Balun structure and antenna

Abstract

The embodiment of the invention provides a balun structure and an antenna, and relates to the technical field of microwave radio frequency. The balun structure comprises a substrate, a first surface of the substrate is provided with a balun signal line, and a second surface of the substrate is provided with a metal patch used for forming a balun ground; the second surface is opposite to the first surface; wherein the balun signal line comprises a vertically arranged main signal line and at least one group of open circuit branches electrically connected with the main signal line, and each group of open circuit branches are symmetrically arranged relative to the main signal line. According to the balun structure and the antenna adopting the balun structure, the balun structure used for antenna low-frequency oscillator feed is improved, the main signal line is provided with at least one group of symmetrical open-circuit branches, and the open-circuit branches can be used for suppressing higher harmonics generated by the low-frequency oscillator in a high-frequency oscillator working band, so that the high-frequency oscillator feed efficiency is improved, and the high-frequency oscillator feed efficiency is improved. Therefore, the port isolation performance between frequency bands in the dual-band antenna is improved.

Description

Technical Field

[0001] This invention relates to the field of microwave radio frequency technology, and in particular to a balun structure and antenna. Background Technology

[0002] With the rapid development of mobile communication technology, factors such as Massive MIMO, new frequency bands, and the coexistence of 2G / 3G / 4G / 5G systems have led to a dramatic increase in the number of antennas in base stations. In order to efficiently utilize spectrum resources, optimize spatial layout, improve system capacity and performance, and reduce energy consumption and cost, multi-band, multi-array, common-aperture antennas have become the mainstream choice for base station antennas today.

[0003] Currently, antenna structures employing alternating high- and low-frequency antenna elements offer advantages such as high flexibility and structural simplicity, making them a future development trend for base station antennas. However, this type of dual-frequency antenna structure generates scattering current on the low-frequency element when the high-frequency element is excited. Since the high-frequency element operates within the higher harmonic band of the low-frequency element, the low-frequency element will generate harmonic interference to the high-frequency element, resulting in poor port isolation between frequency bands and causing a serious deterioration in antenna performance. Summary of the Invention

[0004] The purpose of this invention is to provide a balun structure and antenna to solve the problem of poor port isolation between frequency bands in dual-band antennas, caused by harmonic interference from the low-frequency vibrator to the high-frequency vibrator.

[0005] One embodiment of the present invention provides a balun structure, comprising:

[0006] A substrate having a balun signal line disposed on a first surface and a metal patch for forming a balun ground disposed on a second surface; the second surface is opposite to the first surface.

[0007] The balun signal line includes a vertically arranged main signal line and at least one set of open-circuit branches electrically connected to the main signal line, with each set of open-circuit branches being symmetrically arranged about the main signal line.

[0008] Optionally, in the balun structure, at least one annular groove is formed on the metal patch, and the orthographic projection of the annular groove on the first surface at least covers a portion of the open branch.

[0009] Optionally, in the balun structure, each set of open-circuit stubs includes two sub-stubs located on both sides of the main signal line. The sub-stubs include a connecting end connected to the main signal line and a curved end extending away from the main signal line, the curved end being separate from the main signal line.

[0010] Optionally, in the balun structure, the at least one set of open-circuit stubs includes a first set of open-circuit stubs and a second set of open-circuit stubs, the first set of open-circuit stubs and the second set of open-circuit stubs are arranged sequentially along a first direction, and the curved ends of the first set of open-circuit stubs extend and bend toward the direction of the second set of open-circuit stubs, and the curved ends of the second set of open-circuit stubs extend and bend toward the direction of the first set of open-circuit stubs; the first direction is a direction parallel to the main signal line.

[0011] Optionally, in the balun structure, the extension length of the curved end of the second set of open branches in the first direction is greater than the extension length of the curved end of the first set of open branches in the first direction.

[0012] Optionally, in the balun structure, the first group of open branches and the second group of open branches form a branch combination; along the first direction, in two adjacent branch combinations, the second group of open branches in the first branch combination is adjacent to the second group of open branches in the second branch combination.

[0013] Optionally, in the balun structure, multiple sets of open stubs are arranged sequentially in a first direction parallel to the main signal line, and the multiple sets of open stubs are symmetrical about a first straight line, the first straight line being perpendicular to the first direction.

[0014] Optionally, in the balun structure, the annular groove is either polygonal or circular.

[0015] Optionally, in the balun structure, the balun signal line further includes a branch signal line connected to one end of the main signal line, and the branch signal line and the main signal line are formed in an L-shape.

[0016] One embodiment of the present invention also provides an antenna, wherein the antenna includes the balun structure as described in any of the preceding claims.

[0017] Optionally, the antenna further includes:

[0018] Reflector;

[0019] A first antenna substrate is disposed above and parallel to the reflector, and at least two intersecting first dipoles are disposed on the first antenna substrate;

[0020] The balun structure is disposed between the reflector and the first antenna substrate for feeding the first dipole; the main signal line extends from the reflector to the first antenna substrate.

[0021] Optionally, the antenna further includes:

[0022] A plurality of second antenna substrates are disposed between the reflector and the first antenna substrate, each second antenna substrate having at least two intersecting second dipoles, the second antenna substrates being parallel to the first antenna substrate; the operating frequency of the first dipole is lower than the operating frequency of the second dipole.

[0023] Optionally, in the antenna, each of the first dipoles is respectively provided with one of the balun structures, the balun structures corresponding to the two first dipoles are arranged in a cross shape, and the open stubs on the two balun structures are symmetrical about the intersection line between the two balun structures.

[0024] Optionally, in the antenna, the balun signal line further includes a branch signal line connected to one end of the main signal line, wherein the branch signal line and the main signal line are located on opposite sides of the cross line.

[0025] At least one of the above technical solutions in the specific embodiments of the present invention has the following beneficial effects:

[0026] The balun structure and antenna using the balun structure described in this embodiment of the invention improve the balun structure used for feeding the low-frequency element of the antenna by setting at least one set of symmetrical open-circuit stubs on the main signal line. The open-circuit stubs can suppress the high-order harmonics generated by the low-frequency element in the operating frequency band of the high-frequency element, thereby improving the port isolation performance between the intermediate frequency bands of the dual-frequency antenna. Attached Figure Description

[0027] Figure 1 This is a top view of an antenna employing the balun structure described in an embodiment of the present invention;

[0028] Figure 2 A side view of an antenna employing the balun structure described in an embodiment of the present invention;

[0029] Figure 3 This is a schematic diagram of the structure of the two opposing surfaces of the balun structure described in the related art;

[0030] Figure 4 To adopt Figure 3 The simulation results curve of the balun structure are shown in the figure.

[0031] Figure 5 This is a schematic diagram of the structure of two opposing surfaces using the balun structure described in Embodiment 1 of the present invention;

[0032] Figure 6 To adopt Figure 5 The simulation results curve of the balun structure are shown in the figure.

[0033] Figure 7This is a schematic diagram of the two opposing surfaces of the balun structure described in Embodiment 2 of the present invention;

[0034] Figure 8 To adopt Figure 7 The simulation results curve of the balun structure are shown in the figure.

[0035] Figure 9 This is a schematic diagram of the structure of two opposing surfaces using the balun structure described in Embodiment 3 of the present invention;

[0036] Figure 10 To adopt Figure 9 The simulation results curve of the balun structure are shown in the figure.

[0037] Figure 11 This is a schematic diagram of the structure of the two opposing surfaces of the balun structure described in Embodiment 4 of the present invention;

[0038] Figure 12 To adopt Figure 11 The simulation results curve of the balun structure are shown in the figure.

[0039] Figure 13 This is a schematic diagram of the structure of two opposing surfaces using the balun structure described in Embodiment 5 of the present invention;

[0040] Figure 14 To adopt Figure 13 The simulation results curve of the balun structure are shown in the figure.

[0041] Figure 15 This is a schematic diagram of the structure of the two opposing surfaces of the balun structure described in Embodiment Six of the present invention;

[0042] Figure 16 To adopt Figure 15 The simulation results curve of the balun structure are shown in the figure.

[0043] Figure 17 This is a side view diagram of the antenna in an embodiment of the present invention, showing two balun structures arranged at an intersection. Detailed Implementation

[0044] 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. Based on the described embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "inner," "outer," "upper," and "lower" are used only to indicate relative positional relationships; these relative positional relationships may change accordingly when the absolute position of the described object changes.

[0046] To address the issue in dual-band antennas where the high-frequency vibrator operates within the high-order harmonic band of the low-frequency vibrator, causing harmonic interference and deteriorating port isolation between frequency bands, this invention provides a balun structure and an antenna employing this balun structure. By improving the balun structure used for feeding the low-frequency vibrator, at least one set of symmetrical open-circuit stubs is provided on the main signal line. These open-circuit stubs can suppress the high-order harmonics generated by the low-frequency vibrator within the high-frequency vibrator's operating frequency band, thereby improving the port isolation performance between the intermediate frequency bands of the dual-band antenna.

[0047] To clearly illustrate the specific implementation structure of the balun structure described in the embodiments of the present invention, the antenna using the balun structure described in the embodiments of the present invention will be described first.

[0048] Combination Figure 1 and Figure 2 As shown, in one embodiment, the antenna employing the balun structure described in the embodiments of the present invention includes:

[0049] Reflector 100;

[0050] A first antenna substrate 200 is disposed above and parallel to the reflector 100, and at least two intersecting first dipoles 210 are disposed on the first antenna substrate 200.

[0051] Multiple second antenna substrates 300 are disposed between the reflector 100 and the first antenna substrate 200. Each second antenna substrate 300 is provided with at least two intersecting second dipoles 310. The second antenna substrate 300 is parallel to the first antenna substrate 200. The operating frequency of the first dipole 210 is lower than the operating frequency of the second dipole 310.

[0052] In this configuration, both the first dipole 210 and the second dipole 310 are planar dipoles. At least two first dipoles 210 on the first antenna substrate 200 intersect and are perpendicular to each other, and at least two second dipoles 310 on the second antenna substrate 300 intersect and are perpendicular to each other, forming a ±45° dual-polarization configuration.

[0053] The second dipole 310 on each of the second antenna substrates 300 is formed as a high-frequency vibrator, optionally with an operating frequency range between 1690MHz and 2690MHz, and the first dipole 210 on each of the first antenna substrates 200 is formed as a low-frequency vibrator, optionally with an operating frequency range between 690MHz and 960MHz.

[0054] Multiple high-frequency vibrators are evenly arranged below the low-frequency vibrators and set under the same antenna aperture to form a dual-frequency common-aperture base station antenna.

[0055] Optionally, the first antenna substrate 200 and the second antenna substrate 300 are respectively plexiglass substrates.

[0056] In some embodiments, optionally, each second dipole 310 on the second antenna substrate 300 includes two radiating patches that are centrally symmetrical about the second antenna substrate 300. The radiating patches of the two second dipoles 310 are arranged in a grid pattern and are respectively attached to the lower surface of the second antenna substrate 300. A feed line is provided between the reflector 100 and the second antenna substrate 300 for feeding the second dipoles 310.

[0057] In some embodiments, optionally, each first dipole 210 on the first antenna substrate 200 includes two radiating patches that are centrally symmetrical about the first antenna substrate 200. The radiating patches of the two first dipoles 210 are arranged in a grid pattern and are respectively attached to the lower surface of the first antenna substrate 200. A balun structure 400 is provided between the reflector 100 and the first antenna substrate 200. Each first dipole 210 corresponds to one balun structure 400, which is electrically connected to the corresponding first dipole 210 and used to feed the corresponding first dipole 210. When there are two first dipoles 210, the balun structures 400 corresponding to the two first dipoles 210 are intersected and perpendicularly arranged.

[0058] In this embodiment of the invention, the structure and shape of the radiating patches on the first dipole 210 and the second dipole 310 may be the same or different. The antenna in this embodiment of the invention does not limit the structure and shape of the radiating patches.

[0059] In related technologies, such as Figure 3As shown, the balun structure 400 on the antenna includes an L-shaped balun signal line 412 located on the first surface 411 and a metal patch 414 located on the second surface 413, forming a balun ground. Simulation of a dual-band antenna using this balun structure 400 yields the following inter-band isolation curve: Figure 4 As shown, it can be seen that the inter-band isolation is greater than 15dB across the entire operating frequency range of the high-frequency vibrator. The low-frequency vibrator generates harmonic interference to the high-frequency vibrator, which cannot meet the port isolation performance requirements of the intermediate frequency band of the dual-frequency antenna.

[0060] In this embodiment of the invention, the balun structure has been improved, such as... Figure 5 As shown, in Embodiment 1, the balun structure 400 includes:

[0061] The substrate 410 has a balun signal line 412 disposed on its first surface 411 and a metal patch 414 for forming a balun ground disposed on its second surface 413; the second surface 413 is opposite to the first surface 411.

[0062] The balun signal line 412 includes a vertically arranged main signal line 4121 and at least one set of open-circuit stubs 4122 electrically connected to the main signal line 4121, with each set of open-circuit stubs 4122 being symmetrically arranged about the main signal line 4121.

[0063] By adopting this implementation structure, the balun structure used for feeding the low-frequency vibrator of the antenna is improved, and a set of symmetrical open-circuit stubs 4122 are set on the main signal line 4121. The open-circuit stubs 4122 can reduce the induced current generated on the low-frequency vibrator, thereby suppressing the high-order harmonics generated by the low-frequency vibrator in the operating frequency band of the high-frequency vibrator, thus improving the port isolation performance between the intermediate frequency bands of the dual-frequency antenna.

[0064] In embodiments of the present invention, such as Figure 5 As shown, the balun signal line 412 also includes a branch signal line 4123 connected to one end of the main signal line 4121, wherein the branch signal line 4123 and the main signal line 4121 form an L-shaped configuration.

[0065] In this configuration, the balun structures 400 corresponding to the two first dipoles 210 are arranged in a cross shape. Each balun structure 400 has a slot 420 in the middle part of its substrate 410. The two balun structures 400 are connected and interlocked at the slot 420 to achieve mutual cross-arrangement. The center line of the slot 420 forms the intersection line between the two balun structures 400.

[0066] The slot 420 divides the substrate 410 into two parts: a first plate 4101 and a second plate 4102. The main signal line 4121 is disposed on the first plate 4101, and the branch signal line 4123 is connected to the main signal line 4121 and extends to the second plate 4102.

[0067] Optionally, each set of open-circuit stubs 4122 includes two sub-stubs located on both sides of the main signal line 4121. The sub-stubs include a connecting end 41221 connected to the main signal line 4121 and a bent end 41222 extending away from the main signal line 4121. The bent end 41222 is separated from the main signal line 4121.

[0068] In some embodiments, optionally, at least one set of open-circuit stubs 4122 includes a first set of open-circuit stubs 41223 and a second set of open-circuit stubs 41224. The first set of open-circuit stubs 41223 and the second set of open-circuit stubs 41224 are arranged sequentially along a first direction a, and the bent end 41222 of the first set of open-circuit stubs 41223 extends and bends toward the second set of open-circuit stubs 41224, and the bent end 41222 of the second set of open-circuit stubs 41224 extends and bends toward the first set of open-circuit stubs 41223; the first direction a is a direction parallel to the main signal line 4121.

[0069] With this implementation structure, the first set of open branches 41223 and the second set of open branches 41224 are arranged with their curved ends facing each other.

[0070] In some embodiments, optionally, the extension length of the bent end of the second set of open branch 41224 in the first direction a is greater than the extension length of the bent end of the first set of open branch 41223 in the first direction a.

[0071] Combination Figure 5 As shown, in this embodiment, the extension length of the first group of open-circuit branches 41223 in the first direction a is less than the extension length of the second group of open-circuit branches 41224 in the first direction a. The sub-branches of the first group of open-circuit branches 41223 are formed in the shape of a "6", and the second group of open-circuit branches 41224 are formed in the shape of a "9". The two open-circuit branches with different shapes cooperate with each other to adjust the harmonic interference generated by the low-frequency oscillator on the high-frequency oscillator.

[0072] In some embodiments, optionally, the first group of open branches 41223 and the second group of open branches 41224 form a branch combination; at least two branch combinations are arranged sequentially along the first direction a. Optionally, in this embodiment, in two adjacent branch combinations, the second group of open branches 41224 in the first branch combination 11 is adjacent to the second group of open branches 41224 in the second branch combination 12.

[0073] With this implementation structure, multiple sets of open-circuit branches 4122 are arranged sequentially in the first direction a parallel to the main signal line 4121, and the multiple sets of open-circuit branches 4122 are symmetrical about the first straight line L, and the first straight line L is perpendicular to the first direction a.

[0074] In this first embodiment, combined with Figure 5 As shown, metal patches 414 are respectively disposed on the second surface 413 of the substrate 410, corresponding to the first plate 4101 and the second plate 4102. The metal patches 414 on the first plate 4101 and the second plate 4102 are formed as balun grounds. Using this embodiment, the low-frequency vibrator is fed by a coaxial to balun structure. The balun ground formed by the metal patches 414 is directly connected to the coupling stub, and coupled to the radiating surface on the lower surface of the first antenna substrate through the coupling stub, radiating from the radiating surface.

[0075] In this first embodiment, the balun signal line 412 and the balun terrain of the balun structure 400 become as follows: Figure 5 The structure shown is applied to the low-frequency element of a dual-band antenna. Simulations were performed on a dual-band antenna using this balun structure 400, and the resulting inter-band isolation curves of the dual-band antenna are shown below. Figure 6 As shown. According to Figure 6 It can be determined that the inter-band isolation is greater than 17dB across the entire operating frequency range of the high-frequency oscillator. In related technologies, the balun signal line 412 is formed as follows... Figure 3 The inter-band isolation curve of the dual-band antenna obtained when the L-shaped antenna is shown. Figure 4 In comparison, the isolation at most frequency points was improved. Therefore, the open stubs on the balun signal line have a certain effect on improving the inter-band isolation.

[0076] In Embodiment 2 of the present invention, as follows Figure 7 As shown, compared to Embodiment 1, in Embodiment 2, the open-circuit stub 4122 on the balun signal line 412 includes a first stub assembly 11 located at the top. That is, the open-circuit stub 4122 includes a first group of open-circuit stubs 41223 and a second group of open-circuit stubs 41224 arranged sequentially from top to bottom.

[0077] In this second embodiment, as Figure 7As shown, metal patches 414 are respectively disposed on the second surface 413 of the substrate 410, corresponding to the first plate 4101 and the second plate 4102. An annular groove 415 is formed on the metal patch 414 on the second surface 413. In this embodiment, to cooperate with the open-circuit stub 4122 disposed on the first surface 413 and to suppress the high-order harmonics generated by the low-frequency oscillator within the operating frequency band of the high-frequency oscillator, the position of the annular groove 415 corresponds to the position of the open-circuit stub 4122. That is, the orthographic projection of the annular groove 415 onto the plane (first surface 411) where the open-circuit stub 4122 is located at least partially covers the open-circuit stub 4122. In this embodiment of the invention, the open-circuit stub 4122 is located on the first surface 411 of the first plate 4101, and the annular groove 415 is formed on the metal patch 414 attached to the second surface of the first plate 4101.

[0078] By adopting this implementation method, the introduction of the annular groove 415 disrupts the current distribution on the low-frequency oscillator balun, thereby changing the distribution of the induced current on the low-frequency oscillator and achieving the effect of suppressing high-order harmonics.

[0079] In this second embodiment, when the open branch 4122 on the balun signal line 412 includes the first branch assembly 11 located above, an annular groove 415 is provided on the metal patch 414 of the second surface 413, and the orthographic projection of the annular groove 415 on the plane where the open branch 4122 is located covers at least part of the first branch assembly 11.

[0080] In this embodiment of the invention, optionally, the annular groove 415 is a polygonal annular shape or a circular ring shape. The annular groove 415 is a groove formed on the metal patch 414, and this groove is formed into a closed annular shape on the metal patch 414. For example, the annular groove 415 can be as follows: Figure 7 The quadrilateral shape shown can be a quadrilateral, a circular ring, or an elliptical ring, but is not limited to these specific shapes.

[0081] In this second embodiment, the balun signal line 412 and the balun terrain of the balun structure 400 become as follows: Figure 7 The structure shown is applied to the low-frequency element of a dual-band antenna. Simulations were performed on a dual-band antenna using this balun structure 400, and the resulting inter-band isolation curves of the dual-band antenna are shown below. Figure 8 As shown. In related technologies, the balun signal line 412 is formed as follows: Figure 3 The inter-band isolation curve of the dual-band antenna obtained when the L-shaped antenna is shown. Figure 4In comparison, the frequency band isolation of most frequency points is significantly improved. Therefore, in this second embodiment, the open stub 4122 set on the balun signal line 412 and the annular groove 415 set on the balun ground can help improve the frequency band isolation within a wide operating frequency band.

[0082] In Embodiment 3 of the present invention, as follows Figure 9 As shown, compared to Embodiment 1, in Embodiment 3, the open stub 4122 on the balun signal line 412 includes a second stub assembly 12 located below. That is, the open stub 4122 includes a second group of open stubs 41224 and a first group of open stubs 41223 arranged sequentially from top to bottom.

[0083] Among them, such as Figure 9 As shown, metal patches 414 are respectively disposed on the second surface 413 of the substrate 410, corresponding to the first plate 4101 and the second plate 4102. An annular groove 415 is formed on the metal patch 414 on the second surface 413, and the position of the annular groove 415 on the metal patch 414 corresponds to the position of the second branch assembly 12. That is, the orthographic projection of the annular groove 415 onto the plane where the open branch 4122 is located at least covers a portion of the second branch assembly 12.

[0084] In this third embodiment, the balun signal line 412 and the balun terrain of the balun structure 400 become as follows: Figure 9 The structure shown is applied to the low-frequency element of a dual-band antenna. Simulations were performed on a dual-band antenna using this balun structure 400, and the resulting inter-band isolation curves of the dual-band antenna are shown below. Figure 10 As shown. In related technologies, the balun signal line 412 is formed as follows: Figure 3 The inter-band isolation curve of the dual-band antenna obtained when the L-shaped antenna is shown. Figure 4 In comparison, the frequency band isolation of most frequency points is significantly improved. Therefore, in this third embodiment, the open stub 4122 set on the balun signal line 412 and the annular groove 415 set on the balun ground can help improve the frequency band isolation within a wide operating frequency band.

[0085] In Embodiment 4 of the present invention, as follows Figure 11 As shown, in this fourth embodiment, the open-circuit stub 4122 on the balun signal line 412 includes two first sets of open-circuit stubs 41223 spaced apart, which are formed in a symmetrical structure about the first straight line L. Figure 11As shown, metal patches 414 are respectively disposed on the second surface 413 of the substrate 410, corresponding to the first plate 4101 and the second plate 4102. Two annular grooves 415 are formed on the metal patches 414 on the second surface 413, and these two annular grooves 415 are respectively disposed one-to-one with two first-group open-circuit stubs 41223. That is, the orthographic projection of the annular grooves 415 onto the plane containing the open-circuit stubs 4122 at least partially covers the corresponding first-group open-circuit stubs 41223.

[0086] In this fourth embodiment, the balun signal line 412 and the balun terrain of the balun structure 400 become as follows: Figure 11 The structure shown is applied to the low-frequency element of a dual-band antenna. Simulations were performed on a dual-band antenna using this balun structure 400, and the resulting inter-band isolation curves of the dual-band antenna are shown below. Figure 12 As shown. According to Figure 12 It can be determined that the inter-band isolation is greater than 17dB across the entire operating frequency range of the high-frequency oscillator. In related technologies, the balun signal line 412 is formed as follows... Figure 3 The inter-band isolation curve of the dual-band antenna obtained when the L-shaped antenna is shown. Figure 4 In comparison, the inter-band isolation is improved, especially the improvement in the band isolation of the high-frequency band is significant.

[0087] In Embodiment 5 of the present invention, as Figure 13 As shown, in this fifth embodiment, the open-circuit stub 4122 on the balun signal line 412 includes two second sets of open-circuit stubs 41224 spaced apart, and these two second sets of open-circuit stubs 41224 are formed in a symmetrical structure about the first straight line L. Figure 13 As shown, metal patches 414 are respectively disposed on the second surface 413 of the substrate 410, corresponding to the first plate 4101 and the second plate 4102. Two annular grooves 415 are formed on the metal patches 414 on the second surface 413, and these two annular grooves 415 are respectively disposed one-to-one with two second sets of open-circuit stubs 41224. That is, the orthographic projection of the annular grooves 415 onto the plane containing the open-circuit stubs 4122 at least partially covers the corresponding second set of open-circuit stubs 41224.

[0088] In this fifth embodiment, the balun signal line 412 and the balun terrain of the balun structure 400 become as follows: Figure 13 The structure shown is applied to the low-frequency element of a dual-band antenna. Simulations were performed on a dual-band antenna using this balun structure 400, and the resulting inter-band isolation curves of the dual-band antenna are shown below. Figure 14 As shown. According to Figure 14It can be seen that the inter-band isolation is greater than 19dB across the entire operating frequency range of the high-frequency oscillator. Compared to the balun signal line 412, which only includes the first set of open-circuit stubs 41223, the improvement in inter-band isolation is more significant because the bending end extension length of the second set of open-circuit stubs 41224 is greater than that of the bending end extension length of the first set of open-circuit stubs 41223.

[0089] The simulation results of this embodiment five are consistent with those in related technologies, where the balun signal line 412 is formed as follows: Figure 3 The inter-band isolation curve of the dual-band antenna obtained when the L-shaped antenna is shown. Figure 4 In comparison, the inter-band isolation is significantly improved, especially the improvement in the band isolation of the mid-to-low frequency bands.

[0090] In Embodiment Six of the present invention, in this Embodiment Six, combined with Figure 15 and Figure 5 As shown, similar to Embodiment 1, the open-circuit stub 4122 on the balun signal line 412 includes a first stub combination 11 and a second stub combination 12 arranged sequentially along the first direction a, and the first stub combination 11 and the second stub combination 12 are symmetrical about the first straight line L. In this Embodiment 6, combined with Figure 15 As shown, metal patches 414 are respectively provided on the second surface 413 of the substrate 410, corresponding to the first plate 4101 and the second plate 4102. The metal patches 414 on the second surface 413 have two annular grooves 415, which are respectively provided to correspond to the first branch assembly 11 and the second branch assembly 12.

[0091] In this implementation structure, the low-frequency vibrator is fed by a coaxial balun structure, including a balun ground of annular slot 415 directly connected to a coupling stub, which is coupled to the radiating surface on the lower surface of the first antenna substrate through the coupling stub, and then radiates through the radiating surface.

[0092] In this sixth embodiment, the balun signal line 412 and the balun terrain of the balun structure 400 become as follows: Figure 15 The structure shown is applied to the low-frequency element of a dual-band antenna. Simulations were performed on a dual-band antenna using this balun structure 400, and the resulting inter-band isolation curves of the dual-band antenna are shown below. Figure 16 As shown. According to Figure 16 It can be seen that the inter-band isolation is greater than 22dB across the entire operating frequency range of the high-frequency oscillator, and the inter-band isolation across the entire operating frequency range is significantly improved.

[0093] It should be noted that the balun structures described in Embodiments 1 to 6 above are merely illustrative examples of the implementation methods of this invention, and are not intended to limit the scope of the invention. Not every possible implementation structure will be described in detail here.

[0094] The balun structure described in this invention, by improving the balun structure of the low-frequency vibrator, can suppress high-order harmonics generated by the low-frequency vibrator within the operating frequency band of the high-frequency vibrator, thereby effectively improving the port isolation performance between the intermediate frequency bands of the dual-frequency antenna. The method for improving the port isolation performance between the frequency bands of the dual-frequency antenna proposed in this invention has advantages such as simple design structure, low cost, and ease of debugging, and has certain practical application value.

[0095] One embodiment of the present invention also provides an antenna, wherein the antenna includes the balun structure as described in any of the preceding claims.

[0096] Combination Figure 1 and Figure 2 As shown, in one embodiment of the present invention, the antenna further includes:

[0097] Reflector 100;

[0098] A first antenna substrate 200 is disposed above and parallel to the reflector 100, and at least two intersecting first dipoles 210 are disposed on the first antenna substrate 200.

[0099] The balun structure 400 is disposed between the reflector 100 and the first antenna substrate 200 for feeding the first dipole 210; the main signal line 4121 extends from the reflector 100 to the first antenna substrate 200.

[0100] The antenna further includes:

[0101] Multiple second antenna substrates 300 are disposed between the reflector 100 and the first antenna substrate 200. Each second antenna substrate 300 is provided with at least two intersecting second dipoles 310. The second antenna substrate 300 is parallel to the first antenna substrate 200. The operating frequency of the first dipole 210 is lower than the operating frequency of the second dipole 310.

[0102] Each first dipole 210 is respectively provided with a balun structure 400, and the balun structures 400 corresponding to two first dipoles 210 are arranged in a cross shape. The side view of the intersection of two balun structures 400 is shown in the figure. Figure 17 As shown, the open branch 4122 on the two balun structures 400 is symmetrical about the intersection line between the two balun structures 400.

[0103] By adopting this implementation structure, the balun structure used for feeding the low-frequency element of the antenna is improved, and at least one set of symmetrical open-circuit stubs is set on the main signal line. The open-circuit stubs can suppress the high-order harmonics generated by the low-frequency element in the operating frequency band of the high-frequency element, thereby improving the port isolation performance between the intermediate frequency bands of the dual-frequency antenna.

[0104] Optionally, in each balun structure 400, a protruding extension is provided at both the upper and lower ends of the substrate 410. The balun structure 400 can be fixed between the first antenna substrate 200 and the reflector 100 by means of the extension being inserted into the slots on the first antenna substrate 200 and the reflector 100.

[0105] The antenna employing the balun structure described in the embodiments of the present invention can be combined with Figures 1 to 17 Please refer to the detailed description above; it will not be repeated here.

[0106] The above describes the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A balun structure, characterized in that, include: A substrate, wherein a balun signal line is disposed on a first surface of the substrate and a metal patch for forming a balun ground is disposed on a second surface; The second surface is opposite to the first surface; The balun signal line includes a vertically arranged main signal line and at least one set of open-circuit branches electrically connected to the main signal line, with each set of open-circuit branches being symmetrically arranged about the main signal line.

2. The balun structure according to claim 1, characterized in that, The metal patch has at least one annular groove, and the orthographic projection of the annular groove onto the first surface covers at least a portion of the open branch.

3. The balun structure according to claim 1, characterized in that, Each set of open-circuit stubs includes two sub-stubs located on both sides of the main signal line. Each sub-stub includes a connecting end connected to the main signal line and a curved end extending away from the main signal line. The curved end is separated from the main signal line.

4. The balun structure according to claim 3, characterized in that, The at least one set of open-circuit stubs includes a first set of open-circuit stubs and a second set of open-circuit stubs. The first set of open-circuit stubs and the second set of open-circuit stubs are arranged sequentially along a first direction, and the curved ends of the first set of open-circuit stubs extend and bend toward the direction of the second set of open-circuit stubs, and the curved ends of the second set of open-circuit stubs extend and bend toward the direction of the first set of open-circuit stubs; the first direction is a direction parallel to the main signal line.

5. The balun structure according to claim 4, characterized in that, The extension length of the curved end of the second group of open branches in the first direction is greater than the extension length of the curved end of the first group of open branches in the first direction.

6. The balun structure according to claim 4 or 5, characterized in that, The first group of open branches and the second group of open branches form a branch combination; along the first direction, in two adjacent branch combinations, the second group of open branches in the first branch combination is adjacent to the second group of open branches in the second branch combination.

7. The balun structure according to claim 1, characterized in that, In a first direction parallel to the main signal line, multiple sets of open-circuit branches are arranged sequentially, and the multiple sets of open-circuit branches are symmetrical about a first straight line, which is perpendicular to the first direction.

8. The balun structure according to claim 2, characterized in that, The annular groove is either polygonal or circular in shape.

9. The balun structure according to claim 1, characterized in that, The balun signal line also includes a branch signal line connected to one end of the main signal line, and the branch signal line and the main signal line form an L-shape.

10. An antenna, characterized in that, Includes the balun structure as described in any one of claims 1 to 9.

11. The antenna according to claim 10, characterized in that, The antenna also includes: Reflector; A first antenna substrate is disposed above and parallel to the reflector, and at least two intersecting first dipoles are disposed on the first antenna substrate; The balun structure is disposed between the reflector and the first antenna substrate for feeding the first dipole; the main signal line extends from the reflector to the first antenna substrate.

12. The antenna according to claim 11, characterized in that, The antenna also includes: A plurality of second antenna substrates are disposed between the reflector and the first antenna substrate, each second antenna substrate having at least two intersecting second dipoles, the second antenna substrates being parallel to the first antenna substrate; the operating frequency of the first dipole is lower than the operating frequency of the second dipole.

13. The antenna according to claim 11, characterized in that, Each of the first dipoles is respectively provided with a balun structure, and the balun structures corresponding to the two first dipoles are arranged in a cross shape, and the open branches on the two balun structures are symmetrical about the intersection line between the two balun structures.

14. The antenna according to claim 13, characterized in that, The balun signal line also includes a branch signal line connected to one end of the main signal line, and the branch signal line and the main signal line are located on opposite sides of the cross line.

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