A miniaturized broadband folded dipole base station antenna

Abstract

The application discloses a miniaturized broadband folded dipole base station antenna and relates to the technical field of base station antennas.The miniaturized broadband folded dipole base station antenna comprises a metal reflecting plate, a dielectric plate, a support column assembly and a feed point, the dielectric plate is fixed on the metal reflecting plate through the support column assembly, the surface of the dielectric plate is printed with a microstrip line assembly in the shape of a whole rectangular ring, and the feed point is arranged on the microstrip line assembly and serves as a simulation port of simulation software.The antenna profile height and cross-sectional area are reduced, and the antenna bandwidth is improved through mode fusion and microstrip line coupling.

Description

Technical Field

[0001] This invention relates to the field of base station antenna technology, and more specifically to the field of miniaturized broadband folded dipole base station antenna technology. Background Technology

[0002] Most base station antennas are dipole antennas. A dipole antenna consists of a pair of symmetrically placed conductors (also called "dipole arms"), with their ends connected to a feed line (coaxial feed line). The diameter of the dipole antenna arms is much smaller than the operating wavelength and the arm length. The arms can be a pair of symmetrical thin metal tubes or a pair of symmetrical microstrip lines, etc. A common dipole antenna arm length is half a wavelength (0.5λ, where λ is the free-space wavelength corresponding to the center frequency of the dipole's operating band). It can resonate in odd-mode, i.e., at frequencies corresponding to 0.5λ, 1.5λ, 2.5λ, etc. Among the many operating modes of dipole antennas, the 0.5λ and 1λ modes are the most commonly used, referred to as half-wave mode and full-wave mode, respectively.

[0003] Because second- to fifth-generation communication systems will coexist for a long time, the size of base station antennas, especially their profile height, needs to be as small as possible. Researchers have conducted a series of studies on methods to achieve low profile antennas. There are roughly two methods for achieving low profile antennas: one is to use an artificial magnetic conductor to replace the metal reflector and place it below the dipole; the other is described in IEEE Transactions on Antennas and Propagation, "A New Method of Antenna Height Reduction Based on Half-sized Full-wave..." The method proposed in the paper "Dipole, DOI:10.1109 / TAP.2023.3274291" is based on the idea of ​​replacing a half-wave dipole (i.e., a dipole antenna with an arm length of 0.5λ) with a full-wave dipole (i.e., a dipole antenna with an arm length of 1λ) with a high input impedance. This is because as the distance between the dipole antenna and the reflector decreases, the antenna input impedance drops sharply. To achieve good impedance matching, a full-wave dipole with high input impedance can be used to replace the original half-wave dipole, thereby reducing the antenna profile. The paper presents the structure of a broadband low-profile antenna element based on this principle. The antenna element has dimensions of 60mm × 60mm × 8mm and operates in the frequency band of 2–2.7GHz. If the antenna size is expressed in terms of electrical length, it is 0.47λ × 0.47λ × 0.08λ. The height of the antenna is significantly reduced, but its cross-sectional area is still relatively large.

[0004] On the other hand, with the rapid growth in the number of mobile communication users, higher demands are being placed on the bandwidth of antenna equipment. One major way to broaden antenna bandwidth is to widen the dipole arm. While widening the dipole arm can increase bandwidth, it also increases the size of the antenna and the amount of material used. Summary of the Invention

[0005] The purpose of this invention is to address the technical problem of large profile height and cross-sectional area of ​​base station antennas by providing a miniaturized broadband folded dipole base station antenna. This solution reduces the antenna profile height and cross-sectional area while simultaneously improving antenna bandwidth through mode fusion and microstrip line coupling.

[0006] To achieve the above objectives, the present invention specifically adopts the following technical solution:

[0007] This invention provides a miniaturized broadband folded dipole base station antenna, including a metal reflector, a dielectric substrate, a support column assembly, and a feed point. The dielectric substrate is fixed to the metal reflector by the support column assembly. A microstrip line assembly with an overall rectangular ring shape is printed on the surface of the dielectric substrate. The feed point serves as a simulation port for simulation software and is located on the microstrip line assembly.

[0008] In one embodiment, the microstrip line assembly includes a first microstrip line, a second microstrip line, a third microstrip line, a fourth microstrip line, a fifth microstrip line, and a sixth microstrip line printed on the upper surface of a dielectric substrate.

[0009] The first microstrip line, the second microstrip line, the third microstrip line, the fourth microstrip line, and the fifth microstrip line are connected end to end in sequence to form a rectangular ring. An opening is provided at the connection between the first microstrip line and the fifth microstrip line of the rectangular ring. The power supply point is located at the opening and is electrically connected to the first microstrip line and the fifth microstrip line respectively.

[0010] The sixth microstrip line is located within the rectangular space enclosed by the first, second, third, fourth, and fifth microstrip lines and the feed point.

[0011] In one embodiment, the feed point includes a coaxial feed line, which includes an inner core and an outer core, the inner core being connected to a first microstrip line and the outer core being connected to a fifth microstrip line.

[0012] In one embodiment, the feed point includes a coaxial feed line, which includes an inner core and an outer core, the outer core being connected to a first microstrip line and the inner core being connected to a fifth microstrip line.

[0013] In one embodiment, the lengths of the first microstrip line, the second microstrip line, the third microstrip line, the fourth microstrip line, and the fifth microstrip line are 30mm, 18mm, 53mm, 18mm, and 20mm, respectively; and the widths of the first microstrip line, the second microstrip line, the third microstrip line, the fourth microstrip line, and the fifth microstrip line are all 5mm.

[0014] In one embodiment, the sixth microstrip line has a length of 40 mm and a width of 5.5 mm. The gap width between the sixth microstrip line and the first microstrip line is 1 mm, the gap width between the sixth microstrip line and the second microstrip line is 1.5 mm, and the gap width between the sixth microstrip line and the third microstrip line 23 is 1.5 mm.

[0015] Specifically, the lengths and widths of the first, second, third, fourth, and fifth microstrip lines, as well as the length, width, and position of the sixth microstrip line, affect the antenna's reflection coefficient (|S_t). 11 Both the resonant point and the structure are affected, and researchers can adjust the above structure and dimensions according to the requirements of the indicators.

[0016] In one embodiment, the metal reflector is a component used to reflect the rearward radiation of the dipole antenna, and the length and width of the metal reflector are both 1λ to 1.5λ.

[0017] In one embodiment, the dielectric substrate is made of FR4 material with a relative permittivity of 4.4, a thickness of 1.6 mm, a length of 100 mm, and a width of 80 mm.

[0018] In one embodiment, the support column assembly includes multiple support columns disposed between the metal reflector and the dielectric plate.

[0019] Specifically, the dielectric constant, thickness, and length of the dielectric substrate can be selected according to actual needs, and the above dimensions are preferred dimensions.

[0020] In one embodiment, the medium plate is a rectangular plate, and the number of support columns in the support column assembly is four, with the four support columns corresponding to the four corners of the rectangular plate.

[0021] The beneficial effects of this invention are as follows:

[0022] 1. This invention reduces the antenna profile height and cross-sectional area while simultaneously improving the antenna bandwidth through mode fusion and microstrip line coupling.

[0023] 2. This invention improves the half-wave dipole positioned 0.25λ above the metal reflector by folding its end to form a folded oscillator, thereby increasing the input impedance. It can still function normally when the distance between it and the metal reflector is reduced to 0.087λ, generating the first resonant point. Next, the feed point is shifted to excite a full-wave mode, generating the second resonant point. Finally, a coupling microstrip is added to improve the matching degree of the second resonant point and excite the third resonant point. These three resonant points are integrated, covering the 1.8GHz–2.22GHz frequency band. The overall size of this invention is 0.353λ × 0.12λ × 0.087λ, achieving miniaturization and broadband compared to existing technologies, and possessing significant application value. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of a miniaturized broadband folded dipole base station antenna according to the present invention;

[0025] Figure 2 This is a schematic diagram illustrating the technological evolution of the present invention;

[0026] Figure 3 yes Figure 2 The antennas A to E shown in the image correspond to |S 11 | curve, where (a) is the |S| curve corresponding to antennas A to C. 11 | curve, where (b) is the |S| curve corresponding to antenna D to antenna E. 11 |Curve;

[0027] Figure 4 The vector current distribution diagrams of antenna E (i.e., Embodiment 1 of the present invention) at 1.86GHz, 2.05GHz and 2.18GHz are shown.

[0028] In the attached diagram, the following labels are used: 1-metal reflector, 2-dielectric plate, 21-first microstrip line, 22-second microstrip line, 23-third microstrip line, 24-fourth microstrip line, 25-fifth microstrip line, 26-sixth microstrip line, 3-support column assembly, and 4-feed point. Detailed Implementation

[0029] 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 embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0031] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0032] In the description of the embodiments of the present invention, it should be noted that the terms "inner", "outer", "upper", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use. They 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, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0033] Example 1

[0034] like Figure 1 As shown, this embodiment provides a miniaturized broadband folded dipole base station antenna, including a metal reflector 1, a dielectric substrate 2, a support column assembly 3, and a feed point 4. The dielectric substrate 2 is fixed on the metal reflector 1 by the support column assembly 3. A microstrip line assembly in the shape of a rectangular ring is printed on the surface of the dielectric substrate 2. The feed point 4 serves as a simulation port for simulation software and is set on the microstrip line assembly.

[0035] In one embodiment, the microstrip line assembly includes a first microstrip line 21, a second microstrip line 22, a third microstrip line 23, a fourth microstrip line 24, a fifth microstrip line 25, and a sixth microstrip line 26 printed on the upper surface of the dielectric substrate 2.

[0036] The first microstrip line 21, the second microstrip line 22, the third microstrip line 23, the fourth microstrip line 24 and the fifth microstrip line 25 are connected end to end to form a rectangular ring. An opening is provided at the connection between the first microstrip line 21 and the fifth microstrip line 25 of the rectangular ring. The power supply point 4 is located at the opening and is electrically connected to the first microstrip line 21 and the fifth microstrip line 25 respectively.

[0037] The sixth microstrip line 26 is located within the rectangular space enclosed by the first microstrip line 21, the second microstrip line 22, the third microstrip line 23, the fourth microstrip line 24, the fifth microstrip line 25 and the feed point 4.

[0038] Feed point 4 includes a coaxial feed line, which consists of an inner core and an outer core. The inner core is connected to the first microstrip line 21, and the outer core is connected to the fifth microstrip line 25. Alternatively, feed point 4 includes a coaxial feed line, which consists of an inner core and an outer core. The outer core is connected to the first microstrip line 21, and the inner core is connected to the fifth microstrip line 25.

[0039] The lengths of the first microstrip line 21, the second microstrip line 22, the third microstrip line 23, the fourth microstrip line 24, and the fifth microstrip line 25 are 30mm, 18mm, 53mm, 18mm, and 20mm, respectively; the widths of the first microstrip line 21, the second microstrip line 22, the third microstrip line 23, the fourth microstrip line 24, and the fifth microstrip line 25 are all 5mm.

[0040] The sixth microstrip line 26 has a length of 40mm and a width of 5.5mm. The gap width between the sixth microstrip line 26 and the first microstrip line 21 is 1mm. The gap width between the sixth microstrip line 26 and the second microstrip line 22 is 1.5mm. The gap width between the sixth microstrip line 26 and the third microstrip line 23 is 1.5mm.

[0041] Specifically, the lengths and widths of the first microstrip line 21, the second microstrip line 22, the third microstrip line 23, the fourth microstrip line 24, and the fifth microstrip line 25, as well as the length, width, and position of the sixth microstrip line 26, affect the antenna's reflection coefficient (|S). 11 Both the resonant point and the structure are affected, and researchers can adjust the above structure and dimensions according to the requirements of the indicators.

[0042] The metal reflector 1 is a component used to reflect the rearward radiation of the dipole antenna. The length and width of the metal reflector 1 are both 1λ to 1.5λ.

[0043] The dielectric substrate 2 is made of FR4 material with a relative permittivity of 4.4, a thickness of 1.6 mm, a length of 100 mm, and a width of 80 mm.

[0044] The support column assembly 3 includes four support columns disposed between the metal reflector 1 and the dielectric plate 2.

[0045] The medium plate 2 is a rectangular plate, and the number of support columns in the support column assembly 3 is four, with the four support columns corresponding to the four corners of the rectangular plate.

[0046] Specifically, the dielectric constant, thickness, and length of dielectric substrate 2 can be selected according to actual needs, and the above dimensions are preferred dimensions.

[0047] In this embodiment, the folded dipole antenna has a dimension of 53 mm along the x-axis, 18 mm along the y-axis, and 13 mm along the z-axis (i.e., the height of the support column). If expressed using the free space wavelength λ corresponding to the center frequency of the operating frequency band, these are 0.353λ, 0.12λ, and 0.087λ, respectively.

[0048] To illustrate the working principle of this embodiment, Figure 2 A schematic diagram illustrating the technical evolution of embodiments of this solution is provided. Figure 3 Given Figure 2 The |S| corresponding to antennas A to E 11 |Curve.

[0049] Antenna A is a half-wave dipole positioned 0.25λ above the metal reflector 1, with good matching at the resonant point of 1.86GHz. |S 11 As low as -27.5dB.

[0050] In antenna A, when the distance between the half-wave dipole and the metal reflector 1 decreases to 0.087λ, it becomes antenna B, and its impedance matching deteriorates, with |S| at 1.97GHz. 11 | is -5.8dB, which does not meet the |S requirement. 11 The requirement is ≤-10dB. According to the method proposed in the paper "A New Method of Antenna Height Reduction Based on Half-sized Full-wave Dipole, DOI:10.1109 / TAP.2023.3274291", a low profile can be achieved by replacing the half-wave dipole with other dipoles with high input impedance. A folded dipole is a type of dipole with high input impedance, consisting of two very close and parallel half-wave dipoles connected at their ends, with power fed only in the middle of one of the dipoles. It can be considered as a short-circuited two-wire transmission line of length 0.5λ folded along its longitudinal direction, and its input impedance is approximately four times that of a single half-wave dipole.

[0051] Antenna C uses a folded dipole instead of a half-wave dipole and is placed directly above the metal reflector 1. The distance between the folded dipole and the metal reflector 1 is 0.087λ. At this distance, good impedance matching can be achieved at the center frequency of 1.83GHz. However, although the profile height of antenna C is reduced, its bandwidth is smaller.

[0052] To extend the bandwidth of antenna C, the feed point 4 at the center position is shifted 5mm to one side, forming antenna D. This shift of feed point 4 excites the full-wave mode of the folded dipole, generating an additional resonant point at 2.2GHz. However, antenna D at 2.2GHz has a |S...11 The value is as high as -8.3dB, indicating a poor match.

[0053] To improve the impedance matching of antenna D and further extend its bandwidth, a microstrip line (i.e., the sixth microstrip line 26) was added within the rectangular area enclosed by the offset folded dipole of antenna D, forming antenna E. Due to the coupling effect of the microstrip line, the original resonant point of antenna D at 2.2 GHz shifted to 2.05 GHz, and a new resonant point at 2.18 GHz was generated. The corresponding |S| values ​​for these three resonant points are... 11 All values ​​are less than or equal to -10dB, and the final antenna E can cover the 1.8GHz to 2.22GHz frequency band.

[0054] Figure 4 The vector current distribution diagrams for 1.86 GHz, 2.05 GHz, and 2.18 GHz in this embodiment are shown. The diagrams use grayscale to represent current values; smaller grayscale values ​​indicate larger currents. The arrows in the diagrams indicate the current direction on the antenna. As can be seen from the diagrams: when the antenna resonates at 1.86 GHz, the current is mainly concentrated on the first microstrip line 21 and the fifth microstrip line 25, and the current directions of the first microstrip line 21 and the fifth microstrip line 25 are consistent. Near the feed point 4, there is a maximum current value, consistent with the characteristics of a half-wave mode. When the antenna resonates at 2.05 GHz, a counter-clockwise current loop is formed on the left side of the third microstrip line 23, and on the left side of the second microstrip line 22 and the first microstrip line 21. A maximum current value is formed in the middle of the second microstrip line 22. Furthermore, a clockwise current loop is formed on the right side of the third microstrip line 23, the fourth microstrip line 24, the fifth microstrip line 25, and the right side of the first microstrip line 21. A maximum current value is also formed in the middle of the fourth microstrip line 24, which conforms to the characteristics of the full-wave mode. When the antenna resonates at 2.18 GHz, the current is mainly concentrated on the sixth microstrip line 26. This is because the sixth microstrip line 26 is close to the feed point 4, and the energy of the feed point 4 can be coupled to the sixth microstrip line 26 through the gap between the feed point 4 and the sixth microstrip line 26.

[0055] The above embodiment has only one polarization direction. Researchers can set up another identical embodiment at a position perpendicular to this embodiment to form dual-polarized radiation.

[0056] This embodiment improves the half-wave dipole positioned 0.25λ above the metal reflector 1 by folding its end to form a folded oscillator, thereby increasing the input impedance. Even when the distance between it and the metal reflector 1 is reduced to 0.087λ, it still functions normally, generating the first resonant point. Next, the position of the feed point 4 is shifted to excite a full-wave mode, generating the second resonant point. Finally, a coupling microstrip is added to improve the matching degree of the second resonant point and excite the third resonant point. These three resonant points are integrated, covering the 1.8GHz–2.22GHz frequency band. The overall dimensions of this embodiment are 0.353λ × 0.12λ × 0.087λ, achieving miniaturization and broadband compared to existing technologies, and possessing significant application value.

Claims

1. A miniaturized broadband folded dipole base station antenna, characterized in that, The device includes a metal reflector (1), a dielectric plate (2), a support column assembly (3), and a power supply point (4). The dielectric plate (2) is fixed on the metal reflector (1) by the support column assembly (3). The surface of the dielectric plate (2) is printed with a microstrip line assembly that is in the shape of a rectangular ring. The power supply point (4) serves as the simulation port of the simulation software and is set on the microstrip line assembly. The microstrip line assembly includes a first microstrip line (21), a second microstrip line (22), a third microstrip line (23), a fourth microstrip line (24), a fifth microstrip line (25), and a sixth microstrip line (26) printed on the upper surface of the dielectric substrate (2). The first microstrip line (21), the second microstrip line (22), the third microstrip line (23), the fourth microstrip line (24), and the fifth microstrip line (25) are connected end to end to form a rectangular ring. An opening is provided at the connection between the first microstrip line (21) and the fifth microstrip line (25) of the rectangular ring. The feed point (4) is located at the opening and is electrically connected to the first microstrip line (21) and the fifth microstrip line (25) respectively. The sixth microstrip line (26) is located within the rectangular space enclosed by the first microstrip line (21), the second microstrip line (22), the third microstrip line (23), the fourth microstrip line (24), the fifth microstrip line (25), and the feed point (4).

2. The miniaturized broadband folded dipole base station antenna according to claim 1, characterized in that, The power supply point (4) includes a coaxial feed line, which includes an inner core and an outer core. The inner core is connected to the first microstrip line (21), and the outer core is connected to the fifth microstrip line (25).

3. The miniaturized broadband folded dipole base station antenna according to claim 1, characterized in that, The power supply point (4) includes a coaxial feed line, which includes an inner core and an outer core. The outer core is connected to the first microstrip line (21), and the inner core is connected to the fifth microstrip line (25).

4. A miniaturized broadband folded dipole base station antenna according to claim 2 or 3, characterized in that, The lengths of the first microstrip line (21), the second microstrip line (22), the third microstrip line (23), the fourth microstrip line (24), and the fifth microstrip line (25) are 30 mm, 18 mm, 53 mm, 18 mm, and 20 mm, respectively; the widths of the first microstrip line (21), the second microstrip line (22), the third microstrip line (23), the fourth microstrip line (24), and the fifth microstrip line (25) are all 5 mm.

5. A miniaturized broadband folded dipole base station antenna according to claim 4, characterized in that, The sixth microstrip line (26) has a length of 40 mm and a width of 5.5 mm. The gap width between the sixth microstrip line (26) and the first microstrip line (21) is 1 mm. The gap width between the sixth microstrip line (26) and the second microstrip line (22) is 1.5 mm. The gap width between the sixth microstrip line (26) and the third microstrip line (23) is 1.5 mm.

6. A miniaturized broadband folded dipole base station antenna according to claim 1, characterized in that, The metal reflector (1) is a component used to reflect the rearward radiation of the dipole antenna. The length and width of the metal reflector (1) are both 1λ~1.5λ.

7. A miniaturized broadband folded dipole base station antenna according to claim 1, characterized in that, The dielectric substrate (2) is made of FR4 material with a relative permittivity of 4.4, a thickness of 1.6 mm, a length of 100 mm, and a width of 80 mm.

8. A miniaturized broadband folded dipole base station antenna according to claim 1, characterized in that, The support column assembly (3) includes multiple support columns disposed between the metal reflector (1) and the medium plate (2).

9. A miniaturized broadband folded dipole base station antenna according to claim 7, characterized in that, The medium plate (2) is a rectangular plate, and the number of support columns of the support column assembly (3) is four, and the four support columns are respectively arranged at the four corners of the rectangular plate.

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