Filtering antenna with broadband harmonic suppression characteristic

Abstract

The invention provides a filtering antenna with broadband harmonic suppression characteristics. The antenna provided by the invention comprises a metal floor, a first dielectric substrate, a second dielectric substrate, a metal radiation patch, a metal coupling patch, a plurality of short-circuit metal columns, a feed structure and a plurality of supporting structures, the metal floor is arranged on the lower surface of the first dielectric substrate; the second dielectric substrate is arranged above the first dielectric substrate; the first dielectric substrate and the second dielectric substrate are connected through a plurality of supporting structures; a metal radiation patch is arranged on the upper surface of the first dielectric substrate; a metal coupling patch is arranged on the upper surface of the second dielectric substrate; the lower end of each short-circuit metal column is connected with the metal floor, and the upper end of each short-circuit metal column passes through the first dielectric substrate and is connected with the metal radiation patch. The antenna provided by the invention not only has steep radiation gain filtering response, but also can realize a good harmonic suppression effect in a relatively wide frequency band outside a high-frequency band, and can be used as a preferable scheme of an anti-interference communication antenna.

Description

Technical Field

[0001] This application relates to the field of antenna technology, and relates to a filtering antenna with broadband harmonic suppression characteristics. Background Art

[0002] In the prior art, the design of antennas with out-of-band selection characteristics mostly involves introducing a filter structure into the feeder of the antenna, and obtaining the filtering effect of the antenna radiation gain through the cascade of the filter and the antenna radiator. Generally, when a power amplifier or other non-linear components in a wireless communication system are driven by high-power or non-linear signals, a series of harmonic signals will be generated. These harmonic signals are integer multiples of the original signal frequency and will extend to the frequency bandwidth used by the system. If these harmonic signals are not effectively suppressed, they may introduce interference, resulting in spectrum pollution and communication interference. Therefore, designing a filtering antenna with broadband harmonic suppression characteristics based on traditional filtering antennas can meet the requirements of current and future filtering antennas for radio frequency front-end systems.

[0003] For example, the Chinese patent, publication number: CN117543193A, "A decoupling filtering antenna", is essentially a microstrip antenna fed by slot coupling, and its filtering function is realized by adding short-circuit metal posts on the first dielectric substrate and the second dielectric substrate. In the specific implementation of this patent, it is recorded that decoupling between different filtering antenna units can be achieved, thereby obtaining good performance such as radiation pattern and efficiency. However, this antenna has two patch antenna units, and its physical size is relatively large.

[0004] The Chinese patent, publication number: CN115275603B, "A microstrip filtering antenna based on feeding stub", is essentially using the electromagnetic distribution of the microstrip antenna, using point coupling between adjacent radiation planes, introducing a radiation zero at the upper edge of the passband, and at the same time using the feeding stub of the antenna, introducing a radiation zero at the lower edge of the passband, and finally realizing the integrated design of the filtering antenna. In the specific implementation of this patent, it is recorded that the operating frequency range of the antenna is 2.25 GHz - 2.47 GHz, and the operating bandwidth of the antenna is relatively narrow.

[0005] The Chinese patent, publication number: CN219321623U, "Broadband patch filtering antenna and wireless communication device", this antenna has a three-layer structure, including a dielectric substrate, a radiation patch, a parasitic patch, an upper feeding stub, a lower feeding stub, a metal floor, and short-circuit metal posts. In the specific implementation of this patent, it is recorded that in the frequency band of 2.11 GHz - 3.06 GHz, the operating bandwidth of the antenna can reach 36.8%, but this antenna has a three-layer structure as a whole, and the height of the antenna physical size is relatively high.

[0006] Chinese Patent, Publication No.: CN206225549U, "A Pyramidal Horn Filter Antenna Based on Waveguide Structure", its filtering function is realized by multiple rectangular microwave resonators, and the antenna is used as the last stage to realize the radiation of electromagnetic energy. In this patent, the operating bandwidth of the antenna is relatively narrow. In the specific implementation of this patent, it is recorded that the relative bandwidth of the antenna is only 2.4%, and the polarization mode is relatively single.

[0007] Chinese Patent, Publication No.: CN108258405B, "A Pattern Reconfigurable Filter Antenna", its essence is a planar microstrip filter. The filtering function and the control of the radiation pattern are achieved by controlling the stubs on the feeder line, the multimode resonator, and the coupling between the feeder line and the antenna. In the specific implementation of this patent, it is recorded that when the antenna operates at 5.2 GHz, the impedance bandwidth is 25%. In the design of another part of the antenna, the filtering structure of the feeder line is combined with the band-stop characteristic of the antenna itself to obtain the overall filtering effect of the antenna.

[0008] Chinese Patent, Publication No.: CN109904613B, "A Differential Dual-Band Dual-Polarized Antenna Applied to 5G sub 6G Base Station System", its essence is to introduce band-stop stubs on the feeder line, and to form a dual-band dual-polarized filtering effect through the radiation null points between the two frequency bands generated by the antenna itself. However, the introduction of the feeder line increases the overall insertion loss of the antenna, which is not conducive to the effective radiation of the antenna.

[0009] Chinese Patent, Publication No.: CN111293413B, "Compact Wideband Filter Antenna Based on Cross-Coupling Structure", the radiation null points of the antenna are achieved by controlling the stubs on the feeder line, the slots on the ground plane, and the U-shaped coupling patches respectively, and then a gain filtering effect is obtained. However, in the specific implementation of this patent, it is recorded that the relative operating bandwidth of this antenna is only 20.6%, and the polarization form is relatively single at the same time.

[0010] It can be seen that in the above several antennas, the size of the antenna itself has increased by introducing a filter-like structure into the feeder line, the bandwidth is not very ideal, and most antennas do not pay attention to the harmonic suppression effect in a relatively wide frequency band. Generally speaking, they are not suitable as the preferred solution for a filter antenna with harmonic suppression characteristics. In order to further improve the wideband anti-interference performance of the filter antenna, it is necessary to design a filter antenna with broadband harmonic suppression characteristics to meet the requirements of frequency-domain anti-interference in future wireless communication applications. Summary of the Invention

[0011] To solve the problem that the existing filtering antenna has a narrow radiation gain suppression frequency band, the present application provides a filtering antenna with broadband harmonic suppression characteristics. This antenna not only has a steep radiation gain filtering response, but also can achieve good harmonic suppression effects within a relatively wide frequency band outside the high-frequency band.

[0012] To achieve the above object, the antenna provided by the present application includes: a metal floor, a radiation patch, a dielectric substrate, short-circuit metal posts, and a feeding structure and a supporting structure. Among them, the metal floor is arranged on the lower surface of the first dielectric substrate; the second dielectric substrate is arranged above the first dielectric substrate; an air layer is provided between the first dielectric substrate and the second dielectric substrate; the first dielectric substrate and the second dielectric substrate are connected by a plurality of supporting structures; a metal radiation patch is provided on the upper surface of the first dielectric substrate; a metal coupling patch is provided on the upper surface of the second dielectric substrate; the lower end of each short-circuit metal post is connected to the metal floor, and the upper end of each short-circuit metal post respectively passes through the first dielectric substrate and is connected to the metal radiation patch; the feeding structure is used to transmit microwave signals to the metal radiation patch.

[0013] In the present application, the shape of the metal radiation patch is generally square, and can also be other shapes such as circular or fan-shaped, and is symmetric about the main polarization direction along the center. On the metal radiation patch, two symmetric slits are provided on the bottom edge closest to the feeding structure. The shape of the slit includes, but is not limited to, rectangular, bent, fan-shaped, arc-shaped, etc. The theoretical value of its overall length is 1 / 4 wavelength corresponding to the frequency at the minimum value point of the radiation gain outside the high-frequency band. This slit produces a radiation gain filtering effect and the effect of adjusting impedance matching.

[0014] In some implementation manners, the size of the metal coupling patch is generally smaller than that of the metal radiation patch; the vertical projections of the centers of the metal coupling patch and the metal radiation patch coincide to avoid the metal coupling patch blocking the metal radiation patch. Two symmetric slits are provided on one side of the metal coupling patch close to the bottom edge of the metal radiation patch. This slit produces a radiation gain filtering effect. The shape of the slit includes, but is not limited to, rectangular, bent, fan-shaped, arc-shaped, etc. The theoretical value of its overall length is 1 / 4 wavelength corresponding to the frequency at the minimum value point of the radiation gain outside the low-frequency band.

[0015] In some implementation manners, two symmetric slits are provided on one side of the metal coupling patch far from the bottom edge of the metal radiation patch. This slit extends from the farthest point from the metal coupling patch towards the center of the metal coupling patch. This slit produces a radiation gain filtering effect. The shape of the slit includes, but is not limited to, rectangular, bent, fan-shaped, arc-shaped, etc. The theoretical value of its overall length is 1 / 4 wavelength corresponding to the frequency at the minimum value point of the radiation gain outside the high-frequency band.

[0016] In some implementation manners, the short - circuit metal posts are symmetrically arranged with respect to the center line of the metal radiation patch; the vertical projection at the center of the short - circuit metal posts is located at the center position of the metal radiation patch; the number of the short - circuit metal posts is odd, generally 5 or 7, and there is at least one short - circuit metal post located at the center of the metal radiation patch and two symmetric short - circuit metal posts located at the outer edge of the metal radiation patch.

[0017] In some implementation manners, the feeding structure can adopt other feeding methods such as direct feeding with a coaxial cable or side feeding with a microstrip line. When using direct feeding with a coaxial cable, the inner core of the coaxial cable passes through the first dielectric substrate and is connected to the metal radiation patch arranged on the upper surface of the first dielectric substrate, and the outer skin of the coaxial cable is connected to the metal floor arranged on the lower surface of the first dielectric substrate, thereby forming a feeding port.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention prints a metal radiation patch on the first dielectric substrate and adds metal short - circuit posts, and prints a metal coupling patch on the second dielectric substrate and adds an edge slot, thereby generating a radiation gain zero point outside the working frequency band of the antenna, forming a better radiation gain filtering effect, and can solve the problem of harmonic signals that may interfere with wireless communication.

[0019] 2. The present invention adopts the method of printing a metal coupling patch on the upper - layer second dielectric substrate, which realizes the expansion of the working bandwidth of the antenna while reducing the lateral physical size of the antenna, and is beneficial to the miniaturization design requirements of the antenna.

[0020] 3. Compared with other forms of broadband filtering antennas, the antenna in the present invention has a stable radiation gain within the working frequency band, and also has the advantages of simple structure, easy processing, small volume, light weight, low cost, and easy maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a three - dimensional structure schematic diagram of the present invention; Figure 2 is a top - view of the lower - layer metal patch structure of the present invention; Figure 3 is a top - view of the upper - layer coupling patch of the present invention; Figure 4 is a side - view of the present invention; Figure 5 is a curve graph of the reflection coefficient of the antenna port varying with frequency; Figure 6 is a curve graph of the radiation gain of the antenna port varying with frequency; Figure 7 is the gain pattern of the antenna when operating at 3.5 GHz.

[0022] The meanings of the reference numerals are as follows: 1. First dielectric substrate; 2. Second dielectric substrate; 3. Metal radiation patch; 4. Outer short - circuit metal post; 5. Inner short - circuit metal post; 6. Metal coupling patch; 7. Support post; 8. Coaxial feeder; 9. Metal floor. Detailed implementation manners

[0023] To make the above - mentioned objects, features, and advantages of the present invention more obvious and understandable, the following will describe in detail the specific implementation manners of the present invention with reference to the accompanying drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0024] In the following description, many specific details are set forth to facilitate a thorough understanding of the present invention. However, the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar generalizations without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0025] Meanwhile, in the description of the present invention, it should be noted that the orientation or positional relationships indicated by terms such as "upper, lower, inner, and outer" are based on the orientation or positional relationships shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0026] Unless otherwise clearly defined and limited in the present invention, the terms "installation, connection, and coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection. Similarly, it can be a mechanical connection, an electrical connection, or a direct connection, or can be indirectly connected through an intermediate medium, or can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above - mentioned terms in the present invention can be understood according to specific situations.

[0027] This embodiment provides a filtering antenna with broadband harmonic suppression characteristics. Its three - dimensional structure, top - view structure, and side - view structure are as Figures 1-4 shown, including: 1 - First dielectric substrate; 2 - Second dielectric substrate; 3 - Metal radiation patch; 4 - Outer short - circuit metal post; 5 - Inner short - circuit metal post; 6 - Metal coupling patch; 7 - Support post; 8 - Coaxial feeder; 9 - Metal floor.

[0028] The first dielectric substrate 1 is arranged parallel above the metal floor 9; in this embodiment, the metal floor 9 has a length of 70 mm and a width of 70 mm, the dielectric constant of the first dielectric substrate 1 is 2.65, the length of the first dielectric substrate 1 is 70 mm, the width is 70 mm, and the thickness is 2 mm. There is no air gap between the first dielectric substrate 1 and the metal floor 9.

[0029] One metal coupling patch 6 is provided on the upper surface of the second dielectric substrate 2; in this embodiment, one metal coupling patch 6 is arranged in an irregular rectangular shape, with a length of 30 mm and a width of 30 mm; and four rectangular slots are opened on the metal coupling patch 6 to produce harmonic suppression and radiation gain filtering effects.

[0030] One metal radiation patch 3 is provided on the upper surface of the first dielectric substrate 1; in this embodiment, one metal radiation patch 3 is arranged in an irregular rectangular shape, with a length of 30 mm and a width of 34 mm; 5 inner short - circuit metal posts 5 and 2 outer short - circuit metal posts 4 are added on the metal radiation patch 3, the first dielectric substrate 1 and the metal floor 9 to produce radiation gain filtering effects.

[0031] In this embodiment, there are 7 short - circuit metal posts. The lower end of each short - circuit metal post is connected to the metal floor 9, and the upper end of each short - circuit metal post is respectively connected to the corresponding metal radiation patch 3. The outer skin of the coaxial feeder 8 is connected to the metal floor 9, and the inner core of the coaxial feeder 8 passes through the first dielectric substrate 1 and is connected to the metal radiation patch 3, thus forming a coaxial feeding port. Optionally, the feeding structure in this embodiment can also be changed to microstrip line side - feeding or other feeding schemes.

[0032] In this embodiment, both the metal radiation patch 3 and the metal coupling patch 6 are made of metal materials and are respectively arranged on the first dielectric substrate 1 and the second dielectric substrate 2 by printing or other means.

[0033] In this embodiment, the metal floor 9 is made of metal material; the first dielectric substrate 1 and the second dielectric substrate 2 can be any low - loss dielectric material. As a low - cost preference, F4B is used as the dielectric substrate material in this embodiment.

[0034] To verify the beneficial effects of the antenna of the present invention, the following further explanations are made through experimental simulations: 1. Simulation content Using simulation software, the port reflection coefficient, radiation gain curve of the above - mentioned implementation applied to a filtering antenna with broadband harmonic suppression characteristics are simulated and calculated.

[0035] 2. Simulation results Figure 5It is the reflection coefficient curve when the antenna in this embodiment is fed at the port. It can be seen that the bandwidth with the reflection coefficient of the antenna port less than -10 dB in this embodiment is 26.5% (3.05 - 3.98 GHz), which can cover a relatively wide 5G communication frequency band.

[0036] Figure 6 It is the radiation gain variation curve when the antenna in this embodiment is fed at the port. It can be seen that the gain of the antenna of the present invention within the operating frequency band is 8.2 ± 0.73 dBi. The gain fades significantly outside the operating frequency band, forming a better gain filtering effect and having an excellent suppression effect on the harmonics in the 4 - 10 GHz frequency band, including specific communication frequency bands such as n77 and n78 in the 5G frequency band. Due to this excellent performance, this antenna can be used as a preferred design solution for 5G anti-interference communication antennas.

[0037] Figure 7 It is the radiation pattern when the antenna in this embodiment operates at 3.5 GHz. It can be seen that the maximum radiation gain of the antenna at this frequency point is 8.0 dB, the 3dB beamwidth of the E-plane pattern is 65.6°, and the 3dB beamwidth of the H-plane pattern is 72.9°. The antenna has stable directional radiation characteristics in both main observation planes, verifying the superior performance of the antenna in the 5G frequency band.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A filtering antenna with broadband harmonic suppression characteristics, characterized in that: It includes a metal floor, a first dielectric substrate, a second dielectric substrate, a metal radiation patch, a metal coupling patch, a number of short - circuit metal posts, a feeding structure, and a number of support structures; the metal floor is disposed on the lower surface of the first dielectric substrate; the second dielectric substrate is disposed above the first dielectric substrate; an air layer is provided between the first dielectric substrate and the second dielectric substrate; the first dielectric substrate and the second dielectric substrate are connected by a number of support structures; the metal radiation patch is provided on the upper surface of the first dielectric substrate; the metal coupling patch is provided on the upper surface of the second dielectric substrate; the lower end of each short - circuit metal post is connected to the metal floor, and the upper end of each short - circuit metal post passes through the first dielectric substrate and is connected to the metal radiation patch respectively; the feeding structure is used to transmit microwave signals to the metal radiation patch.

2. The filtering antenna with broadband harmonic suppression characteristics according to claim 1, wherein: The shape of the metal radiation patch includes square, circular, trapezoidal, and fan - shaped, and is symmetric about the main polarization direction.

3. The filtering antenna with broadband harmonic suppression characteristics according to claim 1, wherein: On the metal radiation patch, two symmetric slits are provided on the bottom edge closest to the feeding structure, and these slits produce the effects of radiation gain filtering and impedance matching adjustment. The shape of these slits includes rectangular, bent, fan - shaped, and arc - shaped.

4. A filtering antenna with broadband harmonic suppression characteristics according to claim 1, characterized in that: The size of the metal coupling patch is smaller than that of the metal radiation patch; the vertical projection of the center point of the metal coupling patch coincides with that of the metal radiation patch.

5. A filtering antenna with broadband harmonic suppression characteristics according to claim 1, characterized in that: On the side of the metal coupling patch close to the bottom edge of the metal radiation patch, two symmetric slits are provided, and these slits produce the effect of radiation gain filtering. The shape of these slits includes rectangular, bent, fan - shaped, and arc - shaped.

6. The filtering antenna with broadband harmonic suppression characteristics according to claim 1, wherein: On the side of the metal coupling patch far from the bottom edge of the metal radiation patch, two symmetric slits are provided, and these slits extend from the farthest point from the metal coupling patch towards the center of the metal coupling patch, and these slits produce the effect of radiation gain filtering. The shape of these slits includes rectangular, bent, fan - shaped, and arc - shaped.

7. A filtering antenna with broadband harmonic suppression characteristics according to claim 1, characterized in that: The short - circuit metal posts are symmetrically arranged about the mid - line of the metal radiation patch; the vertical projection at the center of the short - circuit metal posts is located at the center position of the metal radiation patch; the number of short - circuit metal posts is odd, and there is at least one short - circuit metal post located at the center of the metal radiation patch and two symmetric short - circuit metal posts located at the outer edge of the metal radiation patch.

8. A filtering antenna with broadband harmonic suppression characteristics according to claim 1, characterized in that: The forms of the feeding structure include coaxial cable direct feeding and microstrip line side feeding; When using coaxial cable direct feeding, the inner core of the coaxial cable passes through the first dielectric substrate and is connected to the metal radiation patch provided on the upper surface of the first dielectric substrate, and the outer skin of the coaxial cable is connected to the metal floor provided on the lower surface of the first dielectric substrate, thereby forming a feeding port.

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