Dipole antenna and mobile terminal

Abstract

The present application provides a dipole antenna and a mobile terminal. The dipole antenna includes a dielectric plate and an antenna unit and a guide unit printed on the surface of the dielectric plate. The antenna unit includes a microstrip balun. The guide unit is connected to the microstrip balun to change the current distribution of the microstrip balun, thereby correcting the directional pattern of a traditional dipole antenna. In practical applications, the error and interference caused by signal transmission or reception can be reduced.

Description

Technical Field

[0001] The present application relates to the field of communication technology, and in particular to a dipole antenna and a mobile terminal. Background Art

[0002] Dipole antenna (Dipole antenna or doublet) is the earliest used, simplest structure and most widely used type of antenna in radio communications.

[0003] The traditional dipole antenna is made of copper on both sides of the dielectric board to form the two arms of the dipole antenna, the microstrip transmission line and the microstrip balun. The excitation signal is fed from the feeding point and transmitted to the two arms of the dipole antenna through the microstrip balun and the microstrip balun transmission line. However, simulations have found that the single-directional pattern of the traditional dipole antenna is deformed in the operating frequency band of 1.1GHz to 1.63GHz, which will cause errors or interference in signal transmission or reception in practical applications. Summary of the invention

[0004] The present application provides a dipole antenna and a mobile terminal, which can correct the deformation of the single-directional pattern of a traditional dipole antenna and reduce errors or interference in signal transmission or reception.

[0005] The technical solutions provided by this application are as follows:

[0006] The present application provides a dipole antenna, comprising a dielectric plate and an antenna unit and a guide unit printed on the surface of the dielectric plate, wherein the antenna unit comprises a microstrip balun, the guide unit is connected to the microstrip balun, and the guide unit is used to change the current distribution of the microstrip balun.

[0007] In the dipole antenna of the present application, the microstrip balun includes a first microstrip balun and a second microstrip balun connected to each other, and the current guiding unit is connected to the second microstrip balun to change the current distribution of the microstrip balun.

[0008] In the dipole antenna of the present application, the guide unit includes two metal strips, and the two metal strips are respectively arranged at two ends of the second microstrip balun in the length direction to change the current distribution of the microstrip balun.

[0009] In the dipole antenna of the present application, the material of the metal strip is metal copper.

[0010] In the dipole antenna of the present application, the width of the metal strip ranges from 0.5 mm to 1.5 mm.

[0011] In the dipole antenna of the present application, the sum of the length of the metal strip and the length of the second microstrip balun is in the range of greater than one twelfth of the working wavelength and less than one tenth of the working wavelength.

[0012] In the dipole antenna of the present application, the antenna unit includes a first routing line printed on the back of the dielectric plate and a second routing line printed on the front of the dielectric plate, the first routing line includes a first antenna arm and the microstrip balun, the first antenna arm is connected to the first microstrip balun, the second routing line includes a connected second antenna arm and a microstrip transmission line, and the first antenna arm and the second antenna arm are mirror-symmetrical along the microstrip transmission line.

[0013] In the dipole antenna of the present application, the sum of the lengths of the first antenna arm and the second antenna arm is equal to half the working wavelength.

[0014] In the dipole antenna of the present application, the material of the dielectric board includes FR-4 board.

[0015] The present application also provides a mobile terminal, comprising the dipole antenna described in any one of the above items.

[0016] The beneficial effects of the present application are as follows: Different from the prior art, the dipole antenna provided by the present application includes a dielectric plate and an antenna unit and a guide unit printed on the surface of the dielectric plate. The antenna unit includes a microstrip balun. The guide unit is connected to the microstrip balun to change the current distribution of the microstrip balun, thereby correcting the radiation pattern of the traditional dipole antenna, which can reduce the errors and interference caused by signal transmission or reception in practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 A schematic diagram of the front structure of a traditional dipole antenna provided in an embodiment of the present application;

[0019] Figure 2 A first simulated radiation pattern of a conventional dipole antenna provided in an embodiment of the present application;

[0020] Figure 3 A second simulated radiation pattern of a conventional dipole antenna provided in an embodiment of the present application;

[0021] Figure 4 A third simulated radiation pattern of a conventional dipole antenna provided in an embodiment of the present application;

[0022] Figure 5 A fourth simulated radiation pattern of a conventional dipole antenna provided in an embodiment of the present application;

[0023] Figure 6 A frequency-return loss simulation curve diagram of a traditional dipole antenna provided in an embodiment of the present application;

[0024] Figure 7 A schematic diagram of the front structure of a dipole antenna provided in an embodiment of the present application;

[0025] Figure 8 A schematic diagram of current distribution of a conventional dipole antenna provided in an embodiment of the present application;

[0026] Fig. 9 A schematic diagram of current distribution of a dipole antenna provided in an embodiment of the present application;

[0027] Fig.10 A frequency-return loss simulation curve diagram of a dipole antenna provided in an embodiment of the present application;

[0028] Fig.11 A first simulated radiation pattern of a dipole antenna provided in an embodiment of the present application;

[0029] Fig.12 A second simulated radiation pattern of the dipole antenna provided in an embodiment of the present application;

[0030] Fig.13 A third simulated radiation pattern of the dipole antenna provided in an embodiment of the present application;

[0031] Fig.14 A fourth simulated radiation pattern of the dipole antenna provided in an embodiment of the present application;

[0032] Fig.15 Another front structural schematic diagram of the dipole antenna provided in an embodiment of the present application. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0034] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0035] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0036] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0037] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the various specific processes and material examples provided by the present application, but those of ordinary skill in the art can appreciate the application of other processes and / or the use of other materials.

[0038] It should be noted that the thickness and shape in the drawings of the present application do not reflect the actual proportions, and their purpose is only to illustrate the contents of the embodiments of the present application.

[0039] To facilitate understanding, the traditional dipole antenna is first explained:

[0040] See also Figure 1 The conventional dipole antenna 1000 uses a dielectric plate 100 with copper cladding on both sides to form two arms of the dipole antenna, a microstrip transmission line 112 and a microstrip balun 122, wherein, on the front side, the antenna arm 111 and the microstrip transmission line 112 are integrally formed, and on the back side, the antenna arm 121 and the microstrip balun 122 are integrally formed. Specifically, on the front side, the current flows from the feeding point 130 to the microstrip transmission line 112 and then to the antenna arm 111, and on the back side, the current flows from the antenna arm 121 to the microstrip balun 122. The current directions of the microstrip transmission line 112 and the microstrip balun 122 are opposite, so electromagnetic waves will not be radiated. On the two antenna arms, the current directions are the same, so electromagnetic waves will be radiated. However, after simulation, it was found that for the traditional dipole antenna 1000, when its operating frequency band is 1.1GHz-1.63GHz, and the dielectric plate is made of FR-4 plate, with a thickness of 1mm and a size of 50mm*120mm, its simulated radiation pattern is deformed. Specifically, ideally, the traditional dipole antenna should have a three-dimensional ring structure in the operating frequency band of 1.1GHz to 1.63GHz. However, due to Figures 2 to 5 It can be seen that the directional pattern of the traditional dipole antenna has a convex part A in the horizontal 240 degree direction, which may cause errors and interference in signal transmission or reception in practical applications. Figures 2 to 5 The simulated radiation patterns of different viewing directions corresponding to the traditional dipole antenna.

[0041] In order to correct the directional pattern of a traditional dipole antenna and reduce errors and interferences caused by signal transmission or reception in practical applications, an embodiment of the present application provides a dipole antenna.

[0042] See also Figure 7 , Figure 7Schematic diagram of the structure of the dipole antenna provided in the embodiment of the present application. Figure 1 As shown, the dipole antenna 2000 includes a dielectric plate 200 and an antenna unit 210 and a guide unit 220 printed on the surface of the dielectric plate 200 . The antenna unit 210 includes a microstrip balun 2112 . The guide unit 220 is connected to the microstrip balun 2112 . The guide unit 220 is used to change the current distribution of the microstrip balun 2112 .

[0043] Specifically, by arranging the guide unit 220 to be connected to the microstrip balun 2112 , the current transmission path can be extended, thereby changing the current distribution of the microstrip balun 2112 to change the radiation range of the dipole antenna 2000 .

[0044] In this embodiment, the antenna unit 210 includes a first trace 211 printed on the back of the dielectric board 200, the first trace 211 includes a first antenna arm 2111 and a microstrip balun 2112, the microstrip balun 2112 includes a first microstrip balun 2112-1 and a second microstrip balun 2112-2 connected to each other, the first microstrip balun 2112-1 is connected to the first antenna arm 2111, and the guide unit 220 is connected to the second microstrip balun 2112-2 to change the current distribution of the microstrip balun 2112.

[0045] In some embodiments, the current guiding unit 220 includes two metal strips, which are respectively arranged at two ends of the second microstrip balun 2112 - 2 in the length direction to change the current distribution of the microstrip balun 2112 .

[0046] It is easy to understand that, in addition to metal strips, resistors, capacitors and other components can also conduct electricity. However, resistors, capacitors and other components will cause antenna loss and reduce the radiation efficiency of the antenna. Pure metal has the least impact on the antenna. Among them, the dipole antenna 2000 is a symmetrical structure, and the feeding current on the transmission line is symmetrically distributed. Therefore, the guide unit 220 includes two metal strips, which are symmetrically arranged at both ends of the length direction of the second microstrip balun 2112-2 to ensure that the feeding current of the transmission line of the dipole antenna 2000 is symmetrically distributed.

[0047] In this embodiment, by adding metal strips, the current distribution of the microstrip balun 2112 can be changed to generate an additional directional pattern, and the original directional pattern can be corrected. Figure 8 and Fig. 9 ,Depend on Figure 8 It can be seen that the current distribution on the microstrip balun of the traditional dipole antenna is uneven, which is corrected by the metal strip, such as Fig. 9 As shown, the current distribution on the microstrip balun 2112 is uniform.

[0048] In some embodiments, the metal strip is made of copper.

[0049] It is easy to understand that copper's conductivity is second only to silver, and its cost is much lower than silver. Therefore, most factories use copper for processing.

[0050] In some embodiments, the width of the metal strip is in the range of 0.5 mm to 1.5 mm, and the sum of the length of the metal strip and the length of the second microstrip balun 2112 - 2 is in the range of greater than one twelfth of the operating wavelength and less than one tenth of the operating wavelength.

[0051] Specifically, the width of the metal strip mainly affects the port impedance, and the length of the metal strip mainly affects the resonant frequency of the antenna. This application mainly determines the length, width and position of the metal strip through simulation and optimization, so that the metal strip will not have a significant impact on the input impedance, and can match the dipole antenna within a specific operating frequency.

[0052] It is easy to understand that the position, size, etc. of the metal strip provided in the embodiment of the present application do not constitute a limitation to the present application. Adjusting the position and size of the metal strip according to the operating frequency of the dipole antenna and the shape and size of the microstrip balun falls within the protection scope of the present application.

[0053] In some embodiments, the material of the dielectric board 200 includes FR-4 board.

[0054] FR-4 board is a double-sided copper-clad PCB board made of epoxy resin + glass cloth. The dielectric constant of the commonly used FR-4 copper-clad board relative to air is 4.2-4.7. This dielectric constant changes with temperature. In the temperature range of 0-70 degrees, its maximum change range can reach 20%. The change in dielectric constant will cause a 10% change in line delay. The higher the temperature, the greater the delay. The dielectric constant will also change with the signal frequency. The higher the frequency, the smaller the dielectric constant. The dielectric constant is generally designed to be a classic value of 4.4.

[0055] In this embodiment, the dielectric plate 200 has a thickness of 1 mm, a width of 50 mm, and a length of 120 mm.

[0056] In this embodiment, the dipole antenna 2000 also includes a second trace 212 printed on the front side of the dielectric board 200 . The second trace 212 includes a second antenna arm 2121 and a microstrip transmission line 2122 connected to each other. The first antenna arm 2111 and the second antenna arm 2121 are mirror-symmetrical along the microstrip transmission line 2122 .

[0057] Specifically, the central axes of the microstrip transmission line 2122 and the microstrip balun 2112 may coincide with each other, and the first antenna arm 2111 and the second antenna arm 2121 are mirror-symmetrical along the central axes of the microstrip transmission line 2122 and the microstrip balun 2112 .

[0058] It is easy to understand that the antenna unit 210 is printed on the surface of the dielectric plate 200, and the dielectric plate 200 will affect the transmission of electromagnetic waves. Therefore, the waveguide wavelength on the dielectric plate 200 is used as the working wavelength of the antenna unit 210. First, the working wavelength is determined according to the formula: in, λ g is the waveguide wavelength of the electromagnetic wave propagating on the dielectric plate 200, ω is the antenna width, and h is the thickness of the dielectric plate 200. ε re is the effective dielectric constant of the dielectric plate 200, ε r is the dielectric constant of the dielectric plate 200, and λ0 is the free space wavelength of the electromagnetic wave.

[0059] In this embodiment, the sum of the lengths of the first antenna arm 2111 and the second antenna arm 2121 is equal to half the operating wavelength.

[0060] It is easy to understand that when the operating frequency of the dipole antenna is high, coaxial feeding is generally used due to radiation loss and other reasons. However, coaxial feeding causes asymmetric current distribution in the two antenna arms, that is, unbalanced feeding, which affects its input impedance. Therefore, a microstrip balun is used for impedance conversion.

[0061] Specifically, when coaxial feeding is used, its input impedance is generally 50 ohms. When the angle between the first antenna arm 2111 and the second antenna arm 2121 is 180 degrees, the output impedance of the dipole antenna 2000 is generally 73.2. Therefore, a microstrip balun 2112 can be used for impedance matching, which is equivalent to a quarter-wavelength impedance converter. The input impedance of the feeding port can be changed by adjusting the size of the microstrip balun 2112. In addition, the microstrip balun 2112 can also convert unbalanced electromagnetic waves into balanced electromagnetic waves, which is beneficial to the energy transmission of the first antenna arm 2111 and the second antenna arm 2121 and the radiation of the dipole antenna.

[0062] It is easy to understand that the angle between the first antenna arm 2111 and the second antenna arm 2121 may not be 180 degrees. As the angle between the first antenna arm 2111 and the second antenna arm 2121 decreases, the output impedance will also decrease. At this time, the size of the microstrip balun can be adjusted for impedance matching.

[0063] In this embodiment, the angle between the first antenna arm 2111 and the second antenna arm 2121 is 180 degrees. At this time, the dimensions of the dipole antenna 2000 can be: the width w1 of the second antenna arm 2121 and the width w5 of the first antenna arm 2111 are both 3 mm, the length l1 of the second antenna arm 2121 is 49 mm, the length l6 of the first antenna arm 2111 is 48 mm, the length l2 of the microstrip transmission line 2122 is 23 mm, and the width w3 is 1 mm. The length l3 of the microstrip balun 2112 is 11 mm, the width w4 is 2 mm, the l4 is 20 mm, and the length l5 of the second microstrip balun 2112-2 is 8 mm, and the width w2 is 2 mm.

[0064] For further information, see Figure 6 as well as Figures 10 to 14 ,in, Figure 6 The vertical coordinate S(1,1) represents the return loss of the traditional dipole antenna 1000. Figure 6 The horizontal axis represents the operating frequency of the conventional dipole antenna 1000. Fig.10 The ordinate S(1,1) represents the return loss of the dipole antenna 2000 , and the abscissa represents the operating frequency of the dipole antenna 2000 . Figure 6 and Fig.10 The matching of the dipole antenna 2000 in the entire working frequency band is characterized. If the return loss is small, it means that the antenna is well matched. Otherwise, the energy of the feed port will be reflected back by the antenna, resulting in a decrease or deterioration of the performance. It can be seen that the matching of the dipole antenna 2000 is better in the working frequency band of 1.1 GHz to 1.63 GHz. Figures 11 to 14 It can be seen that the simulated radiation pattern of the dipole antenna 2000 is omnidirectional as a whole, and the deformation in the horizontal 240 degree direction is corrected.

[0065] Specifically, by adding the guide unit 220 to change the current distribution on the microstrip balun 2112, there is no need to change the traditional antenna design, and the antenna processing complexity will not be increased, which is conducive to integrated design and is simple and practical.

[0066] In this embodiment, the dipole antenna 2000 may be an LDS antenna or an FPC antenna.

[0067] Among them, FPC (Flexible Printed Circuit) antenna is suitable for almost all small electronic products. It can be used to make complex antennas with more than ten frequency bands such as 4G, with good performance and relatively low cost. LDS antenna technology is laser direct structuring technology, which uses a computer to control the movement of the laser according to the trajectory of the conductive pattern, and projects the laser onto the molded three-dimensional plastic device to activate the circuit pattern within a few seconds. For the design and production of mobile phone antennas, it is to use laser laser technology to directly plate the metal antenna pattern on the molded plastic bracket. This technology can directly laser the antenna on the mobile phone shell. The advantage of this antenna is that the antenna is more stable and can avoid interference from internal components. At the same time, it can also save more design space and make the mobile phone thinner.

[0068] Specifically, the dipole antenna 2000 can be installed in a mobile terminal such as a mobile phone or a computer, and the overall size of the dipole antenna 2000, the distance of the internal wiring, and other designs can be adjusted according to actual conditions.

[0069] Different from the prior art, the dipole antenna 2000 provided in the present application includes a dielectric plate 200 and an antenna unit 210 and a guide unit 220 printed on the surface of the dielectric plate 200. The antenna unit 210 includes a microstrip balun 2112. The guide unit 220 is connected to the microstrip balun 2112 to change the current distribution of the microstrip balun 2112, thereby correcting the radiation pattern of the traditional dipole antenna. In practical applications, it can reduce the errors and interference caused by signal transmission or reception.

[0070] The present application also provides a mobile terminal, which includes the dipole antenna described in the above embodiment.

[0071] In addition to the above embodiments, the present application may also have other implementation modes. Any technical solution formed by equivalent replacement or equivalent replacement falls within the protection scope required by the present application.

[0072] In summary, although the preferred embodiments of the present application have been disclosed as above, the above preferred embodiments are not intended to limit the present application. Ordinary technicians in this field can make various changes and modifications without departing from the spirit and scope of the present application. Therefore, the scope of protection of the present application shall be based on the scope defined in the claims.

Claims

1. A dipole antenna, characterized in that: It comprises a dielectric plate and an antenna unit and a guide unit printed on the surface of the dielectric plate, wherein the antenna unit comprises a microstrip balun, the guide unit is connected to the microstrip balun, and the guide unit is used to change the current distribution of the microstrip balun; The dipole antenna is a symmetrical structure, and the feeding current on its transmission line is symmetrically distributed; The microstrip balun includes a first microstrip balun and a second microstrip balun connected to each other, and the current guiding unit is connected to the second microstrip balun to change the current distribution of the microstrip balun; The guide unit includes two metal strips, which are symmetrically arranged at two ends of the second microstrip balun in the length direction, so as to change the current distribution of the microstrip balun and ensure the symmetrical distribution of the feeding current of the transmission line of the dipole antenna; The antenna unit includes a first trace printed on the back of the dielectric board, the first trace includes a first antenna arm and the microstrip balun, and the first antenna arm is connected to the first microstrip balun.

2. The dipole antenna according to claim 1, characterized in that: The material of the metal strip is metal copper.

3. The dipole antenna according to claim 1, characterized in that: The width of the metal strip ranges from 0.5 mm to 1.5 mm.

4. The dipole antenna according to claim 1, characterized in that: The sum of the length of the metal strip and the length of the second microstrip balun is in the range of greater than one twelfth of the working wavelength and less than one tenth of the working wavelength.

5. The dipole antenna according to claim 1, characterized in that: The antenna unit includes a second routing line printed on the front side of the dielectric board, the second routing line includes a second antenna arm and a microstrip transmission line connected to each other, and the first antenna arm and the second antenna arm are mirror-symmetrical along the microstrip transmission line.

6. The dipole antenna according to claim 5, characterized in that: The sum of the lengths of the first antenna arm and the second antenna arm is equal to half of the operating wavelength.

7. The dipole antenna according to claim 1, characterized in that: The material of the dielectric board includes FR-4 board.

8. A mobile terminal, characterized in that: The mobile terminal comprises the dipole antenna according to any one of claims 1 to 7.

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