KR20070032271A - Enhanced magnetic field communication system - Google Patents

Abstract

An apparatus and method are provided for improving magnetic field communication. One aspect of the invention relates to a method for transmitting and receiving signals using an antenna element electrically connected to a driver and an amplifier. According to various embodiments of the method, a first signal is transmitted from an antenna element and a second signal that has been guided to the antenna element is received. Transmitting the first signal includes driving the first signal through the antenna element using a driver and monitoring the first signal through the input impedance of the amplifier. Receiving the second signal includes reducing the input impedance of the amplifier and receiving the second signal at the amplifier via the reduced input impedance. Various embodiments shield the antenna element from electric and electromagnetic fields. Other aspects are provided herein.

Magnetic Field Communication, Drivers, Amplifiers, Antenna Elements, Input Impedance

Description

Improved Magnetic Field Communication System {ENHANCED MAGNETIC FIELD COMMUNICATION SYSTEM}

Field of technology

The present invention relates generally to communication systems, and more particularly to systems, devices, and methods for receiving and transmitting magnetic field communication signals.

The main mode of signal propagation in some known communication systems over a relatively long distance between the receiving and transmitting antennas is the electromagnetic field. Due to the ability of the electric field to travel relatively long distances, the noise inherent in the electromagnetic field can be an important issue. While known communication antenna designs attempt to optimize the pickup of electromagnetic, electric and magnetic fields, several attempts have been made to reduce the effects of propagating and conducting electromagnetic noise, propagating and conducting electric field noise and propagating and conducting magnetic field noise.

For near field communication applications, the antenna should have good near field performance and block unwanted signals and / or noise from unwanted radiation sources and conduction sources. Examples of such near field communication applications include, but are not limited to, communication between a hearing aid and a telephone receiver, communication between a hearing aid and a hearing aid, and communication between a programmer and a hearing aid. Examples of unwanted radiation sources include radio and television stations, and the like. Examples of unintended radiation sources of unwanted electromagnetic interference (EMI) include computers, televisions, electric motors, and the like. Examples of conductive interference sources are electric fields and electromagnetic radiation that are conducted through electrically conductive objects such as metals, human skin and conductive liquids that significantly interfere with communication.

There are other design challenges facing short range communication systems. In practice, all near field communication systems are compact, battery or RF powered, and low cost. Because of previous requirements, most near field communication systems are half-duplex or simplex communication systems capable of transmitting data in only one direction at a time. Known semi-bidirectional or unidirectional communication systems use electrical or mechanical switches for switching between receive and transmit modes. These switches require a considerable amount of time to switch between modes. Another problem involves additional parts and separate control lines to select between the receive mode and the transmit mode.

The communication system is tuned to transmit and receive a communication signal at a desired resonant frequency. However, the equivalent parallel parasitic capacitance of the coil and the capacitance of the low noise amplifier and other portions of the circuit can have a detrimental and unpredictable effect on the resonant frequency of the communication system.

Accordingly, there is a need in the field of the present invention to provide an improved communication system and method for transmitting and receiving near field data.

summary

The above-mentioned problems are mentioned as the subject matter of the present invention, and will be understood by reading and studying the following detailed description. Various aspects and embodiments of the present invention provide an antenna design that improves low noise amplifier and magnetic field communication and minimizes interference. Embodiments of the present invention reduce common mode EMI pickup by using differentially driven receiver circuitry; Remove a control line that switches between a transmit mode and a receive mode; Provide an adjustable communication bandwidth for the antenna; Reduce DC offset bias problems that reduce RF voltage appearing in receive and transmit circuits; Reduce the time for switching between transmission mode and reception mode; Provide an integrated electrostatic shield for the antenna; Provide at least two selectable RF power levels; It has many advantages, including but not limited to, reducing the effect of parasitic capacitance on the resonant frequency of a communication system.

One aspect of the present invention relates to a communication system for receiving and transmitting signals. According to various embodiments, the circuit includes an antenna element and an electrostatic conductor. The antenna element has a first terminal and a second terminal. The electrostatic conductor is arranged to shield the antenna element from the electric field. If the antenna element is in a magnetic field, the antenna element is adapted to direct the received signal to the first and second terminals. The circuit also includes a driver, a differential amplifier and a switch. The driver is connected to at least one of the first and second terminals to energize the antenna element with the transmitted signal. The differential amplifier has a first input connected to the first terminal of the antenna element and a second input connected to the second terminal of the antenna element. The differential amplifier has a selectable input impedance. The low first input impedance is selected to amplify the received signal from the antenna element, and the high second input impedance is selected to monitor the transmitted signal from the driver, performing self alignment and self diagnostic processing on the communication circuit. Provide the ability to do so. The switch toggles the effective input impedance for the differential amplifier between a second impedance and a first impedance.

According to various embodiments, the circuit comprises an antenna element, an amplifier circuit, a driver circuit and a control line. The antenna element includes first and second terminals, an induction coil electrically connected to the first and second terminals, and an electrostatic conductor that shields the induction coil against an electric field. The amplifier circuit is adapted to amplify a magnetically-induced signal received by the antenna element. The amplifier circuit includes a differential amplifier, a first input impedance, a second input impedance, a predetermined feedback impedance and an impedance shunt. The differential amplifier includes a first input, a second input and an output. The first input impedance is connected between the first input of the amplifier and the first terminal of the antenna element. The second input impedance is connected between the second input of the amplifier and the second terminal of the antenna element. Each of the first input impedance and the second input impedance includes a first element and a second element. The predetermined feedback impedance is connected between the output of the differential amplifier and at least one of the two inputs. The input impedance shunt is connected across the second element for each of the two inputs of the differential amplifier. The driver circuit is adapted to drive the antenna element with the transmitted signal. The control line is connected to the input impedance shunt to selectively shunt the second element for each of the two inputs of the amplifier. The control line is used to receive the self-induced signal received by the antenna element by selectively reducing the effective input impedance of the differential amplifier.

One aspect of the invention relates to a method for transmitting and receiving signals using an antenna element electrically connected to a driver and an amplifier. According to various embodiments of the method, a first signal is transmitted from the antenna element and a second signal that has been guided to the antenna element is received. Transmitting the first signal includes using a driver to drive the first signal through the antenna element and monitoring the first signal through the input impedance of the amplifier. Receiving the second signal includes reducing the input impedance of the amplifier and receiving the second signal at the amplifier via the reduced input impedance.

This Summary describes an overview of some of the teachings of the present application and should not be intended as an exclusive or complete treatment of the present invention. Further details of the invention are set forth in the detailed description and the appended claims. Other aspects will be apparent to those skilled in the art upon reading the following detailed description, and seeing the drawings that form part of that detailed description, each of which is to be interpreted in a limiting sense. Can not be done. It is intended that the scope of the invention only be limited by the appended claims and their equivalents.

1 illustrates a resonant circuit for an antenna element according to various embodiments of the present disclosure.

2 illustrates a coil for an antenna element according to various embodiments of the present disclosure.

3 illustrates an antenna element according to various embodiments of the present disclosure.

4 illustrates a block diagram of a communication circuit for receiving and transmitting signals, in accordance with various embodiments of the present invention.

5 is a block diagram of a communication circuit for receiving and transmitting signals in accordance with various embodiments of the present invention.

6 illustrates a block diagram of a communication circuit for receiving and transmitting signals, in accordance with various embodiments of the present invention.

details

DETAILED DESCRIPTION The following detailed description of the invention refers to the accompanying drawings that illustrate by way of example certain aspects and embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments may be utilized and may be changed structurally, logically, and electrically, without departing from the scope of the present invention. References to "one", "one" or "various" embodiments herein are not necessarily the same embodiment, and such references are intended for one or more embodiments. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims, along with the full scope of legal equivalents of the claims.

1 illustrates a resonant circuit for an antenna element according to various embodiments of the present disclosure. The circuit 100 shown includes an antenna element 102 and a low noise amplifier 104. The antenna element 102 includes an induction coil 106 connected in series with the tuning capacitor 108. Induction coil 106 is shown an equivalent parallel parasitic capacitance 110 and two coil portions 112A, 112B. As discussed below, the induction coil has an electric field shield 114. The capacitive nature of the shield 114 contributes to the parasitic capacitance of the circuit. In various embodiments of the present invention, an additional capacitor 116 is connected in series with the coils 112A, 112B. This additional capacitor 116 makes the resonant circuit less susceptible to parasitic capacitance of the resonant circuit, and allows large tuning capacitors 108 to be used to provide the desired resonant frequency to the circuit. The node that the capacitor connects to the coil is a high impedance node. In receive mode, these high impedance nodes are particularly easy to pick up electric field radiation, and in transmit mode they produce unacceptable high standing voltages that can damage others around the circuit.

2 illustrates a coil for an antenna element according to various embodiments of the present invention. The illustrated coil 202 includes a core 218 having a high permeability surrounded by a coiled wire 220. Various embodiments include a ferrite core 218. In the figure, the coiled wire is covered with an insulator 222 covered by the electrostatic conductor 224. One example of an electrostatic conductor is copper. In the figure, copper tape is wrapped around the insulator. Copper tape serves as electric field shielding. In the presence of an electric field, the electric field shield absorbs the surface charges generated by the electric field.

In various embodiments, as shown in FIG. 1, the coiled wire 220 is separated into a first portion 112A and a second portion 112B. Since the additional capacitor 116 is connected in series between the first coil portion and the second coil portion, additional capacitors, the first and second coil portions, and nodes between the capacitors and the first and second coil portions are connected to the electrostatic conductor. By shielding it from the electric field.

3 illustrates an antenna element 302 according to various embodiments of the present invention. In the figure, wire conductor 320 is coiled around core 318 with high permeability and high electrical resistance. In various embodiments, the core comprises ferrite. In various embodiments, the core material includes air. Other embodiments include other core materials. As shown entirely in the figure, the received magnetic field signal 326 induces a current signal 328 in the coil 320, and the current signal 328 sent to the coil 320 induces a magnetic field signal 326. do. The illustrated antenna element 302 has an electrostatic conductor 314 that is electrically insulated from the coil 320. In the presence of an electric field, the electrostatic conductor absorbs the surface charges generated by the electric field. Thus, the electrostatic conductor functions as a shield against the electric field. In various embodiments, the electrostatic conductor is formed as a strip extending in the longitudinal direction of the coil, as shown in FIG. In various embodiments, the electrostatic conductor is formed as a cylindrical wool, for example as shown in FIG.

In various embodiments, the electric field shield conductor 314 is floating. Electrostatic surface charge is absorbed onto the conductor. Since the same electrical charges originally push each other, the electrostatic surface charges are distributed throughout the conductor. Thus, when the electrostatic conductors are floating, the voltage due to the electric field is applied unevenly (or approximately equally) to each terminal 330A, 330B of the coil 320. As will be explained in more detail below, the same noise signal at each terminal of the coil is rejected by the low noise differential amplifier as common mode noise.

In various embodiments, the electric field shield conductor 314 is grounded or otherwise connected to a reference voltage such that surface charges due to the electric field are removed from the electrostatic conductor. Thus, neither of the coil terminals 330A and 330B is significantly affected by the voltage on the electrostatic conductor.

The signal induced in the coil is received and amplified by a low noise amplifier. In the embodiments described above, the electric field does not contribute significantly to the amplified signal. The electrostatic conductor, in various embodiments, blocks unwanted electric field signals and / or noise when combined with the differential amplifier. Thus, the amplified signal is due to the magnetic field in the antenna element. The circuit of the present invention blocks electric field signals that can travel relatively long distances and can be sources of interference noise. Thus, the present invention provides good short-range communication using only magnetic field signals.

4 illustrates a block diagram of a communication circuit for receiving and transmitting signals, in accordance with various embodiments of the present invention. 5 and 6 may be usefully used to help the description of FIG. 4. The illustrated communication circuit 432 includes an antenna element 402, an amplifier circuit 404 and a transmission drive circuit 434. The figure also shows a signal processing circuit 436. The signal processing circuit 436 includes a processor 438 in communication with the receiver circuit 440 to receive the RF output signal 442 from the low noise differential amplifier 404 representing the signal received at the antenna element 402. . Processor 438 also communicates with transmitter circuitry 444 to send RF input signal 446 to transmit drive circuitry 434, which in turn energizes a signal indicative of RF input signal 446 to antenna element 404. .

The transmission drive circuit 434 serves to energize the antenna element 402 with a signal for transmission at the resonant frequency. The amplifier circuit 404 functions to amplify the signal in preparation for further signal processing of that signal. The amplifier circuit 404 may receive and amplify the self-inducing signal received by the antenna element at the resonant frequency. Additionally, in various embodiments, the amplifier circuit 404 may include an antenna by the transmit drive circuit 434 to allow the energized signal to be monitored and to allow self alignment, tuning optimization, channel selection, and self diagnostics. The energized signal transmitted to the element 402 can be received and amplified. The antenna element 402, the transmit drive circuit 434 and the amplifier circuit 404 are discussed in more detail below.

In various embodiments, antenna element 402 includes an induction coil connected in series with a capacitor. The antenna element is most effective when the resonant frequency of the antenna elements matches the desired communication frequency. The resonant frequency of the antenna element is influenced by the inductance and capacitance of the antenna. Parasitic capacitance in the circuit can also affect the resonant frequency. The received magnetic field induces a current in the induction coil, forwarding it to a low noise differential amplifier.

The illustrated antenna element 402 includes an electric field shield 414. In various embodiments, the electrostatic conductor serves as a shield for the electric field. The electrostatic conductor is insulated from the number of turns of the coil and therefore does not spur the magnetic field. As discussed above, electrostatic conductors conduct electrostatic surface charges due to electric fields. In various embodiments, the electrostatic conductor is connected to a reference potential (eg, ground) such that electrostatic energy is conducted away from the system antenna, so that the electric field does not significantly affect the signal induced in the coil. In these embodiments, the amplifier 404 need not be a differential amplifier because electrostatic energy is removed. In various embodiments, the electrostatic conductor is floating (the conductor is not connected to a reference potential) and therefore functions as an electrostatic equalizer. When the electrostatic conductor functions as an electrostatic equalizer, the surface charge due to the electric field is evenly distributed throughout the electrostatic conductor so that each terminal of the coil is equally affected by the electrostatic charge. The terminals of the coil are connected to the differential amplifier 404. The differential input of the amplifier blocks the common mode voltage, including the voltage contributed by the electrostatic charge distributed throughout the electrostatic conductor.

In various embodiments, the amplifier 404 is a low noise differential amplifier. Various embodiments of the present invention include a low noise voltage driven operational amplifier, and other various embodiments include a low noise current driven operational amplifier. Voltage driven operational amplifiers and current driven operational amplifiers are known to those skilled in the art. The bandpass response of the antenna circuit and the sensitivity of the amplifier to unwanted electric fields can be changed by adjusting the impedance at the amplifier 404. The illustrated low noise differential amplifier includes an impedance switch 448 that is used to adjust the impedance of the amplifier 404 to receive a signal induced in the antenna element 402 by a magnetic field. In various embodiments, for example, impedance switch 448 toggles the effective input impedance of the amplifier between the larger and smaller resistors.

There are several ways to adjust the impedance of the amplifier to achieve the desired band pass response and gain. Various embodiments of the amplifier include various arrangements of various elements that function as input and feedback impedances. Additionally, various embodiments implement an impedance switch having various elements and configurations to adjust the bandpass response and / or gain of the desired amplifier by operating the switch.

In various embodiments, the input impedance of each input to differential amplifier 404 includes a first device connected in series with a second device. The impedance switch includes a transistor that, in operation, forms a shunt across the second element to change the effective input impedance. Thus, in embodiments in which the first and second elements are in series and the second element is selectively divided, the lower first input impedance (first impedance) is formed by the first element and the second input impedance If the (second impedance) is lower, it is formed by the combination of the first element (first impedance) and the second element (third impedance). In various embodiments, the input impedance of each input to the differential amplifier includes a first element connected in parallel with a second element. The impedance switch includes a transistor that, when activated, forms a shunt across the second element to change the effective input impedance. The other switchable impedance network may be characterized by whether the switchable impedance network provides a tunable input impedance or an adjustable feedback impedance, or the switchable impedance network with a high impedance separate from the input impedance and / or the feedback impedance. It is within the scope of the present invention whether or not to switch between low impedance paths.

The transmit driver circuit 434 includes a transmitter driver 450 and a control circuit 452 to control the input impedance of the amplifier and enable the transmitter driver based on whether a carrier signal is detected. The illustrated control circuit includes one RF input 454 for receiving the RF input signal 446 and one RF output 456 for transmitting the corresponding RF signal 458 to the driver. At least one control output 460 is used to control the impedance switch to properly control the impedance of the amplifier and enable the transmitter drive stage via a transmit (XMIT) enable signal.

In various embodiments, when the RF input 454 has a carrier of an appropriate RF drive level, the control circuit 452 raises the effective input impedance of the receiver amplifier via line 462 and through line 464. Trigger at least one output 460 to enable the transmitter. When the circuit shown is in transmit mode, the higher effective input impedance attenuates the input signal allowing the receiver amplifier to monitor the transmit drive signal at the antenna element allowing for self-alignment of the circuit. Receiver input attenuation can avoid excessive circuit load when a transmit signal is received. Thus, with a larger receiver input impedance, the transmitter driver can drive the antenna element more effectively, and the amplifier can be protected from the higher voltage provided by the transmitter when driving. The driver circuit can be monitored by the receiver circuit through a larger input impedance. If the RF input does not have a carrier of the appropriate RF drive level, the circuit shown is in receive mode, and the control circuit triggers at least one output to lower the effective input attenuation of the receiver path and transmits via line 464. Disable. Lower effective receiver attenuation improves the efficiency of the antenna element to receive a magnetic signal and provide a corresponding signal to the amplifier. When the illustrated circuit is in the receive mode, the disabled transmitter is in high impedance mode (e.g., open circuit) to avoid the load on the antenna element upon receiving a magnetically transmitted signal.

In various embodiments, transmitter drive circuit 450 includes a differential push-pull driver stage. When enabled, the driver stage converts the transmission information into a differential output having a low output impedance at the antenna resonant frequency that provides the maximum drive current for the antenna element. In various embodiments, supply power savings may be achieved by disabling one of the outputs using the ground enable control signal 466. In various embodiments, the control circuit or carrier detection circuit triggers the output to provide a ground enable control signal. Disabling one of the outputs causes the RF device level to drop by 6dB.

5 illustrates a block diagram of a communication circuit for receiving and transmitting signals in accordance with various embodiments of the present invention. According to various embodiments of the present invention, the block diagram shown provides the block diagram of FIG. 4 in more detail. The illustrated antenna element 502 includes a coil 512 and a tuning capacitor 508 in series with the coil 512. The illustrated transmitter drive circuit 534 includes a push-pull drive stage 550 and a control circuit 552 for controlling various operations of the circuit based on detecting the RF carrier signal.

The illustrated amplifier 504 includes a voltage-driven amplifier 568. Voltage-driven op amps have a very high input impedance. Those skilled in the art will appreciate that the input R _IN , R _S and feedback R _F resistors set the amplifier gain and the input impedance of the amplifier. The bandpass response of the antenna circuit and the sensitivity of the amplifier to unwanted electric fields can be altered by adjusting the input impedance and / or feedback impedance of the voltage-driven operational amplifier. The input and feedback elements are suitably selected to function as switches to properly adjust the bandpass response and / or gain of the amplifier.

In various embodiments, the effective input impedance of the voltage drive amplifier is adjustable. In the figure, the input impedance network comprises, for each input of the differential amplifier 568, a first element or input resistor R _IN or shuntable resistor R _S connected in series with a second element. . The shunt resistance can be (R _S) so as to be removable from the effective input impedance of the amplifier, the impedance of the shunt 548 is formed over the whole of the shunt resistance is possible (R _S). Other impedance elements can be replaced to provide the desired switch-operation adjustments for band pass and gain. In various embodiments, the switches are formed by a transistor such as a FET transistor coupled in parallel across the shuntable resistors R _S from the carrier detection control circuit to the gates operably connected to the control line. An effective short can be provided by providing a potential to the gate to turn on the transistor. This is shown as logic switches in the figure. When the RF carrier signal is detected, the carrier detection control circuit opens the shunt (e.g., turns off the transistor) to increase the effective input impedance to increase the conduction current to the antenna element. The larger effective input resistance includes both R _IN and R _S for each input of the differential amplifier. If no RF carrier signal is detected, the carrier detection control circuit closes the shunt (eg, turns on the transistor) so that the effective input impedance is smaller to increase the amplification of the magnetic field induced current received by the antenna element. The smaller effective input resistance includes R _IN for each input of the differential amplifier, excluding R _S.

6 shows a block diagram of a communication circuit for receiving and transmitting signals, in accordance with various embodiments of the present invention. According to various embodiments of the present invention, the block diagram shown provides the block diagram of FIG. 4 in more detail. The illustrated amplifier includes a current-driven amplifier. Current-driven amplifiers, also referred to as current mode differential amplifiers, have very low input impedance. The input and feedback resistors set the amplifier gain and input impedance. The bandpass response of the antenna circuit and the sensitivity of the amplifier to unwanted electric fields can be altered by adjusting the input impedance and / or feedback impedance of the current driven op amp. The input and feedback elements are suitably chosen to function as switches to properly adjust the band-pass response and / or gain of the amplifier. In various embodiments, as described above with respect to FIG. 5 and the voltage-driven amplifier, the effective input impedance for the current-driven amplifier is adjustable using impedance shunts.

The present invention can be incorporated into techniques that use various near field communication systems and near field communication systems such as hearing aids. For example, the present invention relates to hearing aids such as in-the-ear, half-shell, and in-the-canal styles, as well as ear- It can also be used for hearing aids. Moreover, it will be understood by those skilled in the art upon reading the description and method aspects of the present invention using the drawings set forth in detail above.

While specific embodiments have been shown and described herein, those skilled in the art will understand that any configuration calculated to achieve the same purpose may be replaced by the specific embodiments shown. This application is intended to cover any adaptations or variations of the present invention. It is to be understood that the above detailed description is exemplary only and is not intended to be limiting. Combinations of the above embodiments and other embodiments will become apparent to those skilled in the art upon reviewing the above description. The scope of the invention should be determined with reference to the appended claims, along with the full scope of legal equivalents of the claims.

Claims (26)

A communication circuit for receiving and transmitting signals, An antenna element having a first terminal and a second terminal; An electrostatic conductor arranged to shield the antenna element from an electric field, the antenna element being configured to direct a received signal to the first and second terminals when in the magnetic field; A driver connected to at least one of the first and second terminals for conducting a signal transmitted to the antenna element; A differential amplifier having a first input connected to a first terminal of the antenna element and a second input connected to a second terminal of the antenna element, the differential amplifier having a selectable input impedance, wherein the low first input impedance is Used to amplify a signal received from an antenna element, and a high second input impedance is used to monitor the transmitted signal from the driver; And A switch to toggle the effective input impedance between the second impedance and the first impedance Communication circuit comprising a. The method of claim 1, And said second impedance comprises a combination of said first impedance and a third impedance. The method of claim 1, The driver comprises a differential driver having a first output terminal connected to the first terminal of the antenna element and a second output terminal connected to the second terminal of the antenna element. The method of claim 3, And a control line for grounding one of the first and second outputs. The method of claim 1, First and second resistors connected in series between the first antenna terminal and the first amplifier input; And A third resistor and a fourth resistor connected in series between the second antenna terminal and the second amplifier input More, The switch is configured to shunt the second resistor and the fourth resistor such that the first impedance corresponds to the first resistor and the third resistor, And wherein the second impedance corresponds to a combination of the first resistor and the second resistor and a combination of the third resistor and the fourth resistor. The method of claim 1, The antenna element includes a first coil portion, a second coil portion, and a capacitor connected in series between the first coil portion and the second coil portion, so that the high voltage between the capacitor and the first and second coil portions is increased. A communication circuit in which impedance nodes are shielded by the electrostatic conductor to reduce standing voltages that are likely to interfere and be damaged. The method of claim 1, The antenna element comprises at least one coil portion, at least one electrostatic conductor disposed around the insulator and an insulator between the at least one coil portion and the at least one electrostatic coil. The method of claim 7, wherein Wherein the electrostatic conductor equally distributes the electrostatic surface charge formed by the electric field across the antenna element to equally affect the first input and the second input of the differential amplifier. The method of claim 7, wherein Wherein said electrostatic conductor is coupled to a reference potential to remove electrostatic surface charges formed by an electric field. A communication circuit for receiving and transmitting signals, An antenna element comprising first and second terminals, an induction coil electrically connected to the first and second terminals, and an electrostatic conductor shielding the induction coil against an electric field; An amplifier circuit for amplifying a self-induced signal received by the antenna element, wherein the amplification circuit A differential amplifier comprising a first input, a second input and an output; A first input impedance connected between the first input of the amplifier and the first terminal of the antenna element; A second input impedance connected between the second input of the amplifier and the second terminal of the antenna element; The first input impedance and the second input impedance each including a first element and a second element; A predetermined feedback impedance connected between the output of the differential amplifier and at least one of the two inputs; And An input impedance shunt connected across the second element for each of the two inputs of the differential amplifier Including-; A driver circuit for driving the antenna element with a transmission signal; And A control line connected to the input impedance shunt that selectively shunts the second element for each of the two inputs of the amplifier to selectively reduce the effective input impedance to the differential amplifier while receiving a signal from the antenna element Communication circuit comprising a. The method of claim 10, For each of the first input impedance and the second input impedance, the first element and the second element are connected in series, Provide a desired first band pass response and a desired first gain for said antenna element while monitoring said transmission signal from said driver circuit, Communication circuitry selected to provide a desired second band pass response and a desired second gain for the antenna element while receiving the self-inducing signal from the antenna element. The method of claim 10, The induction coil includes a first portion and a second portion, the antenna element includes a first capacitor connected in series between the first portion and the second portion of the induction coil, and the first capacitor includes the electrostatic Communication circuit shielded by a conductor. The method of claim 10, The induction coil has a first coil portion and a second coil portion; The first capacitor is connected between the first coil portion and the second coil portion; The electrostatic conductor is disposed in relation to the first capacitor and the first and second coil portions and insulated therefrom to shield the first capacitor and the first and second coil portions from an electric field and a high standing voltage. Communication circuit. The method of claim 13, And a tuning capacitor connected to the induction coil, wherein the first capacitor causes the tuning capacitor to be large enough to significantly reduce the effect of parasitic capacitance upon tuning the antenna element. The method of claim 10, Wherein said amplifier circuit is comprised of a low noise voltage driven operational amplifier. The method of claim 10, Wherein said amplifier circuit is comprised of a low noise current driven operational amplifier. The method of claim 10, And the electrostatic conductor is connected to a ground reference potential to conduct the electrostatic energy away from the antenna element. The method of claim 10, The electrostatic conductor is not connected to a reference potential and the electrostatic strip serves as an electrostatic equalizer for applying a voltage resulting from the electrostatic energy to each of the two inputs of the differential amplifier to reduce the effect of the electrostatic energy. . The method of claim 10, A control circuit for detecting a radio frequency (RF) signal input, the control circuit for supplying a first control signal to the input impedance shunt and a second control signal to the driver circuit, and in response to detecting the RF signal input, The first control signal increases the effective input impedance to the differential amplifier, and the second control signal allows the driver circuit to drive the antenna element with the transmit signal. A method for transmitting and receiving signals using an antenna element electrically connected to a driver and an amplifier, the method comprising: Transmitting a first signal from the antenna element-driving the first signal through the antenna element using the driver; Monitoring the first signal through an input impedance of the amplifier; Receiving a second signal induced in the antenna element, reducing an input impedance of the amplifier; And receiving the second signal at the amplifier via the reduced input impedance. How to include. The method of claim 20, Reducing the input impedance of the amplifier includes changing the gain of the amplifier. The method of claim 20, Reducing the effective input impedance of the amplifier includes changing the band pass response of the antenna element. The method of claim 20, Reducing the input impedance comprises operating a shunt across a portion of the input impedance to reduce the input impedance. The method of claim 20, Shielding the antenna element from an electric field such that the second signal induced in the antenna circuit is primarily due to magnetic field coupling. The method of claim 24, Shielding the antenna element comprises at least partially surrounding a first coil portion, a second coil portion and a capacitor connected in series between the first coil portion and the second coil portion. The method of claim 24, The amplifier comprises a differential amplifier, Spreading a surface charge due to an electric field across the antenna element; And Removing the common mode voltage due to the surface charge using the differential amplifier.

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