CN204375919U - A kind of fractal implantable antenna being operated in MICS frequency range - Google Patents

Abstract

The utility model discloses a fractal implantable antenna working in the MICS frequency band, which is implanted into the muscle layer of the human body, and includes an antenna radiation unit, a differential feed copper column, a dielectric substrate and a floor, and the antenna radiation unit is located in the dielectric On the upper surface of the substrate, the floor is located on the lower surface of the dielectric substrate. Specifically, there are two differential feed copper columns, which are installed on the antenna radiation unit and connected to the differential signal feeder through the dielectric substrate. Fractal technology is used to increase the current path so that the antenna can be miniaturized in the MICS frequency band and has a wide frequency band. In addition, the differential transmission coefficient Γ _dif of the antenna in the MICS frequency band is <-20dB.

Description

A Fractal Implantable Antenna Working in the MICS Frequency Band

technical field

The utility model relates to the field of biological medicine, in particular to a fractal implantable antenna working in the MICS frequency band.

Background technique

At present, implantable medical devices have been used to monitor the physiological and biochemical characteristics of patients in real time and improve the quality of life. These implanted medical devices in use include pacemakers, vagus nerve stimulators, cochlear implants, artificial retinas, and more. Among so many implantable medical devices, the implantable antenna is an indispensable part, and it plays an important role in wireless data transmission between the implantable biomedical device in the human body and the base station outside the body. Since the implantable antenna needs to be implanted into the human body, it is necessary to use biocompatible materials to isolate the antenna from the biological tissue to prevent the human body from rejecting the antenna and to prevent body fluids from corroding the antenna. The frequency band usually used for implantable antennas in biomedicine is the Medical Implant Communication System (MICS) frequency band, which is specified by the European Telecommunications Standards Institute (ETSI) and can be used for human wireless Communication frequency band. However, due to the long wavelength of electromagnetic waves in the MICS frequency band, it is necessary to use miniaturization technology to reduce the size of the antenna, such as using a substrate with a high dielectric constant, using a stacked structure, and using a bent antenna. Secondly, the microchip radio frequency system used in implantable medical equipment generally uses differential circuits to process signals, so the antenna using differential feed technology is convenient for system interface, thus eliminating the need to add baluns (baluns). coming losses.

Utility model content

In order to overcome the shortcomings and deficiencies of the prior art, the utility model provides a fractal implantable antenna working in the MICS frequency band.

The utility model adopts the following technical solutions:

A fractal implantable antenna working in the MICS frequency band, implanted into the muscle layer of the human body, including an antenna radiation unit, a differential feed copper column, a dielectric substrate and a floor, the antenna radiation unit is located on the upper surface of the dielectric substrate, The floor is located on the lower surface of the dielectric substrate, and there are two differential feed copper columns, which are symmetrical about the vertical midline of the antenna radiating unit, installed on the antenna radiating unit, and connected to the differential signal feeder through the dielectric substrate.

The antenna radiation unit is composed of a 4th order Hilbert curve.

The antenna radiation unit is a square with a side length of 9.3 mm, the line width of the Hilbert curve is 0.3 mm, and the width of a single basic unit is 0.9 mm.

The diameter of the differential feed copper pillar is 0.7 mm.

The distance from the differential feeding copper column to the top of the antenna radiating unit is 2.5 mm, and the distance from the left and right edges of the antenna radiating unit is 1.3 mm.

The beneficial effects of the utility model:

Fractal technology is used to increase the current path of the antenna radiation unit so that the antenna can be miniaturized in the MICS frequency band and has a wider frequency band. In addition, the differential transmission coefficient Γ _dif <-20dB in the MICS frequency band. Differential feeding technology is used to make the antenna better connected to the radio frequency integrated circuit of the implantable medical device. Using a dielectric material with a high dielectric constant can reduce the wavelength of electromagnetic waves, thereby realizing miniaturization of the antenna. Biocompatible materials are used to isolate the antenna and biological tissue, so as to avoid the rejection reaction of the human body to the antenna and the corrosion of the antenna by active biological tissue.

Description of drawings

Fig. 1 is a structural diagram of a fractal implantable antenna working in the MICS frequency band of a kind of differential feeding of the utility model;

Fig. 2 is the parameter diagram of the fractal implantable antenna working in the MICS frequency band of a kind of differential feed of the present embodiment of the utility model;

Fig. 3 is the differential reflection coefficient curve diagram of the fractal implantable antenna of a kind of differential feeding of the utility model in the MICS frequency band;

Fig. 4 is a directional diagram at 403MHz of a fractal implantable antenna working in the MICS frequency band of a kind of differential feed of the utility model;

Fig. 5 is a schematic diagram of a working environment of a differentially fed fractal implantable antenna working in the MICS frequency band.

Detailed ways

The utility model will be described in further detail below in conjunction with the embodiments and accompanying drawings, but the implementation of the utility model is not limited thereto.

Example

As shown in Figures 1 and 2, a fractal implantable antenna working in the MICS frequency band includes an antenna radiation unit 1, a differential feed copper column 2A-2B, a dielectric substrate 3 and a floor 4, and the antenna radiation unit 1 It is located on the upper surface of the dielectric substrate 3, and the floor 4 is located on the lower surface of the dielectric substrate 3. The differential feed copper columns are specifically two, symmetrically installed on the antenna radiating unit 1, symmetrical about the vertical center line of the antenna radiating unit, and passing through The differential signal feeder is connected through the dielectric substrate 3, and the differential signal feeder is obtained by feeding the two copper columns into the antenna. The floor 4 is located on the lower surface of the dielectric substrate and has a circular hole to connect the differential signal line to the differential feeder copper column. . It also includes a film of biocompatible material, the film covers the entire surface of the antenna with a thickness of 20 μm, and the entire antenna can be implanted into the muscle layer of the human body.

The antenna radiating unit 1 is composed of a 4th-order Hilbert curve, and the entire antenna is a square with a side length L of 9.3mm. The line width w of the radiation unit of the Hilbert curve antenna is 0.3 mm, and the width w1 of a single basic unit is 0.9 mm. The differential reflection coefficient of the antenna is less than -20dB in the whole MICS frequency band (402-405MHz), and the antenna bandwidth is 372-449MHz. And has better radiation characteristics.

The dielectric substrate 3 is a square Rogers RO3210 dielectric substrate with a side length L of 9.3 mm, a thickness h of 0.635 mm, a relative permittivity ε _r of 10.2, and a loss tangent tan δ of 0.003.

The diameter d of the differential feeding copper pillars 2A-2B is 0.7 mm, and the distances between the copper pillars and the edge of the antenna are respectively 1.3 mm for d1 and 2.5 mm for d2.

The biocompatible material film is Parylene-C, its relative permittivity _εr is 2.95, and its loss tangent tanδ is 0.013.

As shown in Figure 5, the three layers of human tissue are skin, fat, and muscle from top to bottom, and the relative permittivity ε _r , conductivity σ, and density ρ of each tissue at a frequency of 403 MHz have been given in the figure . The working environment of the antenna is to be implanted into the muscle layer of the human body, and the change of the implantation depth dp has little influence on the performance of the antenna.

As shown in Figure 3, the differential reflection coefficients of the antenna at different implantation depths are less than -20dB in the MICS frequency band, and the frequency range covered by the antenna is 372-449MHz.

As shown in Figure 4, the radiation pattern of the antenna on the XOZ plane and the YOZ plane has good outward radiation characteristics.

The antenna has the characteristics of miniaturization. Fractal technology is used to increase the current path of the antenna radiation unit so that the antenna can be miniaturized in the MICS frequency band and has a wide bandwidth. In addition, the differential transmission coefficient Γ _dif <-20dB in the MICS frequency band. Differential feeding technology is used to make the antenna better connected to the radio frequency integrated circuit of the implantable medical device. The use of a dielectric material with a high dielectric constant can reduce the wavelength of the electromagnetic wave and also realize the miniaturization of the antenna. Biocompatible materials are used to isolate the antenna and biological tissue, so as to avoid the rejection of the antenna by the human body and the corrosion of the antenna by the human body environment. Therefore, it can be applied to implantable medical devices.

The above-mentioned embodiment is a preferred implementation mode of the present utility model, but the implementation mode of the present utility model is not limited by the described embodiment, and any other changes, modifications, modifications, Substitution, combination, and simplification should all be equivalent replacement methods, and are all included in the protection scope of the present utility model.

Claims (5)

1. A fractal implantable antenna working in the MICS frequency band, which is implanted into the muscle layer of the human body, is characterized in that it includes an antenna radiation unit, a differential feed copper post, a dielectric substrate and a floor, and the antenna radiation unit is located at The upper surface of the dielectric substrate, the floor is located on the lower surface of the dielectric substrate, and the differential feed copper columns are specifically two, and are symmetrical about the vertical midline of the antenna radiation unit, installed on the antenna radiation unit, and connected to the differential through the dielectric substrate. signal feeder. 2 . The antenna according to claim 1 , wherein the antenna radiating element is composed of a fourth-order Hilbert curve. 3 . 3. The antenna according to claim 2, wherein the antenna radiating element is a square with a side length of 9.3 mm, the line width of the Hilbert curve is 0.3 mm, and the width of a single basic unit is 0.9 mm. mm. 4 . The antenna according to claim 1 , wherein the diameter of the differential feeding copper column is 0.7 mm. 5 . The antenna according to claim 1 , wherein the differential feeding copper column is 2.5 mm away from the top of the antenna radiating unit, and 1.3 mm away from the left and right edges of the antenna radiating unit.