Near field communication device

Abstract

An example discloses a near-field device comprising: a conductive housing physically coupled to a near-field antenna; a near-field antenna having a first feed point and a second feed point and comprising: a first induction coil; a first conductive plate capacitively coupled to the conductive housing and galvanically coupled to the first end of the first induction coil; a second conductive plate capacitively coupled to the conductive housing and galvanically coupled to the second end of the first induction coil; a reference potential; and wherein the conductive housing is galvanically coupled to the reference potential; wherein the first induction coil is configured to receive or transmit a near-field magnetic signal; and wherein the first and second conductive plates and the conductive housing are configured to receive or transmit a near-field electrical signal.

Description

Technical Field

[0001] This specification relates to systems, methods, apparatus, devices, articles of manufacture, and instructions for near-field devices. Background Art

[0002] Discussed herein is near-field interaction between a subject of one or more near-field devices or conductive surfaces on a user's body (i.e., on-body devices) and other conductive surfaces and / or other wireless devices (i.e., off-body devices), based on any of the following: near-field electromagnetic induction (NFEMI), in which a transmitter and receiver are coupled via magnetic (H) and electric (E) fields; near-field electric induction (NFEI), in which a transmitter and receiver are coupled via electric (E) fields; and near-field magnetic induction (NFMI / NFC), in which a transmitter and receiver are coupled via magnetic (H) fields. While RF wireless communication is achieved by propagating RF plane waves through free space, NFEMI, NFEI, NFMI, and NFC use non-propagating, quasi-static E-field and / or H-field signals for communication. Summary of the Invention

[0003] According to an example embodiment, a near-field device includes: a conductive housing physically coupled to a near-field antenna; a near-field antenna having a first feed point and a second feed point, and including: a first induction coil having a first end coupled to the first feed point and a second end coupled to the second feed point; a first conductive plate capacitively coupled to the conductive housing and galvanically coupled to the first end of the first induction coil; a second conductive plate capacitively coupled to the conductive housing and galvanically coupled to the second end of the first induction coil; wherein the first conductive plate is capacitively coupled to the second conductive plate; and a tuning circuit. The resonant circuit is coupled to the first feed point and the second feed point, and includes: a first capacitor group, a second capacitor group, a first resistor group, and a second resistor group; wherein one end of each of the capacitor groups and one end of each of the resistor groups are coupled to the first feed point or the second feed point; a reference potential; wherein the other end of each of the capacitor groups and the other end of each of the resistor groups are coupled to the reference potential; and wherein the conductive housing 302 is coupled to the reference potential in a current manner; wherein the first induction coil is configured to receive or transmit a near-field magnetic signal; and wherein the first conductive plate, the second conductive plate, and the conductive housing are configured to receive or transmit a near-field electrical signal.

[0004] In another exemplary embodiment, the first conductive plate is spaced apart from the conductive housing by a distance D1, generating capacitance Ca1; the second conductive plate is spaced apart from the conductive housing by a distance D2, generating capacitance Ca2; and the first conductive plate is spaced apart from the second conductive plate by a distance D3, generating capacitance Ca3.

[0005] In another example embodiment, D2 is greater than D1; and D2 is greater than D3.

[0006] In another example embodiment, C in Farads a1 =(A1∈ o ∈ r1 ) / D1, where: A1 = effective surface area of ​​the first conductive plate; D1 = distance between the first conductive plate and the conductive housing; ∈ o = the permittivity of free space; and ∈ r1 =relative permittivity of a material between the first conductive plate and the conductive housing; and the material comprises ferrite.

[0007] In another example embodiment, C a2 =(A2∈ o ∈ r2 ) / D2, where: A2 = the effective surface area of ​​the second conductive plate facing the conductive housing; D2 = the distance between the second conductive plate and the conductive housing; ∈ o = the permittivity of free space; and ∈ r2 =relative permittivity of the material between the second conductive plate and the conductive housing; and the material includes ferrite and non-ferrite substrates.

[0008] In another example embodiment, C a3 =(A3∈ o ∈ r3 ) / D3, where: A3 = the effective surface area between the first conductive plate and the second conductive plate; D3 = the distance between the first conductive plate and the second conductive plate; ∈ o = the permittivity of free space; and ∈ r3 =relative permittivity of the material between the first conductive plate and the second conductive plate; and the material is a non-ferrite substrate.

[0009] In another example embodiment, the first capacitor group has a capacitor C1; the second capacitor group has a capacitor C2; V is the voltage across the first feed point and the second feed point; V=Ve Q Ce / (Ce+CT), where: Ve=the equivalent voltage of the voltage induced in capacitors Ca1, Ca2, and Ca3 in volts; Q=the quality factor of the antenna system; Ce=the equivalent capacitance across the first feed point and the second feed point formed by capacitors Ca1, Ca2, and Ca3; and CT=the series sum of capacitors C1 and C2.

[0010] In another example embodiment, the first conductive plate is configured closer to the conductive housing relative to a user; and the second conductive plate is configured closer to the user relative to the conductive housing.

[0011] In another example embodiment, the user is at least one of: a human body, an animal body, a body of a living organism, a body structure of an inanimate object, a robot, a vehicle, a docking system, a physically coupled system, and / or a station on an assembly line.

[0012] In another exemplary embodiment, the reference potential is a ground potential.

[0013] In another example embodiment, a controller is further included; the first capacitor group and the second capacitor group are variably tunable by the controller; and the first resistor group and the second resistor group are variably tunable by the controller.

[0014] In another example embodiment, a second induction coil is additionally included, the second induction coil having a first end electrically coupled to either end of the first induction coil and having a second end electrically coupled to one of the conductive plates.

[0015] In another example embodiment, the near-field antenna and the tuning circuit are surrounded by an enclosure; and the enclosure at least partially covers the conductive housing.

[0016] In another example embodiment, the first induction coil and the feed point are configured to carry a current; and the current is based on the near-field magnetic signal.

[0017] In another example embodiment, the first conductive plate and the second conductive plate are configured to carry a voltage; and the voltage is based on the near-field electrical signal.

[0018] In another example embodiment, the first induction coil has a planar geometry.

[0019] In another example embodiment, the planar geometric shape of the second induction coil is formed into a shape including: a circle, a rectangle, a polygon, an ellipse, or a rhombus.

[0020] In another example embodiment, the first conductive plate and the second conductive plate are configured to have voltages that are 180 degrees out of phase with respect to the reference potential.

[0021] In another example embodiment, the device is embedded in at least one of: a glucose sensor, a wearable device, a smart watch, a smart watch case, a wireless mobile device, an earbud, a hearing aid, a headset, an activity tracker, or a heart rate monitor.

[0022] The above discussion is not intended to represent every example embodiment or every implementation within the scope of the current or future claim sets.The following figures and detailed description also exemplify various example embodiments.

[0023] Various example embodiments can be more fully understood from the following detailed description considered in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is an example of a near-field wireless device.

[0025] Figure 2 is an example dual-coil NFEMI antenna.

[0026] Figure 3 is an example circuit diagram of a near-field wireless device.

[0027] Figure 4 is an example side view of a near-field device positioned near a user.

[0028] Although the present disclosure is susceptible to various modifications and alternative forms, details thereof have been shown by way of example in the drawings and will be described in detail. However, it should be understood that other embodiments besides the specific embodiments described are also possible. All modifications, equivalents, and alternative embodiments that fall within the spirit and scope of the appended claims are also encompassed. DETAILED DESCRIPTION

[0029] In various exemplary embodiments, the first near-field antenna comprises a near-field electric induction antenna (e.g., an NFEI or NFEMI antenna) and is configured for on-body communication. The second near-field antenna comprises a near-field magnetic induction antenna (e.g., an NFC antenna) and is configured for off-body communication.

[0030] For example, an on-body sensor in a first near-field wireless device may be configured to transmit sensor readings to a second on-body near-field wireless device, which collects the sensor readings and possibly other user information. A third off-body wireless device may be a smartphone / NFC reader that powers the second on-body near-field wireless device that collects the sensor readings, thereby causing the second on-body near-field wireless device to transmit the collected sensor readings to the smartphone / NFC reader.

[0031] Note that while the example embodiments discussed herein refer to a user's body, on-body, and off-body, in alternative embodiments of the near-field device 100, the body is broadly defined herein to include at least: a human body, an animal body, a body of a living organism, a body structure of an inanimate object, a robot, a vehicle, a docking system, a physically coupled system, a station on an assembly line, etc.

[0032] H-field antennas (i.e., magnetic antennas) are primarily sensitive to magnetic fields and / or primarily activate magnetic fields when driven by current. Any E-field component from the H-field antenna is greatly reduced (e.g., by -20 dB to -60 dB, a factor of 0.1 to 0.0008 (10% to 0.08%), depending on the antenna design).

[0033] A small loop antenna is an example of an H-field antenna and includes a loop antenna with dimensions much smaller than the wavelength it is used for. The small loop antenna does not resonate at the NFEMI carrier frequency, but is instead tuned to resonate via external reactance. In some exemplary embodiments, the current in the small loop antenna has the same value at all locations in the loop.

[0034] An E-field antenna (i.e., an electric antenna) is primarily sensitive to electric fields and / or primarily activates electric fields when driven by a voltage. Any H-field component from the E-field antenna is greatly reduced (e.g., by -20 dB to -60 dB, a factor of 0.1 to 0.0008 (10% to 0.08%), depending on the antenna design).

[0035] The short loaded dipole antenna is an example E-field antenna and includes a short dipole having dimensions much smaller than the NFEMI carrier frequency and, in some example embodiments, having additional capacitive surfaces at both ends.

[0036] The quasi-static nature of these fields is a result of the combination of the NFEMI antenna size and its carrier frequency. Most of the near-field energy is stored in the form of magnetic and electric fields, while a small amount of RF energy inevitably propagates in free space. Small antenna geometry minimizes radiated waves in free space.

[0037] In some applications, various portions of a near-field device may be enclosed in or electrically blocked by a conductive housing, which may reduce normal near-field communications because the conductive housing may form a Faraday cage.

[0038] Discussed now are example embodiments of near-field devices that have portions that are enclosed by such a conductive housing or would otherwise be electrically blocked by such a conductive housing, but that can still effectively communicate using near-field communications using the teachings below. In some example embodiments, the housing may have windows to allow for better far-field (e.g., WiFi, Bluetooth, etc.) communications and / or magnetic near-field communications.

[0039] Figure 1 is an example of a near-field wireless device 100. The example near-field wireless device 100 includes a near-field antenna 102, a tuning circuit 104, a controller 108, and a transceiver circuit 112.

[0040] The controller 108 is configured to monitor and maintain the operating resonant frequency of the device 100 and the operating bandwidth / quality factor of the near-field signal (e.g., NFEI or NFEMI) carried by the near-field antenna. The controller 108 is configured to adjust the tuning parameters if the operating resonant frequency is different from a preselected resonant frequency and / or the operating bandwidth is different from a preselected bandwidth.

[0041] The tuning circuit 104 is configured to adjust the resonant frequency of the device 100 using a capacitor bank (C bank) and to adjust the bandwidth using a resistor bank (R bank) in response to signals from the controller 108. In some examples, the C bank and R bank discrete components are approximately 130 pF and 5000 ohms, respectively, to support a desired resonant frequency (e.g., 10.6 MHz) and bandwidth (e.g., 400 kHz). The controller 108 is configured to use the tuning circuit 104 to adjust (e.g., increase / decrease) the C bank and R bank values.

[0042] In some example embodiments, transceiver circuitry 112 is configured to inject test signals (e.g., three test signals) into tuning circuitry 104 and antenna 102. Controller 108 is then configured to first monitor the loading of near-field antenna 102 and adjust tuning parameters if the loading differs from a preselected loading.

[0043] Figure 2 2 is an example dual coil NFEMI antenna 200 included within the near-field antenna 102 of the near-field wireless device 100. The antenna 200 includes a short loaded dipole portion 220 having two conductive loading plates 225, 230 and a small loop antenna 205.

[0044] The small loop antenna includes at least two coupled coils 215 and 217. The first coil 215 has an inductance L1, and the second coil 217 has an inductance L2. Coils 215 and 217 can be connected at a connection point 250 to form an inductance greater than the inductance of the first coil 215 and the second coil 217.

[0045] Coils 215 and 217 can each be an air-core coil wound around a ferrite core 210, or they can be in the form of a planar structure. In the ferrite core 210 version, coils 215 and 217 can be wound around the core 210 in an interleaved manner, or wound around each other, i.e., the second coil 217 is wound around the core 210 first, and then the first coil 215 is wound around the core 210 immediately above the second coil 217.

[0046] Connection point 245 couples one end of first coil 215 to first feed point 235 and to the first plate of small loaded dipole 225. Connection point 250 couples the other end of first coil 215 to one end of second coil 217 and to second feed point 240. Connection point 255 couples the other end of second coil 217 to second plate 230 of small loaded dipole 220.

[0047] Figure 3 is an example circuit diagram 300 of the near-field wireless device 100. The example circuit 300 shows the idealized electrical equivalent of the dual-coil near-field antenna 200, the tuning circuit 104, the controller 108, and the transceiver circuit 112.

[0048] The near-field antenna 102 includes a coil (H-field) antenna 205 having a resistor (R3) and including an inductor (L1) 215 and an inductor (L2) 217. In some exemplary embodiments, the near-field antenna 102 includes only one inductor (L1) 215. Inductors 215, 217 can be spiral or planar and surround or attach to a ferrite material or to another carrier material. When the same inductor is attached to the ferrite material, the same inductor requires fewer loop conductors.

[0049] Shown is a short loaded dipole (E-field) antenna 220 having a resistor (R4) and comprising a first conductive plate 225 and a second conductive plate 230. The short loaded dipole (E-field) antenna 220 is further coupled to a conductive housing 302 creating an extended electric (E-field) antenna 304. Feed points 235, 240 are also shown.

[0050] A first capacitor (Ca1) is formed between the first conductive plate 225 and the conductive housing 302, which are separated by a distance D1. A second capacitor (Ca2) is formed between the second conductive plate 230 and the conductive housing 302, which are separated by a distance D2. In some exemplary embodiments, D1 is smaller than D2. A third capacitor (Ca3) is formed between the first conductive plate 225 and the second conductive plate 230, which are separated by a distance D3.

[0051] C in Farads a1 =(A1∈ o ∈ r1 ) / D1, where: A1 = the effective surface area of ​​the plate 225 facing the housing 302 in square meters; D1 = the distance between the plate 225 and the conductive housing 302 in meters; ∈ o = the permittivity of free space in Farads per meter; and ∈ r1 = relative permittivity of the material between the plate 225 and the housing 302.

[0052] C in Farads a2 =(A2∈ o ∈ r2 ) / D2, where: A2 = the effective surface area of ​​the plate 230 facing the housing 302 in square meters; D2 = the distance between the plate 230 and the conductive housing 302 in meters; o = the permittivity of free space in Farads per meter; and ∈ r2 = relative permittivity of the material between the plate 230 and the housing 302.

[0053] C in Faradays a3 =(A3∈ o ∈ r3 ) / D3, where A3 = the effective surface area between plate 225 and plate 230 in square meters; D3 = the distance between plate 225 and plate 230 in meters; ∈ o = the permittivity of free space in Farads per meter; and ∈ r3 = relative permittivity of the material between plates 225 and 230.

[0054] Conductive housing 302 is configured to be positioned a distance D4 from user 306. "User" is broadly defined herein to include humans, biological materials, robots, vehicles, docking systems, physically coupled systems, stations on an assembly line, and other conductive structures.

[0055] The tuning circuit 104 is coupled to the first feed point 235 and the second feed point 240. The tuning circuit 104 includes a first variable tuning capacitor bank (C1), a second variable tuning capacitor bank (C2), a first variable tuning resistor bank (R1), and a second variable tuning resistor bank (R2). The capacitor bank and the resistor bank are coupled to a reference potential 308 (e.g., ground potential). The conductive housing 302 is also coupled to the reference potential 308. The capacitor bank is coupled to the controller 108 via a control line 310, and the resistor bank is coupled to the controller 108 via a control line 312.

[0056] The controller 108 adjusts the first capacitor group (C1) and the second capacitor group (C2) to adjust the resonant frequency (e.g., to 10.6 MHz) of the magnetic antenna 205, the electric antenna 220, and the extended electric antenna 304. The controller 108 adjusts the first resistor group (R1) and the second resistor group (R2) to adjust the bandwidth (e.g., to 400 kHz) of the magnetic antenna 205, the electric antenna 220, and the extended electric antenna 304, such that the bandwidth is sufficient to allow non-propagating quasi-static near-field signals to be received from the antennas 205, 220, and 304.

[0057] In some example embodiments, the capacitor banks (C1), (C2) are tuned equally by the controller 108 using control line 310, and the resistor banks (R1), (R2) are tuned equally by the controller 108 using control line 312, but in other example embodiments, they may be variably tuned.

[0058] When transceiver circuit 112 is in receive mode, received near-field magnetic signals induce voltages in inductor L1 215, and received near-field electrical signals induce voltages in capacitors Ca1, Ca2, and Ca3, which are then converted by L2 217 and tuning circuit 104 to voltages at the input of a low noise amplifier (LNA) in transceiver circuit 112. The LNA is further connected to other baseband receiver circuitry.

[0059] The voltage (V) at the LNA input in the transceiver circuit 112 due solely to the enhanced near-field electric antenna is: V = Ve Q Ce / (Ce + CT), where: Ve = the equivalent voltage in volts of the voltage induced in capacitors Ca1, Ca2, and Ca3; Q = the quality factor of the antenna system 104, 200, 304; Ce = the equivalent capacitance in farads present at the tuning circuit 104, points 235 and 240, and formed by capacitors Ca1, Ca2, and Ca3; and CT = the series sum of capacitors C1 and C2 in farads.

[0060] When the transceiver circuit 112 is in transmit mode, the voltage at the output amplifier in the transceiver circuit 112 sends the voltage to the inductor L1 215, thereby generating a transmitted near-field magnetic signal, and sends the voltage boosted by L2 217 to the capacitors Ca1, Ca2, and Ca3, thereby generating a transmitted near-field electrical signal.

[0061] Figure 4 is an example side view 400 of near field device 100 positioned near user 306. Example 400 shows conductive housing 302, ferrite layer 402, conductive plate 225, substrate 404, conductive plate 230, enclosure 406, distances D1, D2, D3, and D4, and user 306.

[0062] In some exemplary embodiments, the substrate is a dielectric having a thickness of 4 mm and a permittivity of 4.4. The thickness of the conductive material of inductors (L1) 215 and (L2) 217 ​​may be 0.035 mm. Inductors (L1) 215 and (L2) 217 ​​and conductive plate 225 are attached to ferrite layer 402.

[0063] The ferrite layer 402 may have a thickness of 0.1 mm and a magnetic permeability of 150. The ferrite layer 402 is attached to the conductive housing 302. The conductive plate 230 is attached to the substrate 404.

[0064] An encapsulant 406 is positioned around the ferrite layer 402, the conductive plate 225, the substrate 404, the conductive plate 230, and the inductors (L1) 215 and (L2) 217. In some example embodiments, the encapsulant 406 is an ABS material.

[0065] In various exemplary embodiments, the near-field device 100 can be embedded in a medical device positioned on the human body. For example, it can be part of an insulin pump that regularly calibrates the body's glucose level and can also communicate with another glucose-measuring near-field device through the body. The near-field device 100 can also be embedded in various wearable devices (e.g., earbuds, smart watches, clothing sensors, etc.) that require a small form factor for wireless on-body networks.

[0066] Unless a particular order is explicitly stated, the various instructions and / or operational steps discussed in the figures above may be performed in any order. Likewise, those skilled in the art will recognize that while some example instruction sets / steps have been discussed, the material in this specification may be combined in various ways to produce other examples and should be understood within the context provided by this detailed description.

[0067] In some example embodiments, these instructions / steps are implemented as functional and software instructions. In other embodiments, the instructions can be implemented using logic gates, dedicated chips, firmware, and other hardware forms.

[0068] When the instructions are embodied as a set of executable instructions in a non-transitory computer-readable or computer-usable medium, these instructions are implemented on a computer or machine programmed with and controlled by the executable instructions. The instructions are loaded for execution on a processor (e.g., one or more CPUs). The processor includes a microprocessor, a microcontroller, a processor module or subsystem (including one or more microprocessors or microcontrollers), or other control or computing device. The processor may refer to a single component or multiple components. The computer-readable or computer-usable storage medium is considered to be part of an article (or product). An article or product may refer to a single component or multiple components of any manufacture. As defined herein, non-transitory machine or computer-usable media does not include signals, but such media is capable of receiving and processing information from signals and / or other transient media.

[0069] It will be readily understood that the components of the embodiments generally described herein and illustrated in the accompanying drawings may be arranged and designed in a variety of different configurations. Therefore, the detailed description of the various embodiments as represented in the accompanying drawings is not intended to limit the scope of the present disclosure, but is merely illustrative of various embodiments. Although various aspects of the embodiments are presented in the drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

[0070] The present invention may be embodied in other specific forms without departing from the spirit or essential characteristics of the present invention. The described embodiments are to be considered in all respects as illustrative only and not restrictive. The scope of the present invention is therefore indicated by the appended claims rather than by this detailed description. All variations coming within the meaning and range of equivalency of the claims are intended to be encompassed within the scope of the claims.

[0071] References throughout this specification to features, advantages, or similar language do not imply that all features and advantages that may be achieved with the present invention are included in or are present in any single embodiment of the present invention. Rather, language referring to features and advantages should be understood to mean that a specific feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present invention. Thus, discussions of features and advantages, and similar language, throughout this specification may, but do not necessarily, refer to the same embodiment.

[0072] Furthermore, the described features, advantages, and characteristics of the present invention may be combined in any suitable manner in one or more embodiments. Those skilled in the art will recognize, in view of the description herein, that the present invention may be practiced without one or more of the specific features or advantages of a particular embodiment. In other cases, additional features and advantages may be identified in certain embodiments that may not be present in all embodiments of the present invention.

[0073] Reference throughout this specification to "one embodiment," "an embodiment," or similar language means that a particular feature, structure, or characteristic described in connection with the indicated embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment," "in an embodiment," and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.

Claims

1. A near-field device, characterized in that include: a conductive housing physically coupled to the near-field antenna; A near-field antenna having a first feed point and a second feed point, and comprising: a first induction coil having a first end coupled to the first feed point and a second end coupled to the second feed point; a first conductive plate capacitively coupled to the conductive housing and galvanically coupled to the first end of the first induction coil; a second conductive plate capacitively coupled to the conductive housing and galvanically coupled to the second end of the first induction coil; wherein the first conductive plate is capacitively coupled to the second conductive plate; a tuning circuit coupled to the first feed point and the second feed point and comprising: a first capacitor group, a second capacitor group, a first resistor group, and a second resistor group; wherein one end of each of the capacitor groups and one end of each of the resistor groups are coupled to the first feed point or the second feed point; Reference potential; wherein the other end of each of the capacitor groups and the other end of each of the resistor groups are coupled to the reference potential; and wherein the conductive housing is galvanically coupled to the reference potential; wherein the first induction coil is configured to receive or transmit a near-field magnetic signal; and wherein the first conductive plate, the second conductive plate and the conductive housing are configured to receive or transmit near-field electrical signals; The first conductive plate is spaced apart from the conductive housing by a distance D1, generating a capacitance C a1 The second conductive plate is separated from the conductive housing by a distance D2, generating a capacitance C a2 ; and the first conductive plate and the second conductive plate are separated by a distance D3, generating a capacitance C a3 ; The transceiver circuit, when the transceiver circuit is in receiving mode, the received near-field magnetic signal induces a voltage in the first induction coil, and the received near-field electric signal is induced in the capacitor C a1 、C a2 and C a3 A voltage is induced in the first induction coil, which is then converted by the second induction coil and the tuning circuit into a voltage at the input of a low noise amplifier in the transceiver circuit, which is further connected to other baseband receiver circuit systems; when the transceiver circuit is in transmit mode, the voltage at the output amplifier in the transceiver circuit sends the voltage to the first induction coil, thereby generating a transmitted near-field magnetic signal, and sends the voltage raised by the second induction coil to the capacitor C a1 、C a2 and C a3 , thereby generating a transmitted near-field electrical signal.

2. The device according to claim 1: It is characterized by: D2 is greater than D1; and Among them, D2 is greater than D3.

3. The device according to claim 1: It is characterized by: C in Farads a1 =(A1∈ o ∈ r1 ) / D1, where: A1 = effective surface area of ​​the first conductive plate; D1 = distance between the first conductive plate and the conductive housing; ∈ o = the permittivity of free space; and ∈ r1 = relative permittivity of the material between the first conductive plate and the conductive housing; and The material includes ferrite.

4. The device according to claim 1: It is characterized by: C a2 =(A2∈ o ∈ r2 ) / D2, where: A2 = the effective surface area of ​​the second conductive plate facing the conductive housing; D2 = the distance between the second conductive plate and the conductive housing; ∈ o = the permittivity of free space; and ∈ r2 = relative permittivity of the material between the second conductive plate and the conductive housing; and The materials include ferrite and non-ferrite substrates.

5. The device according to claim 1: It is characterized by: C a3 =(A3∈ o ∈ r3 ) / D3, where: A3 = the effective surface area between the first conductive plate and the second conductive plate; D3 = the distance between the first conductive plate and the second conductive plate; ∈ o = the permittivity of free space; and ∈ r3 = relative permittivity of the material between the first conductive plate and the second conductive plate; and The material is a non-ferrite substrate.

6. The device according to claim 1: It is characterized by: The first capacitor group has a capacitor C1; wherein the second capacitor group comprises a capacitor C2; wherein V is the voltage across the first feeding point and the second feeding point; and Where V = Ve Q Ce / (Ce + CT), where: Ve = capacitance C a1 、C a2 and C a3 =Equivalent voltage in volts of the voltage induced in the antenna; Q = quality factor of the antenna system; Ce = capacitance C a1 、C a2 and C a3 The equivalent capacitance across the first feeding point and the second feeding point is formed; and CT=the series sum of the capacitors C1 and C2.

7. The device according to claim 1: It is characterized by: The first conductive plate is configured to be closer to the conductive housing relative to a user; and The second conductive plate is configured to be closer to the user than the conductive housing.

8. The device according to claim 1: It is characterized by: The reference potential is the ground potential.

9. The device according to claim 1, characterized in that: Also includes controller; wherein the first capacitor bank and the second capacitor bank are variably tunable by the controller; and The first resistor group and the second resistor group are variably tunable by the controller.

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