the upper surface of the first dielectric substrate 1. A feed hole 88 with a radius of 0.65 mm and a feed ring groove 9 with an inner radius of 2.1 mm and an outer radius of 2.8 mm are opened on the first coupling layer 4. The feed probe 6 extends to the second dielectric substrate 2 through the feed hole 8.

[0053] like Figure 3As shown, a plurality of periodically distributed metallized vias 11 are formed inside the second dielectric substrate 2. The first coupling layer 4, the metallized vias 11, and the second coupling layer 3 together form a closed substrate integration cavity. The inner radius R5 of the substrate integration cavity is 20.9 mm, the outer radius is 22.4 mm, and the diameter D of the metallized vias 11 is 1.5 mm. The center distance s between two adjacent metallized vias 11 is 2.26 mm. On the upper surface of the second dielectric substrate 2, there is a second coupling layer 3 with a radius R4 of 33 mm. The second coupling layer 3 contains four centrally symmetrical resonant grooves 7. The resonant grooves 7 are arc-shaped grooves, each with an inner radius a of 15 mm, an outer radius c of 19 mm, and a central angle of 50°.

[0054] The specific structural dimensions of each component of the anti-interference high-selectivity omnidirectional planar filter antenna in this embodiment are shown in the table below.

[0055] h1 (mm) 3 h2 (mm) 1.575 W (mm) 90 L (mm) 90 R1 (mm) 0.65 R2 (mm) 2.175 R3 (mm) 33 R4 (mm) 33 R5 (mm) 20.9 a (mm) 15 b1 (mm) 13.1 b2 (mm) 16.6 c (mm) 19 D (mm) 1.5 s (mm) 2.26 d1 (mm) 2.1 d2 (mm) 2.8

[0056] Where h1 and h2 are the thicknesses of the first dielectric substrate 1 and the second dielectric substrate 2, L and W are the length and width of the metal radiating layer 5, the first dielectric substrate 1 and the second dielectric substrate 2, R1 is the radius of the feed probe 6, R2 is the radius of the via 10 on the lower metal radiating layer 5, R3 is the radius of the first coupling layer 4, R4 is the radius of the second coupling layer 3, R5 is the radius of the substrate integrated cavity, a is the inner radius of the resonant groove 7, c is the outer radius of the resonant groove 7, b1 is the inner arc length of the resonant groove 7, b2 is the outer arc length of the resonant groove 7, D is the diameter of the metallized via 11, s is the hole spacing between adjacent metallized vias 11, d1 is the inner radius of the feed ring groove 9, and d2 is the outer radius of the feed ring groove 9.

[0057] In this invention, the first coupling layer 4 operates in the TM02 mode with omnidirectional radiation characteristics under the excitation of the feed probe 6. By placing a closed substrate integrated cavity in the minimum electric field region of the TM02 mode of the first coupling layer 4, a new resonant point and gain radiation zero point are introduced without affecting the resonant mode of the first coupling layer 4. This substrate integrated cavity operates in the TM01 mode with the same omnidirectional radiation characteristics under the direct excitation of the feed probe 6. By etching four rotationally symmetrical arc-shaped grooves in the second coupling layer 3, the resonant frequency and gain radiation zero point frequency of the substrate integrated cavity are significantly reduced, thereby merging the resonant frequency of the substrate integrated cavity with the resonant frequency of the first coupling layer 4. By combining these elements, the bandwidth is broadened, and the gain radiation null point is moved to the lower edge of the passband. In addition, by increasing the radius of the upper surface of the substrate integrated cavity, an outer ring plate 13 divided by a metallized via 11 is obtained. The feed probe 6 excites the outer ring plate 13 through the first coupling layer 4 and the metallized via 11, resulting in the outer ring plate 13 operating in half-TM02 mode. A new resonant point is generated in the band, further broadening the bandwidth. At the same time, due to the coupling effect between the outer ring plate 13 and the first coupling layer 4, a new gain radiation null point is generated in the upper sideband. Through the two gain radiation null points in the upper and lower sidebands, the planar filter antenna has bandpass filtering characteristics.

[0058] Figures 4-7 The simulation results are for this planar filter antenna. Figure 4 As can be seen, the antenna's -10dB |S11| perfectly covers the 5G n78 band (3.3-3.8 GHz); Figure 5 As can be seen, the antenna's highest gain is 5.6 dBi. The gain curve exhibits a bandpass filter response due to the two radiation nulls at the sidebands, and a significant rapid roll-off can be observed outside both operating frequency bands. Figure 6 It can be seen that the antenna has a maximum in-band radiation efficiency of 98% and a maximum out-of-band radiation efficiency of 4%; Figure 7 It can be seen that the antenna has an omnidirectional non-circularity of less than 1.2dB within the operating frequency band, and has stable omnidirectional radiation performance.

[0059] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A high-selectivity, interference-resistant omnidirectional planar filter antenna, characterized in that, It includes a metal radiating layer, a first dielectric substrate, a first coupling layer, a second dielectric substrate, and a second coupling layer arranged in sequence. The second dielectric substrate has a plurality of metallized vias arranged in a ring array to form a substrate integrated cavity with the first coupling layer and the second coupling layer. The metallized vias divide the second coupling layer into an inner patch and an outer ring. The inner patch is uniformly provided with a plurality of resonant grooves. A feed probe extending through to the second dielectric substrate is provided at the bottom center of the metal radiating layer. During the feeding process, the feed probe forms the substrate integrated cavity operating in TM01 mode and generates a first in-band resonant point and a lower sideband gain radiation zero point. The feed probe is also used to capacitively couple and excite the first coupling layer to form a TM02 resonant mode, and excite the outer ring to make the outer ring operate in half-TM02 mode and form a second in-band resonant point. Furthermore, the outer ring can form a coupling effect with the first coupling layer to form an upper sideband gain radiation zero, and the operating excitation of the lower sideband gain radiation zero and the upper sideband gain radiation zero are both cross-coupled.

2. The anti-interference high-selectivity omnidirectional planar filter antenna according to claim 1, characterized in that, A via larger than the feed probe is formed on the metal radiating surface, and the feed probe passes through the via.

3. The anti-interference high-selectivity omnidirectional planar filter antenna according to claim 2, characterized in that, The first coupling layer is provided with a feed hole corresponding to the via, the feed probe passes through the feed hole, and a feed ring groove with a radius larger than the radius of the feed hole is provided outside the feed hole.

4. The anti-interference high-selectivity omnidirectional planar filter antenna according to claim 1, characterized in that, The length and width dimensions of the metal radiating layer, the first dielectric substrate, and the second dielectric substrate are all equal, and the length dimension L and the width dimension W both satisfy the following condition: 0.93λ c ≤L≤1.17λ c 0.93λ c ≤W≤1.17λ c , where λ c The center frequency is the wavelength of the medium.

5. The anti-interference high-selectivity omnidirectional planar filter antenna according to claim 1, characterized in that, The first coupling layer and the second coupling layer are circles with the same radius. The radii R3 of the first coupling layer and R4 of the second coupling layer satisfy the following condition: 0.35λ c ≤R3= R4≤0.45λ c .

6. The anti-interference high-selectivity omnidirectional planar filter antenna according to claim 1, characterized in that, The resonant slot is an arc-shaped slot, and several of the resonant slots are centrally symmetrical. Adjusting the size of the resonant slot can adjust the resonant frequency of the substrate integrated cavity in TM01 mode and the zero point of the lower sideband gain radiation.

7. The anti-interference high-selectivity omnidirectional planar filter antenna according to claim 6, characterized in that, The inner radius *a* and outer radius *c* of the arc-shaped groove satisfy the following conditions: 0.12λ c ≤a≤0.19λ c 0.16λ c ≤c≤0.23λ c .

8. The anti-interference high-selectivity omnidirectional planar filter antenna according to claim 6 or 7, characterized in that, The inner arc length b1 and outer arc length b2 of the arc-shaped groove satisfy the following conditions respectively: 0.11λ c ≤b1≤0.21λ c 0.15λ c ≤b2≤0.25λ c .

9. The filtering method for an anti-interference high-selectivity omnidirectional planar filter antenna as described in any one of claims 1-8, characterized in that, include: During the feeding process, the feeding probe forms a substrate integrated cavity operating in TM01 mode between the first coupling layer, the metallized via and the second coupling layer, and generates a first in-band resonant point and a lower sideband gain radiation zero point. The feed probe capacitively excites the first coupling layer to form a TM02 resonant mode, and excites the outer ring to make the outer ring work in half-TM02 mode and form a second in-band resonant point. The outer ring plate forms a coupling effect with the first coupling layer to form an upper sideband gain radiation zero. The operating excitation of both the lower sideband gain radiation zero and the upper sideband gain radiation zero is cross-coupled.

10. The application of the anti-interference high-selectivity omnidirectional planar filter antenna as described in any one of claims 1-8 in smart meter communication.

Images