System and method for testing a device in a reverberation chamber

Abstract

The present disclosure generally relates to a system and method for testing a device-under- test (DUT), the system comprising a receiver antenna and a transmitter antenna, wherein the DUT is configured to be coupled to or is formed at least partially by the transmitter antenna or the receiver antenna, a receiver processing unit configured to be electrically coupled to the receiver antenna, and a reverberation chamber including configuration means for changing an electromagnetic (EM) reflection behavior inside the reverberation chamber between a plurality of states, and being configured to receive the receiver antenna and the transmitter antenna. The system is configured to perform a plurality of measurements, wherein for each measurement: the reverberation chamber is configured in a respective state among the plurality of states; the transmitter antenna is configured to emit EM waves inside the reverberation chamber based on a modulated signal, wherein the modulated signal includes a frequency chirp in a predetermined frequency range; the receiver antenna is configured to receive said EM waves and provide a receiver signal; and the receiver processing unit is configured to sample the receiver signal in the time-domain to obtain a sampled time-domain signal. The system is further configured to obtain a test result associated with the DUT based on the sampled time-domain signals associated with the plurality of measurements.

Description

[0001] SYSTEM AND METHOD FOR TESTING A DEVICE IN A REVERBERATION

[0002] CHAMBER

[0003] FIELD

[0004] The present disclosure generally relates to a system and method for testing a device-under- test. The present disclosure is especially suitable for determining, for the device-under-test, a total radiated power across a frequency range, or an error vector magnitude, bit error rate, or symbol error rate associated with a digital modulation scheme.

[0005] BACKGROUND

[0006] In recent years, electromagnetic reverberation chambers have become increasingly more popular as a tool for testing and characterizing high-frequency systems and components, such as antennas. A reverberation chamber is typically a screened room or chamber with minimal absorption of electromagnetic energy. Due to the low absorption, very high field strengths can be achieved with moderate input power. Typically, a spatial distribution of the electromagnetic field strength inside the chamber during operation is strongly inhomogeneous. However, by making the reverberation chamber configurable to change its internal electromagnetic reflection behavior, it is possible to obtain, on average across a plurality of measurements, a roughly uniform field distribution. Accordingly, various parameters of the system or component to be tested can be derived using a system involving a reverberation chamber. For example, reverberation chambers may generally be useful for determining antenna properties such as total radiated power (TRP), noise figure (NF), gain, and the like.

[0007] For efficient testing, a total measurement time required to arrive at a test result is preferably minimized. However, the total measurement time may be dependent at least on the number of individual measurements needed to achieve approximate field uniformity on average. Moreover, for characterization at multiple frequencies in a frequency band of interest, conventional systems and methods require a respective plurality of measurements to characterize the system at each given frequency. In addition, specialized high-frequency hardware may be required in conventional systems, increasing the cost of such measurement systems.

[0008] SUMMARY

[0009] It is an object of the present disclosure to provide a measurement system and measurement method in which the abovementioned problem(s) do not occur or at least to a lesser extent. A summary of aspects of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects and / or a combination of aspects that may not be set forth.

[0010] According to an aspect of the present disclosure, a system for testing a device -under-test (DUT) is provided. The system comprises a transmitter antenna and a receiver antenna, wherein the DUT is configured to be coupled to or is formed at least partially by the transmitter antenna or the receiver antenna; a receiver processing unit configured to be electrically coupled to the receiver antenna; and a reverberation chamber including configuration means for changing an electromagnetic, ‘EM’, reflection behavior inside the reverberation chamber between a plurality of states, wherein the reverberation chamber is configured to receive the receiver antenna and the transmitter antenna. The system is configured to perform a plurality of measurements, wherein, for each measurement: the reverberation chamber is configured in a respective state among the plurality of states; the transmitter antenna is configured to emit EM waves inside the reverberation chamber based on a modulated signal, wherein the modulated signal includes a frequency chirp in a predetermined frequency range; the receiver antenna is configured to receive said EM waves and provide a receiver signal to the receiver processing unit; and the receiver processing unit is configured to sample the receiver signal in the time-domain to obtain a sampled time-domain signal. The system is further configured to obtain a test result associated with the DUT based on the plurality of sampled time-domain signals associated with the plurality of measurements.

[0011] With the system above, a test result associated with the DUT can be obtained very time- efficiently, especially since the transmitted signal is a modulated signal having a predetermined bandwidth across which the test result is to be obtained. Moreover, this system allows to avoid expensive specialized high-frequency hardware such as a spectrum analyzer.

[0012] To obtain the test result, the system may be configured to process the sampled timedomain signals, the processing including an averaging operation.

[0013] For example, the system may be configured to determine an average signal by averaging absolute values of the sampled time-domain signals, and optionally convert the average signal to power and / or perform a normalization operation. Alternatively, the system may be configured to convert each sampled time-domain signal to power, and determine an average signal by averaging the converted sampled time-domain signals. Alternatively, the system may be configured to calculate an FFT for each sampled time-domain signal, convert the FFTs to power, and determine an average FFT by averaging the converted FFTs. Alternatively, the system may be configured to calculate an FFT for each sampled time-domain signal, determine an average FFT by averaging the FFTs, and optionally convert the average FFT to power and / or perform a normalization operation. The test result may include a total radiated power, ‘TRP’, at a plurality of frequencies within the predetermined frequency range. When the transmitter antenna is configured to transmit a chirp with a particular bandwidth, the average of the sampled time-domain signal can for example be used to derive the TRP at different frequencies, without the need of repeating measurements at individual frequencies.

[0014] In a preferred embodiment, the modulated signal may be a frequency-modulated continuous wave, ‘FMCW’ , chirp.

[0015] In a further embodiment, the frequency chirp may be substantially linear, and the test result may be obtained based on an envelope of the average of the plurality of sampled time-domain signals. In particular, assuming the frequency chirp is roughly linear, the envelope of the average sampled time-domain signal may be indicative of the TRP at multiple frequencies in the frequency range of the chirp.

[0016] In an even further embodiment, the sampling rate for sampling the receiver signal may be lower than two times a bandwidth of the modulated signal. The applicant has found that, since this testing procedure does not require evaluating the instantaneous value of the average sampled timedomain signal as such but rather its envelope, it is possible to sample the receiver signal a sampling frequency below the Nyquist rate. In other words, the Nyquist frequency associated with the chosen sampling rate may fall within the bandwidth of the modulated signal. As a result, there is no need to implement the receiver processing unit with a very high sampling frequency or with a mixer to down-convert the receiver signal, thereby allowing for a more cost-effective implementation.

[0017] The receiver processing unit may comprise a time-domain sampling unit configured to sample the receiver signal. For example, the time-domain sampling unit may include an analog-to- digital converter, ‘ADC’, preferably being a component of an oscilloscope included in the system.

[0018] The receiver processing unit may further comprise a mixer electrically coupled between the receiver antenna and the time-domain sampling unit. The mixer may be configured to downconvert the receiver signal prior to the sampling by the time-domain sampling unit.

[0019] The receiver processing unit may further comprise a low-frequency amplifier electrically coupled between the mixer and the time-domain sampling unit.

[0020] The receiver processing unit may further comprise a local oscillator, ‘LO’, configured to provide an LO signal to the mixer for down-converting the receiver signal.

[0021] For example, a frequency of the LO signal may correspond to a carrier frequency associated with the modulated signal, or may be a predetermined amount lower than a minimum frequency emitted by the transmitter antenna based on the modulated signal, or may be a predetermined amount higher than a maximum frequency emitted by the transmitter antenna based on the modulated signal. The receiver processing unit may further comprise a high-frequency amplifier electrically coupled between the receiver antenna and the time-domain sampling unit. In so far as the receiver processing unit comprises a mixer, the high-frequency amplifier may be electrically coupled between the receiver antenna and the mixer.

[0022] The receiver processing unit may further comprise a low-pass filter electrically coupled between the receiver antenna and the time-domain sampling unit. In so far as the receiver processing unit comprises a mixer, the low-pass filter may be electrically coupled between the mixer and the time-domain sampling unit.

[0023] The system may further comprise transmitter circuitry configured to be electrically coupled to the transmitter antenna and configured to provide the modulated signal about a carrier frequency to the transmitter antenna.

[0024] The transmitter circuitry may be configured to be arranged inside of the reverberation chamber. For example, the transmitter circuitry and the transmitter antenna may be integrated into a single unit. Alternatively, the transmitter circuitry may be configured to be at least partially arranged outside of the reverberation chamber, in which case the reverberation chamber may further comprise a first feedthrough via which the transmitter antenna and transmitter circuitry can be coupled.

[0025] The receiver processing unit may be configured to be arranged inside of the reverberation chamber. For example, the receiver processing unit and the receiver antenna may be integrated into a single unit. Alternatively, the receiver processing unit may be configured to be at least partially arranged outside of the reverberation chamber, in which case the reverberation chamber may further comprise a second feedthrough via which the receiver antenna and the receiver processing unit can be electrically coupled.

[0026] The receiver processing unit may be configured to obtain the test result. Alternatively, the system may further comprise a central processing unit configured to receive the plurality of sampled time-domain signals or the average of the plurality of sampled time-domain signals from the receiver processing unit, and to obtain the test result based thereon.

[0027] For each measurement, the receiver processing unit may be configured to sample the receiver signal based on a predetermined time period for performing said measurement. In other words, the capturing of the receiver signal may be performed for a predetermined, configurable amount of time, for example depending on when emission of EM waves by the transmitter antenna is initiated. Alternatively, for each measurement, the receiver processing unit is configured to sample the receiver signal based on the receiver signal exceeding a threshold value. In other words, when the receiver signal exceeds the threshold value, capturing of the receiver signal may begin, or a predetermined amount of samples prior to the receiver signal exceeding the threshold value may additionally be taken into account for the sampled time-domain signal according to the present disclosure. In another alternative, the system may further comprise a control unit configured to control the receiver processing unit and / or the transmitter circuitry in dependence of each other.

[0028] The transmitter antenna may form part of an autonomous emitter. That is, the transmitter antenna and for example the transmitter circuitry may be configured to perform its function without needing control and / or any external RF input during the plurality of measurements.

[0029] The configuration means may comprise at least one of the following: at least one movable stirrer, preferably at least one rotatable stirrer; at least one electronically adjustable stirrer; and a moving unit, such as a movable platform, configured to move the transmitter antenna and / or the receiver antenna between a plurality of positions inside the reverberation chamber.

[0030] The reverberation chamber may further comprise at least one static, electromagnetically reflective element arranged at a fixed position and with a fixed orientation within the reverberation chamber.

[0031] According to another aspect of the present disclosure, a method is provided. The method comprises: providing a reverberation chamber including configuration means for changing an electromagnetic, ‘EM’, reflection behavior inside the reverberation chamber between a plurality of states; providing a transmitter antenna and a receiver antenna inside the reverberation chamber, the DUT being coupled to or formed at least partially by the transmitter antenna or the receiver antenna; and performing a plurality of measurements, wherein, for each measurement: the reverberation chamber is configured in a respective state among the plurality of states; the transmitter antenna emits EM waves inside the reverberation chamber based on a modulated signal, wherein the modulated signal includes a frequency chirp in a predetermined frequency range; the receiver antenna receives said EM waves and provides a respective receiver signal to a receiver processing unit; and the receiver processing unit samples the respective receiver signal in the timedomain to obtain a respective sampled time-domain signal. The method further comprises obtaining a test result associated with the DUT based on the plurality of sampled time-domain signals associated with the plurality of measurements. For completeness, any features or components of the system aspect of the present disclosure, described in the summary above and / or in the detailed description below, can be identically or similarly applied to the method aspect of the present disclosure. A repetition of such features for the method aspect is therefore omitted.

[0032] Further aspects and / or embodiments of the present disclosure may become apparent from the detailed description below.

[0033] BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Next, the present disclosure will be described in more detail referring to the appended drawings, wherein: FIG. 1 is a schematic diagram of a system according to an embodiment of the present disclosure;

[0035] FIG. 2A is a signal diagram illustrating an example of a chirp signal;

[0036] FIG. 2B is a signal diagram illustrating an example of a plurality of received chirp signals and an average receiver signal;

[0037] FIG. 2C is a timing diagram illustrating a plurality of measurements according to an embodiment of the present disclosure;

[0038] FIG. 3A is a signal diagram illustrating an example of a 4-QAM signal;

[0039] FIG. 3B is a signal diagram illustrating a plurality of received 4-QAM signals and an average receiver signal; and

[0040] FIG. 4 is a flowchart illustrating a method according to an embodiment of the present disclosure.

[0041] DETAILED DESCRIPTION

[0042] Hereinafter, reference will be made to the appended drawings. It should be noted that identical reference signs will be used to refer to identical or similar components. Moreover, unless explicitly stated otherwise, various elements shown in the appended drawings may not be drawn to scale, and parts may be exaggerated or omitted for convenience of explanation.

[0043] In FIG. 1 , a system 1 for testing a device -under-test (DUT) according to an embodiment of the present disclosure is shown. In particular, FIG. 1 illustrates an in-use configuration of system 1 , including a reverberation chamber 10, a transmitter antenna 20, transmitter circuitry 21, a receiver antenna 30 and a receiver processing unit 40. For the purpose of testing using system 1 , during measurements, at least transmitter antenna 20 and receiver antenna 30 are arranged inside reverberation chamber 10.

[0044] The DUT may be an element, component, or device that is coupled to transmitter antenna 20 or receiver antenna 30, or may be the transmitter antenna 20 or receiver antenna 30 itself. In the former case, the DUT may be formed by transmitter circuitry 21 or by at least part of receiver processing unit 40. In other words, the DUT may be any part of the transmitter chain or the receiver chain. Of course, the DUT may also be a combination of transmitter antenna 20 and transmitter circuitry 21, or a combination of receiver antenna 30 and at least part of receiver processing unit 40.

[0045] In an example, when the DUT corresponds to transmitter antenna 20 and / or transmitter circuitry 21, well-characterized reference components may be used as receiver antenna 30 and / or receiver processing unit 40 to provide a higher test result accuracy. Conversely, when the DUT corresponds to receiver antenna 30 and / or receiver processing unit 40, transmitter antenna 20 and transmitter circuitry 21 may be well-characterized reference components, such that accurate test results can be produced.

[0046] As shown in FIG. 1, transmitter circuitry 21 may be provided externally to reverberation chamber 10 and may be electrically coupled to transmitter antenna 20 via a first feedthrough 1 la of reverberation chamber 10. Alternatively, although not shown in FIG. 1, transmitter circuitry 21 may be partially or even entirely arranged inside reverberation chamber 10 (e.g., integrated with transmitter antenna 20) during measurements.

[0047] Similarly, receiver processing unit 40 may be provided externally to reverberation chamber 10 and may be electrically coupled to receiver antenna 30 via a second feedthrough 1 lb of reverberation chamber 10 as illustrated in FIG. 1. Alternatively, although not shown, receiver processing unit 40 may be partially or even entirely arranged inside reverberation chamber 10 (e.g., integrated with receiver antenna 30).

[0048] Transmitter circuitry 21 is configured to provide, to transmitter antenna 20, a modulated signal, in particular one in a frequency range suitable to be emitted as EM waves by transmitter antenna 20. The modulated signal may for example be a signal modulated using a digital modulation scheme, such as ASK, PSK, FSK, OFDM, QAM, phase-modulated continuous wave (PMCW), or the like. Alternatively, the modulated signal is one modulated in an analog manner, for example involving FMCW, or the like. The modulated signal may refer to a baseband signal (e.g., centered about 0 Hz) but may also refer to an up-converted modulated signal about a carrier frequency. Although not illustrated in detail in FIG. 1, transmitter circuitry 21 may include various components to realize its functionality, including but not limited to a signal generator, a digital-to- analog converter (DAC), a communication processor, a mixer, a local oscillator (LO), amplifier(s), filter(s), and the like, as will be appreciated by the person skilled in the art.

[0049] During a measurement, transmitter antenna 20 is configured to emit EM waves inside of reverberation chamber 10. The EM waves emitted by transmitter antenna 20 reflect internally to reverberation chamber 10 and waves from various propagation paths and angles are received by receiver antenna 30, which is configured to convert the received EM waves into a receiver signal and to provide said receiver signal to receiver processing unit 40.

[0050] Receiver processing unit 40 may include various components for processing the receiver signal. In particular, receiver processing unit 40 is configured to sample the receiver signal in the time-domain to obtain a sampled time-domain signal. To that end, receiver processing unit 40 may include a time-domain sampling unit 46, for example including an analog-to-digital converter (ADC). Time-domain sampling unit 46 may also for example be an oscilloscope.

[0051] When the modulated signal is based on a digital modulation scheme, such as QAM, receiver processing unit 40 may include an in-phase and quadrature demodulator, or IQ- demodulator, as will be appreciated by a person skilled in the art. In that case, the receiver signal may be divided into an in-phase (I) component and a quadrature (Q) component. Accordingly, the I and Q components of the receiver signal may be sampled individually, and the sampled timedomain signal described above may include an I-component and a Q-component. Thus, although not shown explicitly in FIG. 1 , IQ-demodulating means such as separate I- and Q-paths may be included in receiver processing unit 40.

[0052] Depending on the operating frequency, i.e., the frequency of the modulated signal and / or of the EM waves emitted by transmitter antenna 20, time-domain sampling unit 46 may directly sample the receiver signal. However, operating frequencies for measurement of modulated signals using reverberation chambers may typically be relatively high (e.g., more than 2 GHz), and it may be necessary or at least beneficial to first pre-process the receiver signal before time-domain sampling unit 46 is able to effectively acquire the desired information.

[0053] To that end, receiver processing unit 40 may further include a mixer 42 configured to down-convert the receiver signal to a frequency that can be processed by time-domain sampling unit 46. Accordingly, receiver processing unit 40 may also further include a low-pass filter 45 to remove image frequencies caused by the down-conversion by mixer 42, as well as noise outside of the bandwidth of the modulated signal as received by receiver antenna 30. For the purpose of the mixing operation, receiver processing unit 40 may be provided with an oscillation signal or may itself include a local oscillator (LO) configured to provide said oscillation signal.

[0054] Receiver processing unit 40 may further comprise a high-frequency amplifier 41 and / or a low-frequency amplifier 44 to amplify the receiver signal prior to sampling by time-domain sampling unit 46. Further components may be included in the chain of receiver processing unit 40, such as a bandpass filter (not shown) between receiver antenna 30 and mixer 42, or the like.

[0055] Reverberation chamber 10, as shown in FIG. 1, may be a chamber enclosing a space in which transmitter antenna 20 and receiver antenna 30 can be arranged. Typically, reverberation chamber 10 may have electromagnetically reflective inner walls. The walls of reverberation chamber 10 are typically arranged such that the space inside reverberation chamber 10 has a cuboid or similar shape, though various shapes could instead be implemented.

[0056] Further to the above, reverberation chamber 10 includes one or more types of configuration means for changing a reflective behavior inside reverberation chamber 10 between a plurality of states in which reverberation chamber 10 can be configured. Here, changing a reflective behavior may mean changing an EM field distribution that would occur inside reverberation chamber 10, due to differing propagation paths from transmitter antenna 20 to various positions in reverberation chamber 10, with respect to other states of reverberation chamber 10.

[0057] For example, reverberation chamber 10 may include a movable stirrer 12, which can be moved rotationally and / or translationally between a plurality of different positions and / or orientations. In a further example, the movable stirrer 12 may be mechanically rotatable about an axis, e.g., using a motor externally to reverberation chamber 10. A typical movable stirrer includes a plurality of electromagnetically reflective plates (e.g., made of metal), arranged at mutually different positions and / or orientations. This arrangement, combined with the fact that movable stirrer 12 can be moved or rotated, enables various different paths from transmitter antenna 20 to receiver antenna 30 for each position of movable stirrer 12. Thus, each discrete position of movable stirrer 12 can provide a different state for reverberation chamber 10.

[0058] Additionally or alternatively, reverberation chamber 10 may include an electronically adjustable stirrer 13, which can be controlled electronically to change its reflective behavior for EM waves incident thereon. Each possible reflective behavior of electronically adjustable stirrer 13 may provide a different state for reverberation chamber 10.

[0059] Additionally or alternatively, reverberation chamber 10 may include a moving unit 14 configured to move transmitter antenna 20 and / or receiver antenna 30. For example, moving unit 14 may include a movable platform for transmitter antenna 20 and / or a movable platform for receiver antenna 30. A conveyor-type implementation, or the like, is equally envisaged for moving unit 14. Each position of transmitter antenna 20 with respect to reverberation chamber 10 and / or each position of receiver antenna 30 with respect to reverberation chamber 10 may provide a different state for reverberation chamber 10. It is noted that moving unit 14 is merely shown schematically in FIG. 1 rather than with a detailed structural illustration.

[0060] Aside from configuration means 12, 13, 14 of reverberation chamber 10 as described above, reverberation chamber 10 may optionally further include one or more static, electromagnetically reflective elements 15 (e.g., made of metal). Such elements 15 may be referred to as static stirrers or fixed-mode stirrers, and are configured to remain static with respect to reverberation chamber 10 between the plurality of states. For example, these additional static elements 15 may be included to further reduce the symmetry of the inside of reverberation chamber 10.

[0061] Reverberation chamber 10 further comprises a shielding element 16, such as an electromagnetically reflective (e.g., metal) plate, arranged during use between transmitter antenna 20 and receiver antenna 30 to prevent a direct (line-of-sight) propagation from transmitter antenna 20 to receiver antenna 30. Depending on the directionality, position and / or orientation of transmitter antenna 20 and / or receiver antenna 30, however, shielding element 16 may not be needed for performing measurements using reverberation chamber 10. For example, if transmitter antenna 20 employs beamforming, a line-of-sight component towards receiver antenna 30 may be relatively small when the beam is directed away from receiver antenna 30.

[0062] The dimensions of the reverberation chamber may depend on the operating frequency range it is designed for, and thus on the application for which the DUT is designed. In a non- limiting example, if the operating frequency range of signals to be measured in the reverberation chamber is 18 - 140 GHz, e.g., corresponding to a typical frequency range for 5G / 6G communications, automotive radar, sensing, SATCOM, or EMC, a suitable reverberation chamber may have dimensions of 0.5 x 0.6 x 0.8 m.

[0063] System 1 may further include a central processing unit 50 configured to receive, from receiver processing unit 40 (e.g., from time-domain sampling unit 46), data relating to the receiver signal. Central processing unit 50 may gather this data from a plurality of measurements each involving a respective receiver signal with reverberation chamber 10 being configured in a respective state among the plurality of states. In turn, based on data from the plurality of measurements, central processing unit 50 can obtain a test result associated with the DUT. For example, central processing unit 50 may be part of a computer configured to be operatively connected to receiver processing unit 40. Alternatively, receiver processing unit 40 gathers and stores the data and obtains the test result itself, in which case external components such as central processing unit 50 can be omitted.

[0064] System 1 may further include a control unit 60 configured to control transmitter circuitry 21 and / or receiver processing unit 40. For example, control unit 60 may control receiver processing unit 40 synchronously with transmitter circuitry 21 to ensure appropriate measurements. However, control unit 60 may be omitted if receiver processing unit 40 is able to autonomously initiate a measurement and distinguish between different measurements. For example, receiver processing unit 40 may detect that transmitter circuitry 21 is activated based on the receiver signal at receiver antenna 30 exceeding a threshold or trigger value, and cause receiver processing unit 40 to appropriately process the receiver signal. Similarly, control unit 60 may not need to control transmitter circuitry 21 if it is able to operate autonomously. For example, transmitter antenna 20 and transmitter circuitry 21 may be implemented together as an autonomous emitter. For convenience and clarity of illustration, in FIG. 1 , operational coupling between control unit 60 and any other components of system 1 are omitted but can implicitly be present.

[0065] It is noted that central processing unit 50 and control unit 60 may be implemented integrally, i.e., as part of a same device or system, such as a computing device 70 or computer. In other words, computer 70 may be used to realize both central processing unit 50 and control unit 60. That is, computer 70 may be coupled to receiver processing unit 40 for the purpose of processing data and / or control, and may additionally be coupled to one or more other components of system 1, such as reverberation chamber 10 (i.e., configuration means 12, 13, 14), transmitter circuitry 21, and / or receiver processing unit 40, for the purpose of controlling them. However, the present disclosure is not limited to central processing unit 50 and control unit 60 being implemented by the same device, nor to both components being present in system 1. Hereinafter, an operation of system 1 is described in more detail, in which system 1 is configured to perform a plurality of measurements for obtaining a test result associated with the DUT.

[0066] For each measurement among the plurality of measurements, reverberation chamber 10 is configured to operate in a different respective state among the plurality of states, and transmitter antenna 20 emits EM waves inside reverberation chamber 10 in this mode in accordance with the modulated signal. The EM waves received at receiver antenna 30 are converted into a receiver signal, which is then sampled by receiver processing unit 40 in the time-domain to obtain a sampled time-domain signal associated with the respective measurement. This process is repeated for a plurality of measurements to obtain a corresponding plurality of sampled time-domain signals. System 1 can then determine the test result associated with the DUT based on the plurality of sampled time-domain signals.

[0067] These test results may be calibrated using conventional calibration methods, e.g., to determine the losses of reverberation chamber 10, such that measurement accuracy of system 1 can be further increased. In one example, calibrations have already been performed prior using (well- characterized) reference components which enable deriving the losses of reverberation chamber 10. In another example, calibration measurements may be performed before, during, or after obtaining the test result to further calibrate the test result and arrive at the desired metric. As will be appreciated by the skilled person, typical calibration measurements may involve performing the same or similar measurements as described above, but using (well-)characterized reference components instead of the DUT.

[0068] To obtain the test result, system 1 (e.g., receiver processing unit 40 or central processing unit 50) may process the plurality of sampled time-domain signals. At least part of this processing may include an averaging operation.

[0069] In a first example, system 1 may first take an absolute value of each sample of the sampled time-domain signals, and apply an averaging operation to obtain an average signal representing an average of the sampled time-domain signals. Optionally, for example when the sampled timedomain signal represents a current signal or a voltage signal, the processing in this example may optionally further include converting the average signal to power and / or a normalization operation. The test result, such as TRP, can be obtained from the average signal or from the further processed average signal.

[0070] In a second example, each sampled time-domain signal may first be converted to power (e.g., from voltage or current), and an average signal may subsequently be determined by averaging the power-converted sampled time-domain signals. The test result, such as TRP, can be obtained from the resulting average signal. In a third example, the processing may include first calculating an FFT associated with each sampled time-domain signal. Subsequently, the FFTs may be converted to power, and an average FFT may be obtained by determining an average of the power-converted FFTs. The test result, such as TRP, can be obtained from the resulting average FFT.

[0071] In a fourth example, the processing may include first calculating an FFT associated with each sampled time-domain signal. Subsequently, an average FFT may be obtained by averaging the FFTs associated with each sampled time-domain signal. Finally, the average FFT may optionally be converted to power and / or a normalization operation may be performed. The test result, such as TRP, can be obtained from the resulting average FFT or the further processed version thereof.

[0072] The present disclosure is not limited to any of the example processing given above, and various additional or alternative processing are equally envisaged.

[0073] The test result may reflect one or more parameters of the DUT, which can depend on the type of modulated signal used by transmitter antenna 20 and transmitter circuitry 21. This is described in more detail with reference to FIG. 2 A and 2B and with reference to FIG. 3 A and 3B.

[0074] In any given measurement, the reflective behavior of reverberation chamber 10 may generally be such that the field inside reverberation chamber 10 is non-uniform. For example, different points or areas in reverberation chamber 10 may have different transfer functions from transmitter antenna 20 to said point or area, and this transfer function may also be frequencydependent. As such, the time-domain signal obtained at receiver antenna 30 may depend on the state of reverberation chamber 10 and may therefore differ between respective measurements. By taking an average across a plurality of measurements with reverberation chamber 10 being in a different state in each measurement using the same modulated signal, however, these irregularities can be averaged out to thereby obtain an average sampled time-domain signal that can more accurately reflect the test result associated with the DUT. In general, the more measurements are taken, the higher the accuracy may be. Moreover, the lower a correlation is between measurements, the higher the accuracy may be. The number of measurements taken is preferably greater than 100, and more preferably greater than 300, though the present disclosure is not limited thereto. To that end, a correlation coefficient may be used to evaluate whether measurements are mutually correlated, and a selection of a number of substantially uncorrelated or lowly correlated measurements may be made manually or automatically, based on which selection the test result can be obtained.

[0075] Ideally, each state of the plurality of states of reverberation chamber 10 may be sufficiently different from one another such that uncorrelated or substantially uncorrelated sampled timedomain signals are obtained between measurements. To that end, the plurality of states used for the respective plurality of measurements may be selected accordingly beforehand or some of the measurements may be removed as outliers due to their correlation with another measurement being insufficiently low.

[0076] The total time to obtain the test result associated with the DUT may depend on the number of measurements to be performed by system 1 , the bandwidth of the modulated signal, and a predefined minimum time period of no EM wave emission to allow the field inside reverberation chamber 10 to decay between measurements.

[0077] To give an example, if the modulated signal is a chirp with a bandwidth of 7 GHz (e.g., a chirp from 57 GHz to 64 GHz), the chirp time may be about 200 ps, and a pause time in between chirps may be set by the user to 10 ms. Assuming a single chirp occurs for each measurement and a total of 200 measurements are taken, and assuming computation time plays a negligible role, the total time required to obtain the test result associated with the DUT may be about 2 s, which is a substantial improvement with respect to conventional methods employing, for example, a spectrum analyzer in a frequency-based approach.

[0078] It may be possible to allow configuration means 12, 13, 14 of reverberation chamber, whichever are employed, to be continuously changing the electromagnetic reflection behavior of reverberation chamber 10.

[0079] It is noted that, although reference is made above to a plurality of measurements, said plurality of measurements may also refer to sub-measurements of a single continuous measurement. For example, receiver processing unit 40 may continuously sample the receiver signal and obtain, from the continuous sampling, the plurality of (sub-)measurements.

[0080] In FIG. 2A, an example of a chirp signal is shown, wherein the y-axis represents an amplitude of the chirp signal and the x-axis represents time in microseconds. As shown here, a chirp signal is a signal of which the frequency gradually increases over time. Typically, the frequency of the chirp signal may increase substantially linearly over time. This chirp signal generally includes frequency content ranging from the minimum frequency (e.g., at the start of the chirp) to the maximum frequency (e.g., at the end of the chirp).

[0081] A chirp signal such as the one shown in FIG. 2A can be used as the modulated signal in system 1 according to the present disclosure to analyze the performance of the DUT (e.g., transmitter antenna 20 or receiver antenna 30) across a predetermined frequency range.

[0082] In particular, using the system and method described herein with a chirp signal as the modulated signal, a plurality of measurements can be performed, with reverberation chamber 10 being configured in respective states, to obtain a plurality of corresponding sampled time-domain signals. These sampled time-domain signals can then be used to obtain the test result associated with the DUT. To illustrate this, a signal diagram is shown in FIG. 2B indicating, using thin lines, three examples of receiver signals acquired from different measurements. In addition, an average of 100 different receiver signals is illustrated in FIG. 2B using a thick line.

[0083] As can be seen in FIG. 2B, the receiver signal can vary drastically between measurements (i.e., with reverberation chamber 10 being in different states) when compared to the chirp as illustrated in FIG. 2A. This variation may be caused by frequency dependency of reverberation chamber 10 in any given state or configuration. However, when averaging many different receiver signals with reverberation chamber 10 in different configurations, such frequency dependency can substantially cancel out, resulting in the average indicated with a thick line, which resembles the chirp signal of FIG. 2A much more closely.

[0084] For example, by using an averaging operation, the plurality of sampled time-domain signals can be combined and optionally further processed to obtain a test result associated with the DUT. For example, using an FFT of the average signal, the TRP at any given frequency can be calculated. Furthermore, the frequency-linearity of the transmitted chirp can be estimated based on the linearity of the average received chirp. In the special case that the transmitted chirp signal is linear or at least substantially so, the envelope of the received signal may itself be indicative of the TRP at different frequencies.

[0085] Using the system and method described herein with a chirp signal as the modulated signal, it is possible to determine various other metrics of the DUT. As described above, TRP can be determined, not necessarily as a single value but also over frequency, i.e., total radiated power spectral density (PSD). Additionally or alternatively, a frequency response of the DUT can be determined. For example, a shape of the frequency response can be deduced directly, or, assuming the losses in reverberation chamber 10 are known or calibrated using a calibration measurement to calibrate the test result using conventional reverberation chamber calibration methods, the test result may include one or more of: a system gain at any given frequency in the frequency range of the chirp signal, a bandwidth (e.g., knee point) of the receiver chain or of a specific component included in the receiver chain representing the DUT (e.g., an amplifier), or the like. In another example, when the DUT is coupled to or formed at least partially by transmitter antenna 20, various transmitter-side performance metrics can be determined.

[0086] FIG. 2C illustrates an exemplary timing diagram for system 1 according to an embodiment of the present disclosure. In particular, transmitter antenna 20 of FIG. 1 may be configured to sequentially transmit a plurality of chirps C. Each chirp may be substantially identical, and may have a chirp time duration tc. Following each chirp C, a delay time duration td may be provided.

[0087] As illustrated using FIG. 2C, system 1 of FIG. 1 may perform a plurality of measurements, such as a first measurement in a first measurement period Ml, a second measurement in a second measurement period M2, and so forth. For each measurement period, reverberation chamber 10 may be configured in a different state using configuration means 12, 13, 14. Between each measurement period Ml, M2, a pause time duration tp may be included. Here, pause time duration tp is shown to be longer than delay time duration td, though this need not be the case. Pause time duration tp may be set to provide sufficient time for reverberation chamber 10 to be configured in a different state.

[0088] At least one chirp C may be included in each measurement period Ml, M2, and the sampled time-domain signal may represent at least one of said at least one chirps C as received by receiver antenna 30 of FIG. 1. That is, receiver processing unit 40 may be configured to sample at least one of said at least one chirps within each measurement period to obtain the sampled timedomain signal. The resulting sampled time-domain signals obtained during respective measurement periods can be combined to obtain the test result associated with the DUT.

[0089] In some embodiments, a plurality of chirps C may be included in each measurement period for averaging purposes and / or synchronization purposes. For example, the sampled time-domain signal may be obtained by averaging a plurality of sub-signals obtained in a single measurement based on respective chirps C. Additionally or alternatively, some chirps C may be used to estimate chirp time duration tc, delay time duration td, and / or pause time duration tp.

[0090] In FIG. 3A, an example of a 4-QAM signal is shown, wherein the y-axis represents an amplitude of the 4-QAM signal and the x-axis represents time in microseconds. In this example, a symbol time is set to 0.2 microseconds. The 4-QAM signal may for example be used as the modulated signal by system 1 according to the present disclosure. The number of symbols included in the modulated signal, and the symbol pattern, may be predetermined or configurable.

[0091] In FIG. 3B, several receiver signals representing received 4-QAM signals are shown in an overlapping manner using thin lines. In addition, an average of a plurality of receiver signals representing received 4-QAM signals is shown using a thick line. Clearly, although individual receiver signals may deviate quite substantially from one another and in particular from the ideal, transmitted 4-QAM signal, the average of a plurality of receiver signals obtained with reverberation chamber 10 in different configurations or states may reflect the transmitted symbol sequence much more closely. From this average signal, for example, the test result (e.g., a TRP, an EVM, a BER, or an SER) associated with the DUT can be obtained. For completeness, it is noted that FIG. 2C and the accompanying description thereof may apply similarly to the case where the modulated signal is based on a digital modulation scheme. In particular, chirps C in FIG. 2C may equally represent a sequence of bits or symbols associated with the digital modulation scheme used. Hence, a detailed description thereof is not repeated here.

[0092] A method for testing a DUT according to an embodiment of the present disclosure is described below with reference to the flowchart illustrated in FIG. 4. In step SI, a reverberation chamber is provided, the reverberation including configuration means for changing a reflective behavior inside the reverberation chamber between a plurality of states.

[0093] In step S2, a transmitter antenna and a receiver antenna are provided inside the reverberation chamber. The DUT is coupled to or formed at least partially by the transmitter antenna or the receiver antenna.

[0094] In step S3, a plurality of measurements are performed. In particular, for each measurement, the reverberation chamber is configured in a respective state among the plurality of states, the transmitter antenna emits EM waves inside the reverberation chamber based on a modulated signal, the receiver antenna receives said EM waves and provides a receiver signal to a receiver processing unit, and the receiver processing unit samples the receiver signal in the time-domain to obtain a sampled time-domain signal.

[0095] In step S4, a test result associated with the DUT is obtained based on the plurality of sampled time-domain signals.

[0096] For completeness, the above description with reference to preceding figures, in relation to system 1 , apply identically to the method as shown in and described with reference to FIG. 4.

[0097] In addition to the above, the present disclosure may relate to any of the following defined clauses:

[0098] Clause 1. A system (1) for testing a device -under-test, ‘DUT’, the system (1) comprising: a transmitter antenna (20) and a receiver antenna (30), wherein the DUT is configured to be coupled to or is formed at least partially by the transmitter antenna (20) or the receiver antenna (30); a receiver processing unit (40) configured to be electrically coupled to the receiver antenna (30); and a reverberation chamber (10) including configuration means (12; 13; 14) for changing an electromagnetic, ‘EM’, reflection behavior inside the reverberation chamber (10) between a plurality of states, wherein the reverberation chamber (10) is configured to receive the receiver antenna (30) and the transmitter antenna (20), wherein the system (1) is configured to perform a plurality of measurements, wherein, for each measurement: the reverberation chamber (10) is configured in a respective state among the plurality of states; the transmitter antenna (20) is configured to emit EM waves inside the reverberation chamber (10) based on a modulated signal; the receiver antenna (30) is configured to receive said EM waves and provide a receiver signal to the receiver processing unit (40); and the receiver processing unit (40) is configured to sample the receiver signal in the time-domain to obtain a sampled time-domain signal, wherein the system (1) is further configured to obtain a test result associated with the DUT based on the sampled timedomain signals associated with the plurality of measurements. Clause 2. The system (1) according to clause 1, wherein, to obtain the test result, the system (1) is configured to process the sampled time-domain signals, the processing including an averaging operation.

[0099] Clause 3. The system (1) according to clause 2, wherein, to obtain the test result, the system (1) is configured to: determine an average signal by averaging absolute values of the sampled time-domain signals, and optionally convert the average signal to power and / or perform a normalization operation; or convert each sampled time-domain signal to power, and determine an average signal by averaging the converted sampled time-domain signals; or calculate a fast-Fourier transform, TFT’, for each sampled time-domain signal, convert the FFTs to power, and determine an average FFT by averaging the converted FFTs; or calculate an FFT for each sampled timedomain signal, determine an average FFT by averaging the FFTs, and optionally convert the average FFT to power and / or perform a normalization operation.

[0100] Clause 4. The system (1) according to any of the clauses 1-3, wherein, for each measurement, the modulated signal includes at least one frequency chirp in a predetermined frequency range, the modulated signal preferably being a frequency-modulated continuous wave, ‘FMCW’ , chirp, wherein the test result includes a total radiated power, ‘TRP’ , at a plurality of frequencies within the predetermined frequency range.

[0101] Clause 5. The system (1) according to clause 4, wherein the frequency chirp is substantially linear, and wherein the test result is obtained based on an envelope of the average of the plurality of sampled time-domain signals.

[0102] Clause 6. The system (1) according to clause 5, wherein the sampling rate for sampling the receiver signal is lower than two times a bandwidth of the modulated signal.

[0103] Clause 7. The system (1) according to any of the clauses 1-3, wherein the modulated signal is based on a digital modulation scheme, such as amplitude-shift keying, ‘ASK’, phase-shift keying, ‘PSK’, frequency-shift keying, ‘FSK’, orthogonal frequency division multiplexing, ‘OFDM’, or quadrature amplitude modulation, ‘QAM’.

[0104] Clause 8. The system (1) according to clause 7, wherein the modulated signal includes a predetermined sequence of bits or symbols.

[0105] Clause 9. The system (1) according to clause 7 or 8, wherein the test result includes a total radiated power, ‘TRP’, an error vector magnitude, ‘EVM’, a bit error rate, ‘BER’, and / or a symbol error rate, ‘SER’.

[0106] Regarding clause 7 and optional clauses 8 and 9, the applicant has found that conventional methods of determining test results, such as EVM, BER, or SER, using for example an anechoic chamber or an open-air or semi-open-air setup, have spatial dependencies. For example, if the EVM of multiple beams in a 5G communication system should be measured, the transmitter or receiver antenna have to be accurately repositioned for each beam direction. By contrast, the system according to the present disclosure does not exhibit such spatial dependencies and does not require repositioning of the transmitter antenna, thereby reducing measurement time, complexity, and uncertainty. Accordingly, a test result associated with the DUT can be obtained very time- efficiently, especially since the transmitted signal is a modulated signal having a predetermined bandwidth across which the test result is to be obtained. Moreover, this system allows to avoid expensive specialized high-frequency hardware such as a spectrum analyzer.

[0107] Clause 10. The system (1) according to any of the clauses 1-9, wherein the receiver processing unit (40) comprises a time-domain sampling unit (46) configured to sample the receiver signal.

[0108] Clause 11. The system (1) according to clause 10, wherein the time-domain sampling unit (46) includes an analog-to-digital converter, ‘ADC’, preferably being a component of an oscilloscope included in the system (1).

[0109] Clause 12. The system (1) according to clause 11, wherein the receiver processing unit (40) further comprises a mixer (42) electrically coupled between the receiver antenna (30) and the time-domain sampling unit (46), wherein the mixer (42) is configured to down-convert the receiver signal prior to the sampling by the time-domain sampling unit (46).

[0110] Clause 13. The system (1) according to clause 12, wherein the receiver processing unit (40) further comprises a low-frequency amplifier (41) electrically coupled between the mixer (42) and the time-domain sampling unit (46).

[0111] Clause 14. The system (1) according to clause 12 or 13, wherein the receiver processing unit (40) further comprises a local oscillator (43), ‘LO’, configured to provide an LO signal to the mixer (42) for down-converting the receiver signal.

[0112] Clause 15. The system (1) according to clause 12, wherein a frequency of the LO signal: corresponds to a carrier frequency associated with the modulated signal; or is a predetermined amount lower than a minimum frequency emitted by the transmitter antenna (20) based on the modulated signal; or is a predetermined amount higher than a maximum frequency emitted by the transmitter antenna (20) based on the modulated signal.

[0113] Clause 16. The system (1) according to any of the clauses 10-15, wherein the receiver processing unit (40) further comprises a high-frequency amplifier (44) electrically coupled between the receiver antenna (30) and the time-domain sampling unit (46), wherein, in so far as depending on clause 8, the high-frequency amplifier (44) is electrically coupled between the receiver antenna (30) and the mixer (42).

[0114] Clause 17. The system (1) according to any of the clauses 10-16, wherein the receiver processing unit (40) further comprises a low-pass filter (45) electrically coupled between the receiver antenna (30) and the time-domain sampling unit (46), wherein, in so far as depending on claim 10, the low-pass filter (45) is electrically coupled between the mixer (42) and the timedomain sampling unit (46).

[0115] Clause 18. The system (1) according to any of the clauses 1-17, further comprising transmitter circuitry (21) configured to be electrically coupled to the transmitter antenna (20) and configured to provide the modulated signal about a carrier frequency to the transmitter antenna

[0116] (20).

[0117] Clause 19. The system (1) according to clause 16, wherein the transmitter circuitry

[0118] (21) is configured to be arranged inside of the reverberation chamber (10), wherein the transmitter circuitry (21) and the transmitter antenna (20) are preferably integrated into a single unit; or wherein the transmitter circuitry (21) is configured to be at least partially arranged outside of the reverberation chamber (10), wherein the reverberation chamber (10) further comprises a first feedthrough (I la) via which the transmitter antenna (20) and transmitter circuitry (21) can be electrically coupled.

[0119] Clause 20. The system (1) according to any of the clauses 1-19, wherein the receiver processing unit (40) is configured to be arranged inside of the reverberation chamber (10), wherein the receiver processing unit (40) and the receiver antenna (30) are preferably integrated into a single unit; or wherein the receiver processing unit (40) is configured to be at least partially arranged outside of the reverberation chamber (10), wherein the reverberation chamber (10) further comprises a second feedthrough (11b) via which the receiver antenna (30) and the receiver processing unit (40) can be electrically coupled.

[0120] Clause 21. The system (1) according to any of the clauses 1-20, wherein the receiver processing unit (40) is configured to obtain the test result; or wherein the system (1) further comprises a central processing unit (50) configured to receive the plurality of sampled timedomain signals or the average of the plurality of sampled time-domain signals from the receiver processing unit (40), and to obtain the test result based thereon.

[0121] Clause 22. The system (1) according to any of the clauses 1-21, wherein, for each measurement, the receiver processing unit (40) is configured to sample the receiver signal based on a predetermined time period for performing said measurement; or wherein, for each measurement, the receiver processing unit (40) is configured to sample the receiver signal based on the receiver signal exceeding a threshold value; or wherein, in so far as depending on clause 18, the system (1) further comprises a control unit (60) configured to control the receiver processing unit (40) and / or the transmitter circuitry (21) in dependence of each other.

[0122] Clause 23. The system (1) according to any of the clauses 1-22, wherein the transmitter antenna (20) forms part of an autonomous emitter.

[0123] Clause 24. The system (1) according to any of the clauses 1-23, wherein the configuration means comprises at least one of the following: at least one movable stirrer (12), preferably at least one rotatable stirrer; at least one electronically adjustable stirrer (13); and a moving unit (14), such as a movable platform, configured to move the transmitter antenna (20) and / or the receiver antenna (30) between a plurality of positions inside the reverberation chamber (10).

[0124] Clause 25. The system (1) according to any of the clauses 1-24, wherein the reverberation chamber (10) further comprises at least one static, electromagnetically reflective element (15) arranged at a fixed position and with a fixed orientation within the reverberation chamber (10).

[0125] Clause 26. A method for testing a device-under-test, ‘DUT’, comprising: providing

[0126] (51) a reverberation chamber including configuration means for changing an electromagnetic, ‘EM’, reflection behavior inside the reverberation chamber between a plurality of states; providing

[0127] (52) a transmitter antenna and a receiver antenna inside the reverberation chamber, the DUT being coupled to or formed at least partially by the transmitter antenna or the receiver antenna; performing (S3) a plurality of measurements, wherein for each measurement: the reverberation chamber is configured in a respective state among the plurality of states; the transmitter antenna emits EM waves inside the reverberation chamber based on a modulated signal; the receiver antenna receives said EM waves and provides a receiver signal to a receiver processing unit; and the receiver processing unit samples the receiver signal in the time-domain to obtain a sampled time-domain signal; and obtaining (S4) a test result associated with the DUT based on the plurality of sampled time-domain signals associated with the plurality of measurements.

[0128] In the above description, the present disclosure has been explained using detailed embodiments thereof. However, the present disclosure is not limited to these embodiments, and various modifications can be implemented without deviating from the scope of the present disclosure as defined by the appended claims and, in some jurisdictions, their equivalents.

Claims

CLAIMS1. A system (1) for testing a device -under-test, ‘DUT’, the system (1) comprising: a transmitter antenna (20) and a receiver antenna (30), wherein the DUT is configured to be coupled to or is formed at least partially by the transmitter antenna (20) or the receiver antenna (30); a receiver processing unit (40) configured to be electrically coupled to the receiver antenna (30); and a reverberation chamber (10) including configuration means (12; 13; 14) for changing an electromagnetic, ‘EM’, reflection behavior inside the reverberation chamber (10) between a plurality of states, wherein the reverberation chamber (10) is configured to receive the receiver antenna (30) and the transmitter antenna (20), wherein the system (1) is configured to perform a plurality of measurements, wherein, for each measurement: the reverberation chamber (10) is configured in a respective state among the plurality of states; the transmitter antenna (20) is configured to emit EM waves inside the reverberation chamber (10) based on a modulated signal, wherein the modulated signal includes a frequency chirp in a predetermined frequency range; the receiver antenna (30) is configured to receive said EM waves and provide a receiver signal to the receiver processing unit (40); and the receiver processing unit (40) is configured to sample the receiver signal in the time-domain to obtain a sampled time-domain signal, wherein the system (1) is further configured to obtain a test result associated with the DUT based on the sampled time-domain signals associated with the plurality of measurements.

2. The system (1) according to claim 1, wherein, to obtain the test result, the system (1) is configured to process the sampled time-domain signals, the processing including an averaging operation.

3. The system (1) according to claim 2, wherein, to obtain the test result, the system (1) is configured to: determine an average signal by averaging absolute values of the sampled time-domain signals, and optionally convert the average signal to power and / or perform a normalization operation; orconvert each sampled time-domain signal to power, and determine an average signal by averaging the converted sampled time-domain signals; or calculate a fast-Fourier transform, ‘FFT’, for each sampled time-domain signal, convert the FFTs to power, and determine an average FFT by averaging the converted FFTs; or calculate an FFT for each sampled time-domain signal, determine an average FFT by averaging the FFTs, and optionally convert the average FFT to power and / or perform a normalization operation.

4. The system (1) according to any of the previous claims, wherein the modulated signal is a frequency-modulated continuous wave, ‘FMCW’, chirp.

5. The system (1) according to any of the previous claims, wherein the test result includes a total radiated power, ‘TRP’, at a plurality of frequencies within the predetermined frequency range.

6. The system (1) according to any of the previous claims, wherein the frequency chirp is substantially linear, and wherein the test result is obtained based on an envelope of the average of the plurality of sampled time-domain signals.

7. The system (1) according to claim 6, wherein the sampling rate for sampling the receiver signal is lower than two times a bandwidth of the modulated signal.

8. The system (1) according to any of the previous claims, wherein the receiver processing unit (40) comprises a time-domain sampling unit (46) configured to sample the receiver signal.

9. The system (1) according to claim 8, wherein the time-domain sampling unit (46) includes an analog-to-digital converter, ‘ADC’, preferably being a component of an oscilloscope included in the system (1).

10. The system (1) according to claim 9, wherein the receiver processing unit (40) further comprises a mixer (42) electrically coupled between the receiver antenna (30) and the timedomain sampling unit (46), wherein the mixer (42) is configured to down-convert the receiver signal prior to the sampling by the time-domain sampling unit (46).

11. The system (1) according to claim 10, wherein the receiver processing unit (40) further comprises a low-frequency amplifier (41) electrically coupled between the mixer (42) and the time-domain sampling unit (46).

12. The system (1) according to claim 10 or 11, wherein the receiver processing unit (40) further comprises a local oscillator (43), ‘LO’, configured to provide an LO signal to the mixer (42) for down-converting the receiver signal.

13. The system (1) according to claim 12, wherein a frequency of the LO signal: corresponds to a carrier frequency associated with the modulated signal; or is a predetermined amount lower than a minimum frequency emitted by the transmitter antenna (20) based on the modulated signal; or is a predetermined amount higher than a maximum frequency emitted by the transmitter antenna (20) based on the modulated signal.

14. The system (1) according to any of the claims 8-13, wherein the receiver processing unit (40) further comprises a high-frequency amplifier (44) electrically coupled between the receiver antenna (30) and the time-domain sampling unit (46), wherein, in so far as depending on claim 8, the high-frequency amplifier (44) is electrically coupled between the receiver antenna (30) and the mixer (42).

15. The system (1) according to any of the claims 8-14, wherein the receiver processing unit (40) further comprises a low-pass filter (45) electrically coupled between the receiver antenna (30) and the time-domain sampling unit (46), wherein, in so far as depending on claim 10, the low-pass filter (45) is electrically coupled between the mixer (42) and the time-domain sampling unit (46).

16. The system (1) according to any of the previous claims, further comprising transmitter circuitry (21) configured to be electrically coupled to the transmitter antenna (20) and configured to provide the modulated signal about a carrier frequency to the transmitter antenna (20).

17. The system (1) according to claim 16, wherein the transmitter circuitry (21) is configured to be arranged inside of the reverberation chamber (10), wherein the transmitter circuitry (21) and the transmitter antenna (20) are preferably integrated into a single unit, orwherein the transmitter circuitry (21) is configured to be at least partially arranged outside of the reverberation chamber (10), wherein the reverberation chamber (10) further comprises a first feedthrough (I la) via which the transmitter antenna (20) and transmitter circuitry (21) can be electrically coupled.

18. The system (1) according to any of the previous claims, wherein the receiver processing unit (40) is configured to be arranged inside of the reverberation chamber (10), wherein the receiver processing unit (40) and the receiver antenna (30) are preferably integrated into a single unit, or wherein the receiver processing unit (40) is configured to be at least partially arranged outside of the reverberation chamber (10), wherein the reverberation chamber (10) further comprises a second feedthrough (11b) via which the receiver antenna (30) and the receiver processing unit (40) can be electrically coupled.

19. The system (1) according to any of the previous claims, wherein the receiver processing unit (40) is configured to obtain the test result, or wherein the system (1) further comprises a central processing unit (50) configured to receive the plurality of sampled time-domain signals or the average of the plurality of sampled time-domain signals from the receiver processing unit (40), and to obtain the test result based thereon.

20. The system (1) according to any of the previous claims, wherein, for each measurement, the receiver processing unit (40) is configured to sample the receiver signal based on a predetermined time period for performing said measurement, or wherein, for each measurement, the receiver processing unit (40) is configured to sample the receiver signal based on the receiver signal exceeding a threshold value, or wherein, in so far as depending on claim 16, the system (1) further comprises a control unit (60) configured to control the receiver processing unit (40) and / or the transmitter circuitry (21) in dependence of each other.

21. The system (1) according to any of the previous claims, wherein the transmitter antenna (20) forms part of an autonomous emitter.

22. The system (1) according to any of the previous claims, wherein the configuration means comprises at least one of the following: at least one movable stirrer (12), preferably at least one rotatable stirrer;at least one electronically adjustable stirrer (13); and a moving unit (14), such as a movable platform, configured to move the transmitter antenna (20) and / or the receiver antenna (30) between a plurality of positions inside the reverberation chamber (10).

23. The system (1) according to any of the previous claims, wherein the reverberation chamber (10) further comprises at least one static, electromagnetically reflective element (15) arranged at a fixed position and with a fixed orientation within the reverberation chamber (10).

24. A method for testing a device-under-test, ‘DUT’, comprising: providing (SI) a reverberation chamber including configuration means for changing an electromagnetic, ‘EM’, reflection behavior inside the reverberation chamber between a plurality of states; providing (S2) a transmitter antenna and a receiver antenna inside the reverberation chamber, the DUT being coupled to or formed at least partially by the transmitter antenna or the receiver antenna; performing (S3) a plurality of measurements, wherein for each measurement: the reverberation chamber is configured in a respective state among the plurality of states; the transmitter antenna emits EM waves inside the reverberation chamber based on a modulated signal, wherein the modulated signal includes a frequency chirp in a predetermined frequency range; the receiver antenna receives said EM waves and provides a receiver signal to a receiver processing unit; and the receiver processing unit samples the receiver signal in the time-domain to obtain a sampled time-domain signal; and obtaining (S4) a test result associated with the DUT based on the plurality of sampled time-domain signals associated with the plurality of measurements.

Images