Frequency-controllable 5G broadband base station antenna based on balun feed structure

Abstract

The invention discloses a frequency-controllable 5G broadband base station antenna based on a balun feed structure, and belongs to the technical field of antennae, the antenna comprises a radiation structure, a balun structure and a metal reflecting plate from top to bottom, the radiation structure comprises a radiation dielectric substrate, a fan-shaped radiation sheet is etched on the radiation dielectric substrate, and a resonant groove is etched on the fan-shaped radiation sheet. The overall structure of the radiation patch is fan-shaped, the working bandwidth of the antenna can be expanded by etching the resonant tank on the fan-shaped radiation sheet, and the low-frequency cut-off frequency of the antenna can be flexibly controlled by adjusting the distance from the resonant tank to the edge of the fan-shaped radiation sheet or adjusting the size of the resonant tank.

Description

Technical Field

[0001] The present invention relates to the field of antenna technology, and in particular to a frequency-controllable 5G broadband base station antenna based on a balun feeding structure. Background Art

[0002] At present, the structures used in base station antennas are mainly divided into three types: microstrip antenna, electromagnetic dipole antenna and cross dipole. Microstrip antenna adopts a planar structure, which has the advantages of small size, light weight and low manufacturing cost, but its radiation performance is greatly affected by the material of the dielectric substrate, and its relatively narrow bandwidth is difficult to meet broadband applications. Electromagnetic dipole antennas usually have a wide working bandwidth, simple structure, low manufacturing cost, and are suitable for large-scale production and manufacturing; but their large size will increase the installation cost of the antenna. Cross-dipole antennas usually consist of two orthogonal dipoles, with a simple structure, easy to manufacture and install. By adding a broadband feeding network or adjusting the resonator structure, a wider working bandwidth can be achieved; in addition, by adopting printed circuit board technology, miniaturized design can also be achieved. Cross-dipole antennas have a wide range of applications in wireless communications, radars, satellite communications and other fields due to their advantages of miniaturization, broadband and compact structure.

[0003] Existing base station antennas are generally designed for a fixed frequency band. Once the frequency band of the antenna is changed, the structure of the antenna will change greatly. For example, in a document titled Research on Dual-Polarized Cross-Dipole Antennas, the antenna includes a radiation structure, a Y-shaped feeding structure, and a reflection structure. The radiation structure includes a radiation medium substrate and a radiation patch. At this time, if the working frequency band of the antenna needs to be adjusted, the shape of the Y-shaped feeding structure and the radiation patch needs to be adjusted, resulting in a large change in the antenna structure and the inability to flexibly adjust the working frequency band of the antenna. In summary, how to more flexibly adjust the low-frequency cutoff frequency of the antenna is a technical problem that needs to be solved urgently. Summary of the invention

[0004] The purpose of the present invention is to overcome the problems of the prior art and provide a frequency-controllable 5G broadband base station antenna based on a balun feeding structure.

[0005] The objective of the present invention is achieved through the following technical solutions: a frequency-controllable 5G broadband base station antenna based on a balun feeding structure, the antenna comprising a radiation structure, a balun structure and a metal reflector from top to bottom, the radiation structure comprising a radiation medium substrate, characterized in that a fan-shaped radiation plate is formed on the radiation medium substrate, a resonant groove is etched on the fan-shaped radiation plate, and the low-frequency cutoff frequency of the antenna is adjusted by adjusting the distance between the resonant groove and the edge of the fan-shaped radiation plate or adjusting the size of the resonant groove.

[0006] In one example, the resonant slot is a trapezoidal slot, and the low-frequency cutoff frequency of the antenna is adjusted by adjusting the distance between the hypotenuse of the trapezoidal slot and the edge of the fan-shaped radiation piece.

[0007] In one example, a resonance depth adjustment groove is further etched on the fan-shaped radiation piece, and the resonance depth adjustment groove is rectangular or semicircular.

[0008] In one example, the trapezoidal groove is replaced by a U-shaped groove and two second rectangular grooves, the U-shaped groove is arranged between the two second rectangular grooves, and the length or width of the second rectangular groove and / or the opening size and depth of the U-shaped groove are adjusted to adjust the low-frequency cutoff frequency of the antenna.

[0009] In one example, four fan-shaped radiation plates are formed on the radiation medium substrate, and trapezoidal narrow gaps are provided between adjacent fan-shaped radiation plates.

[0010] In one example, a circular groove is etched in the center of the four fan-shaped radiation plates.

[0011] In one example, a first through hole is formed on the radiation medium substrate and the fan-shaped radiation sheet, and the balun structure is connected to the radiation structure via the first through hole.

[0012] In one example, the balun structure includes a first sub-balun structure and a second sub-balun structure, the first sub-balun structure includes a first feeder line, a first balun support structure and a first metal short-circuit plate from top to bottom, and the second sub-balun structure includes a second feeder line, a second balun support structure and a second metal short-circuit plate from top to bottom; The first balun support structure and the second balun support structure are arranged vertically and orthogonally, and the first balun support structure, the second balun support structure, the first metal short-circuit plate and the second metal short-circuit plate are all connected to the fan-shaped radiation plate and the metal reflection plate.

[0013] In one example, the first feed line and the second feed line are n-type gradient structures.

[0014] In one example, two metal microstrip lines of different lengths are loaded on the first feed line and the second feed line.

[0015] It should be further explained that the technical features corresponding to the above examples can be combined or replaced with each other to form a new technical solution.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. In one example, the overall structure of the radiation patch of the present invention is fan-shaped. By etching a resonant groove (a trapezoidal groove or a U-shaped groove and two second rectangular grooves) on the fan-shaped radiation piece, the working bandwidth of the antenna can be expanded. By adjusting the distance between the hypotenuse of the trapezoidal groove and the edge of the fan-shaped radiation piece or adjusting the size of the U-shaped groove and the second rectangular groove, the low-frequency cutoff frequency of the antenna can be flexibly adjusted, that is, the working frequency band of the antenna can be changed without much change in the antenna structure.

[0017] 2. In one example, the resonance depth of the antenna is optimized by etching a resonance depth adjustment groove on the fan-shaped radiation plate.

[0018] 3. In one example, four fan-shaped radiators can further expand the working bandwidth of the antenna, allowing the antenna to cover the 5G mid-frequency band of 3.3GHz~3.6GHz.

[0019] 4. In one example, the resonance point of the antenna can be adjusted by etching circular grooves in the center of four sector-shaped radiation plates.

[0020] 5. In one example, the first feed line and the second feed line are η-shaped, and a rectangular gradient structure is used to enable the antenna to achieve impedance matching function; further, two metal microstrip lines of different lengths are loaded on the η-shaped first feed line and the second feed line, and the resonance depth of the antenna can be further adjusted by adjusting the length of the metal microstrip line. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The specific implementation methods of the present invention are further described in detail below in conjunction with the accompanying drawings. The accompanying drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The same reference numerals are used in these drawings to represent the same or similar parts. The schematic embodiments of the present application and their descriptions are used to explain the present application and do not constitute improper limitations on the present application.

[0022] Figure 1 A schematic diagram of the overall structure of an antenna provided as an example of the present invention; Figure 2 A schematic diagram of a radiation structure provided for an example of the present invention; Figure 3 A schematic diagram of the structure of a fan-shaped radiation piece provided as an example of the present invention; Figure 4 A schematic diagram of the structure of a fan-shaped radiation piece provided for another example of the present invention; Figure 5 A schematic diagram of a balun structure provided for an example of the present invention; Figure 6 A schematic diagram of a first sub-balun structure provided for an example of the present invention; Figure 7 A schematic diagram of a second sub-balun structure provided as an example of the present invention; Figure 8 A schematic diagram of a first balun support structure provided for an example of the present invention; Fig. 9 A schematic diagram of a second balun support structure provided for an example of the present invention; Fig.10 A schematic diagram of the structure of a first metal short-circuit plate provided as an example of the present invention; Fig.11A side view of a first feeder structure provided as an example of the present invention; Fig.12 A side view of a second feeder structure provided as an example of the present invention; Fig.13 It is a schematic diagram of the reflection coefficient simulation result of the preferred example antenna of the present invention; Fig.14 It is a schematic diagram of the simulation results of port isolation of a preferred example antenna of the present invention.

[0023] In the figure: 1-radiation structure; 2-balun structure; 3-metal reflector; 4-radiation medium substrate; 5-fan-shaped radiation plate; 6-first sub-balun structure; 7-second sub-balun structure; 9-first metal short-circuit plate; 10-first feed line; 11-first balun support structure; 12-first coaxial feeding port; 13-second metal short-circuit plate; 14-second feed line; 15-second balun support structure; 16-second coaxial feeding port; 17-trapezoidal narrow gap; 18-trapezoidal groove; 19-first rectangular groove; 20-first through hole; 21-circular groove; 22-fourth through hole; 23-U-shaped groove; 24-second rectangular groove. DETAILED DESCRIPTION

[0024] The technical solution of the present invention is described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] In the description of the present invention, it should be noted that the directions or positional relationships indicated by "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. are directions or positional relationships based on the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the use of ordinal numbers (e.g., "first and second", "first to fourth", etc.) is to distinguish objects, and is not limited to this order, and cannot be understood as indicating or implying relative importance.

[0026] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0028] In one example, a frequency-controllable 5G broadband base station antenna based on a balun feeding structure, such as Figure 1 As shown, the antenna includes a radiation structure 1, a balun structure 2 and a metal reflector 3 from top to bottom. The radiation structure is used to convert electrical signals into electromagnetic waves and transmit them. The balun (feeding) structure is used for impedance transformation and conversion of balanced and unbalanced signals, and transmits the signal from the feeding network (such as coaxial cable) to the radiation structure of the antenna. The metal reflector is used to reflect the electromagnetic waves propagating downward back to the radiation structure, thereby enhancing the radiation directivity of the antenna; optionally, the metal reflector is made of aluminum and has a size of 54mm*54mm*0.508mm. Figure 2 As shown, the radiation structure 1 includes a radiation medium substrate 4, on which a fan-shaped radiation sheet 5 generating electromagnetic radiation is etched or printed. Specifically, the radiation medium substrate 4 is made of FR4_epoxy, with a relative dielectric constant of 4.4, a dielectric loss of 0.02, and a size of 44mm*44mm*0.508mm. Furthermore, a resonant slot is etched on each of the fan-shaped radiation sheets, and the low-frequency cutoff frequency of the antenna is adjusted by adjusting the distance between the resonant slot and the edge of the fan-shaped radiation sheet or adjusting the size of the resonant slot.

[0029] In one example, if Figure 2-Figure 3 As shown, the resonant slot is a trapezoidal slot 18. By adjusting the distance between the hypotenuse of the trapezoidal slot and the edge of the fan-shaped radiating plate, the low-frequency cutoff frequency of the antenna is controlled. Preferably, a resonant depth adjustment slot is also etched on the fan-shaped radiating plate to optimize the resonant depth of the antenna. The resonant depth adjustment slot is a rectangular slot or a semicircular slot. Figure 2-Figure 3 As shown, the resonance depth adjustment groove in this example is a first rectangular groove 19, which is arranged on the bottom side of the trapezoidal groove.

[0030] In one example, if Figure 4As shown, the resonant slot includes a U-shaped slot 23 and two second rectangular slots 24, that is, the trapezoidal slot is replaced by the U-shaped slot and the two second rectangular slots. At this time, the U-shaped slot is arranged between the two second rectangular slots, and the low-frequency cutoff frequency of the antenna is controlled by adjusting the length or width of the second rectangular slot and / or adjusting the opening size and depth of the U-shaped slot.

[0031] In one example, if Figure 2-Figure 4 As shown, four sector-shaped radiation plates 5 of the same size are etched on the radiation medium substrate 4 to further expand the working frequency band of the antenna so that the antenna covers the 5G medium frequency band of 3.3GHz~3.6GHz. More specifically, a trapezoidal narrow gap 17 is provided between adjacent sector-shaped radiation plates, and the low-frequency cutoff frequency can be controlled by controlling the distance between the hypotenuse of the trapezoidal groove and the narrow gap.

[0032] In one example, if Figure 2-Figure 4 As shown, a circular groove 21 is etched in the center of the four sector-shaped radiation plates for adjusting the resonance point of the antenna.

[0033] In one example, if Figure 2-Figure 4 As shown, a first through hole 20 is provided at corresponding positions on the radiation medium substrate and the four fan-shaped radiation plates, preferably a rectangular through hole, so that the balun structure can be inserted into the radiation structure through the first through hole, thereby fixing the antenna structure.

[0034] In one example, if Figure 5 As shown, the balun structure includes a first sub-balun structure 6 and a second sub-balun structure 7. Specifically, as Figure 6 As shown, the first sub-balun structure 6 includes, from top to bottom, a first feed line 10, a first balun support structure 11 (a first balun dielectric substrate), and a first metal short-circuit plate 9 (a first ground plane), that is, the first feed line 10 is the upper copper layer of the first balun support structure 11, and the first metal short-circuit plate 9 is the lower copper layer of the first balun support structure 11. Figure 7 As shown, the second sub-balun structure 7 includes, from top to bottom, a second feed line 14, a second balun support structure 15 (a second balun dielectric substrate) and a second metal short-circuit plate 13 (a second ground plane), that is, the second feed line 14 is the upper copper layer of the second balun support structure 15, and the second metal short-circuit plate 13 is the lower copper layer of the second balun support structure 15.

[0035] Furthermore, the first feeder and the second feeder are used to transmit signals, such as Figure 6-Figure 7 As shown, the first feed line and the second feed line are both η-shaped, preferably an η-shaped gradient structure, that is, the width of the first feed line gradually changes along the length direction, so that the antenna can achieve the impedance matching function. Preferably, the η-shaped first feed line and the second feed line are loaded with two metal microstrip lines of different lengths, and the resonance depth of the antenna is adjusted by adjusting the length of the microstrip line.

[0036] Furthermore, if Figure 8 As shown, the first balun support structure is rectangular, with two rectangular protrusions at both ends, a first groove is provided between the two rectangular protrusions at the upper end of the first balun support structure, and a circular second through hole is provided on a rectangular protrusion at the lower end of the first balun support structure. Fig. 9 As shown, the second balun support structure is rectangular, with two rectangular protrusions at both ends, a second groove is provided between the two rectangular protrusions at the lower end of the second balun support structure, and a circular third through hole is provided on a rectangular protrusion at the lower end of the second balun support structure, and the second groove is clamped on the first groove to realize the vertical orthogonal setting of the first balun support structure and the second balun support structure. Optionally, the material of the first balun support structure and the second balun support structure are both FR4_epoxy, and the thickness is 0.8mm, and the two rectangular protrusions at the upper ends of the first balun support structure and the second balun support structure are both inserted into the radiation structure, specifically the two rectangular protrusions are inserted into the first through holes of the radiation medium substrate and the four fan-shaped radiation plates, and the lower ends of the first balun support structure and the second balun support structure are both inserted into the metal reflector, specifically the two rectangular protrusions at the lower ends of the first balun support structure and the second balun support structure are inserted into the metal reflector, so as to realize the fixation of the antenna structure.

[0037] Furthermore, if Fig.10 As shown, the first metal short-circuit plate includes two separate rectangular plane bodies, each of which is provided with a rectangular protrusion at both ends, and a fourth circular through hole 22 is provided on the rectangular protrusion at the lower end of one of the rectangular plane bodies, and the fourth through hole on the first metal short-circuit plate is arranged corresponding to the second through hole on the first balun support structure. The shape and structure of the second metal short-circuit plate are the same as those of the first metal short-circuit plate, and will not be repeated here.

[0038] More specifically, the antenna of the present invention uses a coaxial line for feeding, such as Figure 11-Figure 12 As shown, the first feeder is provided with a first coaxial feeding port 12, and the second feeder is provided with a second coaxial feeding port 16. For the first coaxial feeding port, the inner conductor of the coaxial line is connected to the lower end of the first feeder, and the outer conductor of the coaxial line is connected to the lower end of the first metal short-circuit plate, thereby avoiding short circuiting the inner and outer conductors of the coaxial line; similarly, for the second coaxial feeding port, the inner conductor of the coaxial line is connected to the lower end of the second feeder, and the outer conductor of the coaxial line is connected to the lower end of the second metal short-circuit plate, thereby avoiding short circuiting the inner and outer conductors of the coaxial line.

[0039] The above examples are combined to obtain a preferred example of the antenna of the present invention, in which the antenna includes a radiation structure, a balun structure and a metal reflector from top to bottom. The radiation structure includes a radiation medium substrate, on which four fan-shaped radiation plates are etched, and a trapezoidal narrow gap is provided between adjacent fan-shaped radiation plates, that is, the entire circular radiation patch is divided into four fan-shaped radiation plates by the trapezoidal narrow gap, each fan-shaped radiation plate is etched with a trapezoidal groove, and a rectangular groove is etched on the bottom edge of the trapezoidal groove; further, a circular groove is etched in the center of the four fan-shaped radiation plates, and a first through hole is provided at the corresponding position of the radiation medium substrate and the four fan-shaped radiation plates. The balun structure includes a first sub-balun structure and a second sub-balun structure. The first sub-balun structure includes a first feed line, a first balun support structure and a first metal short-circuit plate from top to bottom, and the second sub-balun structure includes a second feed line, a second balun support structure and a second metal short-circuit plate from top to bottom; the first feed line and the second feed line are η-type gradient structures, and are both loaded with two metal microstrip lines of different lengths.

[0040] Now the preferred example antenna of the present invention is simulated, as shown in FIG. Fig.13 As shown, the reflection coefficient S of the antenna 11 The working frequency band of less than -10dB is 2.76~3.72GHz, the center frequency is 3.24GHz, and the working bandwidth is 29.6%. The size of the antenna is 0.5λ*0.5λ*0.225λ, where λ is the low-frequency cutoff frequency. Fig.14 As shown in the figure, the isolation S12 of the two antenna ports is better than 33dB in the working frequency band. Figure 13-14 The horizontal axis Freq represents frequency in GHz.

[0041] In summary, the present invention can expand the low-frequency bandwidth of the antenna by etching a trapezoidal groove on the sector-shaped radiation patch, and can adjust the low-frequency cutoff frequency of the antenna by controlling the distance between the hypotenuse of the trapezoidal groove and the sector boundary; by etching a rectangular groove at the bottom of the trapezoidal groove, the resonance depth of the antenna can be increased. The antenna uses a balun structure for feeding, and the balun structure also plays a supporting role. By loading two microstrip lines of different lengths on the η-type feeder, the performance of the antenna can be optimized and the resonance depth of the antenna can be further improved. The antenna structure achieves a voltage standing wave ratio of less than 2 in the 2.75~3.71GHz frequency band, a port isolation better than 32dB, and a relative working bandwidth of 29.7%.

[0042] The above specific implementation methods are detailed descriptions of the present invention. It cannot be determined that the specific implementation methods of the present invention are limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions and substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A frequency-controllable 5G broadband base station antenna based on a balun feeding structure, the antenna comprising a radiation structure, a balun structure and a metal reflector from top to bottom, the radiation structure comprising a radiation medium substrate, characterized in that: A fan-shaped radiating sheet is formed on the radiating medium substrate, and a trapezoidal groove is etched on the fan-shaped radiating sheet. The low-frequency cutoff frequency of the antenna can be adjusted by adjusting the distance between the hypotenuse of the trapezoidal groove and the edge of the fan-shaped radiating sheet.

2. The frequency-controllable 5G broadband base station antenna based on the balun feeding structure according to claim 1, characterized in that: A resonance depth adjustment groove is also etched on the fan-shaped radiation piece, and the resonance depth adjustment groove is rectangular or semicircular.

3. The frequency-controllable 5G broadband base station antenna based on the balun feeding structure according to claim 1, characterized in that: The trapezoidal groove is replaced by a U-shaped groove and two second rectangular grooves, the U-shaped groove is arranged between the two second rectangular grooves, and the length or width of the second rectangular groove and / or the opening size and depth of the U-shaped groove are adjusted to adjust the low-frequency cutoff frequency of the antenna.

4. The frequency-controllable 5G broadband base station antenna based on a balun feeding structure according to any one of claims 1 to 3, characterized in that: Four fan-shaped radiation plates are formed on the radiation medium substrate, and trapezoidal narrow gaps are arranged between adjacent fan-shaped radiation plates.

5. The frequency-controllable 5G broadband base station antenna based on a balun feeding structure according to claim 4, characterized in that: A circular groove is etched at the center of the four fan-shaped radiation plates.

6. The frequency-controllable 5G broadband base station antenna based on a balun feeding structure according to claim 4, characterized in that: The radiation medium substrate and the fan-shaped radiation sheet are provided with a first through hole, and the balun structure is connected to the radiation structure via the first through hole.

7. The frequency-controllable 5G broadband base station antenna based on a balun feeding structure according to claim 1, characterized in that: The balun structure includes a first sub-balun structure and a second sub-balun structure, wherein the first sub-balun structure includes, from top to bottom, a first feeder line, a first balun support structure and a first metal short-circuit plate, and the second sub-balun structure includes, from top to bottom, a second feeder line, a second balun support structure and a second metal short-circuit plate; The first feed line and the second feed line are η-type gradient structures; the first balun support structure and the second balun support structure are vertically orthogonal, and the first balun support structure, the second balun support structure, the first metal short-circuit plate, and the second metal short-circuit plate are all connected to the fan-shaped radiation plate and the metal reflection plate.

8. The frequency-controllable 5G broadband base station antenna based on a balun feeding structure according to claim 7, characterized in that: The first feed line and the second feed line are loaded with two metal microstrip lines of different lengths.

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