A dual-band Wi-Fi antenna

Abstract

The present invention provides a dual-band Wi-Fi antenna, which belongs to the field of wireless communication technology. The antenna includes a substrate, on which a first metal strip, a first loaded inductor, a high-frequency band dipole, a dipole center feeding port, a metal via and at least one frequency band module are arranged. The antenna of the present invention adopts a novel dual-band structure, which makes the structure of the antenna compact. By utilizing the loading characteristics of the inductor, the antenna resonant frequency can be independently adjusted within a certain range, thereby realizing the miniaturization of the antenna. The dual-band implementation method proposed in the present invention can not only realize dual-band, but also realize more frequency bands by adding metal strips. In the present invention, the substrate is wrapped by a metal layer and a metal via, which can greatly reduce the dielectric loss of the substrate, thereby improving the radiation efficiency of the antenna. The dual-band dipole antenna form proposed in the present invention is not only suitable for working in the Wi-Fi frequency band, but also antennas of other wireless frequency bands can adopt this antenna structure. It solves the problem that most dual-band implementation methods are difficult to realize more frequency bands and are independently adjustable, and the design difficulty is relatively high.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless communications, and in particular relates to a dual-band Wi-Fi antenna. Background Art

[0002] Antennas are an indispensable and important component in wireless communication systems and radar systems. The performance of antennas determines the performance and quality of the entire wireless system. With the comprehensive advancement of wireless communication technologies represented by 5G and the Internet of Things, there is an urgent need to develop high-quality antenna components suitable for their application scenarios. Wi-Fi antennas are widely used in wireless systems, and there is a great demand, especially for low-cost, high-efficiency, miniaturized dual-band Wi-Fi antennas. Currently, the commonly used Wi-Fi antennas are mainly monopoles and dipoles, including all-metal structures and printed circuit board structures. In addition, dual-band PIFA antennas are also common antenna structures. In terms of processing technology, since dual-band antennas are more complex than single-band antennas, and the processing difficulty and cost of all-metal structures are relatively high, dual-band antennas generally use PCB processing technology. In order to reduce costs, PCBs generally use low-cost substrates (such as FR4), but the dielectric loss tangent of low-cost substrates is higher, resulting in increased dielectric loss. The frequency of commonly used Wi-Fi antennas has now been raised to 5GHz. In the high frequency band, the dielectric loss caused by low-cost substrates will be greater. In terms of dual-frequency implementation methods, the basic principle of most printed dual-frequency antennas is to combine antennas of two frequency bands and feed them simultaneously to achieve dual-frequency radiation. Common methods include: double-branch monopole, each branch works in one frequency band to achieve dual-frequency; step impedance monopole antenna, controlling the frequency of the first high-order mode to achieve dual-frequency; double-branch PIFA antenna, each branch works in one frequency band to achieve dual-frequency; using matching circuits to enable single-frequency antennas to achieve dual-frequency, etc.

[0003] As for the commonly used dual-band antennas on printed circuit boards, in order to reduce costs, low-cost substrates (such as FR4) are generally used in PCBs. However, the dielectric loss tangent of low-cost substrates is relatively high, resulting in increased dielectric loss. The frequency of commonly used Wi-Fi antennas has now increased to 5GHz. In the high-frequency band, the dielectric loss caused by low-cost substrates will be greater. Low-loss substrates are more expensive and are not suitable for large-scale use.

[0004] As for the currently commonly used all-metal dual-band Wi-Fi antennas, they are generally processed by laser cutting of metal sheets. The advantages are no dielectric loss and high efficiency, but poor processing accuracy, poor antenna consistency, and easy frequency deviation, which will reduce performance. Especially when the bandwidth is narrow, the frequency deviation will increase and reduce radiation efficiency and may also affect the output port of the RF chip.

[0005] As for the current dual-frequency implementation methods, multi-branch antennas will lead to a larger antenna structure, which is not conducive to the use of small-sized devices. The frequency band bandwidth matched by the matching circuit is generally very narrow, and it is easy to deviate due to component tolerance. Most dual-frequency implementation methods are difficult to achieve more frequency bands and independently adjust them, and the design difficulty is relatively high. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, the present invention provides a low-cost and high-efficiency dual-band Wi-Fi antenna, which solves the problem that most dual-band implementation methods are difficult to achieve more frequency bands and independently adjust them, and the design difficulty is relatively high.

[0007] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0008] This solution provides a dual-band Wi-Fi antenna, the antenna comprising a substrate, on which a first metal strip, a first loading inductor, a high-frequency band dipole, a dipole center feeding port, a metal via, and at least one frequency band module are arranged;

[0009] The two ends of the high-frequency band dipole are respectively connected in series with a first loading inductor and a first metal strip, the metal via is arranged on the Z axis of the substrate, the dipole center feeding port is located on the high-frequency band dipole, and the frequency band module is connected in series with the first metal strip.

[0010] The beneficial effects of the present invention are as follows: the antenna of the present invention adopts a novel dual-frequency structure, which makes the antenna structure compact, and utilizes the loading characteristics of the inductor so that the antenna resonant frequency can be independently adjusted within a certain range, thereby realizing the miniaturization of the antenna. The dual-frequency implementation method proposed in the present invention can not only realize dual-frequency, but also realize more frequency bands by adding metal strips. The dual-frequency dipole antenna form proposed in the present invention is not only suitable for working in the Wi-Fi frequency band, but also antennas in other wireless frequency bands can also adopt this antenna structure.

[0011] Furthermore, each of the frequency band modules includes a second loading inductor and a second metal strip connected in series, and the second loading inductor is connected in series with the first metal strip.

[0012] The beneficial effect of the above further solution is that the present invention can achieve more frequency bands by adding metal strips.

[0013] Furthermore, the high-frequency band dipole and the first metal strips located at two ends of the high-frequency band dipole form a large dipole.

[0014] The beneficial effect of the above further solution is that the present invention forms a large dipole through the high-frequency band dipole and the metal strips on both sides to achieve resonance at 2.4 GHz.

[0015] Furthermore, the metal via is equivalent to a combination of a metal edge and metal layers above and below the substrate that wrap the substrate.

[0016] The beneficial effect of the above further scheme is: in the present invention, the use of metal vias on the Z-axis of the substrate is equivalent to the combination of metal edges and metal layers above and below the substrate to wrap the substrate, thereby realizing an equivalent all-metal structure, the interior of the substrate is shielded, no electric field enters the interior of the substrate, and the overall dielectric loss is reduced.

[0017] Furthermore, the medium of the substrate is FR4 with a thickness of 1 mm, a dielectric constant of 4.4, and a loss tangent of 0.02.

[0018] The beneficial effect of the above further solution is that the processing method in the present invention is a mature PCB process, and the processing is simple and the cost is very low. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a 3-D schematic diagram of the antenna in the present invention.

[0020] Figure 2 This is a top view of the antenna in the present invention.

[0021] Figure 3 2 is a diagram showing the electric field amplitude distribution in two frequency bands in this embodiment.

[0022] Figure 4 In this embodiment, d1 Schematic diagram of the S parameters of the antenna when the length changes.

[0023] Figure 5 In this embodiment, d2 Schematic diagram of the S parameters of the antenna when the length changes.

[0024] Figure 6 Graphs 1 and 2 are the antenna performance and radiation patterns in this embodiment.

[0025] Figure 7 FIG. 4 is a schematic diagram of a three-band antenna in this embodiment.

[0026] Figure 8 FIG. 4 is a schematic diagram of S parameters of the triple-band antenna in this embodiment.

[0027] Fig. 9 4 is a performance comparison chart of different types of antennas in this embodiment.

[0028] Among them, 1-first metal strip, 2-first loaded inductor, 3-high frequency band dipole, 4-dipole center feeding port, 5-metal via, 6-second loaded inductor, 7-second metal strip, 8-triple-band antenna feeding port, 9-high frequency band dipole of the tri-band antenna, 10-third loaded inductor, 11-metal strip of the tri-band antenna. DETAILED DESCRIPTION

[0029] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0030] Example

[0031] like Figure 1-Figure 2 As shown, the present invention provides a dual-band Wi-Fi antenna, the antenna includes a substrate, on which a first metal strip 1, a first loading inductor 2, a high-frequency dipole 3, a dipole center feeding port 4, a metal via 5 and at least one frequency band module are arranged; in the antenna, a new dual-band structure is adopted, so that the structure of the antenna is compact, and the loading characteristics of the inductor are utilized so that the antenna resonant frequency can be independently adjusted within a certain range, thereby realizing the miniaturization design of the antenna. The two ends of the high-frequency dipole 3 are respectively connected in series with the first loading inductor 2 and the first metal strip 1, the metal via 5 is arranged on the Z axis of the substrate, the dipole center feeding port 4 is located on the high-frequency dipole 3, and the frequency band module is connected in series with the first metal strip 1. Each frequency band module includes a second loading inductor 6 and a second metal strip 7 connected in series, and the second loading inductor 6 is connected in series with the first metal strip 1. The high-frequency dipole 3 and the first metal strip 1 located at the two ends of the high-frequency dipole 3 form a large dipole. The metal via 5 is equivalent to a combination of a metal edge and metal layers above and below the substrate to wrap the substrate. In this antenna, metal vias and metal combination PCB wrapping methods are used to achieve high radiation efficiency of a low-cost substrate. The substrate medium is FR4 with a thickness of 1 mm, a dielectric constant of 4.4, and a loss tangent of 0.02.

[0032] In this embodiment, if it is a dual-band Wi-Fi antenna, the dual-band Wi-Fi antenna includes the following parameters: the total length l of the antenna is 39 mm; the length l of the first metal strip 1 is d1 is 5.6mm; the single arm length l of the high frequency dipole 3 d2 12mm; the width w of the high-frequency dipole 3 d1 is 3.1 mm; the width w of the first metal strip 1 d2 is 2.65 mm; the diameter D of the metal via 5 is 0.6 mm; the center distance w of the metal via 5 is g 1mm; the width w of the distance between the two arms of the high-frequency dipole 3 s1 is 1 mm; the arm distance w between the first metal strip 1 and the high-frequency dipole 3 s2 is 1mm; the single arm length l of the high frequency dipole 3 d3 It is 12mm.

[0033] In this embodiment, the use of loading inductors is not limited to lumped components. The use of printed distributed inductors can further reduce costs, but the size will be slightly increased. The dual-frequency dipole antenna form proposed by the antenna is not only suitable for working in the Wi-Fi frequency band, but also can be used in antennas of other wireless frequency bands.

[0034] In this embodiment, the substrate material used for the antenna is a 1 mm thick FR4 substrate, with a dielectric constant of 4.4 and a loss tangent of 0.02. The processing method is a mature PCB process, and the processing is simple and the cost is very low. Figure 1 As shown, the antenna consists of a first inductor 2 and a first metal strip 1 connected in series at both ends of a high-frequency dipole 3. The first inductor 2 is 8.6nH. At 2.4GHz, the first inductor 2 is approximately equivalent to a short circuit. The high-frequency dipole 3 and the first metal strips 1 on both sides form a large dipole to achieve resonance at 2.4GHz. In the 5GHz band, the first inductor 2 is approximately open-circuited, the first metal strips 1 on both sides are disconnected, and only the short dipole in the middle works, resonating at 5GHz. Figure 3 From the electric field amplitude distribution, it can be seen that when working at 2.4 GHz, the entire structure is in resonance, and when working at 5 GHz, the electric field is basically concentrated only at the short dipole in the middle. Figure 4 Shows l d1 The S parameters of the antenna when the length changes, Figure 5 Shows l d2 The S parameters of the antenna when the length changes. As can be seen in the figure, l d1 As the frequency becomes shorter, the low frequency part (2.4 GHz) gradually shifts to the high frequency, while the high frequency band (5 GHz) remains basically unchanged. d2 As the frequency becomes shorter, both the low frequency part (2.4 GHz) and the high frequency band (5 GHz) shift toward high frequency. d2 The change mainly affects the high frequency band, so the low frequency band offset is small, which is consistent with the above theory. It can be seen from the figure that the two frequency bands can basically be independently controllable, and they can be designed separately to reduce the difficulty.

[0035] In this embodiment, the metal via 5 used on the Z axis of the substrate is equivalent to the combination of the metal edge and the metal layers above and below the substrate to wrap the substrate, realizing an equivalent all-metal structure, the interior of the substrate is shielded, no electric field enters the interior of the substrate, and the overall dielectric loss is reduced. The diameter of the metal via 5 is 0.6mm. The center spacing is 1mm, and the diameter and center spacing of the metal via 5 will affect the equivalent metal wrapping effect. The diameter and spacing should be as small as possible, but too many metal vias 5 will make the edge of the substrate easy to fall off, which requires a compromise. Figure 6 and Fig. 9 The performance of different types of antennas is demonstrated, among which, Figure 6 (a) is the antenna performance diagram, Figure 6 (b) is the radiation pattern. The radiation efficiency of the antenna can be increased from 70% (77%) to 80% (87%), achieving a lower operating frequency at a smaller size. Considering that the loss tangent of a low-cost substrate in reality will be larger, the actual improved efficiency will be higher. In addition, since the substrate is equivalently fully wrapped in this embodiment, the impact caused by the dielectric constant drift of the low-cost substrate in reality is also minimized.

[0036] In this embodiment, the dual-band implementation method proposed can not only realize dual-band, but also, by extension, more frequency bands can be realized by adding metal strips. The principle is basically similar. To prove this point, a three-band antenna is also designed. Figure 7 As shown, Figure 7 (a) is a schematic diagram of a three-band antenna. Figure 7 (b) is the dimensions of the three-band antenna. Because it is only used to verify the multi-band principle, no metal vias are used. Adding inductors and metal strips on the basis of dual-band can achieve three-band. Figure 8 The S-parameters of the tri-band antenna are shown.

[0037] In this embodiment, Figure 1 As shown, a dual-band miniaturized high-efficiency Wi-Fi antenna, the antenna is loaded with a first metal strip 1, a first loaded inductor 8.6nH2 and a high-frequency dipole 3, a dipole center feeding port 4, and a metal via 5. Figure 7 As shown, if it is a triple-band antenna, the second loading inductor is 30nH6, the third loading inductor is 8.49nH10, the triple-band antenna feeding port is 8, the high-frequency dipole of the triple-band antenna is 9, the second metal strip is 7, and the metal strip of the triple-band antenna is 11. The dimensions are: l = 39mm total length of the dual-band antenna, l d1 =5.6mm Length of the first metal strip 1, l d2 =12mm high frequency dipole 3 single arm length, w d1 =3.1mm high frequency dipole 3 width, D =0.6mm metal via 5 diameter, W g =1mm metal via 5 center spacing, W s1 =1mm Distance between two arms of dipole 3 in high frequency band, W s2 = the distance between the first metal strip and the dipole arm, W d2 =2.65mmThe width of the first metal strip 1, l d3 =12mm Tri-band antenna mid-high frequency dipole 9 single arm length, l d4 =5.6mm The length of the second metal strip 7, l d5 = 6 mm The length of the metal strip 11 of the triple-band antenna, w d3 =3.1mm Tri-band antenna mid-high frequency band dipole 9 width, W d5=2.6mm The width of the second metal strip 7, W d4 =2.65mm The width of the metal strip 11 of the three-band antenna. In this embodiment, the present invention provides a miniaturized, high-efficiency PCB dual-band Wi-Fi antenna, which is made of a low-cost PCB substrate FR4. The present invention proposes a new dual-frequency dipole implementation structure, which realizes dual-frequency radiation on a dipole by using the principle that the inductor is approximately short-circuited in the low-frequency band and approximately open-circuited in the high-frequency band. The resonant frequency of the dipole is mainly determined by the length of the dipole, and the length of the low-frequency dipole is longer than the length of the high-frequency dipole. Two suitable inductors and two small metal strips are connected in series at both ends of the high-frequency dipole. In the high-frequency band, the inductor is approximately open-circuited, and the series-connected metal strips have almost no effect at high frequencies. In the low-frequency band, the inductor is approximately short-circuited, and the original high-frequency band dipole connected in series with two metal strips is equivalent to increasing the length of the dipole, so resonance is also generated in the low-frequency band. At the same time, the use of inductance cannot be completely equivalent to a short circuit in the low-frequency band, and it also has a corresponding loading effect, which reduces the overall length of the antenna. The proposed dual-band implementation method can not only achieve dual-band, but also, by extension, add metal strips to achieve more frequency bands. The principle is basically similar. The main source of loss in Wi-Fi dual-band PCB antennas is dielectric loss. When the electric field passes through the dielectric, current is generated, which reduces efficiency. Therefore, wrapping the substrate completely with metal can avoid dielectric loss. In the PCB process, the cost of metal edging is relatively high. Therefore, the ordinary metal via process is used to approximately wrap the PCB side wall, and the upper and lower metal layers are wrapped, which can greatly reduce dielectric loss.

Claims

1. A dual-band Wi-Fi antenna, characterized in that: The antenna comprises a substrate, on which a first metal strip (1), a first loaded inductor (2), a high-frequency band dipole (3), a dipole center feeding port (4), a metal via (5) and at least one frequency band module are arranged; the metal via (5) is equivalent to a combination of a metal edge and metal layers above and below the substrate that wrap the substrate; Two ends of the high-frequency band dipole (3) are respectively connected in series with a first loading inductor (2) and a first metal strip (1); the metal via (5) is arranged on the Z axis of the substrate; the dipole center feeding port (4) is located on the high-frequency band dipole (3); and the frequency band module is connected in series with the first metal strip (1).

2. The dual-band Wi-Fi antenna according to claim 1, characterized in that: Each of the frequency band modules comprises a second loading inductor (6) and a second metal strip (7) connected in series, and the second loading inductor (6) is connected in series with the first metal strip (1).

3. The dual-band Wi-Fi antenna according to claim 1, characterized in that: The high-frequency band dipole (3) and the first metal strips (1) located at both ends of the high-frequency band dipole (3) form a large dipole.

4. The dual-band Wi-Fi antenna according to claim 1, characterized in that: The medium of the substrate is FR4 with a thickness of 1 mm, a dielectric constant of 4.4, and a loss tangent of 0.02.

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