Method and device for the measurement of electromagnetic fields

Abstract

The invention is related to a method for the measurement of electromagnetic fields radiated from a signal source, comprising the following steps: a) moving a field probe along the ambience of the signal source, b) recording the field signals of the electromagnetic field of the signal source received by the field probe, c) assigning position information to the recorded field signals in such a way that, at least for discrete spatial positions of the field probe during the movement of the field probe, the corresponding spatial position of the field probe is assigned to the respective recorded field signal, d) determining amplitude and phase values of the electromagnetic field for each position information by combined signal processing of the recorded field signals in combination with the position information. In addition, the present invention is related to a device for the measurement of such electromagnetic fields.

Description

[0001]MEISSNERBOLTEMeissner Bolte Applicant: Patentanwälte Rechtsanwälte Partnerschaft mbB Plathnerstraße 3a Technische Universität Hamburg Harburg 30175 Hannover | Germany Am Schwarzenberg-Campus 1 Tel.: +49-5112613478-0 21073 Hamburg Fax: +49-5112613478-10 hannover@meissnerbolte.de www.meissnerbolte.de Our reference: V / TUH-0003-WO Date: 01 September 2023 / 6517 Method and device for the measurement of electromagnetic fields The invention is related to a method for the measurement of electromagnetic fields radiated from a signal source. In addition, the present invention is related to a device for the measurement of such electromagnetic fields. Electromagnetic field measurements are practically used for different purposes, for example for EMI-testing. For example, near-field measurement of such electromagnetic fields is a practical technique for characterizing the fields of antennas and other radiating devices under test in their proximity. However, current commercially available systems for such measurement of electromagnetic fields are relatively complex, large and expensive. Further, for large-scaled scanning tasks in high-resolution a significant time consumption occurs. A method and device for verifying the electromagnetic emission of a vehicle component is disclosed in DE 102019111948 A1. It is an object of the invention to propose improved methods and devices for the measurement of electromagnetic fields which overcome the aforementioned drawbacks. The aforementioned object is achieved by a method for the measurement of electromagnetic fields radiated from a signal source, comprising the following steps: a) moving a field probe along the ambience of the signal source, b) recording the field signals of the electromagnetic field of the signal source received by the field probe, c) assigning position information to the recorded field signals in such a way that, at least for discrete spatial positions of the field probe during the movement of the field probe, the corresponding spatial position of the field probe is assigned to the respective recorded field signal, d) determining amplitude and phase values of the electromagnetic field for each position information by combined signal processing of the recorded field signals in combination with the position information. The invention has the advantage that it allows both amplitude and phase value measurement of electric and magnetic fields using only a single field probe. Even though one or more additional field probes can be used in the present invention for further enhancing the measurement results, it is possible to implement the present invention with only a single field probe, without using for example a second stationary probe. In particular, it is possible to implement the present invention in a small sized low cost portable device which can be battery powered. Due to the novel step of determining amplitude and phase values of the electromagnetic field by the combined signal processing of both the recorded field signals and the position information, a combined demodulation can be done which allows relatively fast and precise measurement of the electromagnetic field. In other words, the position information is not only used for correct graphical representation of the determined amplitude and phase values over the measurement area, but also for the calculation of the amplitude and phase values of the electromagnetic field. In addition to the assignment of position information to the recorded field signals, time information can be assigned to the recorded field signals in such a way that, at least for the same discrete spatial positions of the field probe during the movement of the field probe, the corresponding time value of the measurement taken by the field probe is assigned to the respective recorded field signal. Then, in step d), it is possible to determine amplitude and phase values of the electromagnetic field for each position information by combined signal processing of the recorded field signals in combination with the position information and the time information. This increases the accuracy of the determined amplitude and phase values. In particular, in step d) it is possible to numerically determine amplitude and phase values of the electromagnetic field. The present invention is both suited for near-field measurements and far-field measurements, for example for the characterization of outdoor signal sources. The present invention is suited for measurement of electromagnetic fields in a wide range of frequencies, in particular in the range from Kilohertz to Gigahertz frequencies. According to an advantageous embodiment of the invention, the method is carried out with only a single field probe. This advantageously reduces cost and time efforts for performing electromagnetic field measurements. Also, the present invention can be embodied in a small hand-held device or a uncrewed vehicle, allowing one single field probe to establish a direct connection with the device and eliminating the need for lengthy high-frequency cables. According to an advantageous embodiment of the invention, at least the phase of the electromagnetic field for the respective position information is determined from a complex signal generated by calculation or measurement, for example, Hilbert Transform or down converter mixer. This allows for easy and fast numerical determination of the phase values in the combined signal processing of the recorded field signals in combination with the position information. In particular, the Hilbert Transform allows for both envelope (amplitude) and phase demodulation of the recorded field signals. In the context of this application the term Hilbert Transform shall cover all demodulation methods, whether analog or digital (numerical), which lead essentially to the same amplitude and phase results as the Hilbert Transform. According to an advantageous embodiment of the invention, the RF signals received by the field probe are down converted into in-phase (I) and quadrature (Q) signals which are further evaluated for determining amplitude and phase values of the electromagnetic field. This allows fast simultaneous field sampling at multiple frequencies and therefore improves the performance of the method and device further. In addition, it is easily possible to implement additional sophisticated algorithms like active learning and adaptive sampling, for example for determining the best sampling region and thereby optimizing the collected information per scan time about the field distribution. This can encompass the use of a quickly performed coarse field scan. For example, the method of the invention can be further defined by moving the probe to algorithmically determined measurement locations to adaptively obtain the most relevant field information. According to an advantageous embodiment of the invention, the movement of the field probe is continuously maintained during the measuring process at least between certain discrete spatial positions at which position information is assigned to the recorded field signals. This supports performing a fast scan process of the electromagnetic field. For example, it is possible to record the field signals of the electromagnetic field in a kind of On-the-Fly (OTF) scan process of the field probe. However, in such OTF scan it is possible to stop the movement of the field probe at certain positions (e.g. the above mentioned measurement locations), but moving the field probe again continuously from one stop point to the next stop point. The movement of the field probe can be done manually by a user. It is also possible to do the movement of the field probe automatically, for example by an industrial robot or any other kind of moveable platforms to which the field probe is mounted. The movement of the field probe can be done at a constant speed or at a varying speed. Also a combination of movement phases with constant speed and movement phases with varying speed is possible. According to an advantageous embodiment of the invention, the position information associated with the recorded field signals is determined by at least one position sensor detecting the three-dimensional spatial position of the field probe. This allows for a precise measurement of the spatial position of the field probe. For example, the position sensor can comprise one or more of an inertial measurement unit (IMU), a GPS signal receiver, a camera-based visual position tracking, or other position sensors. For example, for automated measurements where the field probe is mounted on a robot, the position information can also be determined based on internal position sensors of the robot and / or the position control of the stepper motors of the robot and its kinematics. Generally, the term 'position sensor' is meant to be a general term for all types of position measurement approaches, like such as sensor fusion through the utilization of multiple sensor sources. The object of the invention is also achieved by a device for the measurement of electromagnetic fields radiated from a signal source, having a field probe for receiving the field signals of the electromagnetic field of the signal source and having an evaluation device which is configured for a) recording the field signals of the electromagnetic field of the signal source received by the field probe, b) assigning position information to the recorded field signals in such a way that, at least for discrete spatial positions of the field probe during the movement of the field probe, the corresponding spatial position of the field probe is assigned to the respective recorded field signal, c) determining amplitude and phase values of the electromagnetic field for each position information by combined signal processing of the recorded field signals in combination with the position information. With such a device the aforementioned advantages of the invention can also be realized. The device can be implemented as a field scanner, e.g. a portable field scanner. The field probe can be of any kind, for example a H-field probe, a near-field probe, an antenna or a combination of several of such probe elements mounted to a common platform which is moved along the electromagnetic field. According to an advantageous embodiment of the invention, the evaluation device is configured for determining at least the phase of the electromagnetic field for the respective position information by means of complex signal generation, for instance, via the Hilbert Transform or in-phase (I) and quadrature(Q) demodulation. This allows for easy and fast numerical determination of the phase values in the combined signal processing of the recorded field signals in combination with the position information. In particular, the Hilbert Transform allows for both envelope (amplitude) and phase demodulation of the recorded field signals. According to an advantageous embodiment of the invention, device has at least one position sensor which detects the three-dimensional spatial position of the field probe, wherein the position information associated with the recorded field signals is determined by the at least one position sensor. According to an advantageous embodiment of the invention, device has a radio frequency (RF) receiver which is configured for down converting the RF signals received by the field probe into lower frequency signals which are further evaluated by the evaluation device. This allows for an easy and cost efficient further evaluation of the signals received by the field probe. For example, in a very cost efficient solution, the radio frequency receiver can be embodied as a software defined radio (SDR). According to an advantageous embodiment of the invention, device has a real-time (analogue or digital) down converter which is configured for down converting the RF signals received by the field probe into in-phase (I) and quadrature (Q) signals which are further evaluated by the evaluation device. This allows fast simultaneous field sampling at multiple frequencies and therefore improves the performance of the method and device further. In addition, it is easily possible to implement additional sophisticated algorithms like active learning and adaptive sampling, for example for determining the best sampling points and thereby optimizing the collected information per scan time about the field distribution. This can encompass the use of a quickly performed coarse field scan, that is further defined by moving the probe to algorithmically determined measurement locations to adaptively obtain the most relevant field information. For example, the down converter can be a combination of multiple up and down converters. Consider the detailed explanation of the invention through the utilization of data processing with the Hilbert Transform as an illustration. A on-the-fly near-field scan is conducted at a specific frequency, f0. When the field probe is stationary and when it's in motion, it generates two distinct signals. These two signals are a pure sinusoidal signal and a modulated signal, respectively. Given a scanning path from xato xb, and a constant moving speed of v0, the position of the probe is a function of time as ^(^) = ^^+ ^^^ (1) For a stationary field probe located at x which picks up only the x-component of H-field, the magnitude and phase of the received probe signal is expressed as ^(^) = 2^^^^ + ^^(^) (3) where ^^(^^, ^) is the complex H-field to be determinated and ^^(^) denotes its phase. For a moving field probe with its motion defined in (1), at a time instant t, it passes the point x, and receives a signal which is the same as the stationary one picked up at the same location and the same time, namely Next, substituting (1) into (4) and rewriting (4) as the real part of a complex signal yields Note that the probe signal in (4) is directly obtained by data acquisition(DAQ), using an oscilloscope for example. Then the transient complex H-field given in (5) can be easily calculated via the Hilbert Transform. From a signal processing perspective, HT produces a π / 2 phase shift of all frequency components of a transient signal and is frequently used to convert the transient signal of (4) into the complex signal of (5) for envelope and phase demodulation as ^(^) = |ℎ^(^) + ^ℋ[ℎ^(^)]| (6) ^(^) = ∠{ℎ^(^) + ^ℋ[ℎ^(^)]} (7) in which stands for HT. Afterward, by substituting t with (x − xa) / v0, the phase of H-field distribution along the scan path, i.e. ^^(^) , can be retrieved by subtracting 2^^^^ from ^(^) as given in (3). In principle, the single-probe method requires only a one-time DAQ and is constraint-free for high-speed scanning. Furthermore, each sample of a signal in time corresponds to a physical position along the path according to (1), making a fast high-resolution scan achievable. As a summary, this invention proposes a flexible and cost-effective solution for a standalone electromagnetic (EM) field scanner design. Field scanners are used to measure EM fields during the development, optimization and characterization of wireless communication devices or wireless power transfer devices as well as for the mandatory certification tests required by regulatory requirements for product development. The proposed portable device allows magnitude and phase measurements of electric and magnetic fields using only a single field probe to which a general purpose radio frequency (RF) frontend and a signal processing unit may be connected. A three dimensional distribution of the EM fields is obtained by moving the probe through the region of interest and tracking its position as well as the corresponding field samples. The position estimation can be implemented using integrated sensors like inertial measurement units (IMU), GPS sensors or camera based visual position tracking. Moreover, for automated measurements the portable field scanner can be mounted on an industrial robot. In this case, the position tracking can also be done based on the configuration of the stepper motors of the robot and its kinematics. The single-probe phase measurements are enabled by a novel method of combining the on-the-fly (OTF) scan technique with sophiscated signal processing methods. Conventional field scanning approaches require expensive RF measurement equipment, which consists of a robot, field probes and high frequency oscilloscopes or spectrum analyzers. These setups often cover a full laboratory bench and cannot work without mains supply while the proposed invention integrates more functions into a small portable device. Conventional field scanners cannot retrieve phase information of the EM fields without using a second stationary probe. Therefore, only the use of the novel data processing approach based on the OTF method allows the development of a portable field scanner for phase measurements. Moreover, the measurements based on the OTF method are significantly faster than the conventional step-scan approach and therefore save valuable measurement time. The reduction of the measurement time is critical because the characterization of a simple antenna in a volume of only a few cubic centimeters can take about 24 hours when the conventional approach is used. The invention provides a portable and efficient measurement of complete EM fields, especially the fields in a complex form (magnitude and phase), by using compact hardware design and advanced signal processing techniques. The essential new thing of the invention is its flexibility and efficiency of near-field scanning. The essence of the invention is that it solves the continuous near-field measurement with a time-spatial signal processing technique, allowing significant reduction of the system complexity and improvement of the performance. The combination of novel data processing algorithms, a new interpretation of the sampled field measurements together with the movement information of the field probe and the use of flexible and comparatively inexpensive hardware enables a flexible, portable and cost-efficient field scanner. In contrast to any available solution, this device can measure the phase distribution of the field using only a single probe, opens new application scenarios in different environments and is significantly faster than conventional approaches. The advantages of this invention are allowing continuous complex near-field measurements using a compact and simple system set-up. It could be small size and low- cost because of its universal architecture design. It could be high-speed with high- resolution because of its novel signal processing. It could be standalone and attachable to any moving platform, allowing seamless near-field scanning between different areas or spaces. The invention is further explained by some exemplary embodiments using drawings. The drawings show: Figure 1 a device for the measurement of electromagnetic fields, Figure 2 further functional details of the system of figure 1, Figure 3 a general design block diagram of the system, Figure 4 an exemplary movement of the field probe over time, Figure 5 an exemplary transient field probe signal, Figure 5a a complex transient field signal obtained via DHT of Fig.5, Figure 5b a complex transient field signal with phase correction of Fig.5a, Figure 5c a complex transient field signal obtained via I / Q demodulation of Fig.5, Figure 5d magnitude and phase representation of the complex signal in Fig.5c, Figure 5e illustration of converting a transient field signal into a spatial field distribution through utilization of the time-distance curve given by Fig.4, Figure 6 diagrams showing magnitude and phase of the H-field. Figure 1 shows a field probe 1 mounted to a robot 4. The field probe 1 is used for measuring of the electromagnetic field 3 radiated from a signal source 2, e.g. an IoT- device. The field probe 1 is electrically connected to an evaluation device 5. In the evaluation device 5 the field signals received by the field probe 1 are recorded and evaluated, as will be described hereinafter. The evaluation device 5 numerically determines amplitude and phase values of the electromagnetic field 3 and transfers it via an interface to another device 6, for example a display screen for displaying the determined amplitude and phase values. Figure 2 shows the evaluation device 5 of the system of figure 1 with further details. The field probe 1 is connected to a device 7 which might be a radio frequency receiver which converts down the high frequency RF signals received by the field probe 1 into lower frequency signals. As an alternative, the device 7 can be a real-time down converter which directly digitizes the RF signals received by the field probe and converts them into in-phase and quadrature signals. This allows fast simultaneous field sampling at multiple frequencies and therefore improves the performance of the system further. The signals provided from the device 7 are fed to a computer 8. In addition, signals of a position sensor 9 which detects the three-dimensional spatial position of the field probe 1 are fed to the computer 8. The computer can be any commercially available computer, like a PC, Laptop, Notebook, Tablet or Smartphone, or a microprocessor, microcontroller or FPGA, or a combination of such elements. The computer 8 records the signals from device 7 and assigns to these signals a corresponding spatial position of the field probe from the signals received from position sensor 9. Further, the computer 8 also stores time information recorded signals. Therefore, during the scan process of the electromagnetic field 3 by the moving field probe 1, for each of the several measurement items a data set is stored which comprises the signals from device 7, the related spatial position of the field probe 3 and the time of the measurement item. The computer 8 then determines amplitude and phase values of the electromagnetic field 3 for each position information stored from position sensor 9 by performing a combined signal processing of the recorded field signals in combination with the position information and time information of the numerous data sets. During the scan process of the electromagnetic field 3, positional movement of the field probe 1 along the electromagnetic field 3 may be done by the robot 4. However, the robot 4 is an optional feature of the invention. As an alternative, the field probe 1 may be moved along the electromagnetic field 3 by manual movement of the user. If the robot 4 is used, the computer 8 might also produce control signals for controlling the positional movement of the field probe 1 by the robot 4. In Fig.1 the portable field scanner is illustrated as a standalone device or attached to an industrial robot for automated measurements. It can also be attached to other vehicles like cars, drones or boats to cover a wider range of application areas. Fig.2 shows a more detailed block diagram of the system and indicates the flexibility of the modular system approach, which allows to adjust the system for the specific requirements of different applications, e. g. by changing the frequency range, the measurement speed, the accuracy or the system costs. Figure 3 shows further possible combinations of the device of the invention with additional external components. It should be noticed that the device 6 for outputting the results of the determination of amplitude and phase values of the electromagnetic field can be presented in several different ways, as shown in block 6 of figure 3. Figure 4 shows an exemplary movement of the field probe 1 along a defined path in the vicinity of signal source 2, which is plotted over time. The movement can be done by the robot 4, for example at 30 % of full speed. Figure 5 shows the transient signal of the field probe 1 before evaluation through the computer 8. Figure 5 shows the probe signal over time, for example at 5 million sampling points per second. Figure 5a shows the complex transient signal, wherein its real component is linked to the transient signal obtained from figure 5, while its imaginary counterpart is computed through the application of the Hilbert Transform to the real part. Within Figure 5a, the upper diagram showcases the amplitude (magnitude) of the complex transient signal, while the lower diagram partially depicts the phase of the same signal around 1.565 seconds. Figure 5b shows the processed complex transient signal with its phase corrected. This correction is accomplished by subtracting the phase variance between the measurement point and the initial measuring point, which arises from the time delay associated with the OTF scan. For instance, in this case of a continuous 125 kHz signal, the phase variance at 1.565 seconds would equate to zero. Figure 5c presents an alternative approach for generating a complex transient signal using the transient probe signal given in figure 5. Through the utilization of in-phase (I) and quadrature (Q) demodulation techniques, the transient probe signal is down- converted to a lower frequency, in this context, directly to DC, resulting in the acquisition of I-Q signals. Figure 5d depicts the magnitude and phase characteristics of the complex transient signal, where the real and imaginary components are associated with the in-phase (I) and quadrature (Q) signals from figure 5c, respectively. Figure 5e illustrates the methodology for transforming a complex transient signal across time into a complex field distribution along a scanning trajectory. The upper and lower solid curves stand for the magnitudes of the two complex fields. The upper cuver is taken from either figure 5c or figure 5d. The dashed line connecting these two curves illustrates the scanning processes in both the temporal and spatial domains, determined by the sensor's motion as depicted in figure 2. Figure 6 shows in the upper diagram the amplitude (magnitude) of the measured field signal after the determination process of computer 8. The magnitude is shown over the distance of the aforementioned path shown in figure 4. In the lower diagram the phase of the H-field is shown over the distance. Both the magnitude and the phase have been adjusted to relative values to enhance visualization. The portable field scanner may use sophisticated algorithms like active learning and adaptive sampling implemented on the device to determine the best sampling points and thereby optimizes the collected information per scan time about the field distribution. This encompasses the use of a quickly performed coarse (i.e., inaccurate) field scan, that is further refined by moving the probe to algorithmically determined measurement locations to adaptively obtain the most relevant field information. Besides, the performance of the standalone design can be improved by training its on- board sensors using an industry robot. Sensor fusion, combining real-time measurements from various sensors (IMU, GPS, visuals, ...) to obtain reliable position information of the field probe is handled by filtering approaches on-board, combined with machine learning to deal with inaccurate position estimation. Training data for the machine learning approach may be generated using sensor readings as input, and precise location information obtained by the robot to learn a corrected prediction from sensor data to actual location. Training can be performed offline and does not increase the scan time, as the scanner only has to perform inference with a fully trained ML model (shipped with the field scanner). For better understanding, the invention is described with three exemplary embodiments: (1) On-site EM interference testing with wireless power transfer (WPT) devices at 13.56 MHz The device under test (DUT) which emits the electromagnetic fields 3 is placed on a table in the lab. The evaluation device 5 is attached to a robot 4, and its H-field probe 1 is connected to an external USB high-speed digitizer through reserved interfaces. Signal sampling module of the evaluation device 5 are deactivated. The robot scans predetermined paths or surfaces specified by the user, while the evaluation device 5 performs direct data aqqusition from the external USB digitizer and signal processing. The sampling rate of the USB digitizer is set to be above 150 MHz. Subsequently, both the magnitude and phase of the H-field can be obtained using a single field probe, which is not possible with other scanners available in the market. Following the standard field calibration procedure of the field probe, the measurement results of the H-field can be utilized for EMI compliance testing or source replacement of the DUT. (2) Maximum field exposure inspection of internet of things (IoT) devices around 2.4 GHz The evaluation device 5 can be used either handheld or attached to a collaborative robot to scan the near-fields surrounding an IoT device in a realistic operating environment. The scanning process is conducted iteratively, involving fast coarse scans over a large area and slow fine scans in a smaller region. Assuming the operating frequency range of the IoT device is from 2401 MHz to 2411 MHz, the original field probe signal is down- converted to 10 MHz using an RF mixer. The resulting signals from the mixer, namely the in-phase (I) and quadrature (Q) signals, are digitized using an analog-to-digital converter with a sampling rate of 20 MHz. Similar to the signal processing described in the previous example, the envelope and phase of the complex signal, defined by the I-Q signals, are correlated with the field probe's motion. Subsequently, the field distribution is calculated and displayed in real-time on the EM scanner's screen. A machine learning algorithm is employed to model the near-field, and new scan regions are recommended and updated on the screen to guide the user or the robot towards inspecting target areas with maximum field levels and locations. It should be noted that by utilizing a larger sampling bandwidth and employing digital band-pass filters in post-processing, multiple IoT devices operating at different channels around 2.4 GHz can be measured simultaneously. (3) Out-door EM environment characterization in large region from kHz to GHz The evaluation device 5 is mounted on a drone for long-distance and prolonged measurements. The drone's position is tracked using both a GPS receiver and an IMU. By continuously sweeping the local oscillating (LO) frequency of the mixer from MHz to GHz, the spectrum of the field probe signal can be captured in its entirety and rapidly updated during the drone's flight. The same I-Q signal processing technique is applied, correlating the magnitude of the complex signal with the movement of the probe. As the LO frequency changes, the signal magnitude at different locations is associated with different frequencies. This process generates a real-time spatial-frequency spectrum, with spatial resolution continuously improving as the drone flies. A machine learning algorithm is then employed for data regression analysis, providing recommendations to adjust the scan path or terminate the scan. *****

Claims

MEISSNERBOLTE Meissner Bolte Applicant: Patentanwälte Rechtsanwälte Partnerschaft mbB Plathnerstraße 3a Technische Universität Hamburg Harburg 30175 Hannover | Germany Am Schwarzenberg-Campus 1 Tel.: +49-5112613478-0 21073 Hamburg Fax: +49-5112613478-10 hannover@meissnerbolte.de www.meissnerbolte.de Our reference: V / TUH-0003-WO Date: 01 September 2023 / 6517 Claims:

1. Method for the measurement of electromagnetic fields (3) radiated from a signal source (2), comprising the following steps: a) moving a field probe (1) along the ambience of the signal source (2), b) recording the field signals of the electromagnetic field (3) of the signal source (2) received by the field probe (1), c) assigning position information to the recorded field signals in such a way that, at least for discrete spatial positions of the field probe (1) during the movement of the field probe, the corresponding spatial position of the field probe (1) is as- signed to the respective recorded field signal, d) determining amplitude and phase values of the electromagnetic field (3) for each position information by combined signal processing of the recorded field signals in combination with the position information.

2. Method according to claim 1, characterized in that the method is carried out with only a single field probe (1).

3. Method according to any one of the preceding claims, characterized in that at least the phase of the electromagnetic field (3) for the respective position information is determined from a complex signal generated by calculation or measurement, for ex- ample, using a Hilbert Transform or a down converter mixer.

4. Method according to any one of the preceding claims, characterized in that the RF signals received by the field probe (1) are down converted into in-phase (I) and quadrature (Q) signals which are further evaluated for determining amplitude and phase values of the electromagnetic field (3).

5. Method according to any one of the preceding claims, characterized in that the movement of the field probe (1) is continuously maintained during the measuring2 process at least between certain discrete spatial positions at which position infor- mation is assigned to the recorded field signals.

6. Method according to any one of the preceding claims, characterized in that the posi- tion information associated with the recorded field signals is determined by at least one position sensor (9) detecting the three-dimensional spatial position of the field probe (1).

7. Device for the measurement of electromagnetic fields (3) radiated from a signal source (2), having a field probe (1) for receiving the field signals of the electromag- netic field (3) of the signal source (2) and having an evaluation device (5) which is configured for a) recording the field signals of the electromagnetic field (3) of the signal source (2) received by the field probe (1), b) assigning position information to the recorded field signals in such a way that, at least for discrete spatial positions of the field probe (1) during the movement of the field probe (1), the corresponding spatial position of the field probe is as- signed to the respective recorded field signal, c) determining amplitude and phase values of the electromagnetic field (3) for each position information by combined signal processing of the recorded field signals in combination with the position information.

8. Device according to claim 7, characterized in that the evaluation device (5) is config- ured for determining at least the phase of the electromagnetic field (3) for the re- spective position information by means of a complex signal generation, for instance, via the Hilbert Transform or in-phase (I) and quadrature(Q) demodulation.

9. Device according to any one of claims 7 to 8, characterized in that device has at least one position sensor (9) which detects the three-dimensional spatial position of the field probe (1), wherein the position information associated with the recorded field signals is determined by the at least one position sensor (9).

10. Device according to any one of claims 7 to 9, characterized in that device has a ra- dio frequency (RF) receiver which is configured for down converting the RF signals received by the field probe (1) into lower frequency signals which are further evalu- ated by the evaluation device (5).

311. Device according to any one of claims 7 to 10, characterized in that device has a real-time down converter which is configured for down converting the RF signals re- ceived by the field probe (1) into in-phase (I) and quadrature (Q) signals which are further evaluated by the evaluation device (5).

12. Device according to any one of claims 7 to 11, characterized in that device is config- ured to perform algorithms like active learning, path planning and / or adaptive sam- pling for determining the best sampling points and thereby optimizing the collected information per scan time about the field distribution. *****

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