A reconfigurable implantable antenna with left-handed circular polarization and a reconfigurable method

Abstract

The present invention discloses a left-hand circular polarization reconfigurable implantable antenna and a reconfigurable method, comprising a lower dielectric substrate and an upper dielectric substrate, wherein an antenna radiation unit is arranged on the upper surface of the lower dielectric substrate, a metal floor is arranged on the lower surface of the lower dielectric substrate, and the upper dielectric substrate covers the antenna radiation unit, and the antenna radiation unit is divided into two parts by a U-shaped groove, and a switching diode group is arranged on the two arms of the U-shaped groove to connect the two parts of the antenna radiation unit. The present invention has the advantages of large impedance bandwidth, miniaturization, circular polarization, polarization mismatch resistance, high gain, and left-hand circular polarization switchability, and can be applied to mobile medical communications to solve the polarization mismatch problem.

Description

Technical Field

[0001] The invention relates to the field of biomedical telemetry, and in particular to a left-hand circular polarization reconfigurable implantable antenna and a reconfiguration method. Background Art

[0002] Compared with traditional medical treatment, mobile medical treatment can alleviate patients' pain, reduce costs, and provide remote diagnosis. Due to the characteristics of human movement and posture changes, the advantage of using circular polarization in implantable devices is that it can counteract the polarization mismatch caused by the receiving angle of biomedical signals. At present, there are still many problems with circularly polarized implantable antennas. First, today's circularly polarized implantable antennas only consider a single circular polarization mode, which reduces the scope of application of the antenna and may also cause mismatches between circular polarizations; second, circularly polarized implantable antennas occupy too much space, which will affect the user's body.

[0003] Most of the current implantable antenna designs have the disadvantages of being too large in size, having polarization mismatch, and having narrow bandwidth, which makes the implantable devices unable to adapt to the complex environments in practical applications. Summary of the invention

[0004] In order to solve the shortcomings and deficiencies existing in implantable antennas in the field of mobile medical care, the present invention provides a left-hand circular polarization reconfigurable implantable antenna and a reconfiguration method, which has the advantages of miniaturization, large impedance bandwidth, resistance to polarization mismatch, switchable left-hand circular polarization and right-hand circular polarization, and a reconfigurable implantable antenna working in the 2.45 GHz ISM band.

[0005] The present invention adopts the following technical solution:

[0006] A left-handed circularly polarized reconfigurable implantable antenna comprises a lower dielectric substrate and an upper dielectric substrate, wherein an antenna radiating unit is arranged on the upper surface of the lower dielectric substrate, a metal floor is arranged on the lower surface of the lower dielectric substrate, and the upper dielectric substrate covers the antenna radiating unit. The antenna radiating unit is divided into two parts by a U-shaped groove, and a switching diode group is arranged on the two arms of the U-shaped groove for connecting the two parts of the antenna radiating unit.

[0007] Furthermore, the antenna radiation unit is divided into two parts by a U-shaped groove, both ends of the U-shaped groove are arranged at the edges of the antenna radiation unit, the part surrounded by the U-shaped groove is the central metal, and the rest is the peripheral metal, and the central metal is provided with a pad connected to the DC feeding structure.

[0008] Furthermore, the antenna radiation unit and the metal floor are connected via a metal through hole.

[0009] Furthermore, the DC feeding structure includes a first battery, a second battery, a first switch, a second switch, a first RF isolation inductor and a second RF isolation inductor, the positive electrode of the first battery is connected to the negative electrode of the second battery, a first switch is arranged between the two batteries, the first switch and the first RF isolation inductor are connected to a first port, the negative electrode of the first battery is connected to the positive electrode of the second battery and then connected to the second switch, the second switch and the second RF isolation inductor are connected to the second port, and the first port and the second port are respectively connected to a pad and a metal floor.

[0010] Furthermore, the U-shaped groove is composed of three groove arms which are perpendicular to each other in sequence, and a switching diode is arranged on the arms which are parallel to each other in the U-shaped groove.

[0011] Furthermore, the switching diode group includes three switching diodes.

[0012] Furthermore, the metal floor and the antenna radiation unit are rectangular structures.

[0013] Furthermore, it also includes a coaxial feeding structure, which is composed of a 50Ω coaxial line, an inner core of which is connected to the antenna radiation unit through a lower dielectric substrate, and an outer core of which is located on the lower dielectric substrate.

[0014] A method for realizing the reconfiguration of the implantable antenna, comprising:

[0015] When the first switch is connected to the first power supply, the first port of the DC feeding structure is at a positive potential compared to the second port, the switch diode of one side arm of the U-shaped slot is turned on, and the peripheral metal current flows into the central metal through the conducting diode to achieve left-handed circular polarization;

[0016] When the first switch is connected to the second power supply, the first port of the DC feeding structure has a negative potential compared to the second port, the switch diode on the other side arm of the U-shaped slot is turned on, and the current flowing from the peripheral metal to the central metal is reversed, changing the current path and realizing right-hand circular polarization.

[0017] An implantable device comprises the implantable antenna.

[0018] Beneficial effects of the present invention:

[0019] The structure of the present invention can achieve the characteristics of large impedance bandwidth, miniaturization, circular polarization, and resistance to polarization mismatch;

[0020] The present invention loads metal through holes, introduces inductive components, and realizes miniaturization.

[0021] The present invention arranges two groups of diodes on the U-shaped arm, and controls the switches of the two groups of diodes through a DC feeding structure to realize left and right circular polarization, so that the present invention has the characteristics of dual circular polarization switching;

[0022] The present invention has the characteristics of high gain, with a maximum gain of -23.9 dBi and a long reliable transmission distance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a top view of a left-handed circular polarization reconfigurable implantable antenna of the present invention;

[0024] Figure 2 yes Figure 1 Side view of

[0025] Figure 3 is a circuit diagram of the DC feeding structure of the present invention;

[0026] Figure 4 yes Figure 1 Schematic diagram of parameter dimensions in top view;

[0027] Figure 5 yes Figure 2 Schematic diagram of parameter dimensions of the side view;

[0028] Figure 6 It is the S parameter curve and axial ratio of the present invention in the left-hand circular polarization state when the center frequency is 2.45 GHz;

[0029] Figure 7 It is the S parameter curve and axial ratio of the present invention in the right-hand circular polarization state when the center frequency is 2.45 GHz;

[0030] Figure 8 is the planar gain pattern of the present invention in the left-hand circular polarization state at a frequency of 2.45 GHz;

[0031] Fig. 9 is the plane gain pattern of the present invention in the right-hand circular polarization state at a frequency of 2.45 GHz;

[0032] Fig.10 is the axial ratio of the present invention in each direction at a frequency of 2.45 GHz;

[0033] Fig.11 It is a schematic diagram of the human muscle tissue environment of the present invention. DETAILED DESCRIPTION

[0034] The present invention will be further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0035] Example 1

[0036] like Figure 1-Figure 2As shown, a left-hand circular polarization reconfigurable implantable antenna for mobile medical treatment includes an upper dielectric substrate 2B and a lower dielectric substrate 2A. Both dielectric substrates use a 0.635 mm Rogers 3010 substrate. The upper surface of the lower dielectric substrate is provided with an antenna radiation unit, and the lower surface thereof is provided with a metal floor. The antenna radiation unit is divided into two parts by a U-shaped groove. The lower dielectric substrate and the antenna radiation unit are both rectangular structures. The U-shaped groove is composed of three slot lines that are perpendicular to each other. The two end slot lines are connected to one side of the antenna radiation unit. The part surrounded by the U-shaped groove is called the central metal 1A, and the other part is called the peripheral metal 1B.

[0037] The upper dielectric substrate covers the antenna radiation unit and has a shallow groove at the corresponding position of the diode group so that it is closely attached to the radiation patch to play an isolation and protection role.

[0038] Furthermore, two parallel arms of the U-shaped slot are provided with diode groups 4A and 4B, each diode group includes three switching diodes for connecting two parts of the antenna radiation unit, and three parallel diodes in the same direction are provided on each arm for connecting the central metal and the peripheral metal.

[0039] Furthermore, the antenna radiation unit and the metal floor are connected via metal through holes 5A and 5B. The metal through holes 5A and 5B are arranged between the two parallel arms of the U-shaped groove and the edge of the antenna radiation unit, introducing inductive components and achieving miniaturization.

[0040] Furthermore, a pad 1C is provided at a center position on one side of the lower dielectric substrate and is connected to a DC feeding structure.

[0041] like Figure 3 As shown, the DC feeding structure includes a first battery 7A, a second battery 7B, a first switch 8A, a second switch 8B, a first RF isolation inductor 9A and a second RF isolation inductor 9B. The positive electrode of the first battery 7A is connected to the negative electrode of the second battery 7B. The first switch 8A is set between the two batteries. The first switch 8A and the first RF isolation inductor 9A are connected to the first port. The negative electrode of the first battery 7A is connected to the positive electrode of the second battery 7B and then connected to the second switch. The second switch 8B is connected to the second RF isolation inductor 9B and then connected to the second port. The first port 10A and the second port 10B are respectively connected to the pad 1C and the metal floor 3. The first switch is used for state switching, and the RF isolation inductor is used to prevent mutual interference between the DC source and the AC source.

[0042] The DC feeding structure is connected to the antenna via a radio frequency isolation inductor, and the control circuit switch can switch the circular polarization state of the antenna.

[0043] Furthermore, the coaxial feeding structure is composed of a 50Ω coaxial line, the inner core radius is 0.2mm, the outer radius is 0.7mm, the inner core is connected to the antenna radiation unit through the lower dielectric substrate, and the outer core is located on the lower dielectric substrate.

[0044] like Figure 4 and Figure 5 As shown, the preferred dimensions of the various components of this embodiment are as follows:

[0045] The length of the antenna radiation unit is L1 = 7.9 mm, the width is L2 = 5.6 mm, the distance from the edge of the lower dielectric substrate is W2 = 0.5 mm, the width of the U-shaped groove is W1 = 0.5 mm, the isolated central metal 1A is L3 = 5.5 mm long, the width is L4 = 2.5 mm, the lead pad is L5 = 0.8 mm long, the width is L6 = 0.4 mm, and it is connected to the central metal 1A by a metal wire with a width of D1 = 0.2 mm.

[0046] The length S1 of the upper dielectric substrate 2B is 8.9 mm, the width S2 is 6.6 mm, and the size of the side edge of the lower dielectric substrate 2A used to support the pad 1C is 0.5 mm×1 mm.

[0047] The radius of the metal through hole is 0.2 mm, and the distance D5 from the edge of the substrate is 0.8 mm.

[0048] The coaxial feed is on the central axis of the planar radiation patch, with a distance of D4 = 1 mm from the edge, and the radius of the coaxial core is 0.2 mm.

[0049] In this embodiment, the lower dielectric substrate 2A and the upper dielectric substrate 2B are Rogers 3010, which has a relative dielectric constant of 10.2, an electric loss tangent of 0.0035, and a thickness of 0.635 mm.

[0050] The diode model used in the diode group in this embodiment is a Bar50 PIN diode, which is characterized by a small size and good linear characteristics in the radio frequency range. Its size is 1mm× 0.6mm× 0.4mm, and the distance D3 of each diode in the embodiment is 0.9mm. The on-resistance is 2Ω, and the off-resistance is 5kΩ.

[0051] In this embodiment, the first battery 7A and the second battery 7B use 1.5 V batteries, and the first RF isolation inductor 9A and the second RF isolation inductor 9B use inductors of model LQW18AN56NJ00, which are characterized by small size and inductance of 56 nH.

[0052] In this embodiment, the first switch 8A can switch the working state of the antenna, change the circular polarization mode, and realize polarization reconfiguration. The second switch 8B can control the main power supply. The first RF isolation inductor 9A and the second RF isolation inductor 9B can isolate the AC signal to prevent circuit interference.

[0053] In this embodiment, a reconfigurable method for a left-hand circular polarization reconfigurable implantable antenna is described as follows:

[0054] When the first switch is connected to the first power supply, the first port of the DC feeding structure is at a positive potential compared to the second port, the switch diode of one side arm of the U-shaped slot is turned on, and the peripheral metal current flows into the central metal through the conducting diode to achieve left-handed circular polarization;

[0055] When the first switch is connected to the second power supply, the first port of the DC feeding structure has a negative potential compared to the second port, the switch diode on the other side arm of the U-shaped slot is turned on, and the current flowing from the peripheral metal to the central metal is reversed, changing the current path and realizing right-hand circular polarization.

[0056] like Figure 6 and Figure 7 As shown in the figure, when the antenna is in the left-hand circular polarization state, when S11<-10dB, the frequency range is: 2.11-2.63 GHz, the bandwidth is 520 MHz, the relative bandwidth is 21.9%, and when the axial ratio is <3 dB, the frequency range is: 2.38-2.53GHz, the bandwidth is 150 MHz, the relative bandwidth is 6.1%, and the entire 2.45 GHz ISM band is covered; when the antenna is in the right-hand circular polarization state, when S11<-10dB, the frequency range is: 2.11-2.63GHz, the bandwidth is 520 MHz, the relative bandwidth is 21.9%, and when the axial ratio is <3 dB, the frequency range is: 2.39-2.53GHz, the bandwidth is 140 MHz, the relative bandwidth is 5.7%, and the entire 2.45 GHz ISM band is covered.

[0057] like Figure 8 and Fig. 9 As shown, the maximum radiation gain of the antenna is -23.9 dBi, the reliable transmission distance is long, and the transmission efficiency is high. The maximum radiation direction of the antenna pattern of the present invention is the vertical upward direction, and it has good directional radiation characteristics. The antenna realizes different circular polarization working states after the first switch 8A. The half-power beam width (Half-PowerBeamWidth, HPBW) in the left-hand circular polarization state is -40° to 31° (xoz plane) and -30° to 42° (yoz plane). The half-power beam width in the right-hand circular polarization state is -41° to 31° (xoz plane) and -43° to 30° (yoz plane).

[0058] like Fig.10 As shown in the figure, when the antenna works in left-hand circular polarization, the 3dB axial ratio beamwidth (ARBW) is -61° to 21° (xoz plane) and -23° to 62° (yoz plane). In right-hand circular polarization, the 3dB axial ratio beamwidth is -60° to 22° (xoz plane) and -62° to 24° (yoz plane).

[0059] like Fig.11 As shown, the antenna works in the center of a square model of human muscle tissue with a side length of 100 mm and a height of 40 mm. The relative dielectric constant ε of the muscle model at a frequency of 2.45 GHz is r = 52.7, conductivity σ = 1.73S / m, and implantation depth of 15 mm.

[0060] The antenna has the characteristics of large impedance bandwidth, miniaturization, circular polarization, resistance to polarization mismatch, high gain and dual circular polarization switching.

[0061] Example 2

[0062] An implantable device includes the implantable antenna. The implantable antenna includes an antenna radiation unit, an upper dielectric substrate, a lower dielectric substrate, a metal floor, a diode group, a metal through hole, a coaxial feeding structure, and a DC feeding structure. The antenna radiation unit is located on the upper surface of the lower dielectric substrate with a high dielectric constant, and the metal floor is located on the lower surface of the lower dielectric substrate with a high dielectric constant. Radio frequency switching diodes are distributed on the antenna radiation unit. The DC feeding system is connected to the antenna through an RF isolation inductor, and the control circuit switch can switch the circular polarization state of the antenna.

[0063] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A left-handed circularly polarized reconfigurable implantable antenna, characterized in that: The invention comprises a lower dielectric substrate and an upper dielectric substrate, wherein an antenna radiation unit is arranged on the upper surface of the lower dielectric substrate, a metal floor is arranged on the lower surface of the lower dielectric substrate, the upper dielectric substrate covers the antenna radiation unit, the antenna radiation unit is divided into two parts by a U-shaped groove, and a switch diode group is arranged on two arms of the U-shaped groove for connecting the two parts of the antenna radiation unit; The antenna radiation unit is divided into two parts by a U-shaped groove, the two ends of the U-shaped groove are arranged at the edge of the antenna radiation unit, the part surrounded by the U-shaped groove is the central metal, and the rest is the peripheral metal, and the central metal is provided with a pad connected to the DC feeding structure; The antenna radiation unit and the metal floor are connected via a metal through hole; The DC feeding structure includes a first battery, a second battery, a first switch, a second switch, a first RF isolation inductor and a second RF isolation inductor. The positive electrode of the first battery is connected to the negative electrode of the second battery. A first switch is arranged between the two batteries. The first switch and the first RF isolation inductor are connected to a first port. The negative electrode of the first battery is connected to the positive electrode of the second battery and then to the second switch. The second switch and the second RF isolation inductor are connected to the second port. The first port and the second port are connected to a pad and a metal floor, respectively.

2. The implantable antenna according to claim 1, characterized in that: The U-shaped groove is composed of three groove arms which are vertical in sequence, and switching diodes are arranged on the arms which are parallel to each other in the U-shaped groove.

3. The implantable antenna according to claim 2, characterized in that: The switching diode group includes three switching diodes.

4. The implantable antenna according to claim 1, characterized in that: The metal floor and the antenna radiation unit are rectangular structures.

5. The implantable antenna according to claim 1, characterized in that: It also includes a coaxial feeding structure, which is composed of a 50Ω coaxial line, an inner core of which is connected to the antenna radiation unit through a lower dielectric substrate, and an outer core of which is located on the lower dielectric substrate.

6. A method for realizing the reconfiguration of the implantable antenna according to any one of claims 1 to 5, characterized in that: include: When the first switch is connected to the first power supply, the first port of the DC feeding structure is at a positive potential compared to the second port, the switch diode of one side arm of the U-shaped slot is turned on, and the peripheral metal current flows into the central metal through the conducting diode to achieve left-handed circular polarization; When the first switch is connected to the second power supply, the first port of the DC feeding structure has a negative potential compared to the second port, the switch diode on the other side arm of the U-shaped slot is turned on, and the current flowing from the peripheral metal to the central metal is reversed, changing the current path and realizing right-hand circular polarization.

7. An implantable device, characterized in that: The invention comprises the implantable antenna as described in any one of claims 1 to 5.

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