Small size interdigitated capacitively loaded near field sensing node antenna that prevents information leakage

Abstract

The application discloses a small-size interdigital capacitance loaded near-field sensing node antenna capable of preventing information leakage, and belongs to the technical field of wireless communication. The antenna comprises a dielectric substrate, the top layer of the dielectric substrate is etched with an upper bent microstrip line, a lower bent microstrip line and an interdigital capacitance structure arranged at the joint of the upper bent microstrip line and the lower bent microstrip line, the side of the upper bent microstrip line and the lower bent microstrip line away from the interdigital capacitance structure is respectively provided with a first impedance matching resistor and a second impedance matching resistor, and the other side of the first impedance matching resistor and the second impedance matching resistor is respectively provided with an antenna input feed line and an antenna output feed line. The small-size interdigital capacitance loaded near-field sensing node antenna provided by the application effectively reduces the size of the antenna through interdigital capacitance loading, thereby reducing the effective radiation length of the antenna, and the effect of giving consideration to far-field radiation suppression and small size of the antenna is achieved.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and in particular to a small-sized interdigital capacitively loaded near-field sensing node antenna that can prevent information leakage. Background Technology

[0002] Wireless Body Area Networks (WBANs) are short-range wireless communication networks composed of various miniature sensor nodes. They enable real-time acquisition, transmission, and processing of human physiological parameters, effectively simplifying traditional medical testing processes and improving the intelligence level of health monitoring. With the rapid development of information technology and wireless communication technology, WBANs are increasingly widely used in medical fields such as disease prevention, health management, and early diagnosis, becoming an important component of modern smart healthcare systems. However, the human physiological data transmitted in WBAN systems is highly privacy-sensitive. Unauthorized access or theft during transmission over wireless channels can lead to serious privacy violations for patients, resulting in incorrect diagnostic or treatment decisions. Therefore, data security and privacy protection have become one of the key challenges in the research and application of WBAN technology.

[0003] In recent years, researchers have conducted numerous studies to address data security issues in WBANs. [A Lightweight Cloud-Assisted Identity-Based Anonymous Authentication and KeyAgreement Protocol for Secure Wireless Body Area Network.] proposes an identity-based lightweight anonymous authentication and key agreement protocol. This protocol protects user anonymity by encrypting user identity information and dynamic parameters and generates dynamic session keys during communication to ensure the security and reliability of authentication and key agreement. [RC2PAS: Revocable Certificateless Conditional Privacy-Preserving Authentication Scheme in WBANs.] proposes a partition-based revocable certificateless authentication scheme. This scheme achieves efficient revocation and re-registration of user identities through a partition management mechanism, ensuring the security and anonymity of patient biometric data. However, such schemes that use security encryption mechanisms at the protocol and link layers to protect data still have certain limitations. Their encryption and authentication processes usually rely on complex algorithm calculations, which leads to a significant increase in the computing and communication energy consumption of nodes. This makes it difficult to meet the design requirements of low power consumption and lightweight design in WBAN. Therefore, it is necessary to find more cost-effective methods.

[0004] In metamaterial fabric body area networks, each sensor node needs to be coupled and communicate with the metamaterial transmission lines on the fabric via antennas. However, the antennas used in [Wireless Body Sensor Networks Based on Metamaterial Textiles] are still based on the traditional far-field radiation mechanism. Although they can couple with the metamaterial transmission lines, their excessively high radiation gain inevitably increases the risk of electromagnetic signals being intercepted by unauthorized devices during free-space propagation, thus weakening the security of the wireless body area network system during the transmission of sensitive information. Therefore, it is necessary to develop sensor node antennas with low far-field radiation gain to ensure the security of sensitive information.

[0005] The existing patent, CN120581867A, entitled "ISM Band Broadband Antenna for Near-Field Communication in Wireless Body Area Networks Using Metamaterial Fabrics," employs a three-feed structure with a unidirectional current loop to achieve a strong and uniform near-field antenna. It also utilizes a technique of placing resistors at antinodes to reduce the far-field gain to below -15dB and achieves good coupling with the metamaterial fabric, providing good information security in a WBAN (Wireless Body Area Network) environment. However, the introduction of the far-field suppression resistor achieves gain suppression through electrothermal conversion, inevitably at the cost of reduced antenna efficiency. Furthermore, the antenna's design dimensions are 21mm × 26.5mm × 0.8mm, and considering the body area network application environment of sensor node antennas, further miniaturization is still necessary.

[0006] Therefore, there is an urgent need to develop a sensor node antenna with a smaller size that can suppress far-field radiation using a new mechanism, in order to solve the information security problems existing in metamaterial fabric area networks. Summary of the Invention

[0007] The purpose of this invention is to provide a small-sized interdigitated capacitively loaded near-field sensing node antenna that can prevent information leakage. The near-field antenna based on interdigitated capacitive loading can effectively reduce the antenna size and the effective radiation length of the antenna, thereby taking into account the requirements of far-field radiation suppression and miniaturization.

[0008] To achieve the above objectives, the present invention provides a small-sized interdigital capacitor-loaded near-field sensing node antenna that can prevent information leakage, comprising a dielectric substrate. The top layer of the dielectric substrate is etched with an upper bent microstrip line, a lower bent microstrip line, and an interdigital capacitor structure disposed at the junction of the upper and lower bent microstrip lines. An impedance matching resistor unit is disposed on the side of the upper and lower bent microstrip lines away from the interdigital capacitor structure, and a feed line unit is disposed on the side of the impedance matching resistor unit away from the interdigital capacitor structure.

[0009] Preferably, the upper and lower bent microstrip lines are arranged symmetrically in a Π shape, and an interdigitated capacitor structure is used to connect the upper and lower bent microstrip lines.

[0010] Preferably, the upper bent microstrip line, the lower bent microstrip line, and the interdigital capacitor structure together form a square loop radiation structure, and the current flow on the square loop radiation structure is in the same clockwise direction.

[0011] Preferably, the interdigital capacitor structure is composed of several interdigital capacitor cells, which are integrally formed with the upper and lower bent microstrip lines.

[0012] Preferably, far-field gain radiation is suppressed by changing the number and shape of the interdigital capacitor cells.

[0013] Preferably, the impedance matching resistor unit includes a first impedance matching resistor. Second impedance matching resistor The feed line unit includes an antenna input feed line and an antenna output feed line; the first impedance matching resistor Second impedance matching resistor On the other side, antenna input feed lines and antenna output feed lines are respectively provided.

[0014] Preferably, by changing the first impedance matching resistor Second impedance matching resistor The impedance matching degree is adjusted by adjusting the resistance value.

[0015] Preferably, one end of both the antenna input feed line and the antenna output feed line is connected to an SMA connector.

[0016] Therefore, the present invention employs a small-sized interdigital capacitor-loaded near-field sensing node antenna to prevent information leakage, which has the following beneficial effects:

[0017] (1) The square loop structure formed by the top feeder structure has the current in the loop in the same clockwise direction, thus generating a strong and uniform near-field magnetic field.

[0018] (2) Without introducing power-consuming components such as resistors, the antenna radiation gain can be suppressed to below -20dB, which greatly reduces electromagnetic far-field radiation leakage, reduces the risk of information being intercepted during propagation, and ensures high information security of wireless body domain networks.

[0019] (3) The antenna size is only 10mm×9.65mm×0.8mm, which greatly reduces the antenna size and meets the wearing comfort requirements of metamaterial fabric domain network sensing node antenna.

[0020] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the top layer structure of the dielectric substrate according to an embodiment of the present invention;

[0022] Figure 2 This is a current flow distribution diagram of the antenna at the center frequency of 2.45 GHz in an embodiment of the present invention;

[0023] Figure 3 This is a simulated return loss curve (S11) of the antenna when the antenna center operating frequency is 2.45 GHz in an embodiment of the present invention.

[0024] Figure 4 The above diagrams show the far-field radiation gain when the antenna center operates at a frequency of 2.45 GHz in this embodiment of the invention; where (a) is the far-field radiation gain diagram of the H-plane and (b) is the far-field radiation gain diagram of the E-plane.

[0025] Figure 5 The magnetic field distribution diagrams of the xy plane at different heights z above the center frequency of 2.45 GHz in this embodiment of the invention are shown. The heights z are 0 mm, 5 mm, 10 mm, and 15 mm respectively. Among them, (a) is the magnetic field distribution diagram of the xy plane when the height z is 0 mm, (b) is the magnetic field distribution diagram of the xy plane when the height z is 5 mm, (c) is the magnetic field distribution diagram of the xy plane when the height z is 10 mm, and (d) is the magnetic field distribution diagram of the xy plane when the height z is 15 mm.

[0026] Figure 6 This is a magnetic field distribution diagram of the antenna in the yz plane at a center frequency of 2.45 GHz with x=0 mm in an embodiment of the present invention.

[0027] Figure 7 The above are simulation and measured return loss S11 curves of the antenna in this embodiment of the invention.

[0028] Figure Labels

[0029] 1. Upper section bent microstrip line; 2. Interdigital capacitor structure; 3. Lower section bent microstrip line; 4. First impedance matching resistor; 5. Second impedance matching resistor; 6. Antenna input feed line; 7. Antenna output feed line. Detailed Implementation

[0030] The following detailed description of embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0031] The center operating frequency of the antenna is set to 2.45 GHz to meet the requirements of the WBAN operating frequency band.

[0032] Please see Figure 1 A small-sized interdigital capacitor-loaded near-field sensing node antenna that can prevent information leakage includes a dielectric substrate. The top layer of the dielectric substrate is etched with an upper bent microstrip line 1, a lower bent microstrip line 3, and an interdigital capacitor structure 2 disposed at the junction of the upper bent microstrip line 1 and the lower bent microstrip line 3. An impedance matching resistor unit is disposed on the side of the upper bent microstrip line 1 and the lower bent microstrip line 3 away from the interdigital capacitor structure 2. A feed line unit is disposed on the side of the impedance matching resistor unit away from the interdigital capacitor structure.

[0033] The impedance matching resistor unit includes a first impedance matching resistor 4 and a second impedance matching resistor 5. The feed line unit includes an antenna input feed line 6 and an antenna output feed line 7. The antenna input feed line 6 and the antenna output feed line 7 are respectively provided on the other side of the first impedance matching resistor 4 and the second impedance matching resistor 5.

[0034] The upper bent microstrip line 1 and the lower bent microstrip line 3 are arranged symmetrically in a Π shape. Together, they form a square loop radial structure. The interdigitated capacitor structure 2 connects the upper bent microstrip line 1 and the lower bent microstrip line 3. The current flowing through this square loop radial structure is clockwise.

[0035] Far-field gain radiation suppression is achieved by modifying the interdigital capacitor structure 2. The interdigital capacitor structure 2 consists of several interdigital capacitor cells, which are integrally formed with the upper bent microstrip line 1 and the lower bent microstrip line 3. Simultaneously, significant miniaturization of the antenna is achieved by changing the parameters of the interdigital capacitor cells.

[0036] The first impedance matching resistor 4 and the second impedance matching resistor 5 are respectively and The impedance matching degree is adjusted by changing the resistance values ​​of the first impedance matching resistor 4 and the second impedance matching resistor 5.

[0037] Antenna input feed line 6 and antenna output feed line 7 are used as the antenna input port and output port, respectively. The input port and output port are each connected to an SMA connector, which is then connected to a vector network analyzer.

[0038] The substrate material is FR4 rigid board, but flexible dielectric materials such as PI can also be used.

[0039] The interdigital capacitor structure 2 in this embodiment includes six interdigital capacitor cells with the same width and evenly distributed.

[0040] The specific parameters after overall optimization are as follows: , , , , , , , , , , , .

[0041] Figure 2 This is a current flow distribution diagram of the top-level antenna structure at the center frequency of 2.45 GHz in this embodiment. From... Figure 2 As can be seen, the current flows in the same clockwise direction throughout the entire square loop radiation structure, and the loop current will help to form a strong and uniform near-field magnetic field.

[0042] Figure 3 This is a simulated return loss curve S11 for a 2.45GHz antenna in an embodiment of the present invention. The graph shows that S11 has a very low resonant point, indicating that the designed antenna has good operating characteristics.

[0043] Figure 4 This is a far-field radiation gain diagram at a center frequency of 2.45 GHz, according to an embodiment of the present invention. Figure 4 (a) in the diagram is the far-field radiation gain diagram of the H-plane. Figure 4 (b) in the figure shows the far-field radiation gain of the E-plane. As can be seen from the figure, the far-field radiation gain of the H-plane of the antenna is below -21dB, and the far-field radiation gain of the E-plane is below -24dB. This indicates that the embodiment of the present invention achieves excellent far-field radiation suppression and can effectively prevent the leakage of body area network information.

[0044] Figure 5 This is a magnetic field distribution diagram of the xy plane at different heights z above the center frequency of 2.45 GHz for the antenna in this embodiment. The heights z are 0 mm, 5 mm, 10 mm, and 15 mm, respectively.

[0045] Figure 6 This is a magnetic field distribution diagram of the antenna in the yz plane at a center frequency of 2.45 GHz and x = 0 mm in this embodiment. From... Figure 5 and Figure 6As can be seen, the antenna generates a strong and uniform vertical magnetic field within a range of 0mm to 20mm from the top surface of the antenna. The magnetic field strength reaches or exceeds 0.316 (-10dB) A / m. As the distance above the antenna increases, the magnetic field strength gradually weakens and the area of ​​the high-intensity region gradually shrinks. This is a typical characteristic of a near-field antenna, indicating that the magnetic field strength is mainly concentrated near the antenna and attenuates rapidly with increasing distance.

[0046] Figure 7 This is a graph showing the simulated and measured return loss S11 curves of the antenna in this embodiment. The antenna was simulated, and a corresponding physical prototype was fabricated for testing. It can be seen that the simulated and measured center operating frequencies are basically consistent. The simulated S11 at the operating frequency (2.45GHz) is -40.38dB, while the actual measured S11 at the operating frequency (2.46GHz) is -30.24dB. This indicates that the manufactured antenna also possesses good operating characteristics in the actual working environment.

[0047] According to the relevant provisions of the YD / T1644 standard, the specific absorption power (10-gSAR) value per unit mass of human tissue exposed to radio electromagnetic radiation must not exceed 2W / kg to meet electromagnetic radiation safety requirements. The electromagnetic simulation software AnsysHFSS was used to perform human specific absorption rate (SAR) simulation analysis on this invention. The simulation conditions were set as follows: the antenna was placed 1.5mm above the human tissue model, and the input power was 100mW. The simulation results show that at the operating frequency of 2.45GHz, the maximum 10-gSAR value of the antenna is 1.787W / kg, which is lower than the standard limit of 2W / kg. Therefore, the antenna described in this invention meets the human electromagnetic radiation safety standards under the above operating conditions and can be safely applied in wireless body-based local area network systems constructed based on metamaterial fabrics.

[0048] Therefore, this invention employs a small-sized interdigital capacitor to load the near-field sensing node antenna, which prevents information leakage. By using interdigital capacitor loading, the antenna size and effective radiation length can be effectively reduced, thus balancing the requirements for far-field radiation suppression and miniaturization. This invention does not use resistors to dissipate energy to achieve far-field radiation gain suppression, ensuring high antenna efficiency. This invention offers advantages such as miniaturization, high efficiency, and low far-field radiation gain. It effectively addresses the data leakage security problem caused by high far-field radiation gain of electromagnetic waves in wireless body domain network systems constructed from metamaterial fabrics; solves the problem of excessively large antenna sizes in wireless body domain network systems, making them unsuitable for various application scenarios; addresses the issue of low antenna efficiency in near-field communication requiring high information security in wireless body domain network systems; and resolves the dilemma of simultaneously achieving high efficiency, miniaturization, and low far-field radiation performance in wireless body domain network systems operating under human working conditions. Therefore, this near-field antenna can be effectively applied in metamaterial fabric wireless body domain network applications where data transmission security is paramount.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A small-sized interdigital capacitively loaded near-field sensing node antenna that can prevent information leakage, comprising a dielectric substrate, characterized in that: The top layer of the dielectric substrate is etched with an upper bent microstrip line, a lower bent microstrip line, and an interdigital capacitor structure disposed at the junction of the upper and lower bent microstrip lines. An impedance matching resistor unit is disposed on the side of the upper and lower bent microstrip lines away from the interdigital capacitor structure, and a feed line unit is disposed on the side of the impedance matching resistor unit away from the interdigital capacitor structure. The upper and lower bent microstrip lines are arranged symmetrically in a Π shape, and the interdigitated capacitor structure is used to connect the upper and lower bent microstrip lines. The upper bent microstrip line, the lower bent microstrip line, and the interdigital capacitor structure together form a square loop radiation structure. The current flows in the square loop radiation structure in the same clockwise direction and generates a strong and uniform near-field magnetic field. The interdigital capacitor structure consists of several interdigital capacitor cells, which are integrally formed with the upper and lower bent microstrip lines. Far-field gain radiation suppression is achieved by changing the number and shape of the interdigital capacitor cells. At the same time, antenna miniaturization is achieved by changing the parameters of the interdigital capacitor cells. The impedance matching resistor unit includes a first impedance matching resistor. Second impedance matching resistor ; The feed line unit includes an antenna input feed line and an antenna output feed line; a first impedance matching resistor. Second impedance matching resistor On the other side, antenna input feed lines and antenna output feed lines are respectively provided.

2. The small-sized interdigital capacitively loaded near-field sensing node antenna that prevents information leakage according to claim 1, characterized in that: By changing the first impedance matching resistor Second impedance matching resistor The impedance matching degree is adjusted by adjusting the resistance value.

3. The small-sized interdigital capacitively loaded near-field sensing node antenna that prevents information leakage according to claim 1, characterized in that: Both the antenna input feed line and the antenna output feed line have an SMA connector at one end.

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