Generation of a tuning signal for tuning a magnetic antenna

Description

[0001] Embodiments of the present invention relate to tuning a magnetic antenna, and more specifically, to generating a tuning signal for tuning the magnetic antenna. Some embodiments relate to a subscriber of a communications system having a magnetic antenna and a tuning device for generating the tuning signal for tuning the magnetic antenna. Some embodiments relate to generating a tuning voltage.

[0002] Traditionally, electrical antennas or short electrical antennas are used, especially in the area of ​​sensor nodes. For example, if a currently common electrical antenna is used at 868 MHz, a length of approximately 15 cm is required as a ½ lambda radiator. If shorter antennas are used, the antenna gain decreases. Furthermore, the handling of devices with antennas is restricted, since the antennas used become detuned when approaching electrically conductive or dielectric objects, thus further reducing their gain. This places requirements on the environment of sensor nodes, for example. With electrical antennas, it is still not possible to transmit from electrically shielded environments (Faraday cage).

[0003] Magnetic antennas are also known. However, due to their high quality, magnetic antennas have a very narrow band. Therefore, magnetic antennas must be tuned to the desired frequency, for example, when approaching metallic or dielectric objects.

[0004] If a magnetic antenna is operated in close proximity to materials, these can positively or negatively influence the properties of the antenna depending on the material properties (e.g. conductive, dielectric, insulating). As a rule, the magnetic antennas are detuned by the surrounding materials. This means that the resonance tuning is no longer optimal at the operating frequency or the adaptation to the feed resistance is no longer optimal. As a rule, both are impaired, but can be corrected by retuning the antenna (e.g. by changing the resonance capacitor or changing the coupling). This, however, requires user intervention and a measured value with which an optimal setting can be determined.

[0005] US 5,225,847 A describes an automatic tuning system for an antenna in which a single variable reactance element is used to detect the power transmitted to the antenna and the power reflected from the antenna on the feedline. The antenna's variable reactance element is adjusted until the ratio between the transmitted and reflected power on the feedline indicates that the standing wave ratio on the feedline is at a minimum, after which the antenna is tuned. The variable reactance element is adjusted by a stepper motor controlled by a microprocessor programmed to perform calculations to determine when the standing wave ratio reaches a minimum.

[0006] US 2013 / 016018 A1 describes an automatic tuning system for a loop antenna with a single electronically variable reactance element. The electronically variable reactance component of the antenna is automatically minimized by a feedback loop that drives a voltage-variable capacitance until the reactive component of the antenna impedance is practically zero, making the antenna impedance resistive. The electronically variable capacitance is adjusted by a variable high-voltage power supply controlled by a feedback amplifier or a high-voltage feedback amplifier.

[0007] The present invention is based on the object of improving the automatic tuning of a magnetic antenna.

[0008] This problem is solved by the independent patent claims.

[0009] Advantageous further developments can be found in the dependent patent claims.

[0010] Embodiments create a magnetically self-tuned antenna.

[0011] Embodiments provide an antenna arrangement with a magnetic antenna and a tuning device. The magnetic antenna comprises a singly or multiply interrupted loop and at least one tuning element [e.g., a variable capacitor or a capacitance diode] for tuning the magnetic antenna. The tuning device is connected to the tuning element, wherein the tuning device is configured to provide a control signal [e.g., a tuning voltage] for tuning the magnetic antenna as a function of a phase position of a signal leading into the magnetic antenna, and to control the tuning element with the control signal in order to tune the magnetic antenna.

[0012] In embodiments, the loop circumference of the singly or multiply interrupted loop can be 1 / 2 to 1 / 10 of a wavelength of the signal propagating into the magnetic antenna or of a transmission signal to be transmitted or received with the magnetic antenna. For example, the wavelength can be less than or equal to 1.999 m (e.g., at frequencies greater than or equal to 149 MHz), or less than or equal to 0.749 m (e.g., at frequencies greater than or equal to 400 MHz), or less than or equal to 0.375 m (e.g., at frequencies greater than or equal to 800 MHz).

[0013] In embodiments, a frequency of the signal leading into the magnetic antenna or of a transmission signal to be transmitted or received with the magnetic antenna can be greater than or equal to 149 MHz, 400 MHz or 800 MHz or can be in the range from 149 MHz to 930 MHz.

[0014] In embodiments, a frequency of the signal leading into the magnetic antenna or of a transmission signal to be transmitted or received with the magnetic antenna can be within an ISM band (ISM = Industrial, Scientific and Medical Band) or SRD band (SRD = Short Range Device), such as in the range from 169.4000-169.8125 MHz, or in the range from 433.05 MHz to 434.79 MHz, or in the range from 863-870 MHz, or in the range from 902 to 928 MHz.

[0015] In some embodiments, the magnetic antenna can be narrowband. For example, in some embodiments, the magnetic antenna can have a Q factor of 20 to 500. (Note: For magnetic antennas, the bandwidth is defined by the Q factor.)

[0016] In embodiments, the tuning device may be configured to provide the control signal for tuning the magnetic antenna as a function of a phase relationship between the signal leading into the magnetic antenna and a phase signal.

[0017] In embodiments, the phase signal may be based on a current flowing in at least a portion of the loop.

[0018] In embodiments, the phase signal may be based on a magnetic field [e.g., in the near field] generated by the loop [or magnetic antenna].

[0019] In embodiments, the phase signal may be a power coupled out of the magnetic antenna [e.g. inductively].

[0020] In embodiments, the phase signal may be a signal coupled out of a magnetic field of the magnetic antenna.

[0021] In embodiments, the antenna arrangement or the tuning device may comprise a coupling loop configured to provide the phase signal.

[0022] In embodiments, the tuning device may comprise a coupling loop configured to extract power from the magnetic antenna to receive the power extracted from the magnetic antenna [e.g., inductively].

[0023] For example, the magnetic antenna loop and the coupling loop can be arranged or implemented on the same circuit board.

[0024] In embodiments, the tuning device can be designed to control the tuning element with the control signal in order to regulate a phase difference between the signal leading into the magnetic antenna and the phase signal to a predetermined desired value.

[0025] For example, the tuning device can be designed to control the phase difference between the signal leading into the magnetic antenna and the phase signal to the predetermined target value by controlling the tuning element with the control signal.

[0026] For example, the tuning device may be configured to track the control signal to counteract a deviation of the phase difference between the signal leading into the magnetic antenna and the phase signal from the predetermined target value.

[0027] In embodiments, the tuning device may be configured to effect the control of the phase difference between the signal leading into the magnetic antenna and the phase signal to the predetermined desired value using a control loop or a feed-forward control.

[0028] In embodiments, the tuning device may be configured to derive a signal from the signal leading into the magnetic antenna to obtain a derived signal, wherein the tuning device is configured to provide the control signal for tuning the magnetic antenna in dependence on a phase relationship between the derived signal and the phase signal.

[0029] For example, the tuning device can be designed to control the tuning element with the control signal in order to regulate the phase difference between the derived signal and the phase signal to a predetermined target value.

[0030] In embodiments, the tuning device may comprise a signal combiner [e.g. multiplier] configured to the phase signal or a phase-shifted version of the phase signal, and the derived signal or a phase-shifted version of the derived signal, to combine to obtain a combined signal, wherein the tuning device is designed to control the tuning element with the control signal in order to obtain a DC component of the combined signal or a low-pass filtered version of the combined signal to a given setpoint.

[0031] In embodiments, the tuning device may comprise a phase shifter configured to phase-shift one of the derived signal and the phase signal to obtain a phase-shifted signal, wherein the signal combiner [e.g. multiplier] is configured to combine the phase-shifted signal and the other of the derived signal and the phase signal to obtain the combined signal, wherein the phase shifter is configured to phase-shift one of the derived signal or the phase signal such that, in the case of resonance of the magnetic antenna, the phase-shifted signal and the other of the derived signal and the phase signal have a predefined phase difference [e.g. 90°] at the signal combiner.

[0032] In embodiments, the tuning device may include an energy extractor [e.g., a directional coupler or other energy extracting device] configured to extract a portion of the signal forwarding to the magnetic antenna to obtain the derived signal.

[0033] In embodiments, the tuning device may comprise a control amplifier configured to provide the control signal for tuning the magnetic antenna, wherein the control amplifier is configured to drive the tuning element with the control signal in order to control a DC component of the combined signal or a low-pass filtered version of the combined signal to a predetermined target value.

[0034] In embodiments, the directional coupler may have a first terminal, a second terminal, a third terminal, and a fourth terminal, wherein the directional coupler has a first resistor [e.g., of magnitude Z0 / N] connected between the first terminal and the second terminal, wherein the directional coupler has a second resistor [e.g., of magnitude 2N*Z0] connected between the first terminal and the third terminal, wherein the directional coupler has a third resistor [e.g., of magnitude 2N*Z0] connected between the second terminal and the fourth terminal, wherein the directional coupler has a transformer, wherein a first coil of the transformer is connected between the first terminal and the third terminal, and wherein a second coil of the transformer is connected between the second terminal and the fourth terminal [e.g.,wherein the first coil and the second coil have the same number of windings].

[0035] In embodiments, the directional coupler may have a first terminal, a second terminal, a third terminal, and a fourth terminal, wherein the directional coupler has a first resistor [e.g., of magnitude Z0 / N] connected between the first terminal and the second terminal, wherein the directional coupler has a second resistor [e.g., of magnitude 2N*Z0] connected between the first terminal and the third terminal, wherein the directional coupler has a third resistor [e.g., of magnitude 2N*Z0] connected between the second terminal and the fourth terminal, wherein the directional coupler has a transformer, wherein a first coil of the transformer is connected between the first terminal and the second terminal, and wherein a second coil of the transformer is connected between the third terminal and the fourth terminal [e.g.,wherein the first coil and the second coil have the same number of windings].

[0036] Further embodiments include an antenna arrangement with a magnetic antenna and a tuning device. The magnetic antenna comprises a singly or multiply interrupted loop and at least one tuning element [e.g., a variable capacitor or a capacitance diode] for tuning the magnetic antenna. The tuning device is connected to the tuning element, wherein the tuning device is configured to provide a control signal [e.g., tuning voltage] for tuning the magnetic antenna as a function of an amplitude of a signal based on a magnetic field [e.g., in the near field] generated by the loop [or magnetic antenna], and to control the tuning element with the control signal in order to tune the magnetic antenna.

[0037] In embodiments, the tuning device may comprise an induction loop or induction coil configured to provide the signal based on the magnetic field generated by the loop.

[0038] In embodiments, the loop of the magnetic antenna and the induction loop or the induction coil may be arranged [e.g., implemented] on the same circuit board.

[0039] In embodiments, the tuning device may be configured to control the tuning element with the control signal to regulate the amplitude of the signal based on the magnetic field generated by the loop toward a predetermined setpoint value [e.g., such that the amplitude is greater than or equal to a predetermined setpoint value].

[0040] For example, the tuning device can be designed to control the amplitude of the signal based on the magnetic field generated by the loop to the predetermined target value by controlling the tuning element with the control signal.

[0041] For example, the tuning device may be configured to track the control signal to counteract a deviation of the amplitude of the signal based on the magnetic field generated by the loop from the predetermined target value.

[0042] In embodiments, the specified target value can be determined in advance [e.g. during a factory calibration] by a reference measurement in the undisturbed case of the magnetic antenna and / or in the resonance case of the magnetic antenna.

[0043] In embodiments, the tuning device can be designed to determine the predetermined target value by a reference measurement in the undisturbed case of the magnetic antenna and / or in the resonance case of the magnetic antenna.

[0044] In embodiments, a predetermined signal can be transmitted with the magnetic antenna during the reference measurement.

[0045] For example, the predetermined signal may have a predetermined signal shape, predetermined transmission frequency, predetermined bandwidth, predetermined amplitude and / or predetermined modulation type.

[0046] For example, the specified signal can be a sine signal with a standardized transmission voltage.

[0047] In embodiments, the tuning device may be configured to select a control signal parameter from a set of stored control signal parameters associated with corresponding amplitude values ​​depending on the amplitude of the signal based on the magnetic field generated by the loop, and to provide the control signal depending on the control signal parameter [e.g., control signal amplitude].

[0048] In embodiments, the tuning device can be designed to determine a frequency-dependent amplitude distribution of the signal based on the magnetic field generated by the loop in the case of a broadband transmission of a transmission signal or a transmission of the transmission signal at multiple frequencies, and to provide the control signal as a function of the frequency-dependent amplitude distribution.

[0049] In embodiments, the tuning device can be designed to determine, when a transmission signal is transmitted at at least two different frequencies, a tuning direction in which the tuning signal is to be readjusted, based on at least two amplitudes of the signal resulting from the at least two different frequencies of the transmission signal, which amplitudes are based on the magnetic field generated by the loop, and to readjust the tuning signal depending on the determined tuning direction.

[0050] Further embodiments provide an antenna arrangement with an antenna and a tuning device. The antenna comprises at least one tuning element [e.g., a variable capacitor or a capacitance diode] for tuning the antenna. The tuning device is connected to the tuning element, wherein the tuning device is configured to provide a control signal for tuning the antenna as a function of a power or current consumption of a transmitting device connected to the antenna or of at least one active component [e.g., a power transistor] of the transmitting device, and to control the tuning element with the control signal in order to tune the antenna.

[0051] In embodiments, the antenna may be an electrical antenna.

[0052] In embodiments, the antenna may be a magnetic antenna with a single or multiple interrupted loop.

[0053] In embodiments, the tuning device can be designed to control the tuning element with the control signal in order to regulate the power or current consumption of the transmitting device or of the at least one active component of the transmitting device to a predetermined target value range.

[0054] For example, the tuning device can be designed to regulate the power or current consumption of the transmitting device or of at least one active component of the transmitting device to the predetermined target value range by controlling the tuning element with the control signal.

[0055] For example, the tuning device can be designed to track the control signal in order to counteract a deviation of the power or current consumption of the transmitting device or of the at least one active component of the transmitting device from the predetermined value range.

[0056] In embodiments, the specified target value range [e.g. in advance / at the factory] can be determined by a system simulation assuming an ideal or nearly ideal adaptation of the antenna.

[0057] In embodiments, the specified target value range [e.g. in advance / at the factory] can be determined when the transmitting device is terminated with a predefined impedance [e.g. 50 ohms].

[0058] For example, the transmitting device can be terminated with a predefined impedance [e.g., 50 ohms], and the power or current consumption of the transmitting device can be determined (e.g., measured) to obtain the specified target value range. The specified target value range can, for example, correspond to the determined power or current consumption with a tolerance of ± 10% (or ± 5%, or ± 3%).

[0059] In embodiments, the predetermined target value range can be determined based on an antenna measurement [e.g., by means of an antenna tuner].

[0060] For example, during antenna measurement, the point of maximum radiated power can be determined and the power or current consumption of the transmitting device at that point can be determined to obtain the specified target value range. The specified target value range can, for example, correspond to the determined power or current consumption with a tolerance of ± 10% (or ± 5%, or ± 3%).

[0061] In embodiments, the specified target value range [e.g. in advance / at the factory] can be determined based on an average value of the power or current consumption with a short-circuited termination and an open termination of the transmitting device.

[0062] For example, the power or current consumption of the transmitting device with a short-circuited termination and an open connection can be determined and the average value of the power or current consumption of the transmitting device with a short-circuited termination and an open connection can be calculated in order to obtain the specified target value range.

[0063] The specified setpoint range can, for example, correspond to the mean value of the power or current consumption with a tolerance of ± 10% (or ± 5% or ± 3%).

[0064] In embodiments, the specified target value range [e.g. in advance / at the factory] can be determined based on a measurement of a radiation power.

[0065] For example, when measuring the radiated power, the maximum radiated power can be determined and the power or current consumption at the maximum radiated power can be determined (e.g., measured) to obtain the specified target value range. The specified target value range can, for example, correspond to the determined power or current consumption with a tolerance of ± 10% (or ± 5%, or ± 3%).

[0066] In embodiments, the radiated power can be measured with an external antenna or by the tuning device itself with an antenna of the tuning device.

[0067] For example, the antenna of the tuning device can be a coupling loop arranged [e.g. implemented] on the same board as the loop of the magnetic antenna.

[0068] In embodiments, the tuning device can be designed to provide the control signal for tuning the antenna as a function of a current consumption of at least one power transistor of an amplifier of the transmitting device.

[0069] In embodiments, the tuning device can be designed to provide the control signal for tuning the antenna as a function of a difference between supply currents of two power transistors of the amplifier of the transmitting device.

[0070] In embodiments, the tuning device can be designed to provide the control signal for tuning the antenna as a function of a bias current of at least one power transistor of the amplifier of the transmitting device.

[0071] In embodiments, the tuning device may be configured to determine the bias current of the at least one power transistor by measuring a voltage across a resistor in the bias branch of the power transistor.

[0072] In embodiments, the tuning device can be designed to provide the control signal for tuning the antenna as a function of a difference between bias currents of at least two power transistors of the amplifier of the transmitting device.

[0073] In embodiments, the tuning device can be designed to provide the control signal for tuning the antenna as a function of a difference between supply currents of a balanced amplifier of the transmitting device.

[0074] In embodiments, the tuning device can be designed to provide the control signal for tuning the antenna as a function of a difference between supply currents of a Doherty amplifier of the transmitting device.

[0075] In embodiments, the tuning device can be designed to provide the control signal for tuning the antenna as a function of a difference between supply currents of a push-pull amplifier of the transmitting device.

[0076] In embodiments, the tuning device may be configured to provide the control signal for tuning the antenna as a function of a common-mode impedance of the antenna.

[0077] In embodiments, the tuning device can be designed to determine the common-mode impedance of the antenna by means of a measurement signal.

[0078] In embodiments, the tuning device can be designed to determine the power consumption of the transmitting device when a differential mode signal and a common mode signal are alternately fed into the antenna.

[0079] In embodiments, the common-mode signal may be fed in using a balun that allows access to the common-mode mode.

[0080] In embodiments, the tuning device may be configured to provide the control signal for tuning the antenna in dependence on a reflected common-mode signal of the antenna.

[0081] In embodiments, the tuning device may be configured to determine [e.g., measure] the reflected common-mode signal by means of a balun that allows access to the common-mode mode.

[0082] In embodiments, the tuning device may be configured to determine [e.g., measure] the reflected common-mode signal via non-linear properties of a magnetic core of the balun.

[0083] In embodiments, the tuning device may be configured to determine [e.g., measure] a magnetic direct current of the magnetic core by means of a Hall sensor.

[0084] In embodiments, the tuning device can be designed to determine [e.g., to measure] a magnetic direct current of the magnetic core by means of a measuring winding on the magnetic core.

[0085] In embodiments, the balun may be a ring coupler.

[0086] In embodiments, the loop may simply be interrupted, wherein the loop is interrupted by the tuning element.

[0087] In embodiments, the loop may be interrupted multiple times, wherein the loop is interrupted by the tuning element and by one or more capacitance elements.

[0088] In embodiments, the tuning element may be a variable capacitor or a capacitance diode.

[0089] Further embodiments provide a subscriber of a wireless communication system, wherein the subscriber has a transmitting and / or receiving device and an antenna arrangement connected to the transmitting and / or receiving device according to one of the embodiments described herein.

[0090] Further embodiments provide a method for tuning a magnetic antenna with a singly or multiply interrupted loop. The method comprises a step of providing a control signal for tuning the magnetic antenna depending on the phase position of a signal leading into the magnetic antenna. Furthermore, the method comprises a step of controlling a tuning element of the magnetic antenna with the control signal in order to tune the magnetic antenna.

[0091] Further embodiments provide a method for tuning a magnetic antenna with a singly or multiply interrupted loop. The method comprises a step of providing a control signal for tuning the magnetic antenna as a function of an amplitude of a signal based on a magnetic field generated by the loop. Furthermore, the method comprises a step of controlling a tuning element of the magnetic antenna with the control signal in order to tune the magnetic antenna.

[0092] Further embodiments provide a method for tuning an antenna. The method comprises a step of providing a control signal for tuning the antenna depending on the power or current consumption of a transmitting device connected to the antenna or at least one active component of the transmitting device. Furthermore, the method comprises a step of controlling a tuning element of the antenna with the control signal in order to tune the antenna.

[0093] With the magnetic antennas addressed in embodiments, (1) the size of participants in a communication system, such as sensor nodes, can be reduced, (2) independence from the environment can be created through automatic tuning, and / or (3) transmission / reception can be (better) achieved from (partially) electrically shielded environments.

[0094] Embodiments of the present invention are described in more detail with reference to the accompanying figures. They show: Fig. 1a is a schematic view of a subscriber of a communication system according to an embodiment of the present invention, Fig. 1b is a schematic view of a subscriber of a communication system according to an embodiment of the present invention, Fig. 1c is a schematic view of an endpoint of a communication system according to an embodiment of the present invention, Fig. 2 is a schematic view of a magnetic antenna, Fig. 3 is a schematic view of a magnetic antenna with a multiply interrupted (e.g. capacitively shortened) loop according to an embodiment of the present invention, Fig. 4 is a schematic view of a magnetic antenna with a multiply interrupted loop, the loop being octagonal, according to an embodiment of the present invention,5 is a schematic view of an antenna arrangement with a first magnetic antenna and a second magnetic antenna, according to an embodiment of the present invention, Fig. 6a is a schematic block diagram of an antenna arrangement, according to an embodiment of the present invention, Fig. 6b is a schematic block diagram of an antenna arrangement, according to an embodiment of the present invention, Fig. 7 is a schematic block diagram of an antenna arrangement, according to an embodiment of the present invention, Fig. 8 is a diagram showing phase responses of a resonant circuit from [1] with low attenuation and high attenuation, Fig. 9 is a schematic block diagram of an antenna arrangement, according to an embodiment of the present invention, Fig. 10a is a schematic block diagram of a conventional directional coupler, Fig.10b shows a schematic block diagram of a directional coupler according to an exemplary embodiment of the present invention. Fig. 10c shows a schematic block diagram of a directional coupler according to a further exemplary embodiment of the present invention. Fig. 11a shows a schematic block diagram of a transformer according to a first arrangement. Fig. 11b shows a schematic block diagram of a transformer according to a second arrangement. Fig. 12 shows a schematic block diagram of an antenna arrangement according to an exemplary embodiment of the present invention. Fig. 13 shows a schematic block diagram of a measurement setup for determining an output power and a reflected power of an antenna. Fig. 14 shows a schematic block diagram of a measurement setup for determining ideal antenna matching. Fig. 15 shows the current consumption of the transmitting device plotted against the antenna impedance in a Smith chart.16 shows the output power plotted against the antenna impedance in a Smith chart. Fig. 17a shows a diagram showing a curve of a real part R and an imaginary part X of the antenna impedance plotted against the input current. Fig. 17b shows a diagram showing a curve of the output power plotted against the input current. Fig. 18 shows a diagram showing a curve of a real part R and an imaginary part X of the antenna impedance as well as a curve of the output power plotted against the input current. Fig. 19 shows a schematic block diagram of an antenna arrangement according to an embodiment of the present invention. Fig. 20 shows a measurement setup for determining the ideal antenna matching according to an embodiment of the present invention. Fig. 21 shows a schematic block diagram of a transmitting device with a power amplifier according to an embodiment of the present invention.22 shows a schematic block diagram of an antenna arrangement according to an embodiment of the present invention, Fig. 23 shows a schematic block diagram of a ring coupler that enables access to a common-mode mode of a differential port, Fig. 24 shows a schematic view of a magnetic core of a balun and a measuring winding around the magnetic core for detecting the common-mode properties of the balun via the non-linear properties of the magnetic core using the measuring winding, Fig. 25 shows a flow diagram of a method for tuning a magnetic antenna with a singly or multiply interrupted loop according to an embodiment of the present invention, Fig. 26 shows a flow diagram of a method for tuning a magnetic antenna with a singly or multiply interrupted loop according to an embodiment of the present invention, and Fig.27 a flowchart of a method for tuning a magnetic or electrical antenna, according to an embodiment of the present invention. .

[0095] In the following description of the embodiments of the present invention, identical or equivalent elements in the figures are provided with the same reference numerals so that their description is interchangeable.

[0096] Before embodiments of generating a tuning signal for tuning a magnetic antenna are described in Section 2, embodiments of a magnetic antenna are first described in Section 1.

[0097] In the following description, it is assumed, for example, that the magnetic antenna can be implemented in a subscriber of a communication system. 1. Design of a magnetic antenna

[0098] Fig. 1ashows a schematic view of a subscriber 100 of a communications system according to an embodiment of the present invention. The subscriber 100 comprises a transmitting and / or receiving device 102 (e.g., a transmitter) and an antenna arrangement 104 connected to the transmitting and / or receiving device 102, wherein the antenna arrangement 104 has a magnetic antenna 106 with a singly (ie, only once) interrupted loop 108.

[0099] Fig. 1b shows a schematic view of a subscriber 100 of a communications system according to an embodiment of the present invention. The subscriber 100 comprises a transmitting and / or receiving device 102 (e.g., a transmitter) and an antenna arrangement 104 connected to the transmitting and / or receiving device 102. The antenna arrangement 104 has a magnetic antenna 106 with a multiply interrupted loop 108.

[0100] The following primarily describes examples of the Fig. 1b The antenna arrangement 104 shown with the magnetic antenna 106 with the multiply interrupted loop is described. However, it should be noted that the embodiments described below are equally applicable to the Fig. 1a shown antenna arrangement 104 with the magnetic antenna 106 with the single interrupted loop are applicable.

[0101] In embodiments, the loop 108 of the magnetic antenna 106 may be interrupted by capacitance elements 110, such as resonant capacitors. For example, the loop 108 of the magnetic antenna 106, as shown in Fig. 1bFor illustration purposes, the loop 108 of the magnetic antenna 106 may be interrupted twice (e.g., capacitively shortened) by two capacitance elements 110. However, it should be noted that in embodiments, the loop 108 of the magnetic antenna 106 may also be interrupted multiple times by a different number of capacitance elements 110. Thus, in embodiments, the loop 108 of the magnetic antenna 106 may be divided into n segments (or parts, or sections) by n capacitance elements 110, where n is a natural number greater than or equal to two. Segments are referred to herein as the parts or sections of the loop between the respective capacitance elements 110.

[0102] In embodiments, the segments of the multi-interrupted loop 108 can be connected by the capacitance elements 110. In detail, each two segments of the multi-interrupted loop can be connected by a capacitance element connected in series between the two segments. In other words, the segments of the loop 108 of the magnetic antenna 106 and the capacitance elements 110 are alternately connected in series to form a loop.

[0103] The transmitting and / or receiving device 102 can be connected to the magnetic antenna 106 via one of the capacitance elements 110. The one capacitance element on one side and the multiply interrupted loop 108 with the other (or remaining) capacitance elements on the other side can form a parallel resonant circuit (e.g., from the perspective of the transmitting and / or receiving device 102).

[0104] In embodiments, the antenna arrangement 102 may further include a tuning device for tuning the magnetic antenna 106. The tuning device may be configured to automatically tune the magnetic antenna 106.

[0105] Due to the geometric shape of the loop 108 of the magnetic antenna 106, the radiation energy from the magnetic antenna 106 is not radiated uniformly in all directions of a plane. Rather, the antenna pattern of the Fig. 1b shown magnetic antenna 106 has zero points, ie there are areas (eg points) in the antenna pattern where the radiation energy of the magnetic antenna is practically zero. In embodiments, the antenna arrangement 104 may therefore have a second magnetic antenna, as described below with reference to Fig. 5explained in more detail, or an additional electrical antenna. The second magnetic antenna and / or the additional electrical antenna can be arranged such that the zero points of the magnetic antenna 106 are compensated.

[0106] In exemplary embodiments, the subscriber 100 of the communication system can of course be configured not only to send signals to other subscribers of the communication system using the magnetic antenna 106, but also to receive signals from other subscribers of the communication system using the magnetic antenna 106. For this purpose, the subscriber 100 can, for example, have a receiving device (e.g., a receiver) connected to the antenna arrangement 104. Of course, the subscriber 100 can also have a combined transceiver device (e.g., a transceiver) 102.

[0107] In embodiments, the subscriber 100 (or the subscriber's communication system) may be configured to communicate in the ISM band (ISM = Industrial, Scientific and Medical Band), ie to send and / or receive signals in the ISM band.

[0108] In embodiments, the subscriber 100 (or the subscriber's communication system) can be configured to transmit data based on the telegram splitting method. In the telegram splitting method, data, such as a telegram or data packet, is split into a plurality of sub-data packets (or partial data packets, or sub-packets), and the sub-data packets are transmitted from one subscriber to another subscriber (e.g., from the base station to the endpoint, or from the endpoint to the base station) of the communication system using a time and / or frequency hopping pattern, distributed in time and / or frequency (i.e., non-contiguously), wherein the subscriber receiving the sub-data packets reassembles (or combines) them to obtain the data packet. Each of the sub-data packets contains only a part of the data packet.The data packet may also be channel-coded so that only a portion of the sub-data packets is required to decode the data packet error-free.

[0109] In embodiments, the communication system may be a personal area network (PAN) or a low power wide area network (LPWAN).

[0110] The Fig. 1b The subscriber 100 of the communication system shown may be a base station of the communication system. Alternatively, the Fig. 1b The participant 100 of the communication system shown can also be an end point of the communication system, as will be shown below with reference to Fig. 1c is explained.

[0111] In detail, Fig. 1ca schematic view of a subscriber 100 of the communication system, wherein the subscriber 100 is an endpoint, according to an embodiment of the present invention.

[0112] As in Fig. 1c As shown by way of example, the endpoint 100 may be a sensor node in embodiments. For example, in the case of a sensor node, the endpoint 100 may include a sensor 114, such as a temperature sensor, pressure sensor, humidity sensor, or any other sensor, wherein the signals sent by the sensor node 100 depend on a sensor signal provided by the sensor. For example, the sensor may include a microprocessor 112 that processes the sensor signal provided by the sensor to generate data to be transmitted based on the sensor signal, which data is sent by the transmitting device (e.g., transmitting and receiving device) 102, e.g., based on the telegram splitting transmission method.

[0113] Of course, the endpoint 100 can also be an actuator node, wherein the actuator node has an actuator 114. In this case, the processor 112 can, for example, be configured to control the actuator 114 based on a received signal or received data.

[0114] In embodiments, the endpoint 100 may be battery-powered. Alternatively or additionally, the endpoint 100 may include an energy harvesting element for generating electrical energy.

[0115] Detailed embodiments of the magnetic antenna 106 or the antenna array 104 (e.g., for sensor nodes or base stations) are described below. The magnetic antenna 106 or the antenna array 104 can be used for transmitting and / or receiving. 1.1. Application of magnetic antennas in sensor nodes

[0116] A magnetic antenna 106 has a single- or multi-turn current loop 108. During reception, an alternating magnetic field induces a voltage in the loop 108 (induction law); during transmission, a current flowing in the loop 108 generates a magnetic field (Biot-Savart law). If the magnetic antenna 106 is to be operated only at one frequency or a range of small relative bandwidth, its efficiency can be significantly increased by means of a resonant capacitance. The current flow in the loop 108 increases in proportion to the resonance enhancement (expressed by the quality factor Q), i.e., double Q results in double the current flow (and thus double the magnetic field (only possible with the square root when P = constant; only when U = constant would it be linear) with the same input power.Therefore, it is desirable to achieve the highest possible Q factor, which means that both the 108 loop and the capacitance must have the lowest possible losses. Typically, the losses in the 108 loop predominate due to the finite conductivity of the metal used (usually Cu).

[0117] Fig. 2 shows a schematic view of such a magnetic antenna 106. The magnetic antenna 106 comprises, as already mentioned, the loop 108 with one or more windings and the resonant capacitor 110 (C0). The magnetic antenna 106 can be connected via the parallel resonant circuit formed by the resonant capacitor 110 and the loop 108 (coil), for example, to the transmitting and / or receiving device 102 (see Fig. 1 ) can be connected.

[0118] The magnetic antenna 106 has the advantage of high antenna quality with a small design.

[0119] In addition, the magnetic antenna 106 has the advantage that it can be adapted to different environmental conditions, e.g. by automatic tuning.

[0120] Embodiments of the present invention thus relate to a sensor node with a magnetic antenna. The magnetic antenna can be automatically tuned. 1.2 Multiple shortening of the loop of the magnetic antenna

[0121] Fig. 3 shows a schematic view of a magnetic antenna 106 with a multiply interrupted (e.g. capacitively shortened) loop 108. As in Fig. 3As shown by way of example, the loop 108 can be divided into four segments by four capacitance elements 110 (4C0), such as resonant capacitances (e.g., resonant capacitors). However, it should be noted that the loop 108 of the magnetic antenna 106 can also be divided into a different number of segments. Thus, in embodiments, the loop 108 of the magnetic antenna 106 can be divided into n segments by n capacitance elements 110, where n is a natural number greater than or equal to two.

[0122] In exemplary embodiments, the loop 108 of the magnetic antenna can be divided into equidistant segments. Dividing the loop 108 into equidistant segments has the advantage of achieving the lowest overall electric field components. Of course, the loop can also be divided into non-equidistant segments.

[0123] The lower electric fields or the multiple capacitive shortening have the advantage that dielectric material in the immediate vicinity of the antenna detunes its resonance frequency accordingly less.

[0124] Furthermore, the lower electric fields or the multiple capacitive shortening have the advantage that dielectric, lossy material in the immediate vicinity of the antenna reduces its quality factor less.

[0125] Furthermore, the lower electric fields or the multiple capacitive shortening have the advantage that the voltage across the resonant capacitances is correspondingly lower (e.g., half the voltage with double shortening, but then also double the capacitance value). This is particularly advantageous if one or more of the resonant capacitances are to be tunable, since the tuning elements can then have a lower dielectric strength.

[0126] In embodiments, the magnetic antenna 106 (or the loop 108 of the magnetic antenna 106) can be capacitively shortened several times.

[0127] In embodiments, several capacitors 110 are arranged serially in the magnetic loop. 1.3 Special design of the loop of the magnetic antenna

[0128] Loops 108 with a round shape have the best ratio of trace length to spanned (or enclosed) area. However, the space utilization on a typically rectangular circuit board (trace lines) is not optimal.

[0129] Shapes with more than four corners, especially the octagonal shape, offer advantages here. While the area-to-perimeter ratio and thus the quality of the magnetic antenna 106 deteriorates, the efficiency of the magnetic antenna 106 increases for a given rectangular board area because the spanned (or enclosed) area becomes larger. Fig. 4shows a symmetrical design (of the loop 108) of the magnetic antenna 106, but asymmetrical designs (of the loop 108) are also conceivable, in which, for example, the upper and lower sections (e.g. segments of the loop 108) are longer.

[0130] In detail, Fig. 4 a schematic view of a magnetic antenna 106 with a multiply interrupted loop 108, wherein the loop 108 is octagonal in shape.

[0131] As in Fig. 4As shown by way of example, the loop 108 can be divided into eight segments by (e.g., eight) capacitance elements 110, wherein the eight segments can be angular, so that the loop 108 has an octagonal shape. However, it should be noted that the loop 108 can also be divided into a different number of segments and / or have a different shape. Thus, in embodiments, the loop 108 of the magnetic antenna can be m-angular, where m is a natural number greater than or equal to three, such as 3, 4, 5, 7, 8, 9, 10, 11, or 12.

[0132] In embodiments, the magnetic antenna 106 may be implemented on a printed circuit board (PCB).

[0133] In embodiments, the magnetic antenna 106 (or the loop 108 of the magnetic antenna 106) may have sections (or segments) that are not round.

[0134] In embodiments, a routing of the segments of the magnetic antenna 106 (or the loop 108 of the magnetic antenna 106) may be straight in the areas (or in the locations) with components.

[0135] In embodiments, the magnetic antenna 106 (or the loop 108 of the magnetic antenna 106) may have a polygonal shape or more than four corners.

[0136] Such a magnetic antenna 106 has the advantage that the layout is easier to transfer to different layout programs.

[0137] Furthermore, such a magnetic antenna 106 has the advantage that placement of the components is easier, since the cable routing (of the loop 108 of the magnetic antenna 106) is straight at the locations with the components.

[0138] In some embodiments, the diagonal sides (segments of loop 108 of magnetic antenna 106) may have a circular arc shape instead of a square shape to further increase the area and maximize the board space. In return, the advantages of easier component placement and simple layout would be lost.

[0139] Although the Fig. 4 shown antenna arrangement 104 has a magnetic antenna 106 with a multiply interrupted loop 108, it should be noted that the described embodiments also apply to an antenna arrangement 104 with a magnetic antenna 106 with a single interrupted loop 108 (cf. Fig. 1a ) are applicable. 1.4. The loop is implemented on a circuit board

[0140] In embodiments, the loop can be implemented on a printed circuit board (PCB).

[0141] In embodiments, the tuning circuit can be implemented on the same circuit board. 1.5. Multiple antennas

[0142] In embodiments, the antenna assembly 104 may include multiple magnetic antennas.

[0143] This has the advantage that the zero point (e.g. points in the antenna pattern where the radiation energy of the magnetic antenna is practically zero) of a magnetic antenna can be bypassed. 1.5.1 Crossfield Loop with Diversity

[0144] In embodiments, two magnetic antennas may be used, wherein the two magnetic antennas are preferably (e.g., substantially) orthogonal. 1.5.2 Flattened second loop to get out of zero

[0145] To achieve the flattest possible housing, the second magnetic antenna (or the loop of the second magnetic antenna) can be "flattened." With loops that are not round, the resistance of the winding increases compared to the spanned (or enclosed) area, thereby reducing the Q factor. Since the flattened loop spanned a smaller area, its radiation efficiency decreased. While this slightly increased the Q factor, it did not contribute to the radiation. To at least partially compensate for the first Q factor-reducing effect, a wider conductor (less loss) could be used.

[0146] Fig. 5 shows a schematic view of an antenna arrangement 104 with a first magnetic antenna 106 and a second magnetic antenna 112, according to an embodiment of the present invention.

[0147] The first magnetic antenna 106 comprises a multiply interrupted loop 108. As in Fig. 5 As shown by way of example, the loop 108 of the first magnetic antenna can be divided into four segments by four capacitance elements 110. However, it should be noted that the loop 108 of the first magnetic antenna 106 can also be divided into a different number of segments. Thus, in embodiments, the loop 108 of the first magnetic antenna 106 can be divided into n segments by n capacitance elements 110, where n is a natural number greater than or equal to two.

[0148] The second magnetic antenna 112 also includes a loop 114, wherein the loop 108 of the first magnetic antenna 106 and the loop 114 of the second magnetic antenna 112 may be arranged substantially orthogonally to each other.

[0149] As in Fig. 5As shown by way of example, an area defined by the loop 114 of the second magnetic antenna 112 runs orthogonally to an area defined by the loop 108 of the first magnetic antenna 106. In detail, Fig. 5 the area spanned by the loop 108 of the first magnetic antenna 106 is parallel to the xy-plane defined by the coordinate system, while the area spanned by the loop 114 of the second magnetic antenna 112 is parallel to or in the z-axis of the coordinate system.

[0150] In embodiments, a spanned (or enclosed) area of ​​the loop 114 of the second magnetic antenna 112 may be at least a factor of two (e.g., a factor of three, four, five, or ten) smaller than a spanned (or enclosed) area of ​​the loop 108 of the first magnetic antenna 106.

[0151] In other words, the loop 114 of the second magnetic antenna 112 may be "flattened."

[0152] As in Fig. 5 As further indicated, in embodiments, a conductor of the loop 114 of the second magnetic antenna 112 may be at least a factor of two (e.g., a factor of three, four, or five) thicker or wider than a conductor of the loop 108 of the first magnetic antenna 106.

[0153] Of course, the loop 114 of the second magnetic antenna 112 can also be interrupted multiple times, for example by at least two capacitance elements.

[0154] In embodiments, the antenna arrangement 104 may have a second, preferably orthogonal loop 114.

[0155] In embodiments, a wire gauge / width of the second loop 114 may be larger (than a wire gauge / width of the first loop 108), but the second loop 114 may be flatter (than the first loop 108).

[0156] Although the Fig. 5 Although the antenna arrangement 104 shown comprises magnetic antennas with multiple interrupted loops, it should be noted that the described embodiments are equally applicable to an antenna arrangement with magnetic antennas with single interrupted loops. 1.5.3 Combined magnetic / electrical antenna to get out of zero point

[0157] In order to bypass the zero point (e.g. points in the antenna pattern where the radiation energy of the magnetic antenna is practically zero) of the magnetic antenna 106, an electrical antenna can be integrated on the printed circuit board (e.g. PCB) in addition to the magnetic antenna 106, e.g. in the form of a PCB F-antenna, as an "extension" of the loop 108 (e.g. the magnetic ring / octagon).

[0158] In embodiments, an electrical and a magnetic antenna (e.g. on a printed circuit board (e.g. PCB)) can be combined. 1.5.4. Switching the loops

[0159] If several magnetic loops (or magnetic antennas) are combined without further measures, a new zero point is created from a different direction.

[0160] Therefore, the use of multiple magnetic loops (or multiple magnetic antennas) only makes sense if the unused loop(s) (or magnetic antenna(s)) can be switched off. 1.5.4.1. Switching off by interrupting the resonance current

[0161] In some embodiments, the current flow of the unwanted magnetic antenna can be interrupted, for example, using a switch. However, since every switch has a certain residual capacitance, this ultimately results in a significant detuning of the resonant frequency. 1.5.4.2. Switching off by additional inductance (L)

[0162] In some embodiments, one or more resonant capacitors can be connected in parallel with a coil. These form a parallel resonant circuit at the loop's original resonant frequency, interrupting the current flow within it. 1.5.4.3 Change control ratio

[0163] In some embodiments, a slight detuning of the natural resonance of one of the two loops can shift the tuning of the loops and thus the main radiation direction and thus the zero point, since the loops then radiate with different intensities at unchanged high drive power. The unradiated portion of the slightly detuned loop is reflected back and absorbed in the transmitter. 1.5.4.4. Phase-shifted control of magnetic loops

[0164] The zero of a loop depends on its structure in three-dimensional space. This does not change if, for example, only the capacitance of a resonant capacitor is changed. In planar loops there is always a position in which no B field lines penetrate them, namely when these run in the plane of the loop. But even in a three-dimensional loop (or curved B lines), for example in a slightly bent circular ring that does not run exactly in a plane, one can always find a position in which field lines entering from one side and the other side of the loop balance each other out. This leads to compensation, i.e. a zero. Even orthogonal loops would have a zero below 45° if their signals were only directly connected.To avoid this, their received signals can be combined with a 90° phase shift, because then geometric cancellation of the time signals is no longer possible.

[0165] In embodiments, several magnetic loops can be controlled in a phase-shifted manner.

[0166] In embodiments, several self-tuned magnetic loops can be controlled in a phase-shifted manner. 1.5.5. Variation of the radiation ratio over the hop number

[0167] In connection with the Telegram Splitting transmission method [6], transmission diversity (i.e. transmission with different antennas) can be carried out per Telegram, since the Telegram Splitting transmission method allows each sub-data packet (hop) to be transmitted on a different antenna / with different strengths on the antennas.

[0168] This has the advantage that the transmission security of a telegram can be increased.

[0169] In embodiments, different sub-data packets (hops) can therefore be radiated with different intensity on different antennas, so that different sub-data packets are transmitted with different antenna zero points. 1.5.5,1. Execution of the loop where the zero depends on the frequency

[0170] In exemplary embodiments, more or less orthogonal loops with different resonant frequencies can be used, the signals of which are combined, for example, using a decoupled combiner. If the resonant frequencies are close to each other, the loops must already exhibit good geometric orthogonality (i.e., magnetic decoupling). Otherwise, quality degradation and resonance distortions occur. Therefore, the resonant frequency is intentionally slightly detuned. Different sub-data packets (hops) are at different frequencies and are therefore transmitted with different intensities by the loops with different resonances. As a result, the zero point of the magnetic antenna is shifted in each case.

[0171] In exemplary embodiments, the radiation ratio of the magnetic antennas changes over the frequency.

[0172] In exemplary embodiments, the zero point of the antenna shifts over the frequency. 2. Generation of a tuning signal

[0173] Fig. 6a shows a schematic block diagram of an antenna arrangement 104 according to an embodiment of the present invention.

[0174] The antenna arrangement 104 comprises a magnetic antenna 104 with a single (ie, only once) interrupted loop 108 and a tuning element 111 for tuning the magnetic antenna 104.

[0175] The tuning device 120 is designed to provide a tuning signal (e.g., a control signal) 122 for tuning the magnetic antenna 106, and to control the tuning element 111 with the tuning signal 122 in order to tune the magnetic antenna 106.

[0176] In embodiments, the loop 108 of the magnetic antenna may be interrupted by the tuning element 111, where the tuning element 111 may be a variable (or adjustable) capacitance (e.g., variable resonant capacitance). For example, the tuning element 111 may be a variable capacitor or a capacitance diode.

[0177] Fig. 6b shows a schematic block diagram of an antenna arrangement 104 according to an embodiment of the present invention.

[0178] The antenna arrangement 104 comprises a magnetic antenna 104 with a multiply interrupted loop 108 and at least one tuning element 111 for tuning the magnetic antenna 104.

[0179] The tuning device 120 is designed to provide a tuning signal (e.g. control signal) 122 for tuning the magnetic antenna 106, and to control the tuning element 111 with the tuning signal 122 in order to tune the magnetic antenna 106.

[0180] In embodiments, the loop 108 of the magnetic antenna 106 may be interrupted multiple times by capacitance elements 110, such as resonant capacitors. For example, the loop 108 of the magnetic antenna 106, as shown in Fig. 6bFor illustration purposes, the loop 108 of the magnetic antenna 106 may be interrupted twice (e.g., capacitively shortened) by two capacitance elements 110. However, it should be noted that in embodiments, the loop 108 of the magnetic antenna 106 may also be interrupted multiple times by a different number of capacitance elements 110. Thus, in embodiments, the loop 108 of the magnetic antenna 106 may be divided into n segments (or parts, or sections) by n capacitance elements 110, where n is a natural number greater than or equal to two. Segments herein refer to the parts or sections of the loop 108 between the respective capacitance elements 110.

[0181] The at least one tuning element 111 can be one of the capacitance elements 110, wherein the tuning element 111 can be embodied as a variable capacitance element, e.g., as a variable resonant capacitance. For example, the tuning element 111 can be a variable capacitor or a varactor diode. Of course, a subset or all of the capacitance elements 110 can also be tuning elements 111, such as variable capacitance elements (e.g., variable capacitors or varactor diodes). In other words, there can also be multiple tuning elements, e.g., varactor diodes, such as, for example, at n-1 of n interruptions.

[0182] As in the Fig. 6a and 6bAs indicated by way of example, the antenna arrangement 104 can be connected to a source and / or sink 102, such as a transmitting and / or receiving device (e.g., a subscriber 100 of a communications system). However, it should be noted that embodiments of the present invention primarily relate to the antenna arrangement 104, which can be implemented in a variety of different application areas.

[0183] In embodiments, the loop circumference of the singly or multiply interrupted loop can be 1 / 2 to 1 / 10 of a wavelength of the signal propagating into the magnetic antenna or of a transmission signal to be transmitted or received with the magnetic antenna. For example, the wavelength can be less than or equal to 1.999 m (e.g., at frequencies greater than or equal to 149 MHz), or less than or equal to 0.749 m (e.g., at frequencies greater than or equal to 400 MHz), or less than or equal to 0.375 m (e.g., at frequencies greater than or equal to 800 MHz).

[0184] In embodiments, a frequency of the signal leading into the magnetic antenna or of a transmission signal to be transmitted or received with the magnetic antenna can be greater than or equal to 149 MHz, 400 MHz or 800 MHz or can be in the range from 149 MHz to 930 MHz.

[0185] In embodiments, a frequency of the signal leading into the magnetic antenna or of a transmission signal to be transmitted or received with the magnetic antenna can be within an ISM band (ISM = Industrial, Scientific and Medical Band) or SRD band (SRD = Short Range Device), such as in the range from 169.4000 MHz to 169.8125 MHz, or in the range from 433.05 MHz to 434.79 MHz, or in the range from 863 MHz to 870 MHz, or in the range from 902 to 928 MHz.

[0186] In some embodiments, the magnetic antenna can be narrowband. For example, in some embodiments, the magnetic antenna can have a Q factor of 20 to 500. (Note: For magnetic antennas, the bandwidth is defined by the Q factor.)

[0187] In terms of its usable bandwidth, a magnetic antenna can be considered, in a first approximation, as a resonant circuit, which at the resonance point is at the frequency ω 0 = 2 πf0 by definition has the same capacitive and inductive reactive components: X C = 1 ω 0 C = X L = ω 0 L : = X 0

[0188] The antenna losses can be divided into a parallel or serial loss resistance R p or R s be summarized, whereby both replacement models are R p R s = X 0 2 can be converted into each other. Few losses mean high R p or a low R s . As kindness Q is the dimensionless quantity Q = R p X 0 = X 0 R s , which increases with decreasing losses. The usable bandwidth Δ ω a magnetic antenna, the value Δ ω = ω 0 Q This decreases as the quality increases.

[0189] In principle, a high Q factor is desired because, for the same input power, a correspondingly higher resonance current is generated, which in turn is directly proportional to the strength of the desired magnetic field. However, a distinction must be made between two effects: 1) Quality loss due to losses in the antenna elements themselves. These are essentially determined by the losses in the conductor material (usually Cu). This loss resistance, which can be considered serially, can be determined from the reduced conductor cross-section due to the skin effect and the conductor length according to known laws. With a highly irregularly shaped conductor cross-section, the current distribution within it also plays a role. In comparison, the predominantly dielectric losses in the resonant capacitor(s) are negligible as long as sufficiently high-quality capacitors are used. 2) Quality loss due to the radiation of the antenna ("radiation losses"). This effect is desired. In the model, they are referred to as the (serially considered) radiation resistance R s and are calculated for loop antennas consisting of one winding without the addition of ferromagnetic material, with a circumference U ≪ λ 0 4 according to [8] RS=π6Z0Uλ04

[0190] Here, Z 0 = 120 π Ω is the wave impedance of the vacuum and λ 0 is the vacuum wavelength at the resonance frequency. Doubling the loop diameter therefore means 16 times higher R s The smaller the radiation resistance R s the more significant the losses of the antenna elements become. But even with an ideally loss-free antenna, the problem remains that a very small value R s to the source impedance of the transmitter (usually around 50 ohms). The losses of the necessary matching network then become increasingly significant. Ultimately, almost all of the fed-in power goes into the matching network. An example: A loop with U ≪ λ 0 8 has a radiation resistance of only 0.048 ohms.

[0191] Even if this formula for larger antennas, the above assumption U ≪ λ 0 4 no longer suffice, no longer applies exactly, an increase in diameter or circumference still causes an increase in the radiation resistance.

[0192] Detailed embodiments of the generation of the tuning signal 122 (e.g. tuning control variable or tuning voltage) are described below.

[0193] Although in the following embodiments, reference is sometimes made to a magnetic antenna 106 with a single interrupted loop 108 and sometimes to a magnetic antenna 106 with a multiply interrupted loop 108, it should be noted that these embodiments are equally applicable to the respective other embodiment of the magnetic antenna 106. 2.1. Generation of a tuning signal (e.g. tuning voltage) by phase evaluation

[0194] Fig. 7shows a schematic block diagram of an antenna arrangement 104 according to an embodiment of the present invention. The antenna arrangement 104 comprises the magnetic antenna 106 with the tuning element 111 and the tuning device 120 for tuning the magnetic antenna 106.

[0195] The tuning device 120 is designed to provide the tuning signal 122 for tuning the magnetic antenna 106 as a function of a phase position of a signal 124 leading into the magnetic antenna 106 (e.g. leading power or leading wave), and to control the tuning element 111 with the tuning signal 122 in order to tune the magnetic antenna 106.

[0196] In embodiments, the tuning device 120 may be configured to provide the tuning signal 122 for tuning the magnetic antenna 106 depending on a phase relationship between the signal 124 leading into the magnetic antenna (e.g., leading power) and a phase signal 126.

[0197] The phase signal 126 may be based on a current flowing in at least a portion of the loop 108 and / or on a magnetic field generated by the loop 108 or magnetic antenna 106 (e.g., in the near field).

[0198] The phase signal 126 may be a power coupled out of the magnetic antenna 106 (e.g. inductively).

[0199] For example, the antenna assembly 104 may include a coupling loop 128 configured to extract power from the magnetic antenna 106 to obtain the power extracted from the magnetic antenna (e.g., inductively). The loop 108 of the magnetic antenna 106 and the coupling loop 128 may be arranged or implemented on the same circuit board.

[0200] In embodiments, the tuning device 120 may be configured to control the tuning element 111 with the tuning signal 122 in order to regulate a phase difference between the signal 124 leading into the magnetic antenna (e.g., leading power or leading wave) and the phase signal 126 to a predetermined desired value.

[0201] For example, the tuning device can be designed to control the phase difference between the signal 124 leading into the magnetic antenna (e.g. leading power) and the phase signal to the predetermined target value by controlling the tuning element with the control signal.

[0202] For example, the tuning device may be configured to track the control signal to counteract a deviation of the phase difference between the signal 124 leading into the magnetic antenna (e.g., leading power) and the phase signal from the predetermined target value.

[0203] In embodiments, the tuning device may be configured to effect the control of the phase difference between the signal 124 leading into the magnetic antenna (e.g., leading power) and the phase signal to the predetermined desired value using a control loop or a feed-forward control.

[0204] The following describes the functionality of the Fig. 7 shown embodiment of the generation of the tuning signal 122 is described in detail.

[0205] The transmission measurement of a resonant circuit exhibits a magnitude maximum and a phase inflection point at the resonance point. Depending on the degree of coupling of the feeding source to the circuit, this can be between 90° (loose coupling, see [1]) and 0° (tight coupling, see [2]). Fig. 8 ) lay.

[0206] In detail, Fig. 8 in a diagram showing the phase response of a resonant circuit from [1] with low damping and high damping. Fig. 8 the ordinate is the phase shift in degrees and the abscissa is the frequency.

[0207] The phase response is a monotonically increasing arctan -function that depends on a value ϕ 0 (at f = 0) up to a value ϕ 0 + 180° (at f → ∞) (see Fig. 8). The value at resonance is then ϕR = ϕ 0 + 90° and is an inflection point. Sometimes the phase is counted with a negative sign, in which case the above applies accordingly (from monotonically increasing to monotonically decreasing, etc., see [2]).

[0208] Embodiments utilize this fact for automatic frequency adjustment by comparing the phase position of the signal 124 (e.g., leading power) flowing into the loop 108 with a power inductively coupled from the loop 108, for example, via a small coupling loop 128. A directional coupler, for example, can be used to determine the phase position of the leading signal 124 (e.g., leading power). In addition, a further phase offset arises over different line lengths up to the location where the phase comparator is arranged on the circuit board. In some embodiments, a phase shifter Δ ϕ 0 is inserted so that at resonance the two signals have exactly a phase difference of e.g. 90°.

[0209] Phase comparators are well known from the literature. The Gilbert cell (see [4]) frequently used for this purpose essentially acts like a multiplier. Two sinusoidal time signals with a phase shift of Δ ϕ phase shifts deviating from 90° result in the following output signal after multiplication: sin ωt + Δ φ cos ωt = 1 2 sin Δ φ + sin 2 ωt + Δ φ (The amplitudes are normalized to 1 for simplicity). The component with twice the frequency 2 ωt can be easily filtered out with a low-pass filter, so that the DC component ~sin(Δ ϕ) remains. Since the sine function is an odd function, the resulting controlled variable changes sign around the operating point of 90° and is only zero at exactly 90°. When the control loop is closed with the correct sign, the resonant frequency of loop 108 is adjusted due to the virtually infinitely high control gain until the voltage at the multiplier output disappears, which means that the two voltages at the multiplier input have a 90° phase shift. According to the above explanations, loop 108 is then in resonance at the input frequency. Fig. 9 shows a block diagram of the described arrangement. The phase shifter is shown here in the output path of the directional coupler. As already mentioned, it can also be looped into the coupling loop path. This can preferably be selected so that the smaller phase shift is required.

[0210] In detail, Fig. 9 A schematic block diagram of an antenna arrangement 108 according to an embodiment of the present invention. The antenna arrangement 108 includes the magnetic antenna 106 and the tuning device 120.

[0211] As in Fig. 9 As shown, the tuning device 120 can be configured to derive (e.g., branch off) a signal from the signal 124 (e.g., leading power) flowing into the magnetic antenna 106 in order to obtain a derived (e.g., branched off) signal 132. The tuning device 120 can be configured to provide the tuning signal 122 for tuning the magnetic antenna 106 depending on a phase relationship between the derived signal 132 and the phase signal 126.

[0212] For example, the tuning device 120 can be designed to control the tuning element 111 with the tuning signal 122 in order to regulate the phase difference between the derived signal 132 and the phase signal 126 to a predetermined target value.

[0213] In embodiments, the tuning device 120 may further comprise a signal combiner 136 (e.g., multiplier or subtractor) configured to combine (1) the phase signal 126 or a phase-shifted version of the phase signal, and (2) the derived signal 132 or a phase-shifted version 138 of the derived signal 132, to obtain a combined signal 140. The tuning device 120 may be configured to drive the tuning element 111 with the tuning signal 122 in order to regulate (1) a DC component of the combined signal 140 or (2) a low-pass filtered version 146 of the combined signal 140 to a predetermined target value.

[0214] In embodiments, the tuner 120 may further include a phase shifter 134, which may be configured to phase-shift one of the derived signal 132 and the phase signal 126 to obtain a phase-shifted signal 138. The signal combiner (e.g., multiplier or subtractor) 136 may be configured to combine the phase-shifted signal 138 and the other of the derived signal 132 and the phase signal 126 to obtain a combined signal 140. The phase shifter 134 can be designed to phase-shift one of the derived signal 132 or the phase signal 126 such that, in the case of resonance of the magnetic antenna 106, the phase-shifted signal 138 and the other of the derived signal 132 and the phase signal 126 at the signal combiner 136 have a predefined phase difference (e.g., 90° ± 3° or ± 1° or 0.1°).

[0215] In the Fig. 9 In the embodiment shown, the phase shifter 134 is exemplary configured to phase-shift the derived signal 132 to obtain the phase-shifted signal 138, wherein the signal combiner 136 in this case may be configured to combine the phase-shifted signal 138 and the phase signal 126 to obtain the combined signal 140. According to another embodiment, the phase shifter 134 may be configured to phase-shift the phase signal 126 to obtain the phase-shifted signal 138, wherein the signal combiner 136 in this case may be configured to combine the phase-shifted signal 138 and the derived signal 132 to obtain the combined signal 140.

[0216] In embodiments, the tuning device may further include an energy extractor 130 (e.g., a directional coupler or other energy extracting device) configured to extract a portion of the signal 124 (e.g., power) forwarding into the magnetic antenna 106 to obtain the derived signal 132.

[0217] In embodiments, the tuning device 120 may further comprise a control amplifier 144 configured to provide the tuning signal 122 (e.g., control signal) for tuning the magnetic antenna 106, wherein the control amplifier 144 may be configured to drive the tuning element 111 with the tuning signal 122 in order to control (1) a DC component of the combined signal 140 or (2) a low-pass filtered version 146 of the combined signal 140 to a predetermined target value.

[0218] In embodiments, the tuning device 120 may further comprise a low-pass filter 142, which may be configured to low-pass filter the combined signal 140 to obtain a low-pass filtered signal 146 comprising the DC component of the combined signal 140.

[0219] In other words, Fig. 9 shows a block diagram for automatic frequency control using transmitted phase analysis. The control amplifier 144 can generally be implemented as an I controller or PI controller. Especially in frequency-hopping systems [6], it is important to ensure that its settling time is sufficiently short. This can be achieved by selecting a correspondingly short control time constant (e.g., ≤10 µs).

[0220] For the Fig. 9 Various versions of the directional coupler 130 shown are known in the literature. One of them can be found in [5, page 88, Figure 7.3] in a special embodiment. It is shown here in Fig. 10apresented in general form.

[0221] In detail, Fig. 10aa schematic block diagram of a conventional directional coupler 130. The directional coupler 130 comprises a first terminal 150, a second terminal 151, a third terminal 152, and a fourth terminal 153. Furthermore, the directional coupler 130 comprises a first resistor 154 (e.g., of value Z0 / N) connected between the first terminal 150 and the second terminal 151, and a second resistor 155 connected between an intermediate node between two transformers 157_1 and 157_2 and ground. The first transformer 157_1 comprises a first coil 158_1 connected between the first terminal 150 and the third terminal 152, and a second coil 159_1 connected between the intermediate node and ground. The second transformer 157_2 includes a first coil 158_2 connected between the second terminal 151 and the fourth terminal 153, and a second coil 159_2 connected between the intermediate node and ground.

[0222] In contrast to the Fig. 10a In contrast to the two-transformer directional coupler 130 shown, embodiments of the present invention provide a single-transformer directional coupler 130 (reduced number of transformers). Single-transformer directional coupler 130 embodiments are shown in the Fig. 10b and 10c shown.

[0223] Fig. 10bshows a schematic block diagram of a directional coupler 130 according to an embodiment of the present invention. The directional coupler 130 comprises a first terminal 150, a second terminal 151, a third terminal 152, and a fourth terminal 153. The directional coupler 130 further comprises a first resistor 154 (e.g., of value Z0 / N) connected between the first terminal 150 and the second terminal 151, a second resistor 155 (e.g., of value 2N*Z0) connected between the first terminal 150 and the third terminal 152, and a third resistor 156 (e.g., of value 2N*Z0) connected between the second terminal 151 and the fourth terminal 153.The directional coupler 130 further comprises a transformer 157, wherein a first coil 158 of the transformer 157 is connected between the first terminal 150 and the third terminal 152, and wherein a second coil 159 of the transformer 157 is connected between the second terminal 151 and the fourth terminal 153. The first coil 158 and the second coil 159 can have the same number of windings.

[0224] Fig. 10cshows a schematic block diagram of a directional coupler 130 according to an embodiment of the present invention. The directional coupler 130 comprises a first terminal 150, a second terminal 151, a third terminal 152, and a fourth terminal 153. The directional coupler 130 further comprises a first resistor 154 (e.g., of value Z0 / N) connected between the first terminal 150 and the second terminal 151, a second resistor 155 (e.g., of value 2N*Z0) connected between the first terminal 150 and the third terminal 152, and a third resistor 156 (e.g., of value 2N*Z0) connected between the second terminal 151 and the fourth terminal 153.The directional coupler 130 further comprises a transformer 157, wherein a first coil 158 of the transformer 157 is connected between the first terminal 150 and the second terminal 151, and wherein a second coil 159 of the transformer 157 is connected between the third terminal 152 and the fourth terminal 153. The first coil 158 and the second coil 159 can have the same number of windings.

[0225] The Fig. 10b The directional coupler 130 shown is derived from the Fig. 10a shown directional coupler by the two tightly coupled transformers 157_1 and 157_2 of Fig. 10a are combined into one and the resistor 155 in the middle of size N·Z_0 is distributed equally on both sides of the remaining transformer 157 in Fig. 10bwhich results in two resistors 155 and 156 with the value 2N·Z_0. Since resistors are less expensive than transformers, this minimal additional effort is irrelevant. In fact, the shift in the internal resistance can also be done in unequal parts, as long as the value of an imaginary parallel connection of these two resistors always results in the value N·Z_0. In the limiting case, only one resistor with the value N·Z_0 would suffice, which is placed on the left or right side of the transformer 157 of Fig. 10b However, real transformers never have 100% coupling factor, so the strictly symmetrical version of Fig. 10b also leads to a directional coupler behavior that is as symmetrical as possible (ie the two outputs for forward and reverse power then have the same properties as possible for forward or reverse feeding).

[0226] Fig. 10c shows a modification of the Fig. 10b directional coupler 130 shown, in which the transformer 157 is rotated by 90°. It can be shown that this is always possible for ideal transformers with a transformation ratio of 1:1, as long as galvanic isolation is not important. For the proof, see Fig. 11a and 11b .

[0227] Consider a fixed-coupled (k = 100%) transformer with a transformation ratio of 1:1 and infinitely high main inductance (ideal transformer). It is as in Fig. 11a integrated into a network where the voltages related to ground are measured at three nodes U 1 , U 2 and U 3 may be present. The tension U 4 is no longer freely selectable, because it is subject to the circuit requirement U prime = U sec the condition U 4 = U 3 − U sek = U 3 − U 1 − U 2 = U 2 + U 3 − U 1

[0228] If galvanic isolation is not required (and only then!), the transformer can also be rotated by 90°, as shown in Fig. 11bHere, too, the network is expected to exploit the potential U 1 , U 2 and U 3 are given in the same way. Now let U prime = U 1 - U 3 . Because U prime = U sec = U 2 - U 4 must be for U 4 therefore apply: U 4 = − U prim + U 2 = U 2 − U 1 − U 3 = U 2 + U 3 − U 1

[0229] The fourth voltage, determined by the circuit constraint, results in the same value in both cases, thus the networks are equivalent.

[0230] However, since real transformers are not ideal, ie the main inductance is not infinitely large, the leakage inductance is not zero and the coupling factor is less than 100%, depending on the existing transformer and the intended frequency range, the version from Fig. 10b or Fig. 10c deliver better results.

[0231] In embodiments, an evaluation of the phase position of the signal 124 (e.g., leading power) leading into the magnetic loop 108 is carried out, for example by means of a comparison between the phase position of the signal 124 (e.g., leading power) leading into the magnetic loop 108 with the power inductively coupled from the loop 108, for example via a small coupling loop 128.

[0232] Since the tuning direction is known by this method of phase evaluation (in the procedure in the next section, the direction in which tuning must be carried out is not known), a very fast tracking of the resonance is possible, thus enabling tuning per hop in frequency hopping systems, magnetic antennas can thus be used for frequency hopping systems or for telegram splitting systems [6] and [7].

[0233] Embodiments create a directional coupler version with a reduced number of transformers. 2.2. Generation of tuning information / matching information by amplitude evaluation during self-reception

[0234] Fig. 12 shows a schematic block diagram of an antenna arrangement 104 according to an embodiment of the present invention. The antenna arrangement 104 comprises the magnetic antenna 106 with the tuning element 111 and the tuning device 120 for tuning the magnetic antenna 106.

[0235] The tuning device 120 is designed to provide the tuning signal 122 (e.g. tuning voltage) for tuning the magnetic antenna 106 as a function of an amplitude of a signal 160 based on a magnetic field generated by the loop 108 or by the magnetic antenna 106 (e.g. in the near field), and to control the tuning element 111 with the tuning signal 122 in order to tune the magnetic antenna 106.

[0236] In embodiments, the antenna assembly 104 may include an induction loop 162 (or induction coil) configured to provide the signal 160 based on the magnetic field generated by the loop. The loop 108 of the magnetic antenna 106 and the induction loop 162 (or induction coil) may be arranged (e.g., implemented) on the same circuit board.

[0237] In embodiments, the tuning device 120 can be designed to control the tuning element 111 with the tuning signal 122 in order to regulate the amplitude of the signal 160 to a predetermined setpoint value, for example such that the amplitude is greater than or equal to the predetermined (e.g. predefined) setpoint value (e.g. reference value).

[0238] For example, the tuning device 120 can be designed to control the amplitude of the signal based on the magnetic field generated by the loop to the predetermined target value by controlling the tuning element 111 with the tuning signal 122 (e.g. control signal).

[0239] For example, the tuning device 120 may be configured to track the tuning signal 122 (e.g., control signal) to counteract a deviation of the amplitude of the signal based on the magnetic field generated by the loop from the predetermined target value.

[0240] The specified target value can be determined in advance (e.g. during a factory calibration) by a reference measurement in the undisturbed case of the magnetic antenna 106 and / or in the resonance case of the magnetic antenna 106.

[0241] Furthermore or alternatively, the tuning device can be designed to determine the predetermined target value by a reference measurement in the undisturbed case of the magnetic antenna 106 and / or in the resonance case of the magnetic antenna 106.

[0242] During the reference measurement, a predefined signal can be transmitted using the magnetic antenna 106. For example, the predefined signal can have a predefined signal shape, predefined transmission frequency, predefined bandwidth, predefined amplitude, and / or predefined modulation type. For example, the predefined signal can be a sine signal with a standardized transmission voltage.

[0243] Magnetic receiving antennas are typically tuned to the maximum reception level (resonance frequency) or adjusted (power adjustment). Magnetic transmitting antennas are tuned to the maximum radiated power. The tuning information or adjustment information can be obtained as described in detail below in sections 2.2.1 and 2.2.2, whereby the tuning or adjustment of the magnetic antenna 106 can also be automatically adjusted in exemplary embodiments.

[0244] In the following, a detailed embodiment for determining a controlled variable by self-reception is described for a magnetic transmitting antenna. 2.2.1. Self-reception

[0245] In order to obtain a measurable variable that provides information about the adaptation of the magnetic antenna 106, in exemplary embodiments a small induction loop 162 or a small SMD coil 162 can be placed next to the actual magnetic antenna 106 on the circuit board. In the event that the magnetic antenna 106 is well adapted, a voltage with a specific amplitude is induced in this loop 162. If the magnetic antenna 106 is subsequently no longer resonant and adapted at the required frequency due to a nearby body, the amplitude of the induced voltage decreases. This voltage difference can then be detected accordingly. After tapping and rectification, an analog controlled variable can be obtained from it, for example, or a corresponding digital control can be constructed using A / D conversion.

[0246] If different materials are brought into proximity of the magnetic antenna 106, the influence of the materials on the antenna properties can be qualitatively assessed based on the induced measurement voltage. A value determined in an undisturbed situation with a standardized transmission voltage serves as a reference. This reference measurement can also be repeated in an emergency by transmitting a sine tone on one or more frequencies through the magnetic transmitting antenna 106 and receiving it at the induction loop 162. This makes it possible to re-measure and check the resonance curve of the installed magnetic antenna 106 at the site of use. If the obtained induction loop 162 is compared with corresponding tables or reference values, for example in a microcontroller after rectification and A / D conversion, this can be used to implement strategies for optimizing the antenna properties (retuning, adaptation) specifically for the current application situation.

[0247] In embodiments, a tuning signal (e.g. tuning information or matching information) is generated by self-reception.

[0248] In embodiments, a small induction loop 162 or a small SMD coil 160 can be placed on the same (or the same) printed circuit board (PCB) as the magnetic transmitting antenna 106.

[0249] In embodiments, a statement about the tuning or adaptation can be generated from the received power of the induction loop 162 or the SMD coil 162, for example by a comparison with stored calibration information. 2.2.2. Tuning direction or adjustment direction by transmitting on multiple frequencies

[0250] Section 2.2.1 showed how the degree of current alignment or adjustment can be measured.

[0251] However, after measuring one or more variables once, it is not possible to clearly determine in which direction the (magnetic) antenna 106 is detuned or incorrectly adjusted. That is, whether it is currently tuned to a frequency that is too high or too low, or whether it is tuned too inductively or capacitively. Normally, a calibration step would involve transmitting more frequently, measuring each time, and adjusting the magnetic antenna 106 until a target value or target value range (e.g., optimum) is reached.

[0252] This problem can be solved by transmitting at different frequencies and capturing one or more measurement variables. Using this information, a measurement curve can be generated that represents the adaptation over frequency (or by selecting the best point).

[0253] In embodiments, a "calibration tone" or a transmission signal can be transmitted on several frequencies.

[0254] In embodiments, a measurement of self-received power can be carried out on several frequencies.

[0255] In embodiments, the "tuning direction or adaptation direction" can be generated by evaluating the received power curve at the various frequencies. 2.3. Tuning by measuring the power or current consumption of the transmitting device (transmitting ICs)

[0256] An antenna 106 is best tuned when no power is reflected ( P reflect ) or the ratio of the power transmitted into the antenna 106 ( P from ) to reflected power ( Preflect) is maximized. Matching means both matching to a desired impedance and tuning to the desired transmission frequency. The impedance can be changed using a matching network. This changes the matched frequency of the antenna and the efficiency of the amplifier. With magnetic antennas, the receive frequency and the matching are detuned equally. This can be done, for example, by switching capacitors. With electrical antennas, the electrical length and thus the frequency can be detuned using switches, for example. This chapter describes how a tuning signal can be determined to reduce the reflected power. 2.3.1. Measurement setup

[0257] To determine the power going into or out of the antenna 170, for example, a directional coupler 172 and two power meters 174 and 176 can be used, as shown in Fig. 13 is shown.

[0258] Using the Fig. 14 The test setup shown shows that for typical transmitting devices 102 (e.g., transmitter circuits), such as those used for wireless sensor nodes, the input current varies depending on the antenna matching. The test setup includes an ammeter 178 that measures the input current of the transmitting device 102 (e.g., transmitter circuit), a power meter 180 that measures the output power, and a coaxial tuner 182.

[0259] The coaxial tuner 182 can be used to simulate all desired impedances for the required frequency. To achieve this, the tuner 182 can be calibrated using a vector network analyzer (VNA), for example, and then connected to the device under test.

[0260] With the Fig. 14The measurement setup shown can be used to determine the current consumed by the transmitting device 102 (e.g., transmitting system) and the transmitted power for all set complex impedances. As shown in Fig. 14 As shown, the transmitting device 102 (e.g. front end) can now be measured and the curve between output power and input current can be plotted.

[0261] From this, two 3D graphs can be generated showing the input current and output power versus the antenna impedance, as shown in the Fig. 15 and Fig. 16 is shown.

[0262] In detail, Fig. 15 A Smith chart shows the current consumption of the transmitting device 102 plotted against the antenna impedance. The lower area of ​​the Smith chart shows a higher current consumption, while the upper area of ​​the Smith chart shows a lower current consumption. In the middle of the Smith chart, at 50 ohms, the transmitting device 102 consumes approximately 100 mA.

[0263] Fig. 16 shows the output power plotted against the antenna impedance in a Smith chart. The middle section of the Smith chart shows an output power of approximately 18 dBm, with the power decreasing towards the edge of the Smith chart.

[0264] If the impedance and power curves are now plotted schematically against the input current (of the transmitting device 102), the curves shown in Fig. 17a, Fig. 17b and Fig. 18 shown.

[0265] In detail, Fig. 17a in a diagram a curve of a real part R and an imaginary part X of the antenna impedance plotted against the input current of the transmitting device 102. The ordinate describes the impedance in ohms and the abscissa the input current of the transmitting device 102 in mA.

[0266] Fig. 17bshows a diagram of the output power plotted against the input current of the transmitting device 102. The ordinate describes the power and the abscissa the input current of the transmitting device 102 in mA.

[0267] Fig. 18 shows in a diagram a curve of a real part R and an imaginary part X of the antenna impedance as well as a curve of the output power plotted against the input current of the transmitting device 102. Fig. 18 the ordinate represents the impedance in ohms or the power in dBm and the abscissa represents the input current of the transmitting device 102 in mA.

[0268] It turns out that the imaginary part X is strictly monotonically increasing with the input current (of the transmitter 102). From the measuring points "short circuit" to "open", as in Fig. 17aAs shown, the input current (of the transmitting device 102) increases steadily. The curve of the output power versus the input current shows that an input current of approximately 100 mA corresponds to the maximum output power (Pout versus lin). This is at the measurement point (50 + 0j) ohms.

[0269] The measurement setup thus shows that it is possible to make a statement about the quality of the antenna matching by measuring the input current (of the transmitting device 102). 2.3.2. Generation of the tuning signal depending on the power or current consumption of the transmitting device

[0270] Fig. 19shows a schematic block diagram of an antenna arrangement 104 according to an embodiment of the present invention. The antenna arrangement 104 comprises an antenna 106 with a tuning element 111, and the tuning device 120 for tuning the antenna 106. The tuning device 120 is designed to provide the tuning signal 122 for tuning the antenna 106 as a function of a power or current consumption of a transmitting device 102 connected to the antenna 106, and to control the tuning element 111 with the tuning signal 122 in order to tune the antenna 106.

[0271] As in Fig. 19 As shown, in embodiments, the antenna 106 may be a magnetic antenna 106 with a single or multiple interrupted loop 108. However, in embodiments, the antenna 106 may also be an electrical antenna.

[0272] In the following description, it is assumed, for example, that the antenna 106 is a magnetic antenna. However, it should be noted that the exemplary embodiments described below with regard to tuning the antenna depending on the power or current consumption of the transmitting device 102 connected to the antenna 106 or on the power or current consumption of an active component of the transmitting device are also applicable to an electrical antenna.

[0273] In exemplary embodiments, the current consumption of the transmitting device can be determined, for example, using a current meter 186 (e.g., an ammeter). Instead of the current consumption, the power consumption of the transmitting device 102 can also be determined, for example, using a power meter (e.g., a power meter).

[0274] In embodiments, the tuning device 102 can be designed to control the tuning element 111 with the tuning signal 122 in order to regulate the power or current consumption of the transmitting device 102 to a predetermined (e.g., predefined) setpoint range.

[0275] For example, the tuning device 120 can be designed to regulate the power or current consumption of the transmitting device 102 to the predetermined target value range by controlling the tuning element 111 with the tuning signal 122 (e.g. control signal).

[0276] For example, the tuning device 120 can be designed to track the tuning signal 122 (e.g. control signal) in order to counteract a deviation of the power or current consumption of the transmitting device 102 from the predetermined value range.

[0277] The specified target value range (e.g. predefined value range) can, for example, by a system simulation assuming an ideal or nearly ideal adaptation of the magnetic antenna, when terminating the transmitting device 102 with a predefined impedance (e.g. 50 ohms), based on an antenna measurement (e.g. by means of an antenna tuner), based on an average value of the power or current consumption with a short-circuited termination and an open termination of the transmitting device 102, based on a measurement of a radiated power, be determined.

[0278] Fig. 20shows a measurement setup for determining the ideal antenna matching, according to an embodiment of the present invention. The measurement setup comprises a transmitting device 102, a magnetic antenna 106 with the tuning element 111, a matching network 113 between the transmitting device 102 and the magnetic antenna 106, and an ammeter 186 for measuring the current consumption of the transmitting device 102, wherein the tuning signal 122 for tuning the magnetic antenna 106 is generated as a function of the measured current consumption of the transmitting device 102. The Fig. 20 The measurement setup shown can be implemented, for example, in a device such as a subscriber 100 of a communication system.

[0279] As in Fig. 20 As can be seen, the device can now be used in contrast to the Fig. 13can be greatly simplified because, instead of a directional coupler 172 and two power meters 174 and 176, only one ammeter 186 is required in exemplary embodiments. The current measurement can be used for tuning the transmitting antenna 106.

[0280] Calibration of the setup may include the following steps: 1. Determine the ideal current value, and 2. Adjust the (magnetic) antenna 106.

[0281] In the next step, the (magnetic) antenna 106 can be adjusted based on the calibrated current values. During operation, the antenna adjustment can be changed until the desired current (input current of the transmitting device) is reached. Due to the monotonically increasing impedance curve, the direction in which the optimum lies is immediately known after adjusting the (magnetic) antenna 106 once. Adjustment is also possible during operation. The transmission signal can be either a CW signal (CW = continuous wave, i.e. an undamped, i.e. temporally constant radiated wave) or a directly modulated signal, e.g., G-MSK (Gaussian Minimum Shift Keying).

[0282] The (magnetic) antenna 106 can be adjusted using a test signal (CW), whereby the desired signal is only transmitted under optimized conditions, for example. By optimizing the antenna matching, the system operates at optimal efficiency. This can reduce energy consumption.

[0283] The matching network used can, for example, have N-states that can be directly linked to corresponding current values. Thus, the (magnetic) antenna 106 can be matched in just a few steps using a table. This minimizes programming effort.

[0284] By changing the phase of the transmission signal, the (magnetic) antenna 106 can be additionally adjusted.

[0285] If an adjustment is not possible, the system (e.g., the subscriber 100 or the tuning device 120 of the subscriber 100) can interrupt the transmission process and check the adjustment again at a later time. This can save energy because the subscriber (e.g., node) always transmits with optimal efficiency.

[0286] Embodiments have the advantage of saving hardware costs, since no RF coupler and no power meter are required.

[0287] Embodiments have the advantage that there is no attenuation of the output power by the RF coupler.

[0288] These examples have the advantage that an increasing current indicates the direction of the required adjustment. No minimum search is required, allowing the ideal value to be found more quickly.

[0289] Embodiments have the advantage that, in the case of a digital or software-based implementation, this can be easily programmed using an assignment table.

[0290] Embodiments have the advantage that they can be applied to different transmission systems.

[0291] Examples have the advantage of energy efficiency.

[0292] In embodiments, the device (e.g., the subscriber 100 or the tuning device 120 of the subscriber 100) can determine (e.g., measure) the power consumption of the transmitting device 102 (e.g., transmitting IC or transmitting system).

[0293] In embodiments, the device (e.g., subscriber 100) may include a tunable (magnetic) antenna 106.

[0294] In embodiments, the device (e.g., the subscriber 100 or the tuning device 120 of the subscriber 100) can detune the (magnetic) antenna 106 (possibly special case "short circuit" and "open", 50 Ω).

[0295] In embodiments, the device (e.g., the subscriber 100 or the tuning device 120 of the subscriber 100) can use the current information to find an ideal antenna setting (see procedure above).

[0296] In embodiments, the device (e.g., the subscriber 100 or the tuning device 120 of the subscriber 100) can tune the variable (e.g., tunable) (magnetic) antenna 106 by measuring the power consumption of the transmitting device 102 (e.g., transmitting IC).

[0297] In embodiments, the device (e.g., the subscriber 100 or the tuning device 120 of the subscriber 100) can detect a deviation from the adaptation by deviations in the current consumption at ideal adaptation (50 Ω). 2.3.3 Characterization of the system

[0298] In order to be able to make a statement about the measured input current value (of the transmitting device 102) on the antenna matching, the system (e.g. the subscriber 100 or the tuning device 120 of the subscriber 100) can be given information about the current consumption with ideal matching.

[0299] The input current (of the transmitting device 102) can be determined in different ways. In principle, each method can be performed at any stage. 2.3.3.1. Simulation of the system

[0300] In exemplary embodiments, the input current (of the transmitting device 102) with ideal matching (of the magnetic antenna 106) can be determined using a system simulation, e.g., in ADS. If sufficiently good models are available, the simulation can provide a relationship between power consumption and matching of the (magnetic) antenna 106. 2.3.3.2. Measurements with ideal impedance termination

[0301] In embodiments, the desired input current (of the transmitting device 102) can be made with maximum output power, for example during commissioning by storing the current current value at a 50 ohm terminated output. 2.3.3.3. One-time measurement with tuner, e.g. in the laboratory

[0302] In embodiments, a structure as in Fig. 14 Using an antenna tuner 182, each point can be measured and the maximum power found. 2.3.3.4. Measurement on each hardware, e.g. test during commissioning in production

[0303] In some examples, the ideal point can also be achieved by connecting (e.g., screwing) different calibration standards. For example, a 50 ohm termination can be used, which directly indicates the ideal current.

[0304] A termination (e.g., a connector) with an open or short circuit can also be used to determine the direction of the impedance curve. The ideal current can be assumed to be the average between the two (e.g., "open" and "short circuit").

[0305] All three calibration standards ("open", "short circuit", "50 Ohm") can be used together or individually to obtain information about the current flow.

[0306] Other standards other than 50 Ω can also be used if the ideal impedance for maximum performance differs from this. 2.3.3.5. Calibration of current consumption by reception with a reference antenna

[0307] In exemplary embodiments, a radio link can be set up for calibration, whereby the signal emitted by the transmitter with a (magnetic) antenna 106 can be received by another antenna, and the received power can be evaluated. The tuning elements 111 of the (magnetic) antenna 106 can be manually adjusted, and the corresponding received power and current consumption can be recorded. The current consumption at maximum received power is the value to which the calibration is performed during operation. For better reproducibility, the measurement can be performed in a shielded and low-reflection environment, such as an antenna test hall. 2.3.3.6. Measurement with on-board circuitry, e.g. in the field

[0308] In some examples, external calibration plugs can also be implemented directly on the circuit board and switched, for example, via an RF switch. This makes it possible to determine the ideal current even under different operating modes or ambient conditions, such as temperature (cold, warm). 2.3.3.7. Prior knowledge of the antenna impedance curve

[0309] In exemplary embodiments, prior knowledge of the impedance behavior upon detuning of the (magnetic) antenna 106 used can be used to determine the ideal current consumption of the transmitting device 102 (e.g., transmitting system) for the respective impedance profile. A function can be determined that can provide the ideal point between the "short circuit" and "open" cases for the (magnetic) antenna 106 used. This is only necessary if the profile deviates from a straight line (case: the middle between "short circuit" and "open" is ideal). 2.3.3.8. Feedback of the transmitted performance from another participant

[0310] In embodiments, during normal operation (e.g., in the field), the transmitted signal can be received by another participant, which can report back to the transmitting participant how good the received signal was, whereby the transmitting participant can generate a tuning voltage. 2.3.4. Advantages and implementation examples

[0311] Embodiments have the advantage that a calibration of the device (e.g. subscriber 100 or the magnetic antenna 106) can be carried out during operation ("short circuit", "open", 50 Ohm).

[0312] Embodiments have the advantage that the device (e.g. the subscriber 100 or the tuning device 120 of the subscriber 100) can contain adaptation information through prior calibration.

[0313] Embodiments have the advantage that the device (e.g., the subscriber 100 or the tuning device 120 of the subscriber 100) can perform a calibration with fewer standards (e.g., only "short circuit" and "open"), whereby the center can be assumed to be ideal.

[0314] Embodiments have the advantage that the device (e.g. the subscriber 100 or the tuning device 120 of the subscriber 100) can simplify / optimize the calibration through known antenna behavior.

[0315] In embodiments, the device (e.g., the subscriber 100 or the tuning device 120 of the subscriber 100) can measure the power consumption of the transmitting device (e.g., transmitting IC or transmitting system).

[0316] In embodiments, the device (e.g., subscriber 100) may include a tunable (magnetic) antenna 106.

[0317] In embodiments, the device (e.g. the subscriber 100 or the tuning device 120 of the subscriber 100) can detune the (magnetic) antenna 106 (possibly special case short circuit and open, 50 Ω).

[0318] In embodiments, the device (e.g., the subscriber 100 or the tuning device 120 of the subscriber 100) can use the current information to find ideal antenna settings (see procedure above).

[0319] In embodiments, the device (e.g., the subscriber 100 or the tuning device 120 of the subscriber 100) can tune the variable (e.g., tunable) (magnetic) antenna 106 by measuring the power consumption of the transmitting device 102 (e.g., transmitting IC).

[0320] In embodiments, the device (e.g., the subscriber 100 or the tuning device 120 of the subscriber 100) may contain the adaptation information through prior calibration.

[0321] In embodiments, the device (e.g., the subscriber 100 or the tuning device 120 of the subscriber 100) can perform a calibration during operation ("short circuit", "open", "50 Ohm").

[0322] In embodiments, the device (e.g., the subscriber 100 or the tuning device 120 of the subscriber 100) can detect a deviation from the adaptation by deviations in the current consumption at ideal adaptation (50 Ω).

[0323] In embodiments, the device (e.g., the subscriber 100 or the tuning device 120 of the subscriber 100) can perform a calibration, e.g., in operation with fewer standards (e.g., only "short circuit" and "open"), where the center can be assumed to be ideal.

[0324] In embodiments, the device (e.g., the subscriber 100 or the tuning device 120 of the subscriber 100) can perform a calibration, e.g., in operation with 50 ohms as a reference for an ideal adaptation of the antenna 106.

[0325] In embodiments, the device (e.g., subscriber 100 or tuning device 120 of subscriber 100) can use adaptation information (power consumption) to find an optimal transmission time. For example, transmission can only occur once the optimal efficiency is reached.

[0326] In embodiments, the device (e.g., the subscriber 100 or the tuning device 120 of the subscriber 100) may use the antenna matching to save energy.

[0327] In embodiments, the device (e.g., the subscriber 100 or the tuning device 120 of the subscriber 100) may use a phase adjustment to change the antenna matching.

[0328] In embodiments, the device (e.g., subscriber 100) can receive feedback about the transmitted signal from another subscriber in the radio network. 2.4. Power consumption / Other effects of a power amplifier

[0329] Section 2.3 described the tuning (of the magnetic antenna 106) by measuring the power consumption of the transmitting device 102 (e.g., transmitting IC). The transmitting device 102 typically includes a power amplifier that provides the transmission power required for transmission with an antenna 106.

[0330] The power amplifier is typically constructed from several active and passive electronic components. These can be used to acquire electrical measurements that allow conclusions to be drawn about the antenna matching and can thus be used to generate the tuning signal 122 (e.g., tuning voltage). 2.4.1. Measurement of the supply current of the active components

[0331] Measuring the supply current of the active component(s) (e.g., power transistors) of the power amplifier (of the transmitting device 102) is equivalent to measuring the current consumption of the transmitting device (e.g., transmitting IC) and allows for more precise acquisition of the matching information. Other loads in the transmitting device 102 (e.g., transmitting IC) do not interfere with the measurement.

[0332] For two or more active components, a statement about the matching can be made based on the difference in the supply currents. Examples of this would be amplifiers constructed according to the balanced, push-pull, and Doherty principles. Push-pull and Doherty amplifiers in particular are sensitive to reverse power, which in turn manifests itself in a change in operating behavior and thus also in the supply currents. 2.4.2. Measurement of the bias current of the active components

[0333] The direct measurement of power consumption is more complex at higher power levels due to the associated higher voltages (high-level current sense required).

[0334] Metal-semiconductor field-effect transistors (MESFETs) have a Schottky contact at the gate, which at higher RF input powers P in has a rectifying effect, a gate current flows I Bias (see Fig. 21 ). About the parasitic gate-drain capacitance ( C GD ) 192 (of transistor 194) this rectification effect is also dependent on the output power P out . If there is circuit access to the gate terminal, a voltage V meas on the transistor R Bias depending on the gate current; this voltage is at a given input power P in depending on the output power P out and thus the adaptation of the load. Thus, the measuring voltage V measthe possibility of making a statement about the adaptation of the load, i.e. the antenna 106. V meas can be tapped directly via an analog-digital converter and used to control the antenna tuner for tuning, as described in Fig. 21 is shown.

[0335] In detail, Fig. 21 a schematic block diagram of a transmitting device with a power amplifier 190, according to an embodiment of the present invention. As in Fig. 21 As can be seen, a tuning voltage for controlling the antenna tuner can be generated based on (e.g. by) a measurement of the bias current I_Bias of the active components 194. 2.4.3. Generating a tuning voltage by measuring the common-mode of the magnetic antenna

[0336] The antenna loop 108 of a magnetic antenna 106 is a differential load. Using a transformer (balun), this two-pole differential load can be driven by a single-pole source, as shown in Fig. 23 is shown.

[0337] In detail, Fig. 22 A schematic block diagram of an antenna arrangement 104 according to an embodiment of the present invention. The antenna arrangement 104 comprises the magnetic antenna 106 with the loop 108 and the tuning element 111. The magnetic antenna 106 is connected to a source 102, such as a transmitting device, via a transformer 196 (balun). The antenna loop 108 can be differentially controlled so that the common-mode mode Z cc11 is no longer visible upstream of the balun 196.

[0338] As in Fig. 22 As can be seen, the source 102 "sees" the load impedance ZL .

[0339] The magnetic antenna 106 comprising antenna loop 108 and matching element 111 has the differential impedance Z d . The magnetic antenna 106 with the impedance Z cThis parasitic coupling leads to the detuning of the (magnetic) antenna 106 and can be compensated using the matching element 111.

[0340] At the input of the magnetic antenna 106, two impedances can be measured. The differential impedance Z dd 11 describes the push-pull operation (normal operation of the (magnetic antenna 106). The common-mode impedance Z cc 11 describes the common-mode operation, which is caused by undesired coupling with the environment. At the input of the balun 196, only the impedance ZL measurable.

[0341] The generation of a tuning signal (e.g. tuning voltage) 122 for controlling the matching element 111 can be achieved by accessing the common mode resulting from the common mode impedance Z cc 11 results.

[0342] If the magnetic antenna 106 is driven differentially, then the (magnetic) antenna 106 can be supplied with a push-pull or a common-mode signal and a statement about the detuning can be made via the current consumption.

[0343] The common mode can be measured or injected using two methods, which are described below. 2.4.3.1. Measurement and injection of the common-mode mode via the common-mode branch of the Output baluns

[0344] Special baluns 196 allow access to the common mode of the differential port. One example is the so-called ring coupler (also known as a rat-race coupler) in Fig. 23 The common-mode characteristics of the magnetic antenna can then be determined either by an active measurement using a measurement signal or by the reflected power, and a tuning voltage can be derived from this. 2.4.3.2. Measurement of the common-mode mode via the nonlinearity of the magnetic core

[0345] To optimize the size of the 196 balun, especially at low frequencies, magnetic cores with a permeability different from that of vacuum (or air) are used. These magnetic cores exhibit nonlinear behavior.

[0346] Using a measuring winding or a Hall sensor, magnetic direct currents that arise from the non-linear behavior of the magnetic core can be detected, as shown in Fig. 24 is shown.

[0347] In detail, Fig. 24 a schematic view of a magnetic core 198 of a balun 196 and a measuring winding 199 around the magnetic core 198 for detecting the common-mode properties of the balun via the non-linear properties of the magnetic core 198 using the measuring winding. 2.4.4. Examples of implementation

[0348] In embodiments, the device (e.g., the subscriber 102 or the tuning device 120 of the subscriber 100) can measure the power consumption of the power transistor(s) (active components) (e.g., to generate the tuning signal (e.g., tuning voltage)).

[0349] In embodiments, the device (e.g., the subscriber 102 or the tuning device 120 of the subscriber 100) can determine the difference in the supply currents of two power transistors to generate a tuning voltage.

[0350] In embodiments, the device (e.g., the subscriber 102 or the tuning device 120 of the subscriber 100) can detect (e.g., measure) a bias current of the power transistor(s) (e.g., the transmitting device 102) to generate a tuning voltage 122.

[0351] In embodiments, the device (e.g., the subscriber 102 or the tuning device 120 of the subscriber 100) can determine (e.g., determine) a bias current of the power transistor(s) (e.g., the transmitting device 102) by measuring a voltage across a resistor in the bias branch.

[0352] In embodiments, the device (e.g., the subscriber 102 or the tuning device 120 of the subscriber 100) can determine (e.g., determine) a difference in the bias currents of two power transistors (e.g., the transmitting device 102) to generate a tuning signal 122 (e.g., tuning voltage).

[0353] In embodiments, the device (e.g., the subscriber 102 or the tuning device 120 of the subscriber 100) can determine (e.g., determine) a difference in the currents of an amplifier in balanced operation to generate a tuning signal 122 (e.g., tuning voltage).

[0354] In embodiments, the device (e.g., the subscriber 102 or the tuning device 120 of the subscriber 100) can determine (e.g., determine) a difference in the currents of an amplifier in Doherty mode to generate a tuning signal 122 (e.g., tuning voltage).

[0355] In embodiments, the device (e.g., the subscriber 102 or the tuning device 120 of the subscriber 100) can determine (e.g., determine) a difference in the currents of an amplifier in push-pull operation to generate a tuning signal 122 (e.g., tuning voltage).

[0356] In embodiments, the device (e.g., the subscriber 102 or the tuning device 120 of the subscriber 100) can determine (e.g., determine) a common-mode impedance of a magnetic antenna 106 for generating a tuning signal (e.g., tuning voltage).

[0357] In embodiments, the device (e.g., the subscriber 102 or the tuning device 120 of the subscriber 100) can determine (e.g., determine) a common-mode impedance (e.g., of the magnetic antenna 106) using a measurement signal.

[0358] In embodiments, the device (e.g., the subscriber 102 or the tuning device 120 of the subscriber 100) can alternately feed a differential mode signal and a common mode signal into the magnetic antenna 106 and determine the power consumption and use this information to generate a tuning signal 122 (e.g., tuning voltage).

[0359] In embodiments, the device (e.g., subscriber 102 or tuner 120 of subscriber 100) may inject a common-mode signal (e.g., into magnetic antenna 106) using a balun 196 that provides access to the common-mode mode.

[0360] In embodiments, the device (e.g., the subscriber 102 or the tuning device 120 of the subscriber 100) can determine (e.g., measure) a reflected common-mode signal of a magnetic antenna 106 to generate a tuning signal (e.g., tuning voltage).

[0361] In embodiments, the device (e.g., the subscriber 102 or the tuner 120 of the subscriber 100) can determine (e.g., measure) a common-mode signal (e.g., the magnetic antenna 106) using a balun that allows access to the common-mode mode.

[0362] In embodiments, the device (e.g., the subscriber 102 or the tuner 120 of the subscriber 100) may have access to the common mode (e.g., the magnetic antenna) using a ring coupler.

[0363] In embodiments, the device (e.g., the subscriber 102 or the tuner 120 of the subscriber 100) may have access to the common mode (e.g., the magnetic antenna) via the nonlinear properties of a magnetic core.

[0364] In embodiments, the device (e.g., the subscriber 102 or the tuning device 120 of the subscriber 100) may utilize nonlinear properties of a magnetic core (e.g., a balun 196) to measure a magnetic DC current using a Hall sensor.

[0365] In embodiments, the device (e.g., the subscriber 102 or the tuning device 120 of the subscriber 100) may utilize non-linear properties of a magnetic core (e.g., a balun 196) to measure a magnetic DC current using a measuring winding on the magnetic core. 3. Further examples

[0366] Fig. 25shows a flowchart of a method 200 for tuning a magnetic antenna with a singly or multiply interrupted loop, according to an embodiment of the present invention. The method 200 comprises a step 202 of providing a control signal for tuning the magnetic antenna depending on a phase position of a signal leading into the magnetic antenna. Furthermore, the method 220 comprises a step 222 of controlling a tuning element of the magnetic antenna with the control signal in order to tune the magnetic antenna.

[0367] Fig. 26shows a flowchart of a method 210 for tuning a magnetic antenna with a singly or multiply interrupted loop, according to an embodiment of the present invention. The method 210 comprises a step 212 of providing a control signal for tuning the magnetic antenna as a function of an amplitude of a signal based on a magnetic field generated by the loop. Furthermore, the method 210 comprises a step 212 of controlling a tuning element of the magnetic antenna with the control signal in order to tune the magnetic antenna.

[0368] Fig. 27shows a flowchart of a method 220 for tuning an antenna, according to an embodiment of the present invention. The method 220 comprises a step 222 of providing a control signal for tuning the antenna as a function of a power or current consumption of a transmitting device connected to the antenna or of at least one active component of the transmitting device. Furthermore, the method 220 comprises a step 222 of controlling a tuning element of the antenna with the control signal in order to tune the antenna.

[0369] Embodiments of the present invention provide (e.g., self-tuning) magnetic antennas for, for example, sensor nodes. With the Internet of Things (IoT), the number of wirelessly communicating sensor nodes is growing. This also places ever-increasing demands on a small form factor and ease of handling. These requirements are difficult to meet with existing electrical antennas. Embodiments of the present invention enable the use of magnetic antennas in sensor nodes, thus meeting the aforementioned requirements.

[0370] The embodiments of the antenna arrangement described herein, or the generation of the tuning signal for tuning a magnetic antenna, can be used in a communication system, such as that specified in ETSI Standard TS 103 357 [7]. Of course, the embodiments described herein can also be used in other communication systems, such as WLAN, Bluetooth, ZigBee, etc.

[0371] In the following, further embodiments of the present invention are described, which can be used in combination with the embodiments described above or on their own.

[0372] Embodiments provide a subscriber of a wireless communication system, wherein the subscriber has a transmitting and / or receiving device [e.g., a transmitter, receiver, or transceiver] and an antenna arrangement connected to the transmitting and / or receiving device, wherein the antenna arrangement has a magnetic antenna with a single or multiple [e.g., at least twice] interrupted [e.g., subdivided] loop [e.g., current loop].

[0373] In embodiments, the loop may be interrupted [e.g., divided] by one or more capacitance elements [e.g., capacitors, capacitance diodes].

[0374] For example, the loop of the magnetic antenna can be interrupted by at least two capacitance elements [e.g. at least twice].

[0375] In embodiments, the multiply interrupted loop may be interrupted [e.g., divided] into at least two segments by the capacitance elements.

[0376] For example, the loop can be divided into n segments by n capacitance elements, where n is a natural number greater than or equal to two.

[0377] In embodiments, the at least two segments of the multiply interrupted loop may be connected by the capacitance elements.

[0378] For example, the at least two segments of the multi-interrupted loop and the at least two capacitance elements can be connected in series. In other words, two segments of the multi-interrupted loop can each be connected by a capacitance element connected in series between the two segments.

[0379] In embodiments, the single or multiple interrupted loop [e.g., the at least two segments of the loop] and the capacitance elements may form a resonant circuit.

[0380] In embodiments, the loop may form a coil.

[0381] In embodiments, the transmitting and / or receiving device can be connected to the magnetic antenna via one of the capacitance elements [e.g., wherein the one capacitance element and the singly or multiply interrupted loop [e.g., with the other capacitance elements] form a parallel resonant circuit].

[0382] In embodiments, the loop may be ring-shaped or m-corner-shaped, where m is a natural number greater than or equal to four.

[0383] For example, the loop can be square, pentagon, hexagon, heptagon, octagon, nonagon, decagon, eleven-sided, dodecagon, etc.

[0384] In embodiments, the magnetic antenna may be implemented [e.g., realized] on a circuit board.

[0385] In embodiments, the antenna arrangement may include a tuning circuit for tuning the magnetic antenna.

[0386] In embodiments, the tuning circuit and the magnetic antenna may be implemented on the same circuit board.

[0387] In embodiments, the magnetic antenna may be a first magnetic antenna, wherein the antenna arrangement may further comprise a second magnetic antenna, wherein the singly or multiply interrupted loop of the first magnetic antenna and a loop of the second magnetic antenna are arranged substantially orthogonally to one another.

[0388] For example, a first surface spanned by the singly or multiply interrupted loop of the first magnetic antenna and a second surface spanned by the loop of the second magnetic antenna may be orthogonal to each other.

[0389] For example, a main radiation direction / main reception direction of the first magnetic antenna and a main radiation direction / main reception direction of the second magnetic antenna may be orthogonal to each other.

[0390] For example, a zero point of the first magnetic antenna and a zero point of the second magnetic antenna may be different.

[0391] In embodiments, a spanned area of ​​the loop of the second magnetic antenna may be at least a factor of two [e.g., a factor of three, four, five, or ten] smaller than a spanned area of ​​the loop of the first magnetic antenna.

[0392] For example, the loop of the second magnetic antenna may be "flattened".

[0393] In embodiments, the loop of the second magnetic antenna may be non-round in order to adapt to a shape of the subscriber's housing.

[0394] For example, the loop of the second magnetic antenna may be substantially rectangular.

[0395] In embodiments, the first magnetic antenna and the second magnetic antenna may be arranged adjacent to each other.

[0396] In embodiments, a conductor of the loop of the second magnetic antenna may be at least a factor of two [e.g., a factor of three, four, or five] thicker or wider than a conductor of the loop of the first magnetic antenna.

[0397] In embodiments, the loop of the second magnetic antenna may be interrupted multiple times.

[0398] For example, the loop of the second magnetic antenna may be interrupted by at least two capacitance elements [at least twice].

[0399] In embodiments, the subscriber may be configured to deactivate one of the magnetic antennas of the antenna arrangement [e.g., the first magnetic antenna or the second magnetic antenna] in order to change a radiation characteristic [e.g., radiation direction or reception direction; e.g., main lobe] of the antenna arrangement.

[0400] For example, the subscriber may be configured to change a radiation characteristic [e.g., radiation direction or reception direction; e.g., main lobe] of the antenna arrangement by deactivating one of the magnetic antennas of the antenna arrangement [e.g., the first magnetic antenna or the second magnetic antenna].

[0401] In embodiments, one of the magnetic antennas of the antenna arrangement can be deactivated by detuning the respective magnetic antenna [e.g., the first magnetic antenna or the second magnetic antenna].

[0402] In embodiments, one of the magnetic antennas of the antenna arrangement can be deactivated by connecting a coil in parallel to one of the capacitance elements of the loop of the respective magnetic antenna [e.g., the first magnetic antenna or the second magnetic antenna].

[0403] In embodiments, the subscriber may be configured to change a radiation ratio of the antenna arrangement by detuning the natural resonance of at least one of the two magnetic antennas [e.g., the first magnetic antenna or the second magnetic antenna].

[0404] In embodiments, the first magnetic antenna and the second magnetic antenna can be controlled in a phase-shifted manner [e.g., by 90°].

[0405] In embodiments, the subscriber may be configured to divide a data packet to be transmitted [e.g., of the physical layer] into a plurality of sub-data packets and to transmit the plurality of sub-data packets non-contiguously [e.g., using a time and / or frequency hopping method], wherein the subscriber may be configured to change the radiation characteristic of the antenna arrangement at least once between the transmission of two sub-data packets.

[0406] For example, the subscriber may be configured to change the radiation characteristics of the antenna array after each transmitted sub-data packet or after a predetermined number of sub-data packets [e.g. by deactivating the other magnetic antenna of the antenna array].

[0407] In embodiments, the subscriber can be configured to divide a data packet to be transmitted [e.g., of the physical layer] into a plurality of sub-data packets and to send the plurality of sub-data packets non-contiguously using a frequency hopping method [e.g., and time hopping method], wherein the resonant frequencies of the first magnetic antenna and the second magnetic antenna can be intentionally slightly detuned, so that when the plurality of sub-data packets are transmitted, a radiation characteristic [e.g., radiation direction; e.g., main lobe] of the antenna arrangement varies due to the frequencies defined by the frequency hopping pattern.

[0408] For example, the resonant frequency of the first magnetic antenna and / or the second magnetic antenna can be detuned within a range corresponding to the reciprocal Q factor. With a Q factor of Q = 100, the detuning can be achieved within a window of no more than + / - 1%, because even greater detuning results in almost no more power being dissipated.

[0409] In embodiments, the antenna arrangement may comprise a tuning device for tuning the magnetic antenna, wherein the antenna arrangement is configured to automatically tune the antenna.

[0410] In embodiments, the antenna arrangement may further comprise an electrical antenna.

[0411] In embodiments, the transmitting and / or receiving device may be a transmitting device [e.g. transmitter], a receiving device [e.g. receiver] or a transceiver.

[0412] In embodiments, the subscriber may be configured to communicate in the ISM band.

[0413] In embodiments, the subscriber may be an endpoint of the communication system.

[0414] In embodiments, the endpoint may be a sensor node or actuator node.

[0415] In embodiments, the endpoint may be battery powered.

[0416] In embodiments, the endpoint may comprise an energy harvesting element for generating electrical energy.

[0417] In embodiments, the subscriber may be a base station of the communication system.

[0418] Further embodiments provide a communication system with at least two of the participants described herein.

[0419] For example, the at least two participants can be one or more endpoints [e.g., a plurality of endpoints] and one or more base stations. Of course, the at least two participants can also be at least two endpoints or base stations.

[0420] Further embodiments provide a method for operating a subscriber of a communication system, wherein the subscriber has an antenna arrangement, wherein the antenna arrangement has a magnetic antenna with a singly or multiply interrupted loop. The method comprises a step of transmitting and / or receiving communication signals using the magnetic antenna.

[0421] Embodiments of the present invention provide a subscriber (e.g., an endpoint) of a communication system having a magnetic antenna.

[0422] Although some aspects have been described in the context of a device, it should be understood that these aspects also represent a description of the corresponding method, so that a block or component of a device can also be understood as a corresponding method step or as a feature of a method step. Analogously, aspects described in the context of or as a method step also represent a description of a corresponding block, detail, or feature of a corresponding device. Some or all of the method steps may be performed by (or using) a hardware apparatus, such as a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, some or more of the key method steps may be performed by such an apparatus.

[0423] Depending on specific implementation requirements, embodiments of the invention may be implemented in hardware or software. The implementation may be performed using a digital storage medium, such as a floppy disk, a DVD, a Blu-ray Disc, a CD, a ROM, a PROM, an EPROM, an EEPROM, or a FLASH memory, a hard disk, or other magnetic or optical storage device storing electronically readable control signals that can interact or cooperate with a programmable computer system to perform the respective method. Therefore, the digital storage medium may be computer-readable.

[0424] Some embodiments according to the invention thus comprise a data carrier having electronically readable control signals capable of interacting with a programmable computer system such that one of the methods described herein is carried out.

[0425] In general, embodiments of the present invention may be implemented as a computer program product having a program code, wherein the program code is effective to perform one of the methods when the computer program product is run on a computer.

[0426] The program code can, for example, also be stored on a machine-readable medium.

[0427] Other embodiments include the computer program for performing one of the methods described herein, wherein the computer program is stored on a machine-readable carrier.

[0428] In other words, an embodiment of the method according to the invention is thus a computer program which has a program code for carrying out one of the methods described herein when the computer program runs on a computer.

[0429] A further embodiment of the method according to the invention is thus a data carrier (or a digital storage medium or a computer-readable medium) on which the computer program for performing one of the methods described herein is recorded. The data carrier, the digital storage medium, or the computer-readable medium is typically physical and / or non-perishable or non-transient.

[0430] A further embodiment of the method according to the invention is thus a data stream or a sequence of signals that represents the computer program for carrying out one of the methods described herein. The data stream or the sequence of signals can be configured, for example, to be transferred via a data communication connection, for example, via the Internet.

[0431] A further embodiment comprises a processing device, for example a computer or a programmable logic device, which is configured or adapted to carry out one of the methods described herein.

[0432] A further embodiment comprises a computer on which the computer program for performing one of the methods described herein is installed.

[0433] A further embodiment according to the invention comprises a device or system designed to transmit a computer program for performing at least one of the methods described herein to a recipient. The transmission can be electronic or optical, for example. The recipient can be, for example, a computer, a mobile device, a storage device, or a similar device. The device or system can, for example, comprise a file server for transmitting the computer program to the recipient.

[0434] In some embodiments, a programmable logic device (e.g., a field-programmable gate array, an FPGA) may be used to perform some or all of the functionalities of the methods described herein. In some embodiments, a field-programmable gate array may interact with a microprocessor to perform any of the methods described herein. In general, in some embodiments, the methods are performed by any hardware device. This may be general-purpose hardware such as a computer processor (CPU) or method-specific hardware such as an ASIC.

[0435] The devices described herein may be implemented, for example, using a hardware apparatus, or using a computer, or using a combination of a hardware apparatus and a computer.

[0436] The devices described herein, or any components of the devices described herein, may be implemented at least partially in hardware and / or in software (computer program).

[0437] The methods described herein may be implemented, for example, using a hardware apparatus, or using a computer, or using a combination of a hardware apparatus and a computer.

[0438] The methods described herein, or any components of the methods described herein, may be implemented at least partially by hardware and / or by software.

[0439] The above-described embodiments are merely illustrative of the principles of the present invention. It is understood that modifications and variations of the arrangements and details described herein will be apparent to others skilled in the art. Therefore, it is intended that the invention be limited only by the scope of the following claims and not by the specific details presented in the description and explanation of the embodiments herein. Bibliography

[0440] [1] https: / / de.wikipedia.org / wiki / Schwingkreis [2] J. Bollenbeck, R. Oppelt: "A novel tracking filter for high-quality LO signals", UKW-Berichte 3 / 2013, pp. 157 - 176 [3] US 7,890,070 [4] https: / / de.wikipedia.org / wiki / Gilbertzelle [5] J. v. Parpart: "Broadband ferrite high-frequency transformers", Hüthig GmbH, Heidelberg, 1997 [6] DE 10 2011 082 098 B4 [7] ETSI TS 103 357 [8] Klaus W. Kark: "Antennas and radiation fields", 5th edition, Springer Verlag, p. 233

Claims

1. Antenna arrangement (104), comprising: a magnetic antenna (106) comprising a loop (108) interrupted one or several times and at least one tuning element (111) for tuning the magnetic antenna (106), and tuning means (120) connected to the tuning element (111), wherein the tuning means (120) is configured to provide a control signal (122) for tuning the magnetic antenna (106) in dependence on a phase position of a signal (124) advancing into the magnetic antenna (106), and to control the tuning element (111) with the control signal (122) to tune the magnetic antenna (106), wherein the tuning means (120) is configured to provide the control signal (122) for tuning the magnetic antenna (106) in dependence on a phase relationship between the signal (124) advancing into the magnetic antenna (106) and a phase signal (126), wherein the tuning means (120) is configured to derive a signal from the signal (124) advancing into the magnetic antenna (106) to obtain a derived signal (132), wherein the tuning means (120) is configured to provide the control signal (122) for tuning the magnetic antenna (106) in dependence on a phase relationship between the derived signal (132) and the phase signal (126), wherein the tuning means (120) comprises a signal combiner (136) configured to combine - the phase signal (126) or a phase-shifted version of the phase signal (126), and - the derived signal (132) or a phase-shifted version (138) of the derived signal (132), to obtain a combined signal (140), wherein the tuning means (120) is configured to control the tuning element (111) with the control signal (122) to regulate a DC component of the combined signal (140) or a low-pass filtered version (146) of the combined signal (140) to a predetermined set value.

2. Antenna arrangement (104) according to claim 1, wherein the phase signal (126) is based on a current flowing in at least a portion of the loop (108).

3. Antenna arrangement (104) according to one of claims 1 to 2, wherein the phase signal (126) is based on a magnetic field generated by the loop (108).

4. Antenna arrangement (104) according to one of claims 1 to 3, wherein the phase signal (126) is a power coupled out of the magnetic antenna (106).

5. Antenna arrangement (104) according to one of claims 1 to 4, wherein the tuning means (120) is configured to control the tuning element (111) with the control signal (122) to regulate a phase difference between the signal (124) advancing into the magnetic antenna (106) and the phase signal (126) to a predetermined set value.

6. Antenna arrangement (104) according to one of claims 1 to 5, wherein the loop (108) is interrupted once, wherein the loop (108) is interrupted by the tuning element (111).

7. Antenna arrangement (104) according to one of claims 1 to 6, wherein the loop (108) is interrupted several times, wherein the loop (108) is interrupted by the tuning element (111) and by one or several capacitance elements (110).

8. Antenna arrangement (104) according to one of claims 1 to 7, wherein the tuning element (111) is a variable capacitor of a capacitance diode.

9. Antenna arrangement (104) according to one of claims 1 to 8, wherein a loop circumference of the loop interrupted one or several times is 1 / 2 to 1 / 10 of a wavelength of the signal advancing into the magnetic antenna or of a transmitting signal to be transmitted or a receiving signal to be received with the magnetic antenna.

10. Antenna arrangement (104) according to one of claims 1 to 9, wherein a frequency of the signal advancing into the magnetic antenna or of a transmitting signal to be transmitted or of a receiving signal to be received with the magnetic antenna is equal to or higher than 149 MHz, 400 MHz or 800 MHz or is in the range of 149 MHz to 930 MHz.

11. Antenna arrangement (104) according to one of claims 1 to 10, wherein a frequency of the signal advancing into the magnetic antenna or of a transmitting signal to be transmitted or of a receiving signal to be received with the magnetic antenna is within an ISM band.

12. Antenna arrangement (104) according to one of claims 1 to 11, wherein the magnetic antenna comprises a Q of 20 to 500.

13. Participant (100) of a wireless communication system, wherein the participant (100) comprises a transmitting and / or receiving means (102) and an antenna arrangement (104) connected to the transmitting and / or receiving means according to one of claims 1 to 12.

14. Method (200) for tuning a magnetic antenna (106) with a loop (108) interrupted one or several times, comprising: providing (202) a control signal (122) for tuning the magnetic antenna (106) in dependence on a phase position of a signal (124) advancing into the magnetic antenna (106), and controlling (204) a tuning element (111) of the magnetic antenna (106) with the control signal (122) to tune the magnetic antenna (106), wherein the control signal (122) for tuning the magnetic antenna (106) is provided in dependence on a phase relationship between the signal (124) advancing into the magnetic antenna (106) and a phase signal (126), deriving a signal from the signal (124) advancing into the magnetic antenna (106) to obtain a derived signal (132), wherein the control signal (122) for tuning the magnetic antenna (106) is provided in dependence on a phase relationship between the derived signal (132) and the phase signal (126), wherein - the phase signal (126) or a phase-shifted version of the phase signal (126), and - the derived signal (132) or a phase-shifted version (138) of the derived signal (132), are combined to obtain a combined signal (140), controlling the tuning element (111) with the control signal (122) to control a DC component of the combined signal (140) or a low-pass filtered version (146) of the combined signal (140) to a predetermined set value.

15. Computer program for performing the method according to claim 14.