Mobile phone antenna and design method thereof

Abstract

The present invention provides a mobile phone antenna and a design method thereof, wherein the design method of the mobile phone antenna includes: designing a mobile phone floor structure and setting a target characteristic mode; simulating the mobile phone floor structure in a low frequency band to obtain a current distribution diagram and a directional diagram of a characteristic mode consistent with the target characteristic mode; designing a feeding point and a feeding network according to the current distribution diagram and the directional diagram to form the structure of the mobile phone antenna. By using the characteristic mode simulation method, the directional diagram of the low-frequency mobile phone antenna is changed, and the structure of the mobile phone antenna in the low frequency band is designed and optimized, so that the radiation zero point of the directional diagram is directed toward the head of the mobile phone user, thereby enabling the mobile phone antenna to ensure higher performance in the low frequency band. The problem of low-frequency performance regression of existing mobile phones when in use is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of antennas, and in particular to a mobile phone antenna and a design method thereof. Background Art

[0002] With the rapid development of wireless communication technology, people have put forward more and more requirements for antenna design. There are many ideas for the design of existing mobile phone antennas in the low frequency band (below 1GHz), but there is a phenomenon that no matter how the radiation branches are set in the low frequency band, the corresponding radiation pattern is approximately omnidirectional in the direction perpendicular to the metal bottom plate structure of the mobile phone, and the corresponding radiation zero points exist at both ends along the long side of the mobile phone. This is mainly because in the low frequency band, the floor current distribution of the mobile phone is its main radiation source. Therefore, no matter how the antenna structure or matching network is changed, it is difficult to change the main radiation direction and zero point position of the pattern. Due to this phenomenon, people will experience obvious performance regression when using mobile phones, especially when making calls. Summary of the invention

[0003] The object of the present invention is to provide a mobile phone antenna and a design method thereof, so as to solve the problem that the low-frequency band performance of the existing mobile phone is degraded when in use.

[0004] In order to solve the above technical problems, the present invention provides a design method for a mobile phone antenna, and the design method for the mobile phone antenna comprises:

[0005] Design the mobile phone floor structure and set the target characteristic mode;

[0006] Simulating the mobile phone floor structure in a low frequency band to obtain a current distribution diagram and a direction diagram of a characteristic mode consistent with the target characteristic mode;

[0007] The feeding point and the feeding network are designed according to the current distribution diagram and the directional diagram to form the structure of the mobile phone antenna.

[0008] Optionally, in the design method of the mobile phone antenna, the design method of the mobile phone antenna also includes: performing simulation tests on the structure of the mobile phone antenna, and if the test results are qualified, ending the design; if the test results are unqualified, optimizing the feeding point and the feeding point network, and performing simulation tests on the optimized mobile phone antenna structure again, until the test results are qualified, and ending the design.

[0009] Optionally, in the design method of the mobile phone antenna, the method of simulating the mobile phone floor structure in a low frequency band to obtain a current distribution diagram and a directional diagram of a characteristic mode consistent with the target characteristic mode includes:

[0010] Simulating the mobile phone floor structure at a frequency of 1 GHz to obtain current distribution diagrams and directivity diagrams of at least two main characteristic modes;

[0011] The current distribution diagram and the direction diagram of the characteristic mode consistent with the target characteristic mode are selected from the current distribution diagrams and the direction diagrams of all characteristic modes.

[0012] Optionally, in the method for designing a mobile phone antenna, the method for designing a feeding point and a feeding network according to the current distribution diagram and the directional diagram includes:

[0013] According to the current distribution in the current distribution diagram, the feeding points are set in the areas of the mobile phone floor corresponding to the current distribution not being 0;

[0014] The mobile phone floor on which the feeding points are set is simulated and optimized so that the number of the feeding points set on the mobile phone floor does not exceed 4;

[0015] Assigning corresponding amplitudes and phases to all the optimized feeding points;

[0016] A feeding circuit is designed according to the amplitudes and phases of all the feeding points to form a structure of a mobile phone antenna.

[0017] Optionally, in the design method of the mobile phone antenna, before designing the feeding point and the feeding network according to the current distribution diagram and the directional diagram, the design method of the mobile phone antenna also includes: exciting the characteristic mode consistent with the target characteristic mode to increase the weight of the characteristic mode, thereby expanding the current distribution difference in the current distribution diagram.

[0018] In order to solve the above technical problems, the present invention also provides a mobile phone antenna designed using the design method of a mobile phone antenna as described in any of the above items, wherein the mobile phone antenna includes a dielectric plate, a metal bottom plate, a metal top plate and an antenna trace; the metal bottom plate and the metal top plate are respectively located on two surfaces of the dielectric plate, the antenna trace is on the same side as the metal top plate, and the metal top plate is divided into a plurality of metal plates; the width of the antenna trace is 1±0.05mm, and the minimum distance between the antenna trace and the metal top plate is 1mm.

[0019] Optionally, in the mobile phone antenna, the antenna routing includes at least one feeding point and at least one location, the feeding point is electrically connected to the metal top plate, and the location is electrically connected to the metal bottom plate.

[0020] Optionally, in the mobile phone antenna, the antenna routing includes a feeding point and four locations, the feeding point is located at the center of the metal top plate, and the four locations are respectively located in the middle of the edges of the four sides of the metal top plate.

[0021] Optionally, in the mobile phone antenna, the center of the metal top plate coincides with the center of the metal bottom plate, and the four sides of the metal top plate are respectively at least 3 mm shorter than the corresponding four sides of the metal bottom plate.

[0022] Optionally, in the mobile phone antenna, the dielectric plate has a hole corresponding to the location, and the location is electrically connected to the metal base plate through the hole.

[0023] The present invention provides a mobile phone antenna and a design method thereof, wherein the design method of the mobile phone antenna includes: designing a mobile phone floor structure and setting a target characteristic mode; simulating the mobile phone floor structure in a low frequency band to obtain a current distribution diagram and a directional diagram of a characteristic mode consistent with the target characteristic mode; designing a feeding point and a feeding network according to the current distribution diagram and the directional diagram to form the structure of the mobile phone antenna. By using the characteristic mode simulation method, the directional diagram of the low-frequency mobile phone antenna is changed, and the structure of the mobile phone antenna in the low frequency band is designed and optimized, so that the radiation zero point of the directional diagram is directed toward the head of the mobile phone user, thereby enabling the mobile phone antenna to ensure higher performance in the low frequency band. The problem of low-frequency performance regression of existing mobile phones when in use is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A flow chart of the design method of the mobile phone antenna provided in this embodiment;

[0025] Figure 2 Directional diagrams corresponding to the four characteristic modes provided in this embodiment;

[0026] Figure 3 The embodiment provided Figure 2 (c) Current distribution diagram of the corresponding characteristic mode;

[0027] Figure 4 A schematic diagram of the structure of the mobile phone antenna provided in this embodiment;

[0028] Figure 5 A structural side view of the mobile phone antenna provided in this embodiment;

[0029] Figure 6 The final directional pattern of the mobile phone antenna design provided in this embodiment;

[0030] The descriptions of the reference numerals are as follows:

[0031] 10- dielectric plate; 20- metal bottom plate; 30- metal top plate; 40- antenna wiring; 41- feeding point; 42- location. DETAILED DESCRIPTION

[0032] The mobile phone antenna and the design method thereof proposed in the present invention are further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the accompanying drawings are in a very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In addition, the structure shown in the accompanying drawings is often a part of the actual structure. In particular, the emphasis of each accompanying drawing is different, and sometimes different proportions are used.

[0033] At present, characteristic mode technology is usually used to optimize the antenna system to meet relevant needs. The characteristic mode analysis method is a method that has emerged in recent years. It combines the method of moments with the analytical eigenmode theory to solve electromagnetic problems. Through characteristic mode analysis, the characteristic value (λn), characteristic current (Jn), characteristic angle (CA), mode current coefficient MS, etc. of each mode of the antenna can be directly obtained. After adding port excitation, the mode excitation coefficient (MEC), mode weighting coefficient (MWC), different mode excitation power, different mode reflection coefficient and antenna efficiency can be obtained. Using the different mode information obtained by analysis, the antenna resonance characteristics and radiation characteristics of different modes are mastered. With the help of the distribution of characteristic currents of different modes, the best feeding position is selected to excite the required mode, which is also helpful to slot the antenna to fine-tune its resonant position.

[0034] This embodiment provides a design method for a mobile phone antenna that can effectively resist human body retreat based on characteristic mode theory. Figure 1 As shown, the design method of the mobile phone antenna includes:

[0035] S1, design the mobile phone floor structure and set the target characteristic mode;

[0036] S2, simulating the mobile phone floor structure in a low frequency band to obtain a current distribution diagram and a direction diagram of a characteristic mode consistent with the target characteristic mode;

[0037] S3, designing a feeding point and a feeding network according to the current distribution diagram and the directional diagram to form a structure of a mobile phone antenna.

[0038] The design method of the mobile phone antenna provided by the present invention changes the directional pattern of the low-frequency mobile phone antenna through the simulation method of the characteristic mode, designs and optimizes the structure of the mobile phone antenna in the low-frequency band, and makes the radiation zero point of the directional pattern face the head of the mobile phone user, so that the mobile phone antenna can ensure higher performance in the low-frequency band. The problem of low-frequency performance regression of existing mobile phones when in use is solved.

[0039] Furthermore, in this embodiment, the design method of the mobile phone antenna also includes: performing a simulation test on the structure of the mobile phone antenna, and if the test result is qualified, the design is terminated; if the test result is unqualified, the feed point and the feed point network are optimized, and the structure of the optimized mobile phone antenna is simulated again until the test result is qualified, and the design is terminated. Through continuous testing, adjustment and optimization, the final mobile phone antenna can meet the antenna performance requirements of the low frequency band.

[0040] In this embodiment, the method of simulating the mobile phone floor structure in a low frequency band to obtain a current distribution diagram and a direction diagram of a characteristic mode consistent with the target characteristic mode includes:

[0041] Simulating the mobile phone floor structure at a frequency of 1 GHz to obtain current distribution diagrams and directivity diagrams of at least two main characteristic modes;

[0042] The current distribution diagram and the direction diagram of the characteristic mode consistent with the target characteristic mode are selected from the current distribution diagrams and the direction diagrams of all characteristic modes.

[0043] The low frequency band ranges from 824MHz to 960MHz. Selecting 1GHz can well cover all low frequency ranges. After preliminary adjustments on this basis, any frequency in the low frequency band is randomly selected for optimization and adjustment. This can quickly obtain the best design results with less calculation and workload.

[0044] In addition, in this embodiment, the method for designing a feeding point and a feeding network according to the current distribution diagram and the directional diagram includes:

[0045] According to the current distribution in the current distribution diagram, the feeding points are set in the areas of the mobile phone floor corresponding to the current distribution not being 0;

[0046] The mobile phone floor on which the feeding points are set is simulated and optimized so that the number of the feeding points set on the mobile phone floor does not exceed 4;

[0047] Assigning corresponding amplitudes and phases to all the optimized feeding points;

[0048] A feeding circuit is designed according to the amplitudes and phases of all the feeding points to form a structure of a mobile phone antenna.

[0049] All points where the current is not 0 have current, but it is impossible to set up feeding points for the entire mobile phone floor. Therefore, simulation optimization is required to select individual feeding points so that the selected feeding points can meet the feeding needs of the entire mobile phone floor. At the same time, the feeding network is designed based on the characteristics of the feeding points to form a mobile phone antenna. In this way, similar to the reverse thinking method, a mobile phone antenna structure with low-frequency performance less affected by the head and hand can be obtained.

[0050] Since the characteristic mode has a very low corresponding characteristic weight at 1 GHz, it cannot be excited normally. Therefore, before designing the feeding point and the feeding network according to the current distribution diagram and the directional diagram, the design method of the mobile phone antenna also includes: exciting the characteristic mode consistent with the target characteristic mode to increase the weight of the characteristic mode, thereby expanding the current distribution difference in the current distribution diagram.

[0051] The following is a specific example to illustrate how the design method provided in this embodiment can be used to design a mobile phone antenna.

[0052] First, the mobile phone floor structure is designed and the target characteristic mode is set.

[0053] In this embodiment, the size of the mobile phone floor is designed to be the size of a regular mobile phone, 150×80mm, and the mobile phone floor is placed along the XY plane. Generally speaking, since the floor plays a major radiation role, the maximum radiation direction of its directional pattern is in the YZ plane. The directional pattern in the target characteristic mode should be located in the XZ plane, so that the maximum radiation direction of the mobile phone antenna is in the XZ plane, thereby ensuring that when people use mobile phones, the antenna is minimally affected by the head and hands, so as to reduce the performance regression of the antenna in the low frequency band when using the mobile phone.

[0054] Next, the mobile phone floor structure is simulated in the low frequency band to obtain the current distribution diagram and the directional diagram of the characteristic mode consistent with the target characteristic mode. In this embodiment, the current distribution diagram and the directional diagram of the four main characteristic modes at the 1 GHz frequency point are simulated using CST electromagnetic simulation software. Figure 2 As shown in the figure, the corresponding directional diagrams of the four characteristic modes are simulated. Figure 2 It can be seen that Figure 2 The maximum radiation direction of the mobile phone antenna in (c) is in the XZ plane, which is less affected by the head and hand, and meets our target characteristic mode. Figure 2 (c) The corresponding characteristic mode is selected and reserved for the next step.

[0055] Since the characteristic mode has a very low weight in the low frequency band and cannot be excited normally, special means are needed to excite it. Figure 2 (c) corresponding characteristic modes, so as to increase the weight of the characteristic modes and thus expand the current distribution difference in the current distribution diagram.

[0056] Then, continue to use CST software simulation Figure 2 (c) The current distribution in the corresponding characteristic mode, such as Figure 3 As shown in the figure, it can be seen that the current has a strong distribution at specific locations on the four sides of the mobile phone floor, while the voltage in the middle is relatively small. In theory, a feeding point should be set in each area where the current is not zero and the corresponding excitation amplitude and phase should be given to all feeding points to ensure that the excitation direction pattern is consistent with Figure 2 (c) Completely consistent. However, considering the actual situation, it is impossible to set too many feeding points on the mobile phone floor, so it is necessary to reduce the number of feeding points through simulation optimization. In this embodiment, the simplified feeding points are 4, and the four feeding points are respectively distributed near the midpoints of the four sides of the mobile phone floor.

[0057] At the same time, the amplitudes and phases corresponding to the four feeding points are (1, -133°), (1, 61°), (0.52, -177°) and (0.55, -169°). After the corresponding excitation amplitude and excitation phase are respectively transmitted to the four feeding points, the anti-fallback requirements can be met.

[0058] This embodiment also provides a mobile phone antenna designed using the above design method, such as Figure 4 and Figure 5 As shown, the mobile phone antenna includes a dielectric plate 10, a metal bottom plate 20, a metal top plate 30 and an antenna trace 40; the metal bottom plate 20 and the metal top plate 30 are respectively located on two surfaces of the dielectric plate 10, the antenna trace 40 is on the same side as the metal top plate 30, and the metal top plate 30 is divided into a plurality of metal plates; the width of the antenna trace 40 is 1±0.05mm, and the minimum distance between the antenna trace 40 and the metal top plate 30 is 1mm.

[0059] The mobile phone antenna provided in this embodiment changes the directional pattern of the mobile phone antenna in the low frequency band through the characteristic mode simulation method, thereby optimizing the structure of the mobile phone antenna in the low frequency band, so that the radiation zero point of the directional pattern of the mobile phone antenna is directed toward the head of the mobile phone user, so that the mobile phone antenna can ensure higher performance in the low frequency band. The problem of low-frequency performance regression of existing mobile phones when in use is solved.

[0060] In this embodiment, the antenna trace 40 includes at least one feeding point 41 and at least one location 42, the feeding point 41 is electrically connected to the metal top plate 30, and the location 42 is electrically connected to the metal bottom plate 20. Since the metal bottom plate 20 and the metal top plate 30 are located on different surfaces of the dielectric plate 10, and the antenna trace 40 and the metal top plate 30 are on the same side, it is necessary to provide a hole corresponding to the location 42 on the dielectric plate 10, and the location 42 is electrically connected to the metal bottom plate 20 through the hole.

[0061] It is found that when the antenna trace 40 includes a feeding point 41 and four locations 42, the feeding point 41 is located at the center of the metal top plate 30, and the four locations 42 are respectively located in the middle positions of the edges of the four sides of the metal top plate 30, the radiation performance of the mobile phone antenna is the best, the influence of the head and hands is minimized, and it can effectively resist retreat.

[0062] Furthermore, in this embodiment, the center of the metal top plate 30 coincides with that of the metal bottom plate 20, and the four sides of the metal top plate 30 are at least 3 mm shorter than the corresponding four sides of the metal bottom plate 20. In other words, the edge of the vertical projection of the metal top plate 30 on the dielectric plate 10 is at least 3 mm smaller than the edge of the vertical projection of the metal bottom plate 20 on the dielectric plate 10. In this way, the hole for passing the point 42 on the dielectric plate 10 can be set on the outside of the metal top plate 30, ensuring the integrity of the structure of the metal top plate 30 and avoiding the influence of the point 42 on the current radiation of the metal top plate 30.

[0063] See also Figure 1 , which is a schematic diagram of the mobile phone antenna structure designed using the design method provided in this embodiment. It can be seen that the metal top plate 30 is located on one side surface of the dielectric plate 10, the antenna trace 40 is on the same side as the metal top plate 30, and the antenna trace 40 includes four radiating branches, and the metal top plate 30 is divided into four metal plates by using its trace layout. Among them, the four radiating branches of the antenna trace 40 share a feeding point 41, and the feeding point 41 is located in the middle position of the metal top plate 30; each radiating branch extends to the edge center position of the four sides of the metal top plate 30, and a location 42 is provided at the end of the radiating branch. In this way, each side of the metal top plate 30 has good feeding performance, thereby improving the overall radiation performance of the antenna. After simulation using simulation software, the trace layout of each radiating branch is adjusted, and the resulting directional diagram is as shown below. Figure 6 As shown, from Figure 6 It can be seen that the final designed mobile phone antenna not only has good radiation performance, but also has good anti-fallback performance.

[0064] It should be noted that the specific length and size of the antenna trace 40 in the mobile phone antenna are related to the dielectric constant of the corresponding dielectric plate 10. In this embodiment, the thickness of the dielectric plate 10 is selected to be 0.254 mm, the dielectric constant is 2.2, and the designed structure is as follows: Figure 1 Therefore, in other embodiments, due to different sizes and related parameters of the selected dielectric plate 10, the specific layout and structure of the antenna trace 40 are also different. Other similar designs that do not violate the main purpose of the present invention should also fall within the protection scope of the present invention.

[0065] In summary, the mobile phone antenna and its design method provided in this embodiment, the design method of the mobile phone antenna includes: designing the mobile phone floor structure and setting the target characteristic mode; simulating the mobile phone floor structure in the low frequency band to obtain the current distribution diagram and the directional diagram of the characteristic mode consistent with the target characteristic mode; designing the feeding point and the feeding network according to the current distribution diagram and the directional diagram to form the structure of the mobile phone antenna. Through the simulation method of the characteristic mode, the directional diagram of the low-frequency band mobile phone antenna is changed, and the structure of the mobile phone antenna in the low frequency band is designed and optimized, so that the radiation zero point of the directional diagram is directed toward the head of the mobile phone user, so that the mobile phone antenna can guarantee higher performance in the low frequency band. It solves the problem of low-frequency performance regression of existing mobile phones when in use.

[0066] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A method for designing a mobile phone antenna, characterized in that: The design method of the mobile phone antenna includes: Design the mobile phone floor structure and set the target characteristic mode; Simulating the mobile phone floor structure in a low frequency band to obtain a current distribution diagram and a direction diagram of a characteristic mode consistent with the target characteristic mode; Designing a feeding point and a feeding network according to the current distribution diagram and the directional diagram to form a structure of a mobile phone antenna; The design method of the mobile phone antenna also includes: performing a simulation test on the structure of the mobile phone antenna, and if the test result is qualified, the design is terminated; if the test result is unqualified, the feeding point and the feeding network are optimized, and the structure of the optimized mobile phone antenna is simulated again, until the test result is qualified, and the design is terminated; The method of simulating the mobile phone floor structure in a low frequency band to obtain a current distribution diagram and a direction diagram of a characteristic mode consistent with the target characteristic mode includes: Simulating the mobile phone floor structure at a frequency of 1 GHz to obtain current distribution diagrams and directivity diagrams of at least two main characteristic modes; The current distribution diagram and the direction diagram of the characteristic mode consistent with the target characteristic mode are selected from the current distribution diagrams and the direction diagrams of all characteristic modes; the method for designing the feeding point and the feeding network according to the current distribution diagram and the direction diagram comprises: According to the current distribution in the current distribution diagram, the feeding points are set in the areas of the mobile phone floor corresponding to the current distribution not being 0; The mobile phone floor on which the feeding points are set is simulated and optimized so that the number of the feeding points set on the mobile phone floor does not exceed 4; Assigning corresponding amplitudes and phases to all the optimized feeding points; The feeding network is designed according to the amplitude and the phase of all the feeding points to form the structure of the mobile phone antenna; before the feeding points and the feeding network are designed according to the current distribution diagram and the directional diagram, the design method of the mobile phone antenna also includes: exciting the characteristic mode consistent with the target characteristic mode to increase the weight of the characteristic mode, thereby expanding the current distribution difference in the current distribution diagram.

2. A mobile phone antenna designed using the design method of a mobile phone antenna as claimed in claim 1, characterized in that: The mobile phone antenna includes a dielectric plate, a metal bottom plate, a metal top plate and an antenna trace; the metal bottom plate and the metal top plate are respectively located on two surfaces of the dielectric plate, the antenna trace is on the same side as the metal top plate, and the metal top plate is divided into a plurality of metal plates; the width of the antenna trace is 1±0.05mm, and the minimum distance between the antenna trace and the metal top plate is 1mm.

3. The mobile phone antenna according to claim 2, characterized in that: The antenna trace includes at least one feeding point and at least one location, the feeding point is electrically connected to the metal top plate, and the location is electrically connected to the metal bottom plate.

4. The mobile phone antenna according to claim 3, characterized in that: The antenna routing includes a feeding point and four location points. The feeding point is located at the center of the metal top plate, and the four location points are respectively located at the middle positions of the edges of the four sides of the metal top plate.

5. The mobile phone antenna according to claim 4, characterized in that: The centers of the metal top plate and the metal bottom plate coincide with each other, and the four sides of the metal top plate are at least 3 mm shorter than the corresponding four sides of the metal bottom plate.

6. The mobile phone antenna according to claim 3, characterized in that: The dielectric plate has holes corresponding to the locations, and the locations are electrically connected to the metal base plate through the holes.

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