Near Field Communication Device with Variable Path Loss

Abstract

An example discloses a first near-field device, comprising: a near-field antenna; a tuning circuit; a communication unit coupled to the near-field antenna and the tuning circuit; a controller coupled to the tuning circuit and the communication unit; wherein the first near-field device is configured to have a near-field communication channel path loss relative to a second near-field device; wherein the controller is configured to set the path loss to a first channel path loss before detecting contact between the first near-field device and the second near-field device; wherein the controller is configured to set the path loss to a second channel path loss after detecting contact between the first near-field device and the second near-field device; and wherein the first path loss is greater than the second path loss.

Description

Technical Field

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

[0002] Discussed herein is near field interaction between one or more near field devices (i.e., on-body devices) on a user or on a conductive surface body and other conductive surfaces and / or other wireless devices (i.e., off-body devices), the near field interaction being based on any one of: near field electromagnetic induction (NFEMI), where a transmitter and a receiver are coupled by a magnetic (H) field and an electric (E) field; near field electric induction (NFEI), where a transmitter and a receiver are coupled by an electric (E) field; and near field magnetic induction (NFMI / NFC), where a transmitter and a receiver are coupled by a magnetic (H) field. Although 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 first near field device includes: a near field antenna; a tuning circuit; a communication unit coupled to the near field antenna and the tuning circuit; a controller coupled to the tuning circuit and the communication unit; wherein the first near field device is configured to have a near field communication signal path loss relative to a second near field device; wherein the controller is configured to set the path loss to a first signal path loss before detecting contact between the first near field device and the second near field device; wherein the controller is configured to set the path loss to a second signal path loss after detecting contact between the first near field device and the second near field device; and wherein the first path loss is greater than the second path loss.

[0004] In another example embodiment, the first signal path loss enables the first near field device to detect contact between the first near field device and the second near field device.

[0005] In another example embodiment, the first signal path loss blocks data transfer between the first device and the second device; and the second signal path loss enables data transfer between the first device and the second device.

[0006] In another example embodiment, the controller is configured to set the impedance of the near field device to a first impedance and a second impedance; to set the first signal path loss, the controller is configured to set the impedance to the first impedance; and to set the second signal path loss, the controller is configured to set the impedance to the second impedance.

[0007] In another exemplary embodiment, the first impedance is greater than the second impedance.

[0008] In another exemplary embodiment, the controller is configured to set the power level of the near-field device to a first power level and a second power level; to set the first channel field strength, the controller is configured to set the power level to the first power level; and to set the second channel field strength, the controller is configured to set the power level to the second power level.

[0009] In another exemplary embodiment, the first power level is less than the second power level.

[0010] In another exemplary embodiment, the controller is configured to set the center frequency of the near-field antenna to a first center frequency and a second center frequency; to set the first channel path loss, the controller is configured to command the tuning circuit to set the near-field antenna to the first center frequency; and to set the second channel path loss, the controller is configured to command the tuning circuit to set the near-field antenna to the second center frequency.

[0011] In another exemplary embodiment, the second center frequency is greater than the first center frequency.

[0012] In another exemplary embodiment, the center frequency is a resonant center frequency.

[0013] In another exemplary embodiment, the tuning circuit is configured to change the center frequency in response to a command from the controller to change a capacitance tuning parameter in the tuning circuit.

[0014] In another exemplary embodiment, a first frequency band is defined by the first center frequency, and a second frequency band is defined by the second center frequency; and the controller is configured to adapt the first and second center frequencies to resonant frequency and bandwidth variations caused by electromagnetic loads within each of the first and second frequency bands.

[0015] In another exemplary embodiment, the controller is configured to set the bandwidth of the near-field antenna to a first bandwidth and a second bandwidth; to set the first channel path loss, the controller is configured to command the tuning circuit to set the near-field antenna to the first bandwidth; and to set the second channel path loss, the controller is configured to command the tuning circuit to set the near-field antenna to the second bandwidth.

[0016] In another exemplary embodiment, the second bandwidth is narrower than the first bandwidth.

[0017] In another example embodiment, the tuning circuit is configured to change the bandwidth in response to a command from the controller that changes a resistance tuning parameter in the tuning circuit.

[0018] In another example embodiment, a contact detector circuit is further included; wherein the contact detector circuit is configured to output a detected contact signal in response to a parameter change of the tuning circuit; and wherein the parameter is based on a capacitance and / or resistance tuning parameter configured to maintain a center frequency and / or bandwidth of the near field device.

[0019] In another example embodiment, a contact detector circuit is further included; and wherein the contact detector circuit is configured to output a detected contact signal in response to a change in a near field communication signal voltage between the communication unit and the tuning circuit.

[0020] In another example embodiment, a contact detector circuit is further included; wherein the contact detector circuit is configured to output a detected contact signal in response to an actual physical contact between the first near field device and the second near field device.

[0021] In another example embodiment, a contact detector circuit is further included; wherein the contact detector circuit is configured to output a detected contact signal in response to a predefined threshold distance between the first near field device and the second near field device.

[0022] In another example embodiment, the near field antenna includes: an H field antenna configured to receive a non-propagating quasi-static magnetic near field signal; and an E field antenna configured to receive a non-propagating quasi-static electric near field signal from a conductive structure; and a conductive surface of the near field antenna is configured to be coupled to a body upper surface through the non-propagating quasi-static near field electric induction signal.

[0023] The foregoing discussion is not intended to represent every example embodiment or every implementation within the scope of the current or future claim sets. The subsequent drawings and detailed description also illustrate various example embodiments.

[0024] Various example embodiments can be more fully understood by considering the following detailed description in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is an example of a near field wireless device having variable signal path loss.

[0026] Figure 2A is an example near field antenna architecture.

[0027] Figure 2B is an example near field device circuit including a near field antenna, support circuitry, and configured to receive non-propagating quasi-static near field signals.

[0028] Figure 3 is an example of near - field signal path loss.

[0029] Figure 4 is an example state diagram for operating a near - field wireless device.

[0030] While the present disclosure allows for various modifications and alternative forms, the features of the present disclosure have been illustrated by way of example in the figures and will be described in detail. However, it should be understood that other embodiments beyond the specific embodiments described are also possible. All modifications, equivalents, and alternative embodiments falling within the spirit and scope of the appended claims are also covered. Detailed Description

[0031] In various example embodiments, the first near - field antenna includes a near - field electric induction antenna (e.g., NFEI antenna or NFEMI antenna) and is configured for on - body communication. The second near - field antenna includes a near - field magnetic induction antenna (e.g., NFC antenna) and is configured for off - body communication.

[0032] For example, an on - body sensor in the first near - field wireless device can be configured to transmit a reading of the sensor to a second on - body near - field wireless device, which collects the reading of the sensor and may also collect other user information. A third off - body wireless device can be a smart phone / NFC reader that powers the second on - body near - field wireless device collecting the sensor reading and thereby prompts the second on - body near - field wireless device to send the collected sensor reading to the smart phone / NFC reader.

[0033] Note that while the example embodiments discussed herein refer to a user's body, on - body, and off - body, in alternative embodiments of near - field devices, the body is broadly defined herein to include at least: a human body, an animal body, the body of a living organism, the main structure of an inanimate object, a robot, a vehicle, a docking system, a physical coupling system, a station on an assembly line, etc.

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

[0035] A small loop antenna is an example H - field antenna and includes a loop antenna that is much smaller in size than the wavelength it uses. The small loop antenna does not resonate at the NFEMI carrier frequency but is instead tuned to resonance by an external reactance. In some example embodiments, the current in the small loop antenna has the same value at each position of the loop.

[0036] E-field antennas (i.e., electric antennas) are mainly sensitive to the electric field and / or mainly induce an electric field when driven by a voltage. Any H-field component from an E-field antenna is greatly reduced (e.g., reduced by -20 dB to -60 dB, with a factor of 0.1 to 0.0008 (10% to 0.08%), depending on the antenna design).

[0037] A loaded short dipole antenna is an example E-field antenna and includes a short dipole that is much smaller in size than the NFEMI carrier frequency, and in some example embodiments has additional capacitive surfaces at both ends.

[0038] The quasi-static nature of these fields is the 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. The small antenna geometry minimizes the radiation waves in free space.

[0039] When a near-field antenna approaches a conductive body (e.g., a person, an object, etc.), the magnetic near-field signal and the electric near-field signal will be substantially confined to the body and will not radiate significantly in free space. This enhances the security and privacy of such interconnected bodies.

[0040] Various robust near-field communication systems use a frequency band of approximately 10 to 13 MHz and have a communication area around the body that can vary between 30 cm and 1 meter, depending on the antenna and power used for transmission. However, for example embodiments where such communication is preferably blocked until triggered, possibly by detecting physical contact between two or more near-field device users, such robust near-field communication may have started before the defined trigger condition (e.g., physical contact has occurred).

[0041] A near-field device with variable signal path loss is now discussed, which blocks data communication between a first device user and a second device user until a trigger condition, such as physical contact, is met, after which data exchange is performed using near-field communication.

[0042] In some example applications, the near-field device is intended to host communication between two or more users (e.g., users involved in the same application, such as playing the same game together); however, there may be a third user or even a larger group of users nearby and within the normal near-field communication range. Without a way to distinguish users, the near-field device will not know which other near-field device to transmit data to.

[0043] Example embodiments of the variable signal path loss near-field device enable two users to communicate among a potential group of other users.

[0044] Figure 1 is an example of a near - field wireless device 100 with variable signal path loss. The example near - field wireless device 100 includes a near - field antenna 102, a tuning circuit 104 (e.g., an antenna tuning unit (ATU)), a transceiver circuit 112 (e.g., a communication unit), a variable signal path loss controller 108, and a contact detector circuit 114.

[0045] The following discusses Figure 2A example embodiments of the near - field antenna 102.

[0046] The tuning circuit 104 is configured to adjust the resonant frequency of the device 100 using a capacitor bank (C - bank) in response to a signal from the controller 108, and to adjust the bandwidth using a resistor bank (R - bank). In some examples, the discrete values of the C - bank and 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., increment / decrement) the values of the C - bank and R - bank.

[0047] In some example embodiments, the transceiver circuit 112 is configured to inject test signals (e.g., three test signals) into the tuning circuit 104 and the antenna 102. Then, the controller 108 is configured to: first monitor the load of the near - field antenna 102 and adjust the tuning parameters if the load is different from a pre - selected load.

[0048] In various example embodiments, the transceiver circuit 112 includes at least one of the following: a low - noise amplifier (LNA) in a receiver circuit, a transmit power amplifier (PA) in a transmitter circuit, and / or measurement circuitry capable of measuring various signals (e.g., voltages) exchanged at the tuning circuit 104 and the near - field antenna 102.

[0049] The transceiver circuit 112 may also include at least one of the following: a frequency converter (e.g., an up / down converter), a baseband unit, and a communication data processor. The transceiver circuit 112 may be coupled to a user interface (not shown).

[0050] The following discusses Figure 2B example embodiments of the circuitry housing the near - field antenna 102, the tuning circuit 104, and the transceiver circuit 112.

[0051] The variable signal path loss controller 108 configures the device 100 to a first state with a first signal path loss (e.g., at startup and / or in response to an internally or externally generated reset signal). In the first path loss state, the device 100 has a first signal path loss that prevents normal near - field communication between two or more users, but is also configured to respond to a trigger condition, such as physical contact between two users with near - field devices.

[0052] The trigger condition, such as actual physical contact between a pair of users or a predefined threshold distance (e.g., within 5 cm) between a pair of users, is detected by the contact detector circuit 114.

[0053] It can be fully resident in the controller 108, the transceiver circuit 112, or distributed between 108 and 112. The contact detector circuit 114 outputs a detected contact signal.

[0054] In response to a trigger condition, such as physical contact between one or more pairs of users, the controller 108 configures the device 100 to a second state with a second signal path loss. The second signal path loss is lower than the first signal path loss, and thus enables normal near - field communication between two users.

[0055] In some example embodiments, the controller 108 detects the physical contact trigger condition by monitoring the C - set and R - set values required to maintain the center frequency and / or bandwidth stability of the near - field device 100 in the tuning circuit 104 before, during, and after physical contact.

[0056] The controller 108 is configured to change the signal path loss to other near - field devices by adjusting the insertion loss of the device 100, the operating resonant frequency, and the operating bandwidth / quality factor of the near - field signal (e.g., NFEI or NFEMI) carried by the near - field antenna.

[0057] In some example embodiments, the controller 108 is configured to change the signal path loss by commanding the transceiver circuit 112 to insert or remove one or more impedances (e.g., changing the data communication channel insertion loss). In some example embodiments, the controller 108 is configured to set the impedance of the near - field device 100 to a first impedance and a second impedance. For the first signal path loss, the controller 108 is configured to set the impedance to the first impedance. For the second signal path loss, the controller 108 is configured to set the impedance to the second impedance. The first impedance is greater than the second impedance.

[0058] The controller 108 can also be configured to change the channel field strength by commanding the near - field device 100 to operate at two or more power levels (e.g., standby mode and operating mode).

[0059] The controller 108 may also be configured to vary the signal path loss by commanding the tuning circuit 104 to adjust a set of tuning parameters, possibly when operating at a resonant frequency different from a preselected resonant frequency and / or an operating bandwidth different from a preselected bandwidth.

[0060] Thus, in some example embodiments, the controller 108 is configured to set the center frequency of the near - field antenna to a first center frequency and a second center frequency. For a first signal path loss, the controller 108 is configured to command the tuning circuit 104 to set the near - field antenna 102 to the first center frequency. For a second signal path loss, the controller 108 is configured to command the tuning circuit 104 to set the near - field antenna 102 to the second center frequency.

[0061] For Figure 3 the reasons explained in

[0062] the second center frequency is greater than the first center frequency. The center frequency may be a resonant center frequency that changes in response to a command from the controller 108 to change the capacitance tuning parameter in the tuning circuit 104. In some example embodiments, the tuning circuit 104 is set to resonate at two frequency bands with the near - field antenna 102 and is capable of adapting the near - field antenna 102 to small variations in the resonant frequency and bandwidth caused by electromagnetic loading within each frequency band.

[0063] In other example embodiments, the controller 108 is configured to set the bandwidth of the near - field antenna to a first bandwidth and a second bandwidth. For a first signal path loss, the controller 108 is configured to command the tuning circuit 104 to set the near - field antenna 102 to the first bandwidth. For a second signal path loss, the controller 108 is configured to command the tuning circuit 104 to set the near - field antenna 102 to the second bandwidth.

[0063] In some exemplary embodiments, the second bandwidth is narrower than the first bandwidth, where the narrower bandwidth results in a higher quality factor and a stronger near - field communication signal, while the wider bandwidth will result in a lower quality factor and a weaker near - field communication signal. The tuning circuit 104 is configured to change the bandwidth in response to a command from the controller 108 to change the resistance tuning parameter.

[0064] Figure 2A is a first example near - field antenna architecture 200. The antenna 200 includes a loaded short dipole section 220 having two conductive load plates 225, 230 and a small loop antenna 205.

[0065] The small loop antenna includes at least two coupled coils 215 and 217. The first coil 215 has an inductance L1, while the second coil 217 has an inductance L2. The coils 215 and 217 can both be connected at a connection point 250 such that the coils 215 and 217 form an inductance greater than the inductances of the first coil 215 and the second coil 217.

[0066] Both coils 215 and 217 can be air-core coils or wound around a ferrite core 210, as shown, or coils 215 and 217 can be in the form of a planar structure.

[0067] In the form of the ferrite core 210, coils 215 and 217 can be wound around the core 210 in an interleaved manner, or wound one above the 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 on top of the second coil 217.

[0068] Connection point 245 couples one end of the first coil 215 to the first feed connection 235 and the first plate of the small load dipole 225. Connection point 250 couples the other end of the first coil 215 to one end of the second coil 217 and the second feed connection 240. Connection point 255 couples the other end of the second coil 217 to the second plate 230 of the small load dipole 220.

[0069] Figure 2B Example near-field circuit 270 is based on example near-field antenna architecture 200, support circuit 272 and is configured to receive non-propagating quasi-static near-field signals. Near-field circuit 270 is configured to (e.g., in receive mode) receive non-propagating quasi-static near-field signals. It should be noted that near-field antenna 200 can also be coupled to a transmitter circuit (not shown) for two-way communication.

[0070] Coil 215 in near-field antenna 200 having an inductance (L1) and a resistance (R3) forms a magnetic (H-field) antenna 271. Two load plates 225 and 230 in dipole section 220 form an electric (E-field) antenna 220. The two load plates 225 and 230 are conductive structures. Coil 217 having an inductance (L2) increases / raises the transmit voltage of the electric antenna 220 received from a transmitter power amplifier (not shown) coupled to the feed connections 235, 240.

[0071] Support circuit 272 includes a tuning circuit 274, a transceiver 276 (e.g., Figure 1 transceiver 112 in), a communication signal interface 278 and a controller 280. In other example embodiments, support circuit 272 includes a user interface (not shown).

[0072] Tuning circuit 274 is coupled to the first feed point 235 and the second feed point 240. Tuning circuit 274 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 290 (e.g., ground potential). The capacitor bank is coupled to the controller 280 through a control line 282, and the resistor bank is coupled to the controller 280 through a control line 284.

[0073] The controller 280 adjusts the first capacitor bank (C1) and the second capacitor bank (C2) to adjust the resonant frequencies of the magnetic antenna 271 and the electric antenna 220 (e.g., adjust to 10.6 MHz). The controller 280 adjusts the first resistor bank (R1) and the second resistor bank (R2) to adjust the bandwidths of the magnetic antenna 271 and the electric antenna 220 (e.g., adjust to 400 KHz) such that the bandwidths are sufficient to allow reception of non-propagating quasi-static near-field signals from the antennas 271, 220.

[0074] The capacitor banks (C1), (C2) are equally tuned using the control lines 282 from the controller 280, and the resistor banks (R1), (R2) are equally tuned using the control lines 284 from the controller 280.

[0075] The transceiver 276 is coupled between the tuning circuit 274 and the communication signal interface 278. When the near-field circuit 270 is transmitting (i.e., receiving or sending), there is a non-propagating quasi-static near-field signal voltage 288. The transceiver 276 is also coupled to the controller 108 via the control line 286, and the control line 286 changes the insertion loss impedance as previously discussed.

[0076] Figure 3 Is the example near-field signal path loss 300. A comparison of the signal path loss 302 and the frequency 304 between the first near-field communication device and the second near-field communication device is shown. The frequency 304 is in MHz, and the signal path loss 302 is in dB. The signal path loss 302 is defined by the following formula:

[0077]

[0078] Where:

[0079] οP Signal path loss in dB

[0080] οVRx Voltage at the LNA input of the receiver in the first near-field device;

[0081] οVTx Voltage at the near-field antenna of the transmitter in the second near-field device;

[0082] οGTx Gain of the transmitter antenna in dB

[0083] οGTx Gain of the receiver antenna in dB

[0084] As shown, at the lower frequency 304, the path loss 302 increases and the communication range around the near-field device decreases. Therefore, to detect the touch / contact condition, a first center frequency lower than the second center frequency (e.g., below 1 MHz) can be selected. A higher second center frequency (e.g., above 10 MHz) is selected and used for data communication with a higher data rate.

[0085] In some example embodiments, a lower first center frequency is selected such that there is no initial near-field communication when two near-field devices are 1 or 2 meters apart (e.g., before or during a game), and a higher second center frequency is selected such that there is near-field communication when two near-field devices are 1 or 2 meters apart (e.g., before or during a game).

[0086] Figure 4 is an example state diagram 400 for operating the near-field wireless device 100. At the start, the device 100 is placed in a first path loss state with a higher path loss that enables contact detection but blocks data communication.

[0087] Next, after contact is detected, the device 100 is placed in a second path loss state with a lower path loss such that data communication can begin.

[0088] Applications / implementations of the near-field wireless device 100 include various wearable applications and gaming applications.

[0089] For wearable and / or medical applications, two users can signal permission for data communication by touching or being within a predetermined range where contact is detected.

[0090] For gaming applications, two users can signal permission for data communication by enabling contact to be detected at the start of the game (e.g., to switch players or change levels) and / or during the game (e.g., a "high five" to exchange scoring information).

[0091] Unless a specific order is explicitly stated, the various instructions and / or operational steps discussed in the above figures can 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 can be combined in various ways to yield other examples, and should be understood within the context provided in this detailed description.

[0092] In some example embodiments, these instructions / steps are implemented as functional instructions and software instructions. In other embodiments, the instructions can be implemented using logic gates, application specific chips, firmware, and other hardware forms.

[0093] When the instructions are embodied as a set of executable instructions in a non-transitory computer-readable or computer-usable medium, the 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. 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 article of manufacture). The article or article of manufacture may refer to any single manufactured component or multiple components. As defined herein, a non-transitory machine or computer-usable medium does not include a signal, but such a medium may be capable of receiving and processing information from a signal and / or other transitory media.

[0094] It should be readily understood that the components of the embodiments generally described herein and illustrated in the figures can be arranged and designed in a wide variety of different configurations. Thus, the detailed description of the various embodiments represented in the figures is not intended to limit the scope of the present disclosure, but merely to represent the various embodiments. While aspects of the embodiments are presented in the figures, the figures are not necessarily drawn to scale unless specifically indicated.

[0095] The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. Thus, the scope of the present invention is indicated by the appended claims rather than by this detailed description. All changes that come within the meaning and range of equivalency of the claims are embraced within the claims.

[0096] Throughout this specification, the mention of features, advantages, or similar language does not imply that all features and advantages that can be realized by the present invention should be present in or exist in any single embodiment of the present invention. In fact, the language referring to the features and advantages should be understood to mean that a particular feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present invention. Thus, the discussions of features and advantages throughout this specification and similar language may, but do not necessarily, refer to the same embodiment.

[0097] 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 relevant art will recognize that, given 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 instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments of the present invention.

[0098] References throughout this specification to "one embodiment", "an embodiment", or similar language mean 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, 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 first near-field device, characterized in that, Comprising: Near-field antenna; Tuning circuit; Communication unit, which is coupled to the near-field antenna and the tuning circuit; Controller, which is coupled to the tuning circuit and the communication unit; Wherein the first near-field device is configured to have a near-field communication path loss relative to the second near-field device; Wherein the controller is configured to set the path loss to a first signal path loss before detecting contact between the first near-field device and the second near-field device; Wherein the controller is configured to set the path loss to a second signal path loss after detecting contact between the first near-field device and the second near-field device; and Wherein the first signal path loss is greater than the second signal path loss.

2. The device according to claim 1, wherein: The first signal path loss enables the first near-field device to detect contact between the first near-field device and the second near-field device.

3. The device according to claim 1, wherein: The first signal path loss blocks data transfer between the first near-field device and the second near-field device; and Wherein the second signal path loss enables data transfer between the first near-field device and the second near-field device.

4. The device according to claim 1, wherein: [[ID=,15]]The controller is configured to set the impedance of the near-field device to a first impedance and a second impedance; Wherein, to set the first signal path loss, the controller is configured to set the impedance to the first impedance; and Wherein, to set the second signal path loss, the controller is configured to set the impedance to the second impedance.

5. The device according to claim 1, wherein: The controller is configured to set the power level of the near-field device to a first power level and a second power level; Wherein, to set the first channel field strength, the controller is configured to set the power level to the first power level; and Wherein, to set the second channel field strength, the controller is configured to set the power level to the second power level.

6. The device according to claim 1, wherein: The controller is configured to set the center frequency of the near-field antenna to a first center frequency and a second center frequency; Wherein, to set the first signal path loss, the controller is configured to command the tuning circuit to set the near-field antenna to the first center frequency; and Wherein, to set the second signal path loss, the controller is configured to command the tuning circuit to set the near-field antenna to the second center frequency.

7. The device according to claim 6, wherein: The tuning circuit is configured to change the center frequency in response to a command from the controller to change the capacitance tuning parameter in the tuning circuit.

8. The device according to claim 6, wherein: A first frequency band is defined by the first center frequency, and a second frequency band is defined by the second center frequency; and The controller is configured to adapt the first and second center frequencies to resonance frequency and bandwidth variations caused by electromagnetic loads within each of the first and second frequency bands.

9. The apparatus according to claim 1, wherein: The controller is configured to set the bandwidth of the near-field antenna to a first bandwidth and a second bandwidth; wherein, to set the first signal path loss, the controller is configured to command the tuning circuit to set the near-field antenna to the first bandwidth; and wherein, to set the second signal path loss, the controller is configured to command the tuning circuit to set the near-field antenna to the second bandwidth.

10. The apparatus according to claim 1, wherein: It further includes a contact detector circuit; wherein the contact detector circuit is configured to output a detected contact signal in response to one of the following: a change in a parameter of the tuning circuit, a change in the near-field communication signal voltage between the communication unit and the tuning circuit, an actual physical contact between the first near-field device and the second near-field device, a predefined threshold distance between the first near-field device and the second near-field device; and wherein the parameter is based on capacitance and / or resistance tuning parameters configured to maintain the center frequency and / or bandwidth of the near-field device.

Images