A broadband implantable antenna loaded with an L-shaped slot

Abstract

The present invention discloses a broadband implantable antenna loaded with an L-shaped slot. The implantable antenna is a planar structure. The slots on the radiation unit and the ground plane are easy to process and require low processing accuracy. A short-circuit probe is introduced on the antenna to further reduce the size of the antenna. The center frequency of the antenna is tuned by adjusting the size of the four serpentine slots on the radiation unit. At the same time, the broadband operation of the antenna is achieved by slot loading. The antenna structure is simple in design and easy to manufacture. When the antenna is small in size, it can meet the requirements of bandwidth and impedance at the same time.

Description

Technical Field

[0001] The invention belongs to the technical field of antennas, and in particular is a broadband implantable antenna loaded with an L-shaped slot. Background Art

[0002] With the development and progress of science and technology, people have a greater demand for living standards, and medical care is an important condition for ensuring living standards. Therefore, medical care technology is also constantly improving. For example, the development and use of wireless medical equipment can solve remote diagnosis and treatment, and people can find famous doctors without leaving home, which brings great convenience to people. In the entire wireless medical device system, the miniaturized implantable antenna is a very important part of the communication system. As an information transmission device of the system, it transmits signals to the receiving device. In this way, doctors can obtain signals of the patient's physical information to analyze the patient's condition, so they can quickly and efficiently diagnose the patient. Therefore, it becomes more important to improve the broadband performance of the implantable antenna.

[0003] Currently, the commonly used wireless communication and medical communication frequency bands include the Medical Implant Communication Service (MICS) frequency band, the Industrial, Scientific and Medical (ISM) frequency band, the Wireless Local Area Network (WLAN) frequency band and the Ultra-Wideband frequency band. The MICS frequency band refers to the communication equipment using the 402MHz~405MHz frequency band to communicate wirelessly with implanted medical electronic equipment. 402MHz~405MHz has been divided into 10 channels, each with a bandwidth of 300Hz. By dividing the channels, it can be ensured that multiple implantable medical devices can be used in the same area. The 433.1MHz~434.8MHz, 869.7MHz~870MHz, 902.8MHz~928MHz and 2400MHz~2483.5MHz frequency bands in the ISM band are the frequency bands that are currently used more by medical equipment.

[0004] As for implantable antennas, it is more common to work in the ISM band. Compared with MICS and WMTS, it has a wider available frequency band and a higher wireless channel capacity. Therefore, in recent years, many countries have used the 2.4GHz ISM band for biotelemetry. As for implantation methods, it can be placed at the site that needs to be monitored through surgery, or the antenna can be bent into a capsule antenna to increase the application value of the antenna. In the article "Design of Small Circularly Polarized Implantable Antenna Based on Slow-Wave Effect" published by Fan Yi et al., a small circularly polarized implantable antenna was designed. The antenna size was effectively reduced by using the slow-wave effect. The antenna works in the ISM band of 2.4 to 2.48GHz. When installed in an implantable device to communicate with an external receiving device, it has the advantages of anti-multipath fading and flexible mobility. However, the working bandwidth of the antenna is relatively small, only 80MHz. The document with application number 201520033739.2 discloses a fractal implantable antenna working in the MICS frequency band. The antenna adopts a 4th-order Hilbert curve structure and uses a differential feeding copper column. The structure is complex and the processing difficulty is greatly increased. At the same time, the bandwidth of the antenna is 372-449MHz, and its bandwidth is only 77MHz. The bandwidth is too small. Affected by human tissue, the center frequency of the antenna may be offset and not within the bandwidth, and the performance of the antenna is affected. Therefore, it is of great significance to design a broadband ultra-thin implantable antenna with simple structure and small size. Summary of the invention

[0005] In order to solve the problem of small working bandwidth of existing implantable antennas, the present invention provides a broadband implantable antenna loaded with L-shaped slots. The antenna is loaded with L-shaped slots on both the radiation unit and the ground plane, and four serpentine slots are arranged on the radiation unit. At the same time, two short-circuit probes are arranged on the dielectric substrate of the antenna. The structure is compact, and the small-sized antenna has broadband performance, good biocompatibility, and stable performance.

[0006] The technical solution of the present invention to solve the technical problem is to provide a broadband implantable antenna loaded with an L-shaped gap, characterized in that the antenna includes a dielectric substrate, a radiating unit, a coaxial feed, a ground plane, a first short-circuit probe, and a second short-circuit probe; the dielectric substrate is circular, a circular coaxial feed mounting hole is arranged in the middle of the dielectric substrate with the center of the dielectric substrate as the center of the circle, and a short-circuit probe mounting hole is symmetrically arranged on the upper right side and the lower left side of the center of the dielectric substrate; the coaxial feed is installed in the coaxial feed mounting hole of the dielectric substrate, and the first short-circuit probe and the second short-circuit probe are respectively installed in the two short-circuit probe mounting holes; the outer periphery of the radiating unit and the ground plane are both circular and have the same size as the circular side surface of the dielectric substrate, and the two are respectively arranged on the positive and negative circular side surfaces of the dielectric substrate, and matching through holes are arranged at positions corresponding to the coaxial feed, the first short-circuit probe, and the second short-circuit probe for installing the coaxial feed, the first short-circuit probe, and the second short-circuit probe;

[0007] A No. 1 serpentine slot and a No. 3 serpentine slot are respectively arranged on the radiation units on the upper and lower sides of the coaxial feed, the No. 1 serpentine slot and the No. 3 serpentine slot have the same structure and size, and the No. 1 serpentine slot coincides with the No. 3 serpentine slot after rotating 180° to the right around the axis of the dielectric substrate; a No. 2 serpentine slot is arranged on the radiation unit on the left side of the No. 1 serpentine slot, and a No. 4 serpentine slot is arranged on the radiation unit on the right side of the No. 3 serpentine slot; the structure and size of the No. 2 serpentine slot and the No. 4 serpentine slot are the same as those of the No. 1 serpentine slot, the No. 2 serpentine slot is a structure arranged in a state where the No. 1 serpentine slot is rotated 90° to the left, and the No. 4 serpentine slot is a structure arranged in a state where the No. 1 serpentine slot is rotated 90° to the right; the No. 1 short-circuit probe is located on the right side of the No. 1 serpentine slot, and the No. 2 short-circuit probe is located on the right side of the No. 3 serpentine slot;

[0008] A positive first L-shaped slot and a positive second L-shaped slot are respectively arranged on the radiation units at the lower left and upper right of the coaxial feed; the positive first L-shaped slot and the positive second L-shaped slot have the same structure and size, and are both formed by vertically connecting a short rectangular slot and a long rectangular slot, and the short rectangular slots of the two are horizontally arranged at equal distances on the left and right sides of the coaxial feed, and the bottom of the short rectangular slot on the left and the top of the short rectangular slot on the right are located on the straight line where the diameter of the coaxial feed in the horizontal direction is located; the long rectangular slot of the positive first L-shaped slot is located on the radiation unit between the second short-circuit probe and the third serpentine slot, and the long rectangular slot of the positive second L-shaped slot is located on the radiation unit between the first short-circuit probe and the first serpentine slot;

[0009] The second serpentine gap is located above the short rectangular gap of the first L-shaped gap, and the fourth serpentine gap is located below the short rectangular gap of the second L-shaped gap;

[0010] The No. 1 serpentine gap is a structure formed by connecting a number of horizontal strips of equal length from top to bottom with vertical strips. Specifically, the left sides of the two topmost horizontal strips are connected together by a vertical strip, the right sides of the second and third horizontal strips from top to bottom are connected together by a vertical strip, and the left sides of the third and fourth horizontal strips from top to bottom are connected together by a vertical strip. In the above manner, the left and right sides of each horizontal strip are respectively connected with the upper and lower horizontal strips through a vertical strip until they are connected to the bottom horizontal strip; the width of the horizontal strip is the same as that of the vertical strip;

[0011] A back L-shaped slot No. 1 and a back L-shaped slot No. 2 are respectively arranged on the ground plane at the upper, lower, left and right positions of the coaxial feed at the other end. The back L-shaped slot No. 1 and the back L-shaped slot No. 2 have the same structure and size, and both include a horizontal rectangular slot and a vertical rectangular slot. The length of the horizontal rectangular slot is longer than the vertical rectangular slot and the width of the two are the same. The vertical rectangular slots of the two are respectively arranged vertically on the left and right sides of the coaxial feed. The horizontal rectangular slot of the back L-shaped slot No. 1 is arranged between the No. 1 short-circuit probe and the coaxial feed. The horizontal rectangular slit of the back No. 2 L-shaped slit is arranged between the No. 2 short-circuit probe and the coaxial feed; the distance between the right side of the vertical rectangular slit of the back No. 1 L-shaped slit and the left side of the coaxial feed is equal to the distance between the left side of the vertical rectangular slit of the back No. 2 L-shaped slit and the right side of the coaxial feed; the distance between the lower part of the horizontal rectangular slit of the back No. 1 L-shaped slit and the upper part of the coaxial feed is equal to the distance between the upper part of the horizontal rectangular slit of the back No. 2 L-shaped slit and the lower part of the coaxial feed;

[0012] The material of the dielectric substrate is a biocompatible plate;

[0013] The radiation unit and the ground plane are both circular metal patches. The coaxial feed, the No. 1 short-circuit probe and the No. 2 short-circuit probe are cylindrical structures made of metal materials. The heights of the three are the same and are equal to the height of the dielectric substrate. The No. 1 short-circuit probe and the No. 2 short-circuit probe have the same radius, and the radius of the coaxial feed is larger than that of the No. 1 short-circuit probe.

[0014] The antenna is loaded with L-shaped gaps on both the radiation unit and the ground plane, and four serpentine gaps are arranged on the radiation unit. At the same time, two short-circuit probes are arranged on the dielectric substrate of the antenna. The structure is compactly designed. The small-sized antenna has wide-band performance, good biocompatibility and stable performance.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] (1) The implantable antenna is a planar structure. The gaps between the radiation unit and the ground plane are easy to process and require low processing accuracy. A short-circuit probe is introduced on the antenna to further reduce the size of the antenna. The center frequency of the antenna is tuned by adjusting the size of the four serpentine slots on the radiation unit. At the same time, the wide-band operation of the antenna is achieved by slot loading. The antenna structure is simple in design and easy to manufacture. It can meet the requirements of bandwidth and impedance at the same time when the antenna is small in size.

[0017] (2) The antenna in Embodiment 1 of the present invention has a volume of only π×4 2 ×0.635mm 3 In the ISM 2.45GHz band, its operating bandwidth is 2.21-2.63GHz, and the return loss of the antenna at the center frequency reaches -27dB. The antenna has the characteristics of miniaturization, wide bandwidth, and good biocompatibility. It is suitable for the ISM 2.45GHz band and meets the requirements for miniaturization and wide bandwidth of the antenna after implantation in the human tissue environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 1 is a schematic diagram of the front structure of an embodiment of the present invention (in the figure: 1-dielectric substrate; 2-radiation unit; 3-coaxial feed; 4_1-short-circuit probe No. 1; 4_2-short-circuit probe No. 2; 5_1-serpentine gap No. 1; 5_2-serpentine gap No. 2; 5_3-serpentine gap No. 3; 5_4-serpentine gap No. 4; 6_1-positive L-shaped gap No. 1; 6_2-positive L-shaped gap No. 2);

[0019] Figure 2 7 is a schematic diagram of the back structure of an embodiment of the present invention (in the figure: 7-grounding surface; 8_1-back L-shaped gap No. 1; 8_2-back L-shaped gap No. 2);

[0020] Figure 3 is a return loss curve diagram of the antenna of Example 1 of the present invention in skin tissue at a frequency of 2.4 GHz;

[0021] Figure 4 : is the radiation pattern of the antenna of Example 1 of the present invention in skin tissue at a frequency of 2.4 GHz. DETAILED DESCRIPTION

[0022] The specific embodiments of the present invention are given below. The specific embodiments are only used to further illustrate the present invention in detail and do not limit the protection scope of the claims of this application.

[0023] The present invention provides a broadband implantable antenna (hereinafter referred to as antenna) loaded with an L-shaped slot Figure 1-4), characterized in that the antenna comprises a dielectric substrate 1, a radiating unit 2, a coaxial feed 3, a ground plane 7, a first short-circuit probe 4_1, and a second short-circuit probe 4_2; the dielectric substrate 1 is a cylinder, a circular coaxial feed mounting hole is arranged in the middle of the dielectric substrate 1 with the center of the dielectric substrate 1 as the center, and a short-circuit probe mounting hole is symmetrically arranged on the upper right side and the lower left side of the center of the dielectric substrate 1; the coaxial feed 3 is installed in the coaxial feed mounting hole of the dielectric substrate 1, and the first short-circuit probe 4_2 is arranged in the coaxial feed mounting hole of the dielectric substrate 1. The probe 4_1 and the second short-circuit probe 4_2 are respectively installed in the two short-circuit probe installation holes; the outer peripheries of the radiation unit 2 and the ground plane 7 are both circular and have the same size as the circular side of the dielectric substrate 1, and the two are respectively arranged on the positive and negative circular sides of the dielectric substrate 1, and matching through holes are arranged at positions corresponding to the coaxial feed 3, the first short-circuit probe 4_1, and the second short-circuit probe 4_2 for installing the coaxial feed 3, the first short-circuit probe 4_1, and the second short-circuit probe 4_2.

[0024] A first serpentine slot 5_1 and a third serpentine slot 5_3 are respectively arranged on the radiation unit 2 on the upper and lower sides of the coaxial feed 3. The first serpentine slot 5_1 and the third serpentine slot 5_3 have the same structure and size. The first serpentine slot 5_1 overlaps with the third serpentine slot 5_3 after rotating 180° right around the axis of the dielectric substrate 1. A second serpentine slot 5_2 is arranged on the radiation unit 2 on the left side of the first serpentine slot 5_1, and a fourth serpentine slot 5_4 is arranged on the radiation unit 2 on the right side of the third serpentine slot 5_3. The structures and sizes of the second serpentine gap 5_2 and the fourth serpentine gap 5_4 are the same as those of the first serpentine gap 5_1. The second serpentine gap 5_2 is a structure set in a state where the first serpentine gap 5_1 is turned 90° to the left, and the fourth serpentine gap 5_4 is a structure set in a state where the first serpentine gap 5_1 is turned 90° to the right. The first short-circuit probe 4_1 is located on the right side of the first serpentine gap 5_1, and the second short-circuit probe 4_2 is located on the right side of the third serpentine gap 5_3.

[0025] A positive first L-shaped slot 6_1 and a positive second L-shaped slot 6_2 are respectively arranged on the radiation unit 2 at the lower left and upper right of the coaxial feed 3; the positive first L-shaped slot 6_1 and the positive second L-shaped slot 6_2 have the same structure and size, and are both formed by vertically connecting a short rectangular slot and a long rectangular slot, and the short rectangular slots of the two are horizontally arranged at equal distances on the left and right sides of the coaxial feed 3, and the bottom of the short rectangular slot on the left and the top of the short rectangular slot on the right are located on the straight line where the diameter of the coaxial feed 3 in the horizontal direction is located. The long rectangular slot of the positive first L-shaped slot 6_1 is located on the radiation unit 2 between the second short-circuit probe 4_2 and the third serpentine slot 5_3, and the long rectangular slot of the positive second L-shaped slot 6_2 is located on the radiation unit 2 between the first short-circuit probe 4_1 and the first serpentine slot 5_1.

[0026] The second serpentine gap 5_2 is located above the short rectangular gap of the first L-shaped gap 6_1, and the fourth serpentine gap 5_4 is located below the short rectangular gap of the second L-shaped gap 6_2.

[0027] The first serpentine gap 5_1 is a structure formed by connecting a number of horizontal strips of equal length from top to bottom with vertical strips. Specifically, the left sides of the two top horizontal strips are connected together by a vertical strip, the right sides of the second and third horizontal strips from top to bottom are connected together by a vertical strip, and the left sides of the third and fourth horizontal strips from top to bottom are connected together by a vertical strip. In the above manner, the left and right sides of each horizontal strip are connected with the upper and lower horizontal strips through a vertical strip, until they are connected to the bottom horizontal strip. The width of the horizontal strip is the same as that of the vertical strip.

[0028] A back-first L-shaped slot 8_1 and a back-second L-shaped slot 8_2 are respectively arranged on the ground plane 7 at the upper, lower, left and right positions of the coaxial feed 3 at the other end. The back-first L-shaped slot 8_1 and the back-second L-shaped slot 8_2 have the same structure and size, and both include a horizontal rectangular slot and a vertical rectangular slot. The length of the horizontal rectangular slot is longer than the vertical rectangular slot and the width of the two are the same. The vertical rectangular slots of the two are respectively arranged vertically on the left and right sides of the coaxial feed 3. The horizontal rectangular slot of the back-first L-shaped slot 8_1 is arranged between the first short-circuit probe 4_1 and the coaxial feed 3, and the horizontal rectangular slot of the back-second L-shaped slot 8_2 is arranged between the second short-circuit probe 4_2 and the coaxial feed 3. The distance between the right side of the vertical rectangular slot of the back-first L-shaped slot 8_1 and the left side of the coaxial feed 3 is equal to the distance between the left side of the vertical rectangular slot of the back-second L-shaped slot 8_2 and the right side of the coaxial feed 3. The distance between the lower part of the horizontal rectangular slot of the back No. 1 L-shaped slot 8_1 and the upper part of the coaxial feed 3 is equal to the distance between the upper part of the horizontal rectangular slot of the back No. 2 L-shaped slot 8_2 and the lower part of the coaxial feed 3 .

[0029] Preferably, the dielectric substrate 1 is made of a biocompatible plate, such as a Rogers Corporation model RO3010, which is PTFE ceramic with a relative dielectric constant of 10.2.

[0030] Preferably, the radiation unit 2 and the ground plane 7 are circular metal patches, the coaxial feed 3, the first short-circuit probe 4_1, and the second short-circuit probe 4_2 are cylindrical structures made of metal materials, the heights of the three are the same and equal to the height of the dielectric substrate 1, the radius of the first short-circuit probe 4_1 and the second short-circuit probe 4_2 are the same, and the radius of the coaxial feed 3 is larger than that of the first short-circuit probe 4_1.

[0031] Example 1

[0032] This embodiment provides a broadband implantable antenna loaded with an L-shaped slot, the antenna having the structure as described above and the following dimensions:

[0033] The radius of the dielectric substrate 1 is 4 mm and the height is 0.635 mm;

[0034] The radiation unit 2 , the ground plane 7 , the coaxial feed 3 , the first short-circuit probe 4_1 , and the second short-circuit probe 4_2 are all made of copper.

[0035] The radius of the coaxial feed 3 is 0.5 mm; the radius of the first short-circuit probe 4_1 and the second short-circuit probe 4_2 is 0.4 mm. The distance between the centers of the first short-circuit probe 4_1 and the second short-circuit probe 4_2 is The angle between the straight line where the centers of the two circles are located and the vertical symmetry axis of the dielectric substrate 1 is 34.2°.

[0036] The vertical distance between the bottom of the No. 1 serpentine slot 5_1 and the top of the coaxial feed is 1.4 mm; the No. 1 serpentine slot 5_1 is formed by 6 horizontal strips of 1.3 mm long and 0.2 mm wide and 5 vertical strips of 0.2 mm long and 0.2 mm wide, and the distance from the top to the bottom of the No. 1 serpentine slot 5_1 is 2.2 mm.

[0037] The horizontal distance between the left side of the long rectangular slot of the positive No. 2 L-shaped slot 6_2 and the right side of the coaxial feed 3 is 0.9 mm, the size of the long rectangular slot is 3.3 mm×0.2 mm, the size of the short rectangular slot is 2.8 mm×0.2 mm, and the overlapping size of the long rectangular slot and the short rectangular slot at the junction is 0.2 mm×0.2 mm.

[0038] The vertical distance between the bottom of the No. 2 L-shaped slit 6_2 and the top of the No. 4 serpentine slit 5_4 is 0.2 mm, and the vertical distance between the top of the No. 1 L-shaped slit 6_1 and the bottom of the No. 2 serpentine slit 5_2 is 0.2 mm. The horizontal distance between the right side of the No. 2 serpentine slit 5_2 and the left side of the No. 1 serpentine slit 5_1 is 0.2 mm, and the horizontal distance between the right side of the No. 3 serpentine slit 5_3 and the left side of the No. 4 serpentine slit 5_4 is 0.2 mm. The horizontal distance between the left side of the No. 1 serpentine slit 5_1 and the vertical symmetry axis of the dielectric substrate 1 is 0.8 mm.

[0039] The sizes of the horizontal rectangular slits and the vertical rectangular slits of the back No. 1 L-shaped slit 8_1 and the back No. 2 L-shaped slit 8_2 on the ground plane 7 are 3.4mm×0.82mm and 4.4mm×0.82mm respectively, and the overlapping size of the joints of the horizontal rectangular slits and the vertical rectangular slits is 0.82mm×0.82mm.

[0040] The distance between the right side of the vertical rectangular slot of the back first L-shaped slot 8_1 and the left side of the coaxial feed 3 is 2.2 mm. The distance between the lower part of the horizontal rectangular slot of the back first L-shaped slot 8_1 and the upper part of the coaxial feed 3 is 0.28 mm.

[0041] The antenna of this embodiment was tested for performance. The test results are as follows: Figure 3-4 shown. Figure 3 The return loss curve of the antenna of this embodiment in the skin tissue at a frequency of 2.4 GHz. The dielectric constant of human skin tissue at the working frequency of 2.4 GHz is 49.54, and the conductivity is 4.04. Figure 3 It can be seen that the return loss of the antenna is less than -10dB in the 2.21-2.63GHz frequency band, achieving a wide bandwidth, and the minimum return loss is -27dB. The antenna works in human skin tissue. The complex tissue environment will cause the actual bandwidth of the antenna to decrease or shift, so that the center frequency is not within the bandwidth, which in turn affects the antenna performance. However, this antenna achieves a wide bandwidth, and the bandwidth is wide enough to effectively avoid the center frequency of the antenna being out of the bandwidth, so that the antenna can work stably in the 2.40-2.47GHz frequency band.

[0042] Figure 4 This is the radiation pattern of the antenna of this embodiment in the skin tissue at a frequency of 2.4 GHz. In the figure, E refers to the electric field, H refers to the magnetic field, and both the E and H planes are in the shape of an 8, which shows that the wide-band antenna has good radiation characteristics and meets engineering requirements.

[0043] Any matters not described in the present invention are applicable to the prior art.

Claims

1. A broadband implantable antenna loaded with an L-shaped slot, characterized in that: The antenna comprises a dielectric substrate, a radiation unit, a coaxial feed, a ground plane, a first short-circuit probe and a second short-circuit probe; the dielectric substrate is a cylinder, a circular coaxial feed installation hole is arranged in the middle of the dielectric substrate with the center of the dielectric substrate as the center, and a short-circuit probe installation hole is symmetrically arranged on the upper right side and the lower left side of the center of the dielectric substrate; the coaxial feed is installed in the coaxial feed installation hole of the dielectric substrate, and the first short-circuit probe and the second short-circuit probe are respectively installed in the two short-circuit probe installation holes; the outer periphery of the radiation unit and the ground plane are both circular and have the same size as the circular side surface of the dielectric substrate, and the two are respectively arranged on the positive and negative circular side surfaces of the dielectric substrate, and matching through holes are arranged at positions corresponding to the coaxial feed, the first short-circuit probe and the second short-circuit probe for installing the coaxial feed, the first short-circuit probe and the second short-circuit probe; A No. 1 serpentine slot and a No. 3 serpentine slot are respectively arranged on the radiation units on the upper and lower sides of the coaxial feed. The No. 1 serpentine slot and the No. 3 serpentine slot have the same structure and size. The No. 1 serpentine slot is rotated 180° to the right around the axis of the dielectric substrate and then overlaps with the No. 3 serpentine slot. A No. 2 serpentine slot is arranged on the radiation unit on the left side of the No. 1 serpentine slot, and a No. 4 serpentine slot is arranged on the radiation unit on the right side of the No. 3 serpentine slot; the structures and sizes of the No. 2 serpentine slot and the No. 4 serpentine slot are the same as those of the No. 1 serpentine slot, the No. 2 serpentine slot is arranged in a state where the No. 1 serpentine slot is rotated 90° to the left, and the No. 4 serpentine slot is arranged in a state where the No. 1 serpentine slot is rotated 90° to the right; the No. 1 short-circuit probe is located on the right side of the No. 1 serpentine slot, and the No. 2 short-circuit probe is located on the right side of the No. 3 serpentine slot; A positive first L-shaped slot and a positive second L-shaped slot are respectively arranged on the radiation units at the lower left and upper right of the coaxial feed; the positive first L-shaped slot and the positive second L-shaped slot have the same structure and size, and are both formed by vertically connecting a short rectangular slot and a long rectangular slot, and the short rectangular slots of the two are horizontally arranged at equal distances on the left and right sides of the coaxial feed, and the bottom of the short rectangular slot on the left and the top of the short rectangular slot on the right are located on the straight line where the diameter of the coaxial feed in the horizontal direction is located; the long rectangular slot of the positive first L-shaped slot is located on the radiation unit between the second short-circuit probe and the third serpentine slot, and the long rectangular slot of the positive second L-shaped slot is located on the radiation unit between the first short-circuit probe and the first serpentine slot; The second serpentine gap is located above the short rectangular gap of the first L-shaped gap, and the fourth serpentine gap is located below the short rectangular gap of the second L-shaped gap; The No. 1 serpentine gap is a structure formed by connecting a number of horizontal strips of equal length from top to bottom with vertical strips. Specifically, the left sides of the two topmost horizontal strips are connected together by a vertical strip, the right sides of the second and third horizontal strips from top to bottom are connected together by a vertical strip, and the left sides of the third and fourth horizontal strips from top to bottom are connected together by a vertical strip. The left and right sides of each horizontal strip are connected with the upper and lower horizontal strips respectively by a vertical strip until they are connected to the bottom horizontal strip; the width of the horizontal strip is the same as that of the vertical strip; A back L-shaped slot No. 1 and a back L-shaped slot No. 2 are respectively arranged on the ground plane at the upper, lower, left and right positions of the coaxial feed at the other end. The back L-shaped slot No. 1 and the back L-shaped slot No. 2 have the same structure and size, and both include a horizontal rectangular slot and a vertical rectangular slot. The length of the horizontal rectangular slot is longer than the vertical rectangular slot and the width of the two are the same. The vertical rectangular slots of the two are respectively arranged vertically on the left and right sides of the coaxial feed. The horizontal rectangular slot of the back L-shaped slot No. 1 is arranged between the No. 1 short-circuit probe and the coaxial feed. The horizontal rectangular slit of the back No. 2 L-shaped slit is arranged between the No. 2 short-circuit probe and the coaxial feed; the distance between the right side of the vertical rectangular slit of the back No. 1 L-shaped slit and the left side of the coaxial feed is equal to the distance between the left side of the vertical rectangular slit of the back No. 2 L-shaped slit and the right side of the coaxial feed; the distance between the lower part of the horizontal rectangular slit of the back No. 1 L-shaped slit and the upper part of the coaxial feed is equal to the distance between the upper part of the horizontal rectangular slit of the back No. 2 L-shaped slit and the lower part of the coaxial feed; The material of the dielectric substrate is a biocompatible plate; The radiation unit and the ground plane are both circular metal patches. The coaxial feed, the No. 1 short-circuit probe and the No. 2 short-circuit probe are cylindrical structures made of metal materials. The heights of the three are the same and are equal to the height of the dielectric substrate. The No. 1 short-circuit probe and the No. 2 short-circuit probe have the same radius, and the radius of the coaxial feed is larger than that of the No. 1 short-circuit probe.

2. The broadband implantable antenna loaded with an L-shaped slot according to claim 1, characterized in that: The radius of the dielectric substrate is 4 mm and the height is 0.635 mm.

3. The broadband implantable antenna loaded with an L-shaped slot according to claim 1, characterized in that: The radius of the coaxial feed is 0.5 mm; the radius of the No. 1 short-circuit probe and the No. 2 short-circuit probe is 0.4 mm; the distance between the centers of the No. 1 short-circuit probe and the No. 2 short-circuit probe is The angle between the straight line where the centers of the two circles are located and the symmetry axis in the vertical direction of the dielectric substrate is 34.2°.

4. The broadband implantable antenna loaded with an L-shaped slot according to claim 1, characterized in that: The vertical distance between the bottom of the No. 1 serpentine slot and the top of the coaxial feed is 1.4 mm; the No. 1 serpentine slot is composed of 6 horizontal strips of 1.3 mm long and 0.2 mm wide and 5 vertical strips of 0.2 mm long and 0.2 mm wide. The distance from the top to the bottom of the No. 1 serpentine slot is 2.2 mm.

5. The broadband implantable antenna loaded with an L-shaped slot according to claim 1, characterized in that: The horizontal distance between the left side of the long rectangular slot of the No. 2 L-shaped slot and the right side of the coaxial feed is 0.9mm, the size of the long rectangular slot is 3.3mm×0.2mm, the size of the short rectangular slot is 2.8mm×0.2mm, and the overlapping size of the long rectangular slot and the short rectangular slot is 0.2mm×0.2mm.

6. The broadband implantable antenna loaded with an L-shaped slot according to claim 1, characterized in that: The vertical distance between the bottom of the No. 2 L-shaped gap and the top of the No. 4 serpentine gap is 0.2 mm, and the vertical distance between the top of the No. 1 L-shaped gap and the bottom of the No. 2 serpentine gap is 0.2 mm; the horizontal distance between the right side of the No. 2 serpentine gap and the left side of the No. 1 serpentine gap is 0.2 mm, and the horizontal distance between the right side of the No. 3 serpentine gap and the left side of the No. 4 serpentine gap is 0.2 mm; the horizontal distance between the left side of the No. 1 serpentine gap and the vertical symmetry axis of the dielectric substrate 1 is 0.8 mm.

7. The broadband implantable antenna loaded with an L-shaped slot according to claim 1, characterized in that: The sizes of the horizontal rectangular seams and vertical rectangular seams of the back No. 1 L-shaped seam and the back No. 2 L-shaped seam on the ground surface are 3.4mm×0.82mm and 4.4mm×0.82mm respectively, and the overlapping size of the joints of the horizontal rectangular seams and the vertical rectangular seams is 0.82mm×0.82mm.

8. The broadband implantable antenna loaded with an L-shaped slot according to claim 1, characterized in that: The distance between the right side of the vertical rectangular slit of the back No. 1 L-shaped slit and the left side of the coaxial feed is 2.2 mm; the distance between the lower part of the horizontal rectangular slit of the back No. 1 L-shaped slit and the upper part of the coaxial feed is 0.28 mm.

9. The broadband implantable antenna loaded with an L-shaped slot according to claim 1, characterized in that: The material model of the dielectric substrate is RO3010 from Rogers Corporation, and the relative dielectric constant is 10.

2.

10. The broadband implantable antenna loaded with an L-shaped slot according to claim 1, characterized in that: The radiation unit, the ground plane, the coaxial feed, the first short-circuit probe and the second short-circuit probe are all made of copper.

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