KR20240025135A - Triple band antenna and implantable device - Google Patents

Abstract

The antenna according to this embodiment includes: a ground plane in which an L-shaped slot is formed; a first dielectric substrate in contact with the ground plane; a radiating patch in contact with the first dielectric substrate and resonating in three different frequency bands; a second dielectric substrate in contact with the radiation patch; and a power feeding structure that penetrates the ground plane and the first dielectric substrate and supplies power to the radiation patch, wherein the antenna has no short pin between the radiation patch and the ground plane.

Description

Triple band antenna and implantable device comprising same {TRIPLE BAND ANTENNA AND IMPLANTABLE DEVICE}

The present technology relates to a triple-band antenna and an implantable device containing the same.

Miniaturized implantable medical devices (IMDs) enable highly accurate treatment and diagnostic methods in clinical and medical research, and are useful in a variety of applications such as capsule endoscopy, blood glucose monitoring implants, pacemakers, and intracranial manometry. It is used extensively. The implantable device can communicate wirelessly with a control device outside the body through an attached antenna.

Antennas mounted on implantable devices have different radiation characteristics compared to antennas located in free space. Antennas for implantable devices need to consider many aspects, such as bandwidth and size, and patient safety issues such as specific absorption rate (SAR), licence-exempt operating frequencies, biocompatibility, and tissue integration. Various frequency bands are used in implantable device applications, such as the Medical Implant Communication Service band (402-405 MHz).

The design process of small insertable antennas for these wavelength bands is very difficult. The range of the industrial, scientific, and medical bands (ISM) 902-928 MHz and 2400-2483.5 MHz) varies by country. However, the higher bandwidth 2.4 GHz ISM band is suitable for high-resolution data transmission from implantable devices to external monitoring stations and has the added benefit of smaller antenna size.

Recently, several implantable antennas have been proposed for biomedical applications. Examples of these implantable antennas include a circularly polarized double-layer implantable antenna operating at 915 MHz, a multilayer helical antenna for endoscopy applications operating at 2.4 GHz, and a compact implantable antenna operating in the 2400 MHz band.

The circularly polarized double-layer implantable antenna has a limited bandwidth as it has a simulation bandwidth of 97MHz, and the multilayer helical antenna has a large volume of 302.05mm ³ and a complex shape, and has a small gain of -32dBi, which may be inappropriate for use in implantable devices. In addition, small implantable antennas operating in the 2400 MHz band use resistance, which makes manufacturing the antenna quite complicated and increases loss.

Other implantable antennas proposed in the prior art operate with acceptable performance in a single band, but suffer from the disadvantage of being bulky for insertion within the body, and because they operate in a single band, they provide various functions such as wake up and wireless charging along with biotelemetry. It is not suitable to meet the requirements of multitasking implantable devices because it requires operating frequencies for other functions such as the same. Accordingly, there is an increasing demand for multiband implantable antennas for implantable devices.

This embodiment is intended to solve these difficulties in the prior art. That is, one of the problems to be solved by this embodiment is to provide an antenna that has a small volume so that it can be used with an implantable device and can operate in multiple bands.

The antenna according to this embodiment includes: a ground plane in which an L-shaped slot is formed; a first dielectric substrate in contact with the ground plane; a radiating patch in contact with the first dielectric substrate and resonating in three different frequency bands; a second dielectric substrate in contact with the radiation patch; and a power feeding structure that penetrates the ground plane and the first dielectric substrate and supplies power to the radiation patch, wherein the antenna has no short pin between the radiation patch and the ground plane.

According to one aspect of this embodiment, the L-shaped slot includes an opening formed at one end of the ground plane.

According to one aspect of this embodiment, the thickness of the first dielectric substrate is greater than the thickness of the second dielectric substrate.

According to one aspect of this embodiment, the three different frequency bands include two ISM bands (industrial, scientific, medical bands) and a midfield band located between the two ISM bands.

According to one aspect of this embodiment, the two ISM bands are a 900 MHz band and a 2400 MHz band, respectively, and the midfield band is a 1900 MHz band.

According to one aspect of this embodiment, the antenna receives power through the midfield band and transmits and receives data to and from the outside through the two ISM bands.

According to one aspect of this embodiment, the resonant frequency in the midfield band and the resonant frequency of the ISM band with a frequency greater than the midfield band are determined by the shape of the L-shaped slot, the feed structure, and the radiation. It can be adjusted by adjusting the connection point of the patch.

According to one aspect of this embodiment, the power feeding structure is not electrically connected to the ground plane and the first dielectric substrate.

According to one aspect of this embodiment, the radiation patch includes a first arm including a meander pattern, and a second arm including a meander pattern, wherein the first arm and the The second arms are connected to each other at the center in the longitudinal direction of the radiation patch, and the feed structure is connected to a side end side of the second arm.

The implantable device according to this embodiment operates in two ISM bands (industrial, scientific, medical bands) and a midfield band located between the two ISM bands, and receives power through the midfield band. , an antenna for transmitting and receiving data to and from the outside in the two ISM bands; a power unit including a battery that charges power received by the antenna; a power and data processing device that processes the data and the power; and a housing made of a human-friendly material, wherein the antenna has no short pin between the radiating patch and the ground plane.

According to this embodiment, an antenna of small volume can be formed, providing the advantage of further reducing the volume of an implantable device.

FIG. 1(a) is a diagram illustrating a state in which the implantable device according to this embodiment is implanted in the human body, and FIG. 1(b) is an exploded perspective view of the implantable device according to this embodiment.
FIG. 2(a) is a diagram illustrating an outline of a radiation patch of an antenna according to this embodiment, and FIG. 2(b) is a diagram illustrating an outline of a ground plane of an antenna according to this embodiment.
FIG. 3(a) is a cross-sectional view schematically showing the cross section including the power feeder, and FIG. 3(b) is a transparent perspective view illustrating the outline of the antenna according to this embodiment.
Figures 4(a) and 4(b) are diagrams showing current distribution when the antenna according to this embodiment operates at the first resonant frequency.
Figures 5(a) and 5(b) are diagrams showing current distribution when the antenna according to this embodiment operates at the second resonant frequency.
Figures 6(a) and 6(b) are diagrams showing current distribution when the antenna according to this embodiment operates at the third resonance frequency.
Figure 7(a) is a diagram showing the change in reflection coefficient in response to the feeding point change, Figure 7(b) is a diagram showing the change in the real part of Z in response to the feeding point change, and Figure 7(c) is a diagram showing the change in the real part of Z in response to the feeding point change. This is a diagram showing the change in the imaginary part of Z in response to the point change.
Figure 8(a) is a diagram showing the change in S11 according to the length of the opening slot of the L-shaped slot formed on the ground plane, and Figure 8(b) is a diagram showing the change in S11 according to the length of the opening slot of the L-shaped slot formed on the ground plane. This is a diagram showing the change in the real part of Z according to the change, and Figure 8(c) is a diagram showing the change in the real part of Z according to the length of the slot on the opening side of the L-shaped slot formed in the ground plane.
Figure 9(a) is a diagram showing the change in S11 according to the length of the L2 slot of the L-shaped slot formed on the ground plane, and Figure 9(b) shows Z according to the length of the L2 slot of the L-shaped slot formed on the ground plane. It is a diagram showing the change in the real part (Real(Z)) of This is a drawing.
FIG. 10(a) is a diagram showing link margin versus distance when the antenna of this embodiment operates at 915 MHz, and FIG. 10(b) illustrates link margin versus distance when the antenna of this embodiment operates at 1900 MHz. This is a diagram, and FIG. 10(c) is a diagram showing link margin versus distance when the antenna of this embodiment operates at 2450 MHz.

Hereinafter, this embodiment will be described with reference to the attached drawings. The antenna according to this embodiment includes a ground plane 110 on which an L-shaped slot 112 is formed, a first dielectric substrate 120 in contact with the ground plane 110, and the first dielectric substrate 120. A radiation patch 130 that is in contact with and resonates in three different frequency bands, a second dielectric substrate 140 in contact with the radiation patch 130, the ground plane 110, and the first dielectric substrate ( 120 and includes a power feeding structure 150 that feeds power to the radiation patch 130, and the antenna 100 has a short pin between the radiation patch 130 and the ground plane 110. ) is not there.

The implantable device 10 according to this embodiment operates in two ISM bands (industrial, scientific, medical bands) and a midfield band located between the two ISM bands, receives power in the midfield band, and An antenna 100 that transmits and receives data to and from the outside in two ISM bands; a power supply unit 200 including a battery that charges power received by the antenna; a power and data processing device 300 that processes the data and the power; and a housing (H) made of a human-friendly material, wherein the antenna 100 has no short pin between the radiating patch and the ground plane.

FIG. 1(a) is a diagram illustrating a state in which the implantable device 10 according to this embodiment is implanted in the human body, and FIG. 1(b) is a diagram illustrating a state in which the implantable device 10 according to this embodiment is implanted in the human body. ) is an exploded perspective view. Figure 1(a) illustrates that the implantable device 10 according to this embodiment is implanted into the skull and deep tissues such as the heart of the human body. However, this is only an example and can be transplanted and used in other tissues such as the liver and small intestine.

Referring to FIG. 1(b), the implantable device 10 according to this embodiment includes a housing (H) including a container (H1) and a container cover (H2), an antenna 100, a power source 200, and power. and a data processing device 300. The housing H is made of biocompatible material. In one embodiment, the biocompatible material may be ceramic alumina (Al ₂ O ₃ , εr = 9.8). The container H1 and the container cover H2 may have a thickness ranging from 0.1 mm to 0.3 mm. Additionally, the implantable device 10 according to this embodiment has dimensions of 13 mm in width, 8 mm in height, and 3.25 mm in height, and may have a volume of 338 mm ³ .

The power and data processing device 300 wirelessly receives a power signal from an external device (not shown) and charges the battery included in the power supply unit 200. The power supply unit 200 provides driving power to the power and data processing device 300. The power and data processing device 300 receives data provided to the implantable device 10 from the antenna 100 and processes it. Additionally, the power and data processing device 300 processes biometric information detected by a sensor (not shown) included in the implantable device 10 and provides the processed information to the outside through the antenna 100. In one embodiment, a sensor (not shown) collects various biometric information such as blood pressure, blood sugar, heart rate, and pulse rate at the location where the device 10 is located, and provides the collected information to the power and data processing device 300. You can.

FIG. 2(a) is a diagram illustrating an outline of a radiation patch 130 of the antenna 100 according to the present embodiment, and FIG. 2(b) is a diagram showing the ground plane of the antenna 100 according to the present embodiment. (ground patch, 110) This is a drawing showing the outline. FIG. 3(a) is a cross-sectional view schematically showing the cross section including the power feeder 150, and FIG. 3(b) is a transparent perspective view schematically showing the antenna 100 according to this embodiment.

2(a), 2(b), 3(a), and 3(b), the antenna 100 includes a ground plane 110, a first substrate 120, and a radiation patch ( 130) and a second substrate 140 may be stacked. In one embodiment, the first substrate 120 and the ground plane 110 may be Rogers RT/duroid 6010 (εr = 10.2, tanδ = 0.0035) with a thickness of 0.25 mm. The second substrate 140 and the radiation patch 130 may each be formed of Rogers RT/duroid 6010 (εr = 10.2, tanδ = 0.0035) with a thickness of 0.127 mm.

By adopting a material with a high dielectric constant of relative dielectric constant of 10 or more, the resonance frequency can be reduced and the size can be reduced. The thickness of the second substrate 120 is smaller than the thickness of the first substrate 130, thereby shifting the resonance frequency to a lower band, which makes it possible to miniaturize the antenna. Accordingly, an antenna that has been miniaturized to a high degree can be formed from this configuration. Furthermore, the second substrate 130 provides the additional advantage of isolating the antenna from lossy materials included in the antenna 100 and stabilizing variations in effective dielectric constant surrounding the antenna. The size of the antenna according to this embodiment is, for example, 7 mm × 5 mm × 0.377 mm (13.195 mm ³ ).

As shown, the radiation patch 130 includes two arms 132 and 134 that are left and right symmetrical in a meander shape. The ground plane 110 has an L-shaped open slot 112, so that the bandwidth is improved, the resonant frequency can be moved to the target band, and the size of the antenna can be miniaturized.

The antenna 100 is excited with the power feed 150. In one embodiment, the power feed 150 has a diameter of 0.4 mm and may be a 50 ohm coaxial feed. As shown, the power feed 150 is connected to the radiating patch 130 through a via hole 152 that is not in electrical contact with the ground plane 110 to excite the radiating patch 130. Additionally, the ground plane 110 includes an L-shaped slot 112. In this embodiment, the bandwidth can be increased by forming the L-shaped slot 120, and the resonant frequency can be moved to the desired band. Furthermore, by placing the power feed 140 at a desired location (X = 2mm, Y = 0.5mm), the bandwidth could be increased and the resonance frequency could be moved.

Figures 4(a) and 4(b) are diagrams showing the current distribution when the antenna according to this embodiment operates at the first resonant frequency, and Figure 4(b) shows the current distribution when the antenna according to this embodiment operates at the first resonant frequency. 2 This diagram shows the current distribution when operating at the resonant frequency.

Referring to FIG. 4(a), the current in the radiating patch 130 follows the longest path while maintaining a unidirectional direction. Therefore, the antenna resonates in a 1/4 wavelength monopole mode in the first frequency band. In the embodiment illustrated in FIGS. 4(a)-4(b), the first frequency band may be 915 MHz.

Figure 5(a) shows the current distribution of the radiating patch 130 when resonating in a second frequency band greater than the first frequency. In the drawing, it can be seen that the direction of the current changes twice in each part indicated by a blue circle. The radiation patch 130 according to this embodiment operates in a full-wavelength resonance full wavelength loop antenna mode as illustrated. In one embodiment, the second frequency band is a 1900 MHz band, which may be at least 500 MHz higher than the first frequency band described above.

However, the resonant frequency can be moved to the desired band by changing the shape of the L-shaped slot and/or changing the position of the power feed 150.

FIG. 6(a) shows the current distribution of the radiating patch 130 when the radiating patch 130 resonates in a third frequency band greater than the second frequency. As described above, it can be seen that the direction of the current changes twice in each circled part of the drawing. The radiation patch 130 according to this embodiment operates in a full-wavelength resonance full wavelength loop antenna mode as illustrated. In one embodiment, the third frequency band is a 2450 MHz band, which may be at least 500 MHz higher than the above-mentioned second frequency band.

Considering the current distribution in the ground plane 110 illustrated in FIGS. 4(b), 5(b), and 6(b), a strong current is observed adjacent to the L-shaped slot 112. From this, it can be easily understood that the resonance frequency can be adjusted by adjusting the arrangement and/or size of the L-shaped slot 112.

analyze

Below, all design elements that have a significant impact on the performance of the antenna according to this embodiment are analyzed. Figure 7 is a diagram showing the influence of S11 on the change in feeding point position and the influence of the impedance of the antenna. Figure 7(a) is a diagram showing the change in reflection coefficient (S11) on the change in feeding point, and Figure 7 ( b) is a diagram showing the change in the real part (Real(Z)) of Z in response to the feeding point change, and Figure 7(c) shows the change in the imaginary part (Imag(Z)) in Z in response to the feeding point change. It is a drawing.

Referring to FIGS. 7(a) to 7(c), the location of the feeding point not only improves impedance matching at the resonant frequency of the antenna according to this embodiment, but also improves impedance matching at the second and third frequencies. It can be seen that it shifts. It can be seen that the imaginary part of Z (Imag Z), illustrated in Figure 7(c) at 915 MHz, is close to 0 for all feeding points at the first resonance frequency of 915 MHz.

However, the real part (Re Z) of Z illustrated in FIG. 7(b) changes greatly depending on the feeding point location. For feeding points P1, P2, and P3 at 915 MHz, the values of Re Z are 120, 121, and 1, respectively. At position P4, Re Z is approximately 40, so the impedances are matched. In the S-parameter plot shown in Figure 7(a), a deep null is formed at 915 MHz.

For the second resonance at 1900 MHz at feeding point P1, the antenna has a capacitive impedance. Therefore, it is necessary to reduce the capacitance, and the capacitance can be reduced by moving the supply location. As the supply position moves to P2, P3, and P4, the capacitive reactance decreases and approaches zero at P4. Re Z for the second resonance frequency at P4 is about 48, resulting in good impedance matching as shown in the S-parameter plot in Figure 7(a).

The feeding point is P1, and the impedance at the third resonance frequency of 2450 MHz is inductive. Moving the feeding point to P2, P3, and P4 reduces the inductance, and at P4, Imag Z is 0 and Re Z is 60, so good impedance matching can be obtained, which can be seen in Figure 7(a). In the antenna according to this embodiment, the feeding point is selected as P4, which has resonance depths of -17, -22, and -18 dB at three different resonance frequencies of 915, 1900, and 2450 MHz, respectively.

Figure 8(a) is a diagram showing the change in S11 according to the length of the opening slot of the L-shaped slot formed on the ground plane, and Figure 8(b) is a diagram showing the change in S11 according to the length of the opening slot of the L-shaped slot formed on the ground plane. It is a diagram showing the change in the real part (Real(Z)) of Z according to the change, and Figure 8(c) shows the real part (Real(Z)) of Z according to the length of the slot on the opening side of the L-shaped slot formed on the ground plane. This is a drawing showing the changes.

The performance of the antenna according to this embodiment is sensitive to the slot and feeding point location of the patch. Additionally, since the slots in the ground plane play an important role in achieving the required impedance bandwidth and matching, analysis was performed on each element of the ground slot, denoted L1 and L2.

As shown in Figure 8(a), as L1 changes from 3mm to 6mm, the change in the 915MHz band is negligible, but it can be seen that the matching of the 1900 and 2450MHz bands is improved. On the other hand, the impedance plots (Re indicates that it is close to .

At the second resonant frequency of 1900 MHz, the impedance is inductive for L1 = 3 mm and 4 mm, while it is capacitive for L1 = 6 mm. However, at L1 = 5mm, Imag Z is close to 0 and Re Z is about 44, so good impedance matching results can be obtained at 1900MHz.

Additionally, for the third resonance at 2450 MHz, increasing L1 from 3 mm to 4 mm changes the impedance from inductive to capacitive. As L1 further increases to 5 mm, Imag Z approaches 0 and Re Z is around 65. For L1 = 6 mm, Imag Z becomes inductive and Re Z is approximately 33. Therefore, L1 = 5 mm was chosen as the optimal length of slot L1, giving resonance depths of -17, -23, and -18 dB at 915, 1900, and 2450 MHz, respectively.

Figure 9(a) is a diagram showing the change in S11 according to the length of the L2 slot of the L-shaped slot formed on the ground plane, and Figure 9(b) shows Z according to the length of the L2 slot of the L-shaped slot formed on the ground plane. It is a diagram showing the change in the real part (Real(Z)) of This is a drawing.

When increasing the ground slot length L2 from 2 mm to 5 mm, the matching of the primary resonance at 915 MHz becomes worse, while the resonance at the second frequency moves upward and then downward in frequency, as shown in Figure 9(a). Go to Similarly, by increasing L2 the third resonance at 2450 MHz not only shifts the frequency but also changes the impedance.

Referring to the impedance plots in Figures 9(b) and (c), for the first resonance at 915 MHz, Imag Z is zero for all values of L2 except 5 mm, which is capacitive. The Re Z value for L2 = 4mm is 38, which is close to 50, providing good impedance matching at the first resonance.

For the second resonance at 1900 MHz, Imag Z is capacitive when L2 = 2 mm. When L2 increases to 3 mm, Imag Z becomes inductive and is zero at L2 = 4 mm. Further increasing L2 to 5 mm makes the Imag Z capacitive again. Therefore, L2 = 4mm achieves the second resonance at 1900 MHz, where Re Z is 44.

At the third resonant frequency, at 2450 MHz, when L2 increases from 2 mm to 5 mm, Imag Z changes from inductive to capacitive and changes to a value of 0 at L2 = 4 mm, where Re Z is approximately 67. Based on this analysis, the value of L2 = 4 mm was considered the optimal value for slot L2, where resonance depths were observed to be -17, -23 and -19 dB at 915, 1900 and 2450 MHz, respectively.

For wireless communications, the range of a telemetry link is determined by link budget analysis. The quality of wireless links is sensitive to various types of loss, such as reflection, path loss, polarization mismatch loss, and absorption. To ensure the efficiency of the proposed antenna, it is important to study the communication link between the inserted antenna and external control/monitoring devices. Link Margin (LM) is used to measure the link characteristics of the proposed antenna according to changes in communication distance, and can be calculated using the equation below.

[Equation 1]

(d is the distance between the transmitting and receiving antennas, λ is the free-space wavelength, CNRlink is the ratio of the signal power received from an external antenna at a certain distance to the noise power density of the implanted transmitting antenna at a certain power level, and CNRrequired is the It is related to sensitivity and is the ratio of carrier to noise required at the receiving end to meet the requirements of a particular communication speed for bit error rate, Lf is the path loss)

parameter variable value Frequency (MHz) f _T 915/1900/2450 Antenna Gain (dBi) G _t -27.2/-22.2/-19.9 Distance (m) d 0 - 10 Transmitter Power (dBm) Pt -16 Temperature (K) T ₀ 273 Boltzmann constant k 1.38 × 10 ^-23 Noise power density (dB/Hz) No 203.93 Ideal - BPSK (dB) Eb/No 9.6 Receiver noise figure (dB) NF 3.5

The implantable device 10 of this embodiment adopts BPSK modulation, the required bit error rate is less than 1 × 10 ^-5 , and the bit rates (Br) are 7 kb/s, 100 kb/s, and 10 Mb/s. The input power of the implant system was set to 25 μW at 915, 1900, and 2450 MHz. The external monopole antenna had a gain (Gr) of 2dBi. Link margin (LM) was calculated at 915, 1900, and 2450 MHz. The values of other parameters are listed in Table 1.

The change in communication link margin (LM) according to distance was calculated using a mathematical equation and is shown in Figure 10. Figure 10(a) shows that at 915 MHz with 20 dB headroom, the implanted device 10 can communicate at bit rates of 7 and 100 kb/s at distances of 12 m and 10 m. However, when the data rate is increased to 10Mb/s, the transmission range is reduced to 1m at 915MHz.

Similarly, in Figure 10(b) the transmission range is shown at 1900 MHz with a link margin of 20 dB. For bit rates of 7 and 100 kb/s, the communication range is 12 m and 10 m, respectively. As is the case with the 915MHz band, when the data rate increases to 10Mb/s, the useful communication range drops to about 1m at 1900MHz.

Similarly, in the case of 2450MHz using the same link margin (LM) as shown in Figure 10(c), the proposed antenna can effectively communicate over distances of 12m and 8m at data rates of 7kb/s and 100kb/s, respectively. At a data rate of 10 Mb/s, the effective range is reduced to 0.5 m.

Although the present invention has been described with reference to the embodiments shown in the drawings to aid understanding, these are embodiments for implementation and are merely illustrative, and those skilled in the art will be able to make various modifications and equivalents therefrom. It will be appreciated that other embodiments are possible. Therefore, the true technical protection scope of the present invention should be determined by the attached patent claims.

10: Implantable device
100: antenna 110: ground plane
112: L-shaped slot 120: first substrate
130: radiating patch 132: first arm
134: second arm 140: second substrate
150: Feeding structure 152: Via
200: Power unit 300: Power and data processing device

Claims (10)

With an antenna, said antenna:
A ground plane with an L-shaped slot;
a first dielectric substrate in contact with the ground plane;
a radiating patch in contact with the first dielectric substrate and resonating in three different frequency bands;
a second dielectric substrate in contact with the radiation patch; and
It includes a power feeding structure that penetrates the ground plane and the first dielectric substrate and feeds power to the radiation patch,
The antenna is an antenna without a short pin between the radiating patch and the ground plane. According to paragraph 1,
The L-shaped slot is,
An antenna including an opening formed at one end of the ground plane. According to paragraph 1,
The thickness of the first dielectric substrate is,
An antenna that is large compared to the thickness of the second dielectric substrate. According to paragraph 1,
The three different frequency bands are
An antenna including two ISM bands (industrial, scientific, medical band) and a midfield band located between the two ISM bands. According to paragraph 4,
The two ISM bands are:
They are 900 MHz band and 2400 MHz band, respectively.
The midfield band is
Antenna in the 1900 MHz band. According to paragraph 4,
The antenna receives power in the midfield band,
An antenna that transmits and receives data to and from the outside in the two ISM bands. According to paragraph 4,
The resonant frequency in the midfield band and the resonant frequency of the ISM band with a higher frequency than the midfield band are,
An antenna that is adjustable by adjusting the shape of the L-shaped slot and the connection point of the feeding structure and the radiating patch. According to paragraph 1,
The feeding structure is
An antenna that is not electrically connected to the ground plane and the first dielectric substrate. According to paragraph 1,
The radiation patch is,
A first arm including a meander pattern,
It includes a second arm including a meander pattern,
The first arm and the second arm are connected to each other at the center of the radiation patch in the longitudinal direction,
The feeding structure is an antenna connected to a side end of the second arm. An implantable device, the implantable device comprising:
An antenna that operates in two ISM bands (industrial, scientific, medical bands) and a midfield band located between the two ISM bands, receives power in the midfield band, and transmits and receives data to the outside through the two ISM bands;
a power supply unit including a battery that charges power received by the antenna;
a power and data processing device that processes the data and the power; and
Includes a housing made of human-friendly material,
The antenna is an implantable device without a short pin between the radiating patch and the ground plane.