Broadband terminal MIMO antenna loaded with defected ground structure and design method thereof

Abstract

The invention relates to the technical field of communication antennas, in particular to a broadband terminal MIMO antenna loaded with a defected ground structure and a design method of the broadband terminal MIMO antenna loaded with the defected ground structure, and the broadband terminal MIMO antenna comprises a dielectric substrate, a folded monopole antenna pair loaded with an antenna branch knot, an electromagnetic decoupling structure and the defected ground structure. N folded monopole antenna pairs are arranged along the long edge of the dielectric substrate at intervals, each folded monopole antenna pair comprises a folded monopole antenna with an upper surface metal layer in mirror symmetry and an antenna branch with a lower surface metal layer in mirror symmetry, and the folded monopole antennas and the antenna branch are connected through metal through holes; the electromagnetic decoupling structure is located between the folded monopole antenna pairs and comprises a parasitic decoupling structure of an upper surface metal layer and a neutral line structure of a lower surface metal layer, and the antenna branch knot is directly connected with the neutral line structure; the defected ground structures are located between adjacent folded monopole antenna pairs. According to the invention, a multi-resonance mode can be introduced to meet the multi-frequency communication requirement, and the isolation is improved to more than 18dB by adopting an electromagnetic decoupling technology and a defected ground structure.

Description

Technical Field

[0001] The present invention relates to the technical field of communication antennas, and in particular to a broadband terminal MIMO antenna with a loaded defective ground structure and a design method thereof. Background Art

[0002] Multiple-Input Multiple-Output (MIMO) technology is one of the important technologies in the field of mobile communications in recent decades. By deploying multiple antennas in mobile terminals, the channel capacity is multiplied, thereby significantly improving the transmission rate.

[0003] When MIMO technology is applied to mobile devices, due to the limited space inside the phone, the spacing between antenna elements decreases, exacerbating the coupling effect between antennas. This coupling reduces the isolation between antennas, affecting the overall radiation efficiency of the antennas, leading to reduced signal quality and limited communication speeds. Therefore, decoupling methods are needed to reduce the coupling strength between antennas.

[0004] Furthermore, modern smart terminals must support multi-band communications, from sub-6 GHz to millimeter waves, to meet the demands of diverse wireless standards such as 5G, Wi-Fi, and Bluetooth. Therefore, a multi-band approach is necessary to expand the antenna's operating frequency band. This multi-band antenna design also exacerbates the problem of coupling between antennas, particularly between different frequency bands. This coupling effect can significantly degrade antenna performance. Therefore, research on decoupling technologies between multi-band antennas has become a key area of ​​research in smart terminal antenna design.

[0005] In summary, how to meet the high isolation requirements of MIMO antennas across a wide frequency band is a technical problem that urgently needs to be solved. Summary of the Invention

[0006] The object of the present invention is to provide a broadband terminal MIMO antenna with a loaded defective ground structure and a design method thereof, so as to solve the technical problem of how to meet the high isolation requirement of the MIMO antenna in a broadband frequency band.

[0007] The present invention is implemented through the following technical solutions: a broadband terminal MIMO antenna loaded with a defective ground structure, comprising a dielectric substrate, a folded monopole antenna pair loaded with antenna branches, an electromagnetic decoupling structure, and a defective ground structure;

[0008] The dielectric substrate is provided with N folded monopole antenna pairs spaced apart along its long side, where N is an even number greater than or equal to 2, and the folded monopole antenna pairs are composed of two mirror-symmetrical folded monopole antennas and two mirror-symmetrical antenna branches, wherein the folded monopole antennas are located on the upper surface metal layer, the antenna branches are located on the lower surface metal layer, and the folded monopole antennas and the antenna branches are connected via metal through-holes;

[0009] The electromagnetic decoupling structure is located between the folded monopole antenna pair and includes a parasitic decoupling structure provided on the upper surface metal layer and a neutralization line structure provided on the lower surface metal layer. The neutralization line structure is directly connected to the antenna branch. The folded monopole antenna pair has a first resonant path and a second resonant path. The first resonant path is electrically decoupled by the parasitic decoupling structure, and the second resonant path is directly connected to the antenna branch by the neutralization line structure to achieve magnetic decoupling.

[0010] The defective ground structure includes a first defective ground structure and a second defective ground structure, wherein the first defective ground structure is arranged along the long side of the lower surface metal layer and is located between adjacent folded monopole antenna pairs, and the second defective ground structure is arranged along the lower surface metal layer and is located between adjacent folded monopole antenna pairs. The second defective ground structure is equivalent to a filter, which is used to block the propagation of the coupling current coupled from the folded monopole antenna to the floor on the lower surface metal layer.

[0011] According to a preferred embodiment, the folded monopole antenna is formed by folding an "L"-shaped antenna branch several times.

[0012] According to a preferred embodiment, a feeding port is provided at the front end of the folded monopole antenna, and a non-metallized through hole is provided between the feeding port and the lower surface metal layer.

[0013] According to a preferred embodiment, the parasitic decoupling structure is a rectangular patch.

[0014] According to a preferred embodiment, the central symmetry line of the parasitic decoupling structure coincides with the mirror symmetry line of the folded monopole antenna.

[0015] According to a preferred embodiment, two long sides of the upper surface metal layer are respectively provided with N / 2 folded monopole antenna pairs, and the second defective ground structure is provided on the short side of the lower surface metal layer.

[0016] According to a preferred embodiment, the value of N is set to 4.

[0017] According to a preferred embodiment, the first defective ground structure and / or the second defective ground structure is an I-shaped groove etched on the lower surface metal layer.

[0018] The present invention further provides a method for designing a broadband terminal MIMO antenna with a defective ground structure as described above, comprising:

[0019] The electromagnetic decoupling structure design is completed by loading the parasitic decoupling structure on the upper surface metal layer and the neutralization line structure on the lower surface metal layer;

[0020] The first resonant path bI1 and the second resonant path aI1 are designed according to T2T3bI1+aI1+T1I1=0 to achieve electromagnetic decoupling between the folded monopole antennas, wherein a+b=1, I1 represents the current generated when the first antenna is excited, aI1 represents the current generated by I1 flowing to the second antenna through the neutralization line structure, T1 represents the coupling coefficient between the first antenna and the second antenna, T1I1 represents the current generated by the first antenna directly coupling to the second single antenna, T2 represents the coupling coefficient between the first antenna and the parasitic decoupling structure, T2bI1 represents the current generated by bI1 coupling to the parasitic decoupling structure, T3 represents the coupling coefficient between the second antenna and the parasitic decoupling structure, and T2T3bI1 represents the current generated by T2bI1 coupling to the second antenna; wherein the first antenna and the second antenna represent the folded monopole antenna and its corresponding antenna branches;

[0021] According to engineering requirements, select appropriate microwave dielectric materials as dielectric substrates;

[0022] Electromagnetic simulation software is used for simulation modeling and antenna parameters are optimized. When the simulation output results meet the design requirements including isolation, the antenna design is completed.

[0023] The technical solution of a broadband terminal MIMO antenna loaded with a defective ground structure provided by the present invention has at least the following advantages and beneficial effects: (1) through the synergistic effect of the parasitic decoupling structure on the upper surface and the neutralization line structure on the lower surface, two current paths are generated, which effectively increases the current coupling path between the antennas, makes the coupled currents cancel each other, realizes efficient electromagnetic decoupling within the antenna pair, and improves the isolation to more than 18dB; (2) the "I"-shaped defective ground structure between adjacent folded monopole antenna pairs extends the current propagation path, blocks the direct propagation of the coupled current on the floor, and significantly improves the isolation performance between different antenna pairs; (3) the folded monopole antenna pair combined with the design of the antenna branches can introduce multi-resonance modes, support some frequency bands of N79 and WLAN 5GHz frequency band, and meet the needs of multi-frequency communication; (4) by designing the monopole antenna as an "L"-shaped branch folding structure, the antenna size is significantly reduced without affecting the radiation performance, thereby adapting to the narrow space layout of the mobile terminal. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of the upper surface metal layer of the broadband terminal MIMO antenna provided in Example 1 of the present invention;

[0025] Figure 2 A schematic diagram of the lower surface metal layer of the broadband terminal MIMO antenna provided in Example 1 of the present invention;

[0026] Figure 3A schematic diagram of the three-dimensional structure of a wideband terminal MIMO antenna provided in Example 1 of the present invention;

[0027] Figure 4 The electromagnetic decoupling equivalent model of the folded monopole antenna provided in Example 1 of the present invention;

[0028] Figure 5 An equivalent model of the defective ground structure provided in Example 1 of the present invention;

[0029] Figure 6 A curve showing how the reflection coefficient |S11| varies with bandwidth, provided in Example 1 of the present invention;

[0030] Figure 7 A curve showing how the transmission coefficient |S21| varies with bandwidth, provided in Example 1 of the present invention;

[0031] Figure 8 Comparison of S parameters of the ground structure with and without defects provided in Example 1 of the present invention;

[0032] Figure 9 The S-parameter simulation results of the eight-element broadband antenna provided in Example 1 of the present invention;

[0033] Figure numerals: 1-monopole antenna, 2-feeding port, 3-metal through hole, 4-parasitic decoupling structure, 5-dielectric substrate, 6-first defective ground structure, 7-second defective ground structure, 8-neutral line structure, 9-lower surface metal layer, 10-antenna branch. DETAILED DESCRIPTION

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0035] Example 1

[0036] The embodiment of the present invention provides a broadband terminal MIMO antenna with a defective ground structure, see Figures 1 to 3 As shown, Figure 1 The schematic diagram of its upper surface is shown in Figure 2. Figure 2 The schematic diagram of its lower surface is shown in Figure 2. Figure 3 A schematic diagram of its three-dimensional structure.

[0037] Specifically in this embodiment, the broadband terminal MIMO antenna loaded with a defective ground structure includes a dielectric substrate 5, a folded monopole antenna pair loaded with antenna branches 10, an electromagnetic decoupling structure, and a defective ground structure.

[0038] The dielectric substrate 5 is a rectangular structure measuring 100 mm x 60 mm. It is made of the microwave dielectric material Kappa 438, which has a relative dielectric constant of 4.38, a dielectric loss tangent of 0.005, and a thickness of 0.762 mm. Both the upper and lower surfaces of the substrate are covered with a 0.035 mm thick copper layer. The upper surface metal layer is used to print the folded monopole antenna pair, the parasitic decoupling structure 4, and the first defective ground structure 6. The lower surface metal layer 9 is used to arrange the antenna branches 10, the neutralization line structure 8, and the second defective ground structure 7.

[0039] In this embodiment, the dielectric substrate 5 is provided with N folded monopole antenna pairs spaced apart along its long side, where N is an even number greater than or equal to 2, and the folded monopole antenna pair consists of two mirror-symmetrical folded monopole antennas 1 and two mirror-symmetrical antenna branches 10, wherein the folded monopole antenna 1 is located on the upper surface metal layer, the antenna branches 10 are located on the lower surface metal layer 9, and the folded monopole antenna 1 and the antenna branches 10 are connected through metal through-holes 3; in order to increase the bandwidth of the antenna, the antenna branches 10 are set to be rectangular, and each rectangular antenna branch 10 is placed along the long side of the lower surface metal layer 9; in some embodiments, N is 4, that is, a total of 8 antenna units, forming an eight-unit MIMO antenna.

[0040] Each folded monopole antenna 1 is formed by folding an L-shaped antenna branch 10 twice. In this embodiment, the folded monopole antenna 1 measures 7.1mm x 5mm. The folding design reduces the antenna's size, allowing it to fit into the confined space of a terminal. Furthermore, a feed port 2 is provided at the front end of the folded monopole antenna 1, with a non-metallized through-hole provided between the feed port 2 and the lower surface metal layer 9.

[0041] Furthermore, the electromagnetic decoupling structure is located between the pair of folded monopole antennas, including a parasitic decoupling structure 4 arranged on the upper surface metal layer and a neutral line structure 8 arranged on the lower surface metal layer 9. The neutral line parasitic structure is arranged between the two antenna branches 10 corresponding to the two folded monopole antennas 1 and is directly connected to the antenna branches 10.

[0042] Regarding the parasitic decoupling structure 4, in some embodiments, the parasitic decoupling structure 4 is a rectangular patch whose central symmetry line coincides with the mirror symmetry line of the folded monopole antenna 1 and is symmetrically placed on the centerline of the folded monopole antenna pair. When the folded monopole antenna 1 is excited, the parasitic decoupling structure 4 couples with the excited folded monopole antenna 1, increasing the current coupling path ACC'A' between the folded monopole antenna 1, thereby improving the isolation of the folded monopole antenna pair.

[0043] Regarding the neutralization line structure 8, in some embodiments, a straight neutralization line structure 8 is opened on the long side of the lower surface metal layer 9; the antenna branch 10 is directly connected to the neutralization line structure 8, thereby increasing the current coupling path ABB'A' between the monopole antennas 1, thereby improving the isolation between the folded monopole antenna pairs; specifically, this embodiment generates two current paths through the synergistic effect of the upper surface parasitic decoupling structure 4 and the lower surface neutralization line structure 8, effectively increasing the current coupling path between the antennas, making the coupled currents cancel each other out, and realizing efficient electromagnetic decoupling inside the folded monopole antenna pair, so that the isolation can be increased to more than 18dB.

[0044] In addition, the antenna branch 10 can introduce multi-resonance modes, covering the 4.7-6.9 GHz frequency band, supporting part of the N79 frequency band and WLAN 5 GHz, thereby expanding the working bandwidth and meeting multi-frequency communication needs.

[0045] In this embodiment, the folded monopole antenna pair has a first resonant path and a second resonant path. The first resonant path is electrically decoupled through the parasitic decoupling structure 4, and the second resonant path is magnetically decoupled by being directly connected to the antenna branch 10 through the neutral line structure 8.

[0046] The defective ground structure includes a first defective ground structure 6 and a second defective ground structure 7, wherein the second defective ground structure 7 is arranged along the lower surface metal layer 9 and is located between adjacent folded monopole antenna pairs. The second defective ground structure 7 is equivalent to a filter. By extending the path of the floor current, the current energy flowing from the excited folded monopole antenna pair to the unexcited folded monopole antenna pair is reduced, thereby blocking the propagation of the coupling current from the antenna to the floor on the lower surface metal layer 9, thereby improving the isolation between the folded monopole antenna pairs.

[0047] Regarding the configuration of the defective ground structure, if the folded monopole antenna pair is only provided on one side of the upper surface metal layer, then a first defective ground structure 6 can be provided on the long side of the upper surface metal layer; and if both long sides of the upper surface metal layer are provided with a folded monopole antenna pair, for example, the two long sides of the upper surface metal layer are respectively provided with N / 2 folded monopole antenna pairs, the value of N is set to 4, and the two long sides are each provided with 2 folded monopole antenna pairs, then a second defective ground structure 7 needs to be provided corresponding to the short side of the lower surface metal layer 9, so as to improve the isolation between the folded monopole antenna pairs on the two long sides.

[0048] In a preferred implementation of this embodiment, the first defective ground structure 6 and / or the second defective ground structure 7 is an I-shaped groove etched on the lower surface metal layer 9; corresponding to the four folded monopole antenna pairs set above, this embodiment loads four I-shaped grooves on the lower surface metal layer 9, and the four I-shaped grooves are respectively placed on the center lines of the long side and the short side of the lower surface metal layer 9, thereby improving the isolation between adjacent folded monopole antenna pairs.

[0049] The broadband terminal MIMO antenna provided in this embodiment implements electromagnetic decoupling between two monopole antennas 1 in a folded monopole antenna pair based on a designed electromagnetic decoupling structure. The specific theoretical principles are as follows:

[0050] See also Figure 4 As shown, Figure 4 It is the equivalent model of electromagnetic decoupling of folded monopole antenna.

[0051] from Figure 4 As can be seen in the figure, when the first antenna is excited, current I1 is generated. When current I1 passes through metal via 3, two current paths aI1 and bI1 are generated. aI1 flows to the second antenna through the lower antenna branch 10 and neutralization line structure 8. bI1 couples to the parasitic decoupling structure 4 to form current T2bI1. T2bI1 then couples to the second antenna to form current T2T3bI1. The total current of the first antenna is directly coupled to the second antenna to form current T1I1. Therefore, when T2T3bI1+aI1+T1I1=0, electromagnetic decoupling is achieved between the two antennas through the electromagnetic decoupling structure combining neutralization line structure 8 and parasitic decoupling structure 4. Here, T1 represents the coupling coefficient between the first antenna and the second antenna, T2 represents the coupling coefficient between the first antenna and the parasitic decoupling structure 4, and T3 represents the coupling coefficient between the second antenna and the parasitic decoupling structure 4. The first and second antennas represent the folded monopole antenna 1 and its corresponding antenna branch 10.

[0052] See also Figure 5 As shown, Figure 5 It is the equivalent circuit model of defective ground structure.

[0053] from Figure 5 It can be seen from the figure that when the first monopole antenna resonates, a coupling current I0 is generated. The addition of the second defective ground structure 7 in the form of an I-shaped groove is equivalent to a filter. When I0 passes through the second defective ground structure 7 in the form of an I-shaped groove, the coupling current I0 resonates on the second defective ground structure 7, blocking the propagation of the coupling current I0 on the lower surface metal layer 9, thereby improving the isolation between adjacent folded monopole antenna pairs.

[0054] Furthermore, according to engineering requirements, suitable microwave dielectric materials are selected as dielectric substrates, and electromagnetic simulation software is used for simulation modeling, and the antenna parameters are optimized. When the simulation output results meet the design requirements including isolation, the antenna design is completed.

[0055] Specifically, in order to verify the influence of the antenna branch 10 and the electromagnetic decoupling structure on the antenna performance, Figure 6 Curves showing the variation of the reflection coefficient |S11| with frequency for comparative examples 1 and 2 and the solution provided in this embodiment are given. Comparative example 1 is an antenna design solution with only the folded monopole antenna 1, and comparative example 2 is an antenna design solution with an antenna branch 10 added on the basis of comparative example 1. The solution provided in this embodiment further adds an electromagnetic decoupling structure on the basis of comparative example 2.

[0056] from Figure 6 It can be seen that the resonance point of the antenna can be increased by adding the antenna branch 10. When the antenna branch 10 and the electromagnetic decoupling structure are added at the same time (here is mainly the role of the parasitic decoupling structure 4), the matching of the antenna can be improved, and at the same time, an antenna resonance point is added; according to the results, when the antenna branch 10 and the electromagnetic decoupling structure are added at the same time, the bandwidth of the antenna reflection coefficient below -10dB is 4.7-5.9GHz.

[0057] To further verify the wide-band decoupling performance of the folded monopole antenna pair, Figure 7 Curves showing how the transmission coefficient |S21| of Comparative Example 1, Comparative Example 2, and the solution provided in this embodiment changes with frequency are given.

[0058] from Figure 7 It can be seen that when the bandwidth is 4.7-5.9 GHz, when only the antenna branch 10 is added without adding the electromagnetic decoupling structure, the antenna isolation is improved to 12.5 dB. When the antenna branch 10 and the electromagnetic decoupling structure are added at the same time, the antenna isolation reaches 18 dB. According to the results, the solution provided in this embodiment can meet the requirements of high isolation in a wide frequency band and is suitable for the requirements of smart terminal antennas.

[0059] In order to further verify the decoupling performance of the defective ground structure, Figure 8 The S parameter comparison of the structure with and without defects is given.

[0060] from Figure 8As can be seen, within the operating frequency band of 4.7 GHz to 5.9 GHz, when no "I"-shaped defective ground structure is applied, the isolation between the second and third antennas is better than 12 dB. The second and third antennas refer to a pair of adjacent folded monopole antennas with the same long side. The isolation between the first and fifth antennas is better than 23 dB. In this embodiment, the first and fifth antennas refer to a pair of adjacent folded monopole antennas with different long sides. When an "I"-shaped defective ground structure is applied, the isolation between the second and third antennas is better than 18 dB, and the isolation between the first and fifth antennas is better than 25 dB.

[0061] See further Figure 9 As shown, Figure 9 The S-parameter simulation results of the eight-element broadband antenna provided in this embodiment are given. According to the results, the operating frequency band of the solution provided in this embodiment is 4.7 GHz-5.9 GHz, and the isolation is better than 18 dB.

[0062] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A broadband terminal MIMO antenna with a loaded defective ground structure, characterized in that: It comprises a dielectric substrate (5), a folded monopole antenna pair loaded with antenna branches (10), an electromagnetic decoupling structure, and a defective ground structure; The dielectric substrate (5) is provided with N folded monopole antenna pairs at intervals along its long side, N being an even number greater than or equal to 2, the folded monopole antenna pairs consisting of two mirror-symmetrical folded monopole antennas (1) and two mirror-symmetrical antenna branches (10), wherein the folded monopole antennas (1) are located on the upper surface metal layer, the antenna branches (10) are located on the lower surface metal layer (9), and the folded monopole antennas (1) and the antenna branches (10) are connected via metal through-holes (3); The electromagnetic decoupling structure is located between the folded monopole antenna pair and includes a parasitic decoupling structure arranged on the upper surface metal layer and a neutral line structure (8) arranged on the lower surface metal layer (9). The neutral line structure (8) is directly connected to the antenna branch (10). The folded monopole antenna pair has a first resonant path and a second resonant path. The first resonant path is electrically decoupled by the parasitic decoupling structure (4), and the second resonant path is magnetically decoupled by being directly connected to the antenna branch (10). The defective ground structure comprises a first defective ground structure (6) and a second defective ground structure (7), wherein the first defective ground structure (6) is arranged along the long side of the lower surface metal layer (9) and is located between adjacent folded monopole antenna pairs, and the second defective ground structure (7) is arranged along the lower surface metal layer (9) and is located between adjacent folded monopole antenna pairs, and the second defective ground structure (7) is equivalent to a filter, which is used to block the propagation of the coupling current coupled from the folded monopole antenna (1) to the floor on the lower surface metal layer (9).

2. The broadband terminal MIMO antenna with a loaded defective ground structure according to claim 1, wherein: The folded monopole antenna (1) is formed by folding an "L"-shaped antenna branch (10) several times.

3. The broadband terminal MIMO antenna with a loaded defective ground structure according to claim 2, wherein: A feeding port (2) is provided at the front end of the folded monopole antenna (1), and a non-metallized through hole is provided between the feeding port (2) and the lower surface metal layer (9).

4. The broadband terminal MIMO antenna with a loaded defective ground structure according to claim 1, wherein: The parasitic decoupling structure (4) is a rectangular patch.

5. The broadband terminal MIMO antenna with a loaded defective ground structure according to claim 4, characterized in that: The central symmetry line of the parasitic decoupling structure (4) coincides with the mirror symmetry line of the folded monopole antenna (1).

6. The broadband terminal MIMO antenna with a loaded defective ground structure according to claim 1, wherein: The two long sides of the upper surface metal layer are respectively provided with N / 2 folded monopole antenna pairs, and the second defective ground structure (7) is provided on the short side of the lower surface metal layer (9).

7. The broadband terminal MIMO antenna with a loaded defective ground structure according to claim 6, wherein: The value of N is set to 4.

8. The broadband terminal MIMO antenna with a loaded defective ground structure according to claim 6, wherein: The first defective ground structure (6) and / or the second defective ground structure (7) are "I"-shaped grooves etched on the lower surface metal layer (9).

9. A method for designing a broadband terminal MIMO antenna with a loaded defective ground structure according to any one of claims 1 to 8, characterized in that: include: The electromagnetic decoupling structure design is completed by loading a parasitic decoupling structure (4) on the upper surface metal layer and loading a neutralization line structure (8) on the lower surface metal layer (9); The first resonant path bI1 and the second resonant path aI1 are designed according to T2T3bI1+aI1+T1I1=0, respectively, to realize electromagnetic decoupling between the folded monopole antenna (1), wherein a+b=1, I1 represents the current formed when the first antenna is excited, aI1 represents the current formed when I1 flows to the second antenna through the neutral line structure (8), T1 represents the coupling coefficient between the first antenna and the second antenna, T1I1 represents the current formed when the first antenna is directly coupled to the second single antenna, T2 represents the coupling coefficient between the first antenna and the parasitic decoupling structure (4), T2bI1 represents the current formed when bI1 is coupled to the parasitic decoupling structure (4), T3 represents the coupling coefficient between the second antenna and the parasitic decoupling structure (4), and T2T3bI1 represents the current formed when T2bI1 is coupled to the second antenna; wherein the first antenna and the second antenna represent the folded monopole antenna and its corresponding antenna branches; According to engineering requirements, select appropriate microwave dielectric materials as dielectric substrates; Electromagnetic simulation software is used for simulation modeling and antenna parameters are optimized. When the simulation output results meet the design requirements including isolation, the antenna design is completed.

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