A novel multi-layer coupled LOOP antenna

Abstract

The present invention discloses a novel multi-layer coupled LOOP antenna. On a test ground of 40*100 mm², by using a relatively small clearance area of 5*6 mm², the ground plane is used as part of the current loop, and a π-type matching network and coplanar waveguide feeding are adopted to achieve impedance matching of the input port. The grounded rectangular patch effectively improves the reactance characteristics of the antenna, reduces the Q value, overcomes the problem of the small working bandwidth of the LOOP antenna itself, and enables the antenna to operate in the Bluetooth frequency band. The lower surface of the antenna adopts a T-shaped-like coupling to improve the coupling effect, introduce capacitive parasitic parameters, and reduce the inductive reactance of the antenna structure itself; the upper surface of the antenna adopts multi-segment coupling, which extends the effective current path of the antenna, increases the electrical length, and reduces the resonance frequency of the antenna. In addition, the structure of the antenna is simple and the method is novel, and it also has good omnidirectional characteristics and good radiation efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of LOOP (loop) antennas applied to the Bluetooth frequency band, and relates to a novel multi-layer coupled LOOP antenna, in particular to a novel multi-layer coupled LOOP antenna adopting a multi-layer trace coupling technology. Background Art

[0002] With the rapid development of wireless communication technologies, intelligent mobile terminal devices have become indispensable electronic products in people's lives. An antenna is an important device for transmitting and receiving radio waves among them, and its working performance is closely related to the design space and design environment. As people's requirements for mobile terminal products are getting higher and higher, the space left for antenna design is getting smaller and smaller. For a smaller clearance area, for a communication frequency band, a longer trace is required to achieve it. Although the equivalent electrical length of the built-in antenna can be lengthened by using the traditional LOOP structure, the drawback is that the working bandwidth of the antenna is too narrow, and the corresponding working frequency band is often difficult to cover. And the existing LOOP antenna has complex traces and great design difficulty, which greatly limits its wide application in the field of wireless communication. Summary of the Invention

[0003] The main purpose of the present invention is to propose a novel multi-layer coupled LOOP antenna in view of the deficiencies of the prior art, specifically a novel multi-layer coupled LOOP antenna adopting a multi-layer trace coupling technology. It is required to use a smaller clearance area (5*6 mm 2 ) on a test ground plane of 40*100 mm to implement a LOOP antenna that meets the requirements of working in the Bluetooth frequency band. In addition, the dielectric substrate of the antenna uses a low-cost FR4 material with a loss tangent of 0.022. The performance indicators of the antenna: in the Bluetooth frequency band of 2.4 - 2.48 GHz, it is required to meet S11 < -10 dB, the gain of the working frequency band is above 0.5 dB, and in addition, the working efficiency of the antenna should reach above 70% to ensure the working performance of the antenna. 2

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A novel multi-layer coupled LOOP antenna, comprising:

[0006] A test ground (1) and a LOOP antenna;

[0007] The test ground (1) has a square structure, which is located on the lower surface of the antenna dielectric substrate (33) and on the upper surface of the test substrate (34). A notch is opened at the central position of one side as a clearance area (9), and the LOOP antenna is arranged on the clearance area (9);

[0008] ​The described LOOP antenna includes an antenna main body part (2), a grounding metal sheet (3), a lumped excitation (7), a coplanar waveguide feeder (8), and a matching network;

[0009] The described matching network is between the antenna main body part (2) and the lumped excitation (7);

[0010] The described antenna main body part (2) includes an antenna dielectric substrate (33), and an upper surface trace (31) and a lower surface trace (32) of the antenna located on the upper and lower surfaces of the antenna dielectric substrate (33) respectively; both ends of the upper surface trace (31) of the antenna are respectively connected to both ends of the lower surface trace (32) of the antenna through a first connection line (10) and a second connection line (11) that penetrate the antenna dielectric substrate (33);

[0011] The upper surface trace (31) of the antenna includes a first horizontal trace (12), a second horizontal trace (13), a third horizontal trace (14), a fourth horizontal trace (15), a fifth horizontal trace (16) that are arranged in parallel and have a certain gap therebetween, and a first vertical conductor (17), a second vertical conductor (18), a third vertical conductor (19), a fourth vertical conductor (20) that are arranged in parallel and have a certain gap therebetween; the first vertical conductor (17) and the fourth vertical conductor (20) are respectively located at both ends of the upper surface of the antenna dielectric substrate (33); the first horizontal trace (12), the second horizontal trace (13), the third horizontal trace (14), the fourth horizontal trace (15), the fifth horizontal trace (16) are arranged in sequence from top to bottom and are located between the first vertical conductor (17) and the fourth vertical conductor (20); the second vertical conductor (18) and the third vertical conductor (19) are located between the first vertical conductor (17) and the fourth vertical conductor (20) and are close to the fourth vertical conductor (20); the outer side of the first vertical conductor (17) is connected to the first connection line (10), and the inner lower end is connected to one end of the fourth horizontal trace (15) and one end of the fifth horizontal trace (16); the lower end of the second vertical conductor (18) is connected to the other end of the fourth horizontal trace (15), and the upper end is connected to one end of the third horizontal trace (14); the lower end of the third vertical conductor (19) is connected to the other end of the fifth horizontal trace (16), and the upper end is connected to one end of the second horizontal trace (13); a first "U" - shaped structure that rotates 90° counter - clockwise is formed by the third horizontal trace (14), the fourth horizontal trace (15), and the second vertical conductor (18); a second "U" - shaped structure that rotates 90° counter - clockwise is formed by the fifth horizontal trace (16), the third vertical conductor (19), and the second horizontal trace (13); the first "U" - shaped structure is nested inside the second "U" - shaped structure and they do not touch; there is a gap between the other end of the second horizontal trace (13), the other end of the third horizontal trace (14) and the first vertical conductor (17); the outer side of the fourth vertical conductor (20) is connected to the second connection line (11), the inner upper end is connected to one end of the first horizontal trace (12), and there is a gap between the other end of the first horizontal trace (12) and the first vertical conductor (17); an L - shaped structure that first rotates 90° clockwise and then flips horizontally is formed by the first horizontal trace (12) and the fourth vertical conductor (20); the second "U" - shaped structure is nested inside the L - shaped structure that first rotates 90° clockwise and then flips horizontally and they do not touch;

[0012] The antenna lower surface trace (32) includes a sixth horizontal trace (21), a seventh horizontal trace (22), a first trace (23), an eighth horizontal trace (24), a ninth horizontal trace (25), a second trace (26), and fifth, sixth, seventh, and eighth vertical conductors (27, 28, 29, 30) that are arranged in parallel with a certain gap therebetween; the fifth vertical conductor (27) and the eighth vertical conductor (30) are respectively located at both ends of the lower surface of the antenna dielectric substrate (33); the sixth horizontal trace (21), the seventh horizontal trace (22), the first trace (23), the eighth horizontal trace (24), the ninth horizontal trace (25), and the second trace (26) are located between the fifth vertical conductor (27) and the eighth vertical conductor (30), and the sixth horizontal trace (21), the seventh horizontal trace (22), the first trace (23), the eighth horizontal trace (24), and the ninth horizontal trace (25) are arranged in parallel from top to bottom with a certain gap therebetween, and the second trace (26) coincides with the extension line of the first trace (23); the outside of the fifth vertical conductor (27) is connected to the first connection line (10), and the midpoint of the inside is connected to one end of the first trace (23); the other end of the first trace (23) is connected to the midpoint of the sixth vertical conductor (28); the sixth vertical conductor (28) is located between the fifth vertical conductor (27) and the eighth vertical conductor (30), the lower end is connected to one end of the eighth horizontal trace (24), and the upper end is connected to one end of the seventh horizontal trace (22); the seventh horizontal trace (22), the sixth vertical conductor (28), and the eighth horizontal trace (24) form a third "U" - shaped structure that rotates 90° counterclockwise; the seventh vertical conductor (29) is located between the sixth vertical conductor (28) and the eighth vertical conductor (30), the upper end is connected to one end of the sixth horizontal trace (21), the lower end is connected to one end of the ninth horizontal trace (25), and the midpoint is connected to one end of the second trace (26); the sixth horizontal trace (21), the seventh vertical conductor (29), and the ninth horizontal trace (25) form a fourth "U" - shaped structure that rotates 90° counterclockwise; the third "U" - shaped structure is nested inside the fourth "U" - shaped structure and they do not touch; there is a gap between the other ends of the sixth horizontal trace (21), the seventh horizontal trace (22), the eighth horizontal trace (24), the ninth horizontal trace (25) and the fifth vertical conductor (27); the outside of the eighth vertical conductor (30) is connected to the second connection line (11), and the midpoint of the inside is connected to the other end of the second trace (26);

[0013] The coplanar waveguide feeder (8) is an L-shaped feeder rotated 90° clockwise, including an integrally formed vertical feeder, a first horizontal feeder, and a second horizontal feeder; the outside of the vertical feeder is connected to the eighth vertical conductor (30), the lower end of the inside is connected to one end of the grounding metal sheet (3), and the upper end of the inside is connected to one end of the horizontal feeder; the coplanar waveguide feeder (8) is not in contact with the test ground;

[0014] The grounding metal sheet (3) is used to connect the test ground (1) and the antenna main body part (2);

[0015] The matching network includes a first matching element (4), a second matching element (5), and a third matching element (6); the lower end of the first matching element (4) is connected to the upper end of the first horizontal feeder, and the upper end is connected to the test ground; one end of the second matching element (5) is connected to the other end of the first horizontal feeder, and the other end is connected to one end of the second horizontal feeder; the other end of the second horizontal feeder is connected to the lumped excitation (7); the lower end of the third matching element (6) is connected to the upper end of the second horizontal feeder, and the upper end is connected to the test ground;

[0016] The lumped excitation (7) is located between the test ground (1) and the coplanar waveguide feeder (8); the feeder width of the coplanar waveguide feeder (8) and the ground slots at its upper and lower ends satisfy impedance matching;

[0017] Preferably, the first connecting wire (10) and the second connecting wire (11) adopt a metal edge wrapping process to realize the conduction of the wiring of the upper and lower parts of the antenna;

[0018] Preferably, for the lumped excitation (7) to achieve good matching, the ratio of the width of the coplanar waveguide feeder (8) to the gaps on both sides thereof satisfies the impedance characteristics of the coplanar waveguide and realizes impedance matching with the 50Ω at the input end, so as to achieve reflectionless input. The coplanar waveguide characteristic impedance formula is as follows:

[0019]

[0020]

[0021] where Zc is the equivalent resistance of the coplanar waveguide feeder (8), C CPW is the total capacitance of the coplanar waveguide feeder (8), ε eff represents the effective dielectric constant of the antenna dielectric substrate (33), s represents the width of the coplanar waveguide feeder (8), and w is the width of the gaps on both sides of the coplanar waveguide feeder (8);

[0022] Preferably, the line spacing between the wirings on the upper surface of the antenna is of equal width;

[0023] Preferably, the line width of the trace (32) on the lower surface of the antenna is of equal width, and the line spacing between the traces on the lower surface is also of equal width, both less than 0.001 working wavelengths;

[0024] Preferably, the LOOP antenna satisfies the 3612 package size;

[0025] Preferably, the antenna dielectric substrate (33) and the test substrate (34) are of the same height;

[0026] Preferably, the distances from the antenna main body part (2) and the grounding metal sheet (3) to the edge of the test substrate (34) are the same;

[0027] Preferably, the gaps between the transverse feeder of the coplanar waveguide feeder (8) and both sides of the test ground are of equal width;

[0028] Preferably, a π-type impedance matching is adopted among the lumped excitation (7), the coplanar waveguide feeder (8) and the antenna main body part (2) in the matching network to move the working frequency band to the center of the Smith chart, so that a good impedance matching can be achieved in the working frequency band; the first matching element (4), the second matching element (5), and the third matching element (6) are equivalent to a capacitor, a capacitor, and an inductor respectively;

[0029] Preferably, the first matching element (4), the second matching element (5), and the third matching element (6) are connected through the coplanar waveguide feeder (8), and each matching element adopts a 0402 package size.

[0030] Working principle:

[0031] For the novel multi-layer capacitive coupling LOOP antenna, its working frequency band covers the Bluetooth frequency band. The size of the test ground is 40*100mm 2, belonging to the size specifications of common handheld electronic communication devices. For the designed new multi-layer coupled LOOP antenna, the ground plane is also part of the antenna radiation, effectively lengthening the equivalent electrical length of the antenna, enabling the antenna to design the wiring in a limited design space. In a relatively small clearance area of 5mm * 6mm, a FR4 dielectric substrate with a 3612 size is used, and capacitive coupled line structures are adopted on both the upper and lower layers of the substrate. In addition, both ends of the antenna structure are connected to the ground plane, and a loop current will be generated between the antenna structure and the ground plane. The grounding metal sheet can be equivalent to a shunt small inductor, which is used to adjust the reactance characteristics of the antenna, reduce the quality factor of the antenna, and thus expand the operating bandwidth. In essence, the spacing between the coupled lines can effectively introduce parasitic capacitance. The closer the distance between adjacent traces, the stronger the coupling effect. There is parasitic inductance in the traces. The parasitic capacitance generated by the line spacing and the parasitic inductance of the traces form a resonant circuit, generating a resonant frequency near the operating frequency point, which can effectively expand the bandwidth. The lower surface uses bent double coupled lines, which lengthen the coupling length between the traces in a folded form and can improve the coupling effect; while the upper surface uses L-shaped coupled microstrip lines. In order to achieve the effective electrical length for the antenna to operate in the Bluetooth band, multi-section coupling technology is adopted to lengthen the effective path of the current and reduce the resonant frequency to the operating frequency band. In addition, the entire antenna is above the clearance area and has a certain distance from the ground plane, which can effectively reduce the mirror coupling interference and improve the operating performance of the antenna. The signal comes out from the excitation source and passes through the coplanar waveguide feeder, which can make the energy be transmitted to the antenna structure as much as possible and is also for better realizing the impedance matching of the port and the connection with the matching circuit elements. The matching network part adopts a π-type network, which consists of a shunt inductor, a series capacitor, and a shunt capacitor in sequence. The components adopt a 0402 package size and are used to adjust the impedance matching of the input port. In the Smith chart, the operating frequency band is moved near the center to obtain the best -10dB impedance bandwidth.

[0032] The beneficial effects of the present invention are as follows:

[0033] (1) For the LOOP antenna designed by the present invention, by using the ground plane to participate in the antenna radiation technology, the resonant frequency of the antenna can be flexibly adjusted by adjusting the current intensity on the ground plane and the current path on the antenna.

[0034] (2) The LOOP antenna in the present invention has a 3612 size and uses a relatively small clearance area of 5 * 6mm 2 and adopts a multi-line coupling technology to introduce capacitive parasitic parameters. Multi-line coupling can improve the coupling effect, thereby better improving the deficiencies of the electrically small antenna, such as too high self-inductance, too large Q, and narrow bandwidth, and designing a small antenna that can cover the Bluetooth band.

[0035] (3) The matching network in the present invention adopts the capacitive and inductive loading technology to form a π-type matching network, which can effectively adjust the impedance matching and impedance bandwidth of the antenna, enabling the antenna to have better matching and transmission characteristics, and also facilitating the performance debugging of the antenna after actual processing.

[0036] (4) The feeding method of the present invention adopts the coplanar waveguide feeding technology, which operates in the even-mode. The energy is fed into the main body of the antenna from the central conductor, and the width and gap of the coplanar waveguide satisfy the input impedance matching characteristics.

[0037] (5) The structure in the present invention is very simple and easy to design. By skillfully using the LC resonance characteristics, a capacitive reactance is introduced through the coupling line and ingeniously added to the antenna design. The structure parameters have high adjustability and excellent performance parameters, and can be applied to wireless communication systems. Description of the Drawings

[0038] Figure 1 It is a top view schematic diagram of a new type of multi-layer coupled LOOP antenna.

[0039] Figure 2 It is a top view schematic diagram of the LOOP antenna, the clearance area, and the test ground.

[0040] Figure 3 It is a schematic diagram of the structure of the new type of multi-layer coupled LOOP antenna, where (a) is the schematic diagram of the upper surface trace of the LOOP antenna, (b) is the schematic diagram of the lower surface trace of the LOOP antenna, and (c) is the side view schematic diagram of the LOOP antenna structure.

[0041] Figure 4 It is the S 11 result diagram of the new type of multi-layer coupled LOOP antenna simulated by simulation software and applicable to mobile devices.

[0042] Figure 5 It is the gain result diagram of the new type of multi-layer coupled LOOP antenna simulated by simulation software and applied to mobile devices.

[0043] Figure 6 It is the radiation efficiency result diagram of the new type of multi-layer coupled LOOP antenna simulated by simulation software and applied to mobile devices.

[0044] Figure 7 It is the radiation pattern of the new type of multi-layer coupled LOOP antenna simulated by simulation software at (a) and (b) respectively.

[0045] Markings in the figure: Test ground 1, Antenna main body 2, Grounding metal sheet 3, First matching element 4, Second matching element 5, Third matching element 6, Lumped excitation 7, Coplanar waveguide feeder 8, Clearance area 9, First connection line 10, Second connection line 11, First horizontal trace 12, Second horizontal trace 13, Third horizontal trace 14, Fourth horizontal trace 15, Fifth horizontal trace 16, First vertical conductor 17, Second vertical conductor 18, Third vertical conductor 19, Fourth vertical conductor 20, Sixth horizontal trace 21, Seventh horizontal trace 22, First trace 23, Eighth horizontal trace 24, Ninth horizontal trace 25, Second trace 26, Fifth vertical conductor 27, Sixth vertical conductor 28, Seventh vertical conductor 29, Eighth vertical conductor 30, Antenna upper surface trace 31, Antenna lower surface trace 32, Antenna dielectric substrate 33, Test ground substrate 34. Detailed implementation

[0046] In order to better elaborate the technical solutions, design purposes, and advantages designed in the present invention, the content of the present invention will be described in more detail in combination with the embodiments and the accompanying drawings. The specific embodiments used here are only for illustration and do not limit the present invention.

[0047] The terms "first", "second", etc. used in the present invention are for better distinguishing structures and briefly describing similar or identical structures, but these structures are not limited by these terms.

[0048] In this embodiment, a new type of multi-layer coupled LOOP antenna is proposed. As shown in the attached drawings Figure 1 It includes a test ground and a LOOP antenna. Among them, the LOOP antenna needs to be placed on the test ground for performance simulation. During design, the LOOP antenna is set on one side of the test ground, on the clearance area of the 5*6mm2 area, and a certain distance to the ground is reserved for the antenna in the clearance area. Based on the above structure, the setting of the antenna position can reduce the mirror coupling interference effect of the ground plane and also meet the requirements of the processing technology.

[0049] In this embodiment, as shown in the attached drawings Figure 2 The LOOP antenna includes an antenna main body 2, a grounding metal sheet 3, a lumped excitation 7, a matching network, and a coplanar waveguide feeder 8. The first matching element 4, the second matching element 5, and the third matching element 6 in the matching network are equivalent to a capacitor, a capacitor, and an inductor respectively. The series-parallel capacitors and the parallel inductor form a π-type matching network, which is used to adjust the input impedance of the antenna and achieve impedance matching at the input port.

[0050] In this embodiment, as Figure 3As shown in (a), the upper surface trace 31 of the antenna is shown. The current comes from the coplanar waveguide feeder 8, passes through the second connecting line 11, enters the fourth vertical wire 20, then reaches the first horizontal trace 12. Through coupling, the current is coupled to the second horizontal trace 13, the third vertical wire 19, the third horizontal trace 14, and the second vertical wire 18, and then flows through the fourth horizontal trace 15 and the fifth horizontal trace 16 respectively to converge at the first vertical wire 17. Through the first connecting line 10, the current flows to the test ground 1. Based on the above structure, it can be known that by introducing parasitic capacitance through current coupling, the reactance characteristics of the antenna can be effectively adjusted. Multi-path coupling can lengthen the effective current path to a certain extent and reduce the resonance frequency of the antenna.

[0051] In this embodiment, as Figure 3 As shown in (b), the lower surface trace 32 of the antenna is shown. The current comes from the coplanar waveguide feeder 8, enters the eighth vertical wire 30, passes through the second trace 26 to reach the seventh vertical wire 29. The current is divided into two branches and flows to the sixth horizontal trace 21 and the ninth horizontal trace 25. Then through current coupling, it is coupled to the seventh horizontal trace 22, the eighth horizontal trace 24, and the sixth vertical wire 28. After passing through the first trace 23, it reaches the fifth vertical wire 27 and finally flows to the test ground 1 to form a current loop. Based on the above structure, it can be known that this structure is similar to T-type coupling, and the capacitive reactance component can be introduced to reduce the inductive reactance value of the antenna itself, realizing resonance near the operating frequency.

[0052] In this embodiment, a side view of a novel multi-layer coupled LOOP antenna is given. As Figure 3 shown in (c), the lower surface trace 32 of the antenna and the test ground 1 are on the same plane. The LOOP antenna is located above the test ground 1. The test ground 1 is located on the upper surface of the test substrate 34 and on the lower surface of the antenna dielectric substrate 33. The upper surface trace 31 of the antenna is located on the upper surface of the antenna dielectric substrate 33. Based on the above structure, the antenna needs to test the corresponding radiation performance on the test ground of the corresponding size. The ground plane is also part of the antenna radiation.

[0053] In some specific embodiments, the size of the test ground is 40mm * 100mm; the antenna dielectric substrate uses FR4 material and meets the 3216 package size.

[0054] In some specific embodiments, Figure 4 is to use simulation software to simulate the S 11 parameter result diagram of a novel multi-layer coupled LOOP antenna. Its -10dB impedance bandwidth covers the frequency band from 2.39GHz to 2.48GHz. The designed operating frequency point is 2.45GHz, and within the WIFI frequency band, it meets the impedance bandwidth index of the Bluetooth antenna.

[0055] In some specific embodiments, Figure 5It is a result graph showing the variation of the gain of a new type of multi-layer coupled LOOP antenna with the operating frequency simulated by simulation software. It can be seen that near the operating frequency band, the gain of the antenna can reach 0.7 dB.

[0056] In some specific embodiments, Figure 6 It is a result graph showing the variation of the radiation efficiency of a new type of multi-layer coupled LOOP antenna with the operating frequency simulated by simulation software, and it has a good radiation efficiency of more than 73% in the operating frequency band.

[0057] In some specific embodiments, Figure 7 It is a pattern of a new type of multi-layer coupled LOOP antenna simulated by simulation software at and respectively. It can be seen from the pattern that the antenna has good omnidirectional characteristics and excellent working performance.

[0058] For the above-described embodiments, they are introduced in great detail, but this should not be construed as a limitation on the scope of the present invention. It should be noted that for those skilled in the art, without departing from the inventive principle of the present invention, some technologies can be modified and improved, and any modifications and improvements made should be within the protection scope of the present invention.

Claims

1. A novel multi-layer coupled LOOP antenna, characterized in that Comprising: A test ground (1) and a LOOP antenna; The test ground (1) has a square structure and is located on the lower surface of the antenna dielectric substrate (33) and on the upper surface of the test base substrate (34); A notch is provided at the central position on one side thereof to form a clearance area (9), and the LOOP antenna is arranged on the clearance area (9); The LOOP antenna includes an antenna main body part (2), a grounding metal sheet (3), a lumped excitation (7), a coplanar waveguide feeder (8), and a matching network; The matching network is located between the antenna main body part (2) and the lumped excitation (7); The antenna main body part (2) includes an antenna dielectric substrate (33), and an upper surface trace (31) and a lower surface trace (32) of the antenna which are respectively located on the upper and lower surfaces of the antenna dielectric substrate (33); both ends of the upper surface trace (31) of the antenna are respectively connected to both ends of the lower surface trace (32) of the antenna through a first connection line (10) and a second connection line (11); the first connection line (10) and the second connection line (11) penetrate through the antenna dielectric substrate (33); The upper surface trace (31) of the antenna includes a first horizontal trace (12), a second horizontal trace (13), a third horizontal trace (14), a fourth horizontal trace (15), a fifth horizontal trace (16) that are arranged in parallel with gaps therebetween, and a first vertical conductor (17), a second vertical conductor (18), a third vertical conductor (19), a fourth vertical conductor (20) that are arranged in parallel with gaps therebetween; the first vertical conductor (17) and the fourth vertical conductor (20) are respectively located at two ends of the upper surface of the antenna dielectric substrate (33); the first horizontal trace (12), the second horizontal trace (13), the third horizontal trace (14), the fourth horizontal trace (15), the fifth horizontal trace (16) are arranged in sequence from top to bottom and are located between the first vertical conductor (17) and the fourth vertical conductor (20); the second vertical conductor (18) and the third vertical conductor (19) are located between the first vertical conductor (17) and the fourth vertical conductor (20) and are close to the fourth vertical conductor (20); the outside of the first vertical conductor (17) is connected to the first connection line (10), and the lower end of the inside is connected to one end of the fourth horizontal trace (15) and one end of the fifth horizontal trace (16); the lower end of the second vertical conductor (18) is connected to the other end of the fourth horizontal trace (15), and the upper end is connected to one end of the third horizontal trace (14); the lower end of the third vertical conductor (19) is connected to the other end of the fifth horizontal trace (16), and the upper end is connected to one end of the second horizontal trace (13); a first "U" - shaped structure that rotates 90° counterclockwise is formed by the third horizontal trace (14), the fourth horizontal trace (15), and the second vertical conductor (18); a second "U" - shaped structure that rotates 90° counterclockwise is formed by the fifth horizontal trace (16), the third vertical conductor (19), and the second horizontal trace (13); the first "U" - shaped structure is nested inside the second "U" - shaped structure and they do not touch; there is a gap between the other ends of the second horizontal trace (13) and the third horizontal trace (14) and the first vertical conductor (17); the outside of the fourth vertical conductor (20) is connected to the second connection line (11), the upper end of the inside is connected to one end of the first horizontal trace (12), and there is a gap between the other end of the first horizontal trace (12) and the first vertical conductor (17); an L - shaped structure that first rotates 90° clockwise and then flips horizontally is formed by the first horizontal trace (12) and the fourth vertical conductor (20); the second "U" - shaped structure is nested inside the L - shaped structure that first rotates 90° clockwise and then flips horizontally and they do not touch; The antenna lower surface trace (32) includes a sixth horizontal trace (21), a seventh horizontal trace (22), a first trace (23), an eighth horizontal trace (24), a ninth horizontal trace (25), a second trace (26), and fifth, sixth, seventh, and eighth vertical conductors (27, 28, 29, 30) that are arranged in parallel with gaps therebetween; the fifth vertical conductor (27) and the eighth vertical conductor (30) are respectively located at two ends of the lower surface of the antenna dielectric substrate (33); the sixth horizontal trace (21), seventh horizontal trace (22), first trace (23), eighth horizontal trace (24), ninth horizontal trace (25), and second trace (26) are located between the fifth vertical conductor (27) and the eighth vertical conductor (30), and the sixth horizontal trace (21), seventh horizontal trace (22), first trace (23), eighth horizontal trace (24), and ninth horizontal trace (25) are arranged in parallel with gaps therebetween from top to bottom in sequence, and the second trace (26) coincides with the extension line of the first trace (23); the outer side of the fifth vertical conductor (27) is connected to the first connection line (10), and the midpoint of the inner side is connected to one end of the first trace (23); the other end of the first trace (23) is connected to the midpoint of the sixth vertical conductor (28); the sixth vertical conductor (28) is located between the fifth vertical conductor (27) and the eighth vertical conductor (30), the lower end is connected to one end of the eighth horizontal trace (24), and the upper end is connected to one end of the seventh horizontal trace (22); the seventh horizontal trace (22), the sixth vertical conductor (28), and the eighth horizontal trace (24) form a third "U" - shaped structure rotated counterclockwise by 90°; the seventh vertical conductor (29) is located between the sixth vertical conductor (28) and the eighth vertical conductor (30), the upper end is connected to one end of the sixth horizontal trace (21), the lower end is connected to one end of the ninth horizontal trace (25), and the midpoint is connected to one end of the second trace (26); the sixth horizontal trace (21), the seventh vertical conductor (29), and the ninth horizontal trace (25) form a fourth "U" - shaped structure rotated counterclockwise by 90°; the third "U" - shaped structure is nested inside the fourth "U" - shaped structure and they do not touch; there are gaps between the other ends of the sixth horizontal trace (21), seventh horizontal trace (22), eighth horizontal trace (24), ninth horizontal trace (25) and the fifth vertical conductor (27); the outer side of the eighth vertical conductor (30) is connected to the second connection line (11), and the midpoint of the inner side is connected to the other end of the second trace (26); The coplanar waveguide feeder (8) is an L - shaped feeder rotated clockwise by 90°, and includes a vertical feeder, a first horizontal feeder, and a second horizontal feeder; the outer side of the vertical feeder is connected to the eighth vertical conductor (30), the lower end of the inner side is connected to one end of the grounding metal sheet (3), and the upper end of the inner side is connected to one end of the horizontal feeder; the coplanar waveguide feeder (8) does not contact the test ground; The described grounding metal sheet (3) is used to connect the test ground (1) and the antenna main body part (2); The described matching network includes a first matching element (4), a second matching element (5), and a third matching element (6); the lower end of the first matching element (4) is connected to the upper end of the first horizontal feeder, and the upper end is connected to the test ground; one end of the second matching element (5) is connected to the other end of the first horizontal feeder, and the other end is connected to one end of the second horizontal feeder; the other end of the second horizontal feeder is connected to the lumped excitation (7); the lower end of the third matching element (6) is connected to the upper end of the second horizontal feeder, and the upper end is connected to the test ground; The described lumped excitation (7) is located between the test ground (1) and the coplanar waveguide feeder (8); The operating frequency band of the described novel multi-layer coupled LOOP antenna covers the Bluetooth frequency band.

2. The novel multi-layer coupled LOOP antenna according to claim 1, wherein The ratio of the width of the described coplanar waveguide feeder (8) to the gap on both sides of it satisfies the impedance characteristics of the coplanar waveguide, realizes impedance matching with 50Ω at the input end, and realizes reflectionless input.

3. A novel multi-layer coupled LOOP antenna according to claim 1, characterized in that, The line spacings between the first horizontal trace (12) and the second horizontal trace (13), between the second horizontal trace (13) and the third horizontal trace (14), between the fourth horizontal trace (15) and the fifth horizontal trace (16), between the second vertical conductor (18) and the third vertical conductor (19), and between the third vertical conductor (19) and the fourth vertical conductor (20) are of equal width.

4. A novel multi-layer coupled LOOP antenna according to claim 1, characterized in that, The line widths of the sixth horizontal trace (21), the seventh horizontal trace (22), the eighth horizontal trace (24), and the ninth horizontal trace (25) are of equal width, and the line widths of the first trace (23), the second trace (26), the sixth vertical conductor (28), and the seventh vertical conductor (29) are of equal width; the line spacings between the sixth horizontal trace (21) and the seventh horizontal trace (22), between the eighth horizontal trace (24) and the ninth horizontal trace (25), and between the sixth vertical conductor (28) and the seventh vertical conductor (29) are of equal width.

5. A novel multi-layer coupled LOOP antenna according to claim 4, characterized in that, The described line spacings are all less than 0.001 working wavelengths.

6. A novel multi-layer coupled LOOP antenna according to claim 1, characterized in that, The described LOOP antenna meets the 3612 package size.

7. A novel multi-layer coupled LOOP antenna according to claim 1, characterized in that, The thicknesses of the described antenna dielectric substrate (33) and the test ground substrate (34) are the same.

8. A novel multi-layer coupled LOOP antenna according to claim 1, characterized in that, The distances from the described antenna main body part (2) and the grounding metal sheet (3) to the edge of the test ground substrate (34) are the same.

9. A novel multi-layer coupled LOOP antenna according to claim 1, characterized in that, The first horizontal feeder and the second horizontal feeder of the described coplanar waveguide feeder (8) are set with equal-width gaps on both sides of the test ground.

10. A novel multi-layer coupled LOOP antenna according to claim 1, characterized in that, The described matching network adopts π-type impedance matching, and the first matching element (4), the second matching element (5), and the third matching element (6) all adopt the package size of 0402 specification.

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