Near field communication device

Abstract

An example discloses a near-field device comprising: a conductive housing physically coupled to the near-field device; 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, a second end coupled to the second feed point, and a connection point, and a conductive plate capacitively coupled to the conductive housing and to the first end of the first induction coil; a tuning circuit; a reference potential; wherein the other end of each of the capacitor group and the other end of each of the resistor group are coupled to the reference potential; wherein the connection point is galvanically coupled to the reference potential; and wherein the conductive housing is galvanically coupled to the reference potential.

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 the near-field device; 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, a second end coupled to the second feed point, and a connection point, and a conductive plate capacitively coupled to the conductive housing and to the first end of the first induction coil; a tuning circuit coupled to the first feed point and the second feed point and including 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; wherein the connection point is galvanically 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 conductive plate and the conductive housing are configured to receive or transmit a near-field electrical signal.

[0004] In another example embodiment, the voltage at the connection point is zero volts.

[0005] In another example embodiment, the voltage at the connection point is the same as the voltage at the reference potential.

[0006] In another example embodiment, the reference potential is ground potential.

[0007] In another example embodiment, the near-field device comprises only one conductive plate.

[0008] In another example embodiment, the first induction coil is wrapped around the conductive housing.

[0009] In another example embodiment, the first induction coil is completely wrapped around the exterior of the conductive housing.

[0010] In another example embodiment, a ferrite sheet is additionally included between the first induction coil and the conductive housing.

[0011] In another example embodiment, a transceiver is further included, the transceiver being coupled to the tuning circuit, the first feed point, and the second feed point; and wherein the transceiver includes only one low noise amplifier (LNA) and / or power amplifier connected to the first feed point and the second feed point.

[0012] In another example embodiment, the conductive plate is spaced apart from the conductive housing by a distance D1, thereby generating a capacitance Cal; the conductive housing is configured to be spaced apart from the user by a distance D2; and wherein D2 is smaller than D1.

[0013] In another example embodiment, C in Farads a1 =(A1∈ o ∈ r1 ) / D1, where: A1 = the effective surface area of the conductive plate; D1 = the distance between the conductive plate and the conductive housing; and And wherein the material is a non-ferrite substrate.

[0014] In another example embodiment, the first capacitor group has a capacitance C1; the second capacitor group has a capacitance C2; V is the voltage at the first feed point and the second feed point; and V=Ve Q Ce / (Ce+CT), where: Ve=the equivalent voltage induced in the capacitor Ce in volts; Q=the quality factor of the antenna system; Ce=the equivalent capacitance at the first feed point and the second feed point formed by the capacitor Ca1; and CT=the series sum of the capacitors C1 and C2.

[0015] 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.

[0016] In another example embodiment, a controller is further included; wherein the first capacitor bank and the second capacitor bank are variably tunable by the controller; and wherein the first resistor bank and the second resistor bank are variably tunable by the controller.

[0017] 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 the conductive plate.

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

[0019] In another exemplary 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 conductive plates 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 present every example embodiment or every implementation within the scope of current or future claim sets.The figures and detailed description also illustrate various example embodiments.

[0023] Various example embodiments may 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 4A is an example side view of a near-field device positioned near a user.

[0028] Figure 4B is an example front view of a near-field device.

[0029] While 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 are possible besides the specific embodiments described. All modifications, equivalents, and alternative embodiments falling within the spirit and scope of the appended claims are also encompassed. DETAILED DESCRIPTION

[0030] 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.

[0031] 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.

[0032] 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.

[0033] H-field antennas (i.e., magnetic antennas) are primarily sensitive to magnetic fields and / or primarily induce 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).

[0034] 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.

[0035] An E-field antenna (i.e., an electric antenna) is primarily sensitive to electric fields and / or induces primarily 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).

[0036] 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.

[0037] The quasi-static nature of these fields is a result of the combination of the NFEMI antenna's 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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 discrete components of the C bank and the R bank 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.

[0043] 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.

[0044] 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 a conductive loading plate 230 and a small loop antenna 205.

[0045] 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.

[0046] Coils 215, 217 can each be an air-core coil wound around ferrite core 210, or they can be in the form of a planar structure. In the case of a ferrite core 210, coils 215 and 217 can be wound around core 210 in a staggered manner, or wound around each other, i.e., second coil 217 is wound around core 210 first, and then first coil 215 is wound around core 210 immediately following second coil 217. Additional embodiments of these coils 215, 217 are discussed below.

[0047] Connection point 245 couples one end of first coil 215 to first feed point 235. 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 conductive loading plate 230 of small loaded dipole 220.

[0048] 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.

[0049] The near-field antenna 102 includes a coil (H-field) antenna 205 having a resistance (R3) and including an inductor (L1) 215 and an inductor (L2) 217. In some example embodiments, the near-field antenna 102 includes only one inductor (L1) 215.

[0050] Inductors 215, 217 can be spiral or planar and surround or attach to a ferrite material or another carrier material. When the same inductor is attached to a ferrite material, fewer loops of conductor are required. When in transmit mode, inductor (L2) 217 provides an increase in transmit voltage compared to the output voltage of the power amplifier in transceiver circuit 112.

[0051] In some example embodiments, there is only one inductor (L1) 215. Also, in some example embodiments, the coils 215, 217 are wrapped around the outside of the conductive housing 302 with the ferrite sheet between the coils 215, 217 and the conductive housing 302. This wrapped embodiment produces a very unique magnetic (H) field flux.

[0052] Placing the magnetic (H-field) antenna 205 outside of the conductive housing 302 has the advantage of eliminating various obstructions to the near-field magnetic field lines by, for example, conductive parts in the near-field device 102 (e.g., printed circuit boards, electromechanical components, and other conductive structures that may generate eddy currents that generate a magnetic field flux opposing the H-field signal flux in response to the magnetic (H-field) antenna 205).

[0053] Shown is a short loaded dipole (E-field) antenna 220 having a resistor (R4) (not shown) and including a conductive loading plate 230. In some exemplary embodiments, the electric antenna includes only one conductive plate. The short loaded dipole (E-field) antenna 220 is further coupled to a conductive housing 302, which creates an extended electric (E-field) antenna 304. Feed points 235, 240 are also shown.

[0054] A capacitor ( Ca1 ) is formed between the conductive loading plate 230 and the conductive housing 302 , which are separated by a distance D1 .

[0055] C in Farads a1 =(A1∈ o ∈ r1 ) / D1, where: A1 = the effective surface area of the plate 230 facing the housing 302 in square meters; D1 = the distance between the plate 230 and the conductive housing 302 in meters; and

[0056] Conductive housing 302 is configured to be positioned a distance D2 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.

[0057] In some example embodiments, conductive plate 230 is closer to user 306 at distance (D2) than distance (D1) between conductive plate 230 and conductive housing 302. Both conductive housing 302 and conductive plate 230 are capacitively coupled to user 306.

[0058] 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 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.

[0059] The capacitor bank and the resistor bank are coupled to a reference potential 308 (eg, ground potential). The conductive housing 302 and the connection point 216 of the inductor ( L1 ) 215 are galvanically coupled to the reference potential 308 .

[0060] In some example embodiments, connection point 216 is at the center point of inductor (L1) 215. By placing connection point 216 at the center point, inductor (L1) 215 enables near-field signals received from and / or transmitted to feed points 235, 240 to be balanced if the voltage at reference potential 308 is zero volts, even if there is only one conductive plate 230 in electric (E-field) antenna 220.

[0061] When there is only one conductive plate 230 , and / or in other example embodiments having more than one conductive plate, connection point 216 enables a simpler transceiver 112 requiring only one LNA and / or power amplifier connected to feed points 235 and 240 .

[0062] Without connection point 216 , transceiver 112 would require two LNAs and / or power amplifiers, one connected to access the voltage between feed point 235 and reference potential 308 , and the other connected to access the voltage between reference potential 308 and feed point 240 .

[0063] 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.

[0064] 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.

[0065] When transceiver circuit 112 is in receive mode, received near-field magnetic signals induce a voltage in inductor L1 215, and received near-field electrical signals induce a voltage in capacitor Ca1, which is then converted by L2 217 and tuning circuit 104 to a voltage at the input of a low-noise amplifier (LNA) in transceiver circuit 112. The LNA is in turn connected to other baseband receiver circuitry.

[0066] 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 induced in capacitor Ce in volts; 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 capacitor Ca1; and CT = the series sum of capacitors C1 and C2 in farads.

[0067] 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 capacitor Ca1, thereby generating a transmitted near-field electrical signal.

[0068] Figure 4A 4 is an example side view of near-field device 100 positioned near user 306. Example 400 shows conductive housing 302, ferrite layer 402, substrate 404, conductive plate 230 at distances D1 and D2, and user 306. In some example embodiments, all necessary electronics of the device (e.g., tuning circuit 104, controller 108, transceiver circuit 112) are integrated within conductive housing 302.

[0069] In some exemplary embodiments, substrate 404 is a dielectric having a thickness of 4 mm and a permittivity of 4.4. The thickness of the conductive material (e.g., wire) of inductors (L1) 215 and (L2) 217 may be 0.15 mm. Inductors (L1) 215 and (L2) 217 are attached to ferrite layer 402.

[0070] 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 (e.g., metal) housing 302. The conductive plate 230 is attached to the substrate 404. In some example embodiments, the purpose of the substrate 404 is to increase the distance D1+D2 between the conductive housing 302 and the user 306 in order to improve the near-field electric (E-field) antenna 220 signal strength.

[0071] The coils 215 , 217 may be helically wound around the conductive housing 302 and the ferrite material 402 , or wound in a zigzag pattern around the ferrite material 402 on one or more sides of the conductive housing 302 .

[0072] Figure 4B is an example front view 408 of the near field device 100. Here, the substrate 404 and the conductive plate 230 are located on opposite sides of the conductive housing 302, so the conductive plate 230 is shown as a dashed line.

[0073] In an exemplary embodiment, where one or both of the coils 215 , 217 are helically wound around the conductive housing 302 and the ferrite material 402 , as shown, the H-field flux lines 410 of the near-field magnetic (H) antenna 205 are equal on both sides of the conductive housing 302 .

[0074] 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-level-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.

[0075] Unless a specific order is explicitly stated, the various instructions and / or operational steps discussed in the above figures may be performed in any order. Additionally, 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 also produce other examples and should be understood within the context provided by this detailed description.

[0076] 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.

[0077] When instructions are implemented as an executable instruction set 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 devices. A 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 any manufactured single component or multiple components. A non-transitory machine or computer-usable medium as defined herein does not include signals, but such media is capable of receiving and processing information from signals and / or other transient media.

[0078] 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 illustrated in the figures, 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 accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise indicated.

[0079] The present invention may be implemented 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 merely illustrative and non-restrictive. Therefore, the scope of the present invention is indicated by the appended claims rather than by this detailed description. All variations within the meaning and scope of equivalents of the claims are intended to be encompassed within the scope of the claims.

[0080] References throughout this specification to features, advantages, or similar language do not imply that all features and advantages that may be realized with the present invention are included in or may be used 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, discussion of features, advantages, and similar language throughout this specification may, but do not necessarily, refer to the same embodiment.

[0081] In addition, 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 relevant art will recognize that, in view of the description herein, 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 recognized in certain embodiments that may not be present in all embodiments of the present invention.

[0082] 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 device; 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, a second end coupled to the second feed point, and a connection point at a center point of the first induction coil; a conductive plate capacitively coupled to the conductive housing and to the first end of the first induction coil; 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 the first capacitor group and the first resistor group is coupled to the first feed point, and one end of the second capacitor group and the second resistor group is coupled to the second feed point; Reference potential; wherein the other end of each of the first capacitor group and the second capacitor group and the other end of each of the first resistor group and the second resistor group are coupled to the reference potential; wherein the connection point is galvanically coupled to the reference potential; and wherein said conductive housing is galvanically coupled to said reference potential; wherein the first induction coil is configured to receive or transmit a near-field magnetic signal; and The conductive plate and the conductive housing are configured to receive or transmit near-field electrical signals.

2. The device according to claim 1: It is characterized by: The voltage at the connection point is zero volts.

3. The device according to claim 1: It is characterized in that The voltage at the connection point is the same as the voltage at the reference potential.

4. The device according to claim 1: It is characterized in that The reference potential is the ground potential.

5. The device according to claim 1: It is characterized in that The first induction coil is wound around the conductive housing.

6. The device according to claim 1: It is characterized in that Also included is a ferrite sheet between the first induction coil and the conductive housing.

7. The device according to claim 1: It is characterized in that additionally comprising a transceiver coupled to the tuning circuit, the first feed point, and the second feed point; and The transceiver comprises only one low noise amplifier LNA and / or power amplifier connected to the first feeding point and the second feeding point.

8. The device according to claim 1: It is characterized in that The conductive plate is spaced apart from the conductive housing by a distance D1, thereby generating a capacitance Ca1; wherein the conductive plate is configured to be spaced apart from the user by a distance D2; and Where D2 is smaller than D1.

9. The device according to claim 8: It is characterized in that C in Farads a1 =(A1∈ o ∈ r1 ) / D1, where: A1 = the effective surface area of the conductive plate; D1 = the distance between the conductive plate and the conductive housing; = the permittivity of free space; and = relative permittivity of the material between the conductive plate and the conductive housing; and The material is a non-ferrite substrate.

10. The device according to claim 8: It is characterized in that 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 feed point and the second feed point; and Where V = Ve Q Ce / (Ce + CT), where: Ve = the equivalent voltage induced in capacitor Ce in volts; Q = the quality factor of the antenna system; Ce = the equivalent capacitance at the first feed point and the second feed point formed by capacitor Ca1; and CT = the series sum of capacitors C1 and C2.

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