MEASUREMENT APPARATUS AND METHOD FOR CHARACTERIZING A RADIO FREQUENCY DEVICE WITH MULTIPLE ANTENNAS - Patent application

Abstract

An embodiment of the present invention is a measurement apparatus for characterizing a radio frequency device (110) that includes multiple antennas (120), such as a large array of patch antennas. The measurement apparatus includes a dielectric waveguide slab (130) having multiple frequency conversion structures (150) disposed within or on the dielectric waveguide slab. The measurement apparatus further includes multiple waveguide transitions (140) disposed at different locations on the dielectric waveguide slab and coupled to respective radio frequency components (160). The radio frequency components are configured to transmit and / or receive radio signals, such as a transmitter, receiver, or transceiver. A frequency conversion structure is associated with each of the multiple antennas and configured to perform a frequency conversion on the received signal, resulting in a frequency converted signal.

Description

[Technical field]

[0001] The present invention relates to over-the-air (OTA) antenna testing. The present invention relates to a measurement apparatus for characterizing radio frequency devices with multiple antennas. Further embodiments of the present invention relate to an automatic test equipment comprising a measurement apparatus and a device under test position. Further embodiments of the present invention relate to a method for characterizing a device under test (DUT) with multiple antennas. An embodiment of the present invention relates to near-field testing or probing by using a frequency conversion structure or sensor. An embodiment of the present invention relates to OTA testing of large mmWave antenna array modules. [Background technology]

[0002] There are several conventional methods for OTA testing of antenna arrays. For example, antenna arrays can be tested in an anechoic chamber or box environment by probing them at large distances, e.g., from less than a meter to several meters. The disadvantage of this conventional method is that these measurements are slow and the equipment is large, so that this method is not suitable for clean production environments.

[0003] Small arrays, e.g., modules containing 4-8 elements, can be tested over short distances, e.g., about 0.5 meters, using a small number of absorbers. This measurement method is much more suitable for production environments than the long-distance methods mentioned above. However, this method remains time consuming, as many array elements are tested sequentially.

[0004] Recent measurement methods propose that modules containing small arrays, such as 4-8 elements, can be probed or tested with a probe adapter in the reactive near-field of the antenna elements. This measurement setup is compact and allows parallel measurements of the array elements, and is therefore well suited for applications in production testing. The drawback is that for a given array topology, a rather complex dedicated probe adapter is required, a problem that grows even more complex as the number of array elements increases.

[0005] Even if the above-described method at least partially solves the problem of test modules that include small arrays, e.g., having 4-8 elements, the method is not capable of testing future mobile communication devices, which are expected to include several complex antenna arrays in a small form factor operating at millimeter wave frequencies.

[0006] Also, it is expected that the front-end electronics and antennas will be integrated into the module to avoid the use of mmWave interconnects, so that the points between the transceiver and the antennas will not be accessible for testing.

[0007] Additionally, multi-antenna mmWave modules are expected to require OTA testing, e.g., per-element or per-channel testing, and possibly OTA calibration at the production level.

[0008] In view of this situation, there is a need for measurement apparatus and concepts that provide an improved compromise between the complexity, size, and cost of devices under test (DUTs) that include antenna arrays having a large number of antenna elements. Summary of the Invention [Means for solving the problem]

[0009] One embodiment of the present invention is a measurement apparatus for characterizing, eg, testing or measuring, a radio frequency device that comprises multiple antennas, such as a patch antenna or a large array of patch antennas.

[0010] The measurement device comprises a dielectric waveguide slab or dielectric slab having a plurality of frequency conversion structures, e.g., frequency conversion sensors, disposed within or on the dielectric waveguide slab.

[0011] The measurement apparatus further comprises a plurality of waveguide transitions disposed at different locations of the dielectric waveguide slab, for example along a circumference of the dielectric waveguide slab, and coupled to respective radio frequency components.

[0012] The radio frequency components are configured to transmit and / or receive radio signals, such as a transmitter, receiver, or transceiver.

[0013] A frequency translation structure is associated with each antenna of the plurality of antennas and configured to perform a frequency translation on the received signal to obtain a frequency translated signal.

[0014] The frequency conversion structure is configured to couple each antenna to the dielectric slab in a frequency conversion manner, thereby establishing frequency conversion coupling between the antenna and the multiple waveguide transitions to provide frequency conversion coupling between the antenna and the radio frequency component.

[0015] The measurement device is configured to use a frequency conversion coupling between the antenna and the radio frequency component to characterize the radio frequency device. For example, the radio frequency device may include an antenna and / or a radio frequency front end connected to the antenna.

[0016] The measurement device of the present invention makes it possible to test large antenna arrays with a large number of antenna elements in a compact setup suitable for a production environment with a reasonable number of test channels operating in parallel.

[0017] By using a test probe adapter that can be specific to multiple antennas of the DUT or antenna under test, the measurement device can be manufactured in or with a technology of reasonably low complexity. The low complexity makes the measurement device easy to use in a manufacturing and / or production environment. This is therefore a key differentiator over the conventional reactive near-field probing techniques or measurement devices described above.

[0018] The antenna array of the DUT may comprise many separate radiators or multiple antennas. The antenna array or radiators / antennas of the DUT may radiate or transmit signals in the direction of the absorber over a not very far distance, such as a distance of about 10 wavelengths.

[0019] Without disturbing the radiator, i.e., the complex feed impedance of the radiator remains unaffected, a dielectric waveguide slab having a thickness of less than half the free-space wavelength can be placed at a close distance or near-field distance to the radiator, between the antenna array and the absorber.

[0020] The dielectric slabs can have two functionalities: first, they can carry or contain small antenna-diode circuits close to each radiator, which are small compared to the wavelength of the transmitted signal and therefore do not affect the radiator. Because the small antenna-diode circuits are contained in the dielectric waveguide slab, they can be called on-slab-circuits.

[0021] The small, inefficient antenna of the on-slab circuit may receive only a small portion of the wave or signal transmitted by the radiator. The diodes or other nonlinear elements of the on-slab circuit may convert or redirect the received signal to another frequency, for example by doubling its frequency. Finally, the on-slab circuit may transmit the frequency converted or redirected frequency signal into a dielectric waveguide slab guided surface wave mode, for example using a small mode launcher.

[0022] The second functionality of the dielectric waveguide slab then enables the dielectric waveguide slab to guide or transport surface wave modes to the outer edge of the dielectric waveguide slab.

[0023] Mode launchers and receivers along the circumference of the dielectric waveguide slab can receive signals, for example through waveguide transitions. By applying phase comparison of or on several received signals, for example as a kind of triangulation, it is possible to find the specific location of the radiator of the DUT. Triangulation can be further improved, for example, by comparing both magnitude and phase information of different received versions of the same transmitted signal.

[0024] The important features of this inventive measurement device can be concluded as follows: First, the frequency conversion structure (or probe) can be an electrically isolated device structure such as an antenna and a diode located in or on a planar dielectric waveguide slab. Thus, the fabrication of a dielectric waveguide slab operating at mm-wave frequencies with a frequency conversion structure (or probe card) specific to a given antenna array to be tested is feasible, for example, by standard circuit board manufacturing processes.

[0025] Second, the dielectric waveguide slab may be transparent (or at least nearly transparent) to the transmitted signals or waves of the DUT's antenna array because of its thickness, which may be, for example, less than half a free-space wavelength, and because there are no continuous metal traces on or within the dielectric waveguide slab.

[0026] Third, a dielectric waveguide slab may also be used as a waveguide to carry or guide a signal from an on-slab circuit, for example, through a waveguide transition to a radio frequency component located, for example, at a dielectric waveguide slab edge. The transmission of a guided signal or wave has much lower transmission losses than the transmission of a radiated signal or wave because the guided signal or wave propagates within the plane of the dielectric waveguide slab, whereas radiation spreads in all directions in three-dimensional space.

[0027] This embodiment of the present invention therefore allows for sufficiently accurate characterization of one of the DUT's multiple antennas whilst being robust and cost-effective and therefore may be fully usable in a test environment.

[0028] In a preferred embodiment, the measurement device comprises a signal evaluation circuit coupled to the radio frequency component and configured to characterize the radio frequency device by evaluating a signal received by the radio frequency component. The signal received by the radio frequency component is based on a signal transmitted by an antenna and frequency converted by a frequency conversion coupling between the antenna and the radio frequency component. Having a dedicated signal evaluation circuit speeds up the evaluation of the signal received by the radio frequency component.

[0029] According to a further embodiment, the signal evaluation circuit is configured to determine the location of the transmitting antenna using triangulation, i.e. the transmitting antenna is determined based on, for example, amplitude and phase information of the signal received at the radio frequency components. The signal evaluation circuit uses triangulation based on amplitude and phase information to reduce the number of radio frequency components, in contrast to the conventional measurement device described above, for example, the number of radio frequency components being linearly proportional to the number of antennas of the DUT, i.e. each radiator is measured by at least one radio frequency component. The triangulation can determine the location of, for example, the frequency conversion structure excited by the antenna of the DUT or a corresponding antenna, and thus the location of the DUT antenna can be concluded.

[0030] In a preferred embodiment, the measurement device comprises a signal evaluation circuit coupled to the antenna of the DUT and configured to characterize the radio frequency device by evaluating a signal received by the antenna. The signal received by the antenna is based on a signal transmitted by a radio frequency component and frequency converted by a frequency conversion coupling between the antenna and the radio frequency component, e.g. by a frequency conversion structure. Having a dedicated signal evaluation circuit speeds up the evaluation of the signal received by the antenna. Also, it is possible to perform measurements in both directions and test both the transmit and receive directions of the antenna of the DUT.

[0031] According to further embodiments, the radio frequency components are configured to transmit signals having different frequencies, for example, simultaneously. By transmitting signals at different predefined frequencies, it is possible, for example, to identify or distinguish signals of different radio frequency components when the signals are transmitted simultaneously. Also, by transmitting signals having different frequencies simultaneously, a frequency conversion (mixing) can be performed in the frequency conversion structure, which allows for flexible adjustment of the frequency of the signals re-radiated by the frequency conversion structure.

[0032] In a preferred embodiment, the radio frequency components are configured to simultaneously transmit signals at two different frequencies. The transmitted signals are mixed by a frequency conversion structure. The measurement device is configured to evaluate a mixed signal obtained based on the simultaneously transmitted signals in order to characterize the radio frequency device. The mixed signal can thus be distinguished from the (strong) signals transmitted by the radio frequency components and radiated from the local frequency conversion structure. For example, it is not necessary to transmit a signal by each and every radio frequency component at the same time and to distinguish those transmitted signals having different frequencies. It is sufficient to transmit only two signals at different frequencies at the same time. The amplitude and phase of the signal depend on the distance from the transmitting radio frequency component. Therefore, every frequency conversion structure mixes signals having different amplitudes and phases. The measurement device evaluates the mixed signal in order to characterize the radio frequency device.

[0033] In a preferred embodiment, the radio frequency components are configured to transmit signals at two or more different frequencies simultaneously. The measurement device is configured to simultaneously test separate branches of the radio frequency device, e.g. separate antennas and / or separate radio frequency front ends connected to antennas, using different signals at different frequencies. For example, testing one or more branches using signals at a first frequency and testing one or more other branches using signals at a second frequency accelerates testing. Thus, radio frequency devices having two or more branches configured to operate at different frequencies can also be tested in a similar manner.

[0034] According to a further embodiment, the dielectric waveguide slab has a thickness of less than half the free space wavelength of the signal or the frequency of the signal transmitted by one or more of the antennas or by one or more of the radio frequency components. The thickness of the dielectric waveguide slab is small compared to the wavelength of the signal. The dielectric waveguide slab is therefore, for example, at least substantially transparent to the signal. The signal experiences only small transmission losses and the degradation of the antenna properties may be small.

[0035] In a preferred embodiment, the dielectric waveguide slab comprises one or more layers. Single and / or multi-layer structures are simple structures and can be cost effectively produced by standard circuit board manufacturing processes.

[0036] According to a further embodiment, one or more layers of the dielectric waveguide slab are made of silicon and / or quartz and / or polymers and / or ceramics, which are dielectric materials commonly used in standard circuit board manufacturing processes. The choice of standard materials results in low complexity and low production costs.

[0037] According to further embodiments, the multiple frequency conversion structures are positioned in the reactive near-field of each associated antenna of the multiple antennas, for example within less than half a free space wavelength of a signal transmitted or received by each associated antenna. Placing the frequency conversion structures in the reactive near-field of the associated antennas allows for measuring or characterizing single antenna elements separately, minimizing disturbances caused by or interference with other antennas of the same multiple antennas.

[0038] In a preferred embodiment, the frequency conversion structure comprises an antenna structure, a mode coupler, e.g., a mode launcher, and one or more nonlinear elements, such as diodes, respectively. The antenna structure is configured to couple with the field of an associated antenna of each of the multiple antennas. The mode coupler is configured to couple the frequency conversion structure with the dielectric slab, e.g., by exciting a mode in the dielectric slab or by coupling to a mode in the dielectric slab. The one or more nonlinear elements are coupled with the antenna structure and the mode coupler. The one or more nonlinear elements are configured to perform a frequency conversion, e.g., such that the frequency of a signal received via the mode coupler is different from the frequency of a signal transmitted via the antenna structure or such that the frequency of a signal received via the antenna structure is different from the frequency of a signal transmitted via the mode coupler. In other words, the frequency conversion structure couples an associated antenna element of the multiple antennas of the DUT with a dielectric waveguide slab and converts the frequency of the signal with the help of the one or more nonlinear elements, which allows a good localization of the origin of the frequency converted signal.

[0039] According to further embodiments, the antenna structure of the frequency conversion structure is smaller than the associated antenna of the plurality of antennas. For example, the maximum extension of the antenna structure of the frequency conversion structure is at least twice, or at least five times, or at least ten times smaller than the maximum extension of the associated antenna, or the area of ​​the antenna structure of the frequency conversion structure is at least twice, or at least five times, or at least ten times smaller than the area of ​​the associated antenna. Since the maximum extension and / or area of ​​the antenna structure of the frequency conversion structure is smaller than the maximum extension and / or area of ​​the associated antenna, the antenna structure receives only a small portion of the signal transmitted by the associated antenna, and the associated antenna receives the signal transmitted by the antenna structure. Furthermore, the small antenna structure of the frequency conversion structure does not significantly distort the field radiated by the antenna of the DUT.

[0040] In a preferred embodiment, the antenna structure or the frequency conversion structure of the frequency conversion structure is placed in the environment of the radiating edge of the associated patch antenna of the multiple antennas, for example in the vicinity of the radiating edge of the associated patch antenna. By positioning the antenna structure or the frequency conversion structure itself at the radiating edge of the associated patch antenna, a stronger received signal is obtained at the frequency conversion structure.

[0041] According to a further embodiment, one or more nonlinear elements, such as diodes, of the frequency conversion structure are fabricated from silicon and / or gallium arsenide, which are commonly used materials for nonlinear elements. The use of commonly used standard materials reduces complexity and cost while improving the manufacturability of the nonlinear elements of the dielectric waveguide slab frequency conversion structure and the manufacturability of the measurement device itself.

[0042] According to a further embodiment, the one or more nonlinear elements of the frequency conversion structure comprise Schottky diodes. Schottky diodes typically have a low forward voltage drop and very fast switching action. The high switching speed and low threshold voltage of Schottky diodes make them well suited for frequency conversion structures designed for signals in the millimeter wavelength range.

[0043] According to a further embodiment, one or more nonlinear elements of the frequency conversion structure comprise a photodiode configured to bias the frequency conversion structure when illuminated. The photodiode in the frequency conversion structure can further affect the frequency converted signal by simply illuminating the photodiode. By (wirelessly) biasing using the photodiode, the conversion efficiency of the frequency conversion structure can be improved. Furthermore, the use of the photodiode even makes it possible to wirelessly activate or deactivate the frequency conversion structure by controlling the illumination of the photodiode.

[0044] In a preferred embodiment, the photodiode is configured to reduce or minimize the conversion losses of the frequency conversion structure when illuminated. Minimizing or reducing converter losses results in a stronger received signal.

[0045] According to a further embodiment, the photodiode is configured to selectively activate the frequency conversion structure when illuminated. Using the photodiode as a switch allows characterizing the antenna elements of multiple antennas one by one without one measurement affecting another. Also, the selective activation of the frequency conversion structure can be performed wirelessly rather than in combination with an electrically controlled metal wire, helping to avoid distortion of the radiated electric field.

[0046] In a preferred embodiment, the photodiode is configured to generate an alternating signal when illuminated with modulated light, allowing all kinds of influences and / or modulations to be applied to the frequency converted signal.

[0047] According to a further embodiment, the measurement device is configured to illuminate the photodiode with light modulated at a modulation frequency, and the frequency conversion structure is configured such that the modulation frequency determines the frequency conversion of the frequency conversion structure such that the frequency difference between the frequency of the input signal of the frequency conversion structure, e.g. the frequency of the signal obtained by the antenna structure, and the frequency of the output signal of the frequency conversion structure, e.g. the frequency of the signal coupled to the dielectric waveguide slab, is determined by the modulation frequency. Thus, any kind of modulated signal can be realized as the output or frequency converted signal of the frequency conversion structure.

[0048] According to a further embodiment, the measurement device comprises one or more laser diodes or light emitting diodes configured to illuminate the photodiodes of one or more corresponding frequency conversion structures with, for example, a quasi-constant light intensity to provide bias and / or with a modulated light intensity to perform frequency conversion. The use of commonly available light emitting or laser diodes improves the manufacturability of the measurement device and reduces production costs. Moreover, an effective control of multiple frequency conversion structures is possible in this way.

[0049] According to a further embodiment, the frequency of the signal and / or the frequency converted signal is between 30 GHz and 300 GHz. Using mmWave signals or signals with frequencies between 30 and 300 GHz, measurement equipment is prepared for envisaged future mobile communication devices.

[0050] According to a further embodiment, the signal and / or the frequency translated signal is a chirp signal, which is adapted to test all frequencies within a given frequency range and is therefore ideally suited in a test environment or measurement device.

[0051] Further embodiments of the present invention create respective methods and respective automatic test equipment comprising the above mentioned measurement apparatus.

[0052] It should be noted, however, that the methods and automatic test equipment are based on the same considerations as the corresponding measurement devices. Furthermore, the features, functionality and details of the methods and / or automatic test equipment may be supplemented by any of the features or functionality and details described herein for the measurement devices, both individually and in combination. [Brief description of the drawings]

[0053] Embodiments according to the present application are described below with reference to the accompanying drawings, in which: FIG. [Figure 1] 1 is a schematic diagram of an embodiment of a measurement device for characterizing a radio frequency device having multiple antennas; [Diagram 2] FIG. 2 is a schematic diagram of another embodiment of a measurement device for characterizing a radio frequency device comprising multiple antennas; [Figure 3a] Photograph of a conventional far-field radiation pattern measurement setup. [Figure 3b] 1A and 1B are photographs and schematic diagrams of a conventional compact range radiation pattern measurement setup; [Figure 4] FIG. 1 is a schematic diagram of another conventional far-field measurement setup. [Diagram 5] FIG. 1 is a schematic diagram of a conventional measurement technique for measuring modules containing small arrays (4-8 elements) in the reactive near-field. [Figure 6] FIG. 1 is a schematic diagram of an exemplary radio frequency device of a possible future handheld device to be measured. [Figure 7] FIG. 1 is a schematic diagram of a hypothetical measurement device for characterizing radio frequency equipment of envisioned future handheld devices. [Figure 8a] FIG. 2 is a schematic diagram of another embodiment of a test apparatus. [Figure 8b] 8b is a schematic diagram of the embodiment of FIG. 8a in which a single antenna of the antenna array transmits a signal that is received by a transceiver, or multiple transceivers simultaneously coherently transmit signals that constructively interfere at the location of a highlighted single receiving antenna in the antenna array. [Figure 9a] 1 is a schematic diagram of another embodiment of a measurement device for characterizing radio frequency devices having transducer structures and their mounts; [Figure 9b] FIG. 9b is an enlarged schematic diagram of the embodiment of transduction structures and their mounts of FIG. 9a. [Figure 10a] FIG. 2 is a schematic diagram of a measurement device section having a dielectric waveguide slab. [Figure 10b] 1 is a schematic diagram of one embodiment of a measurement device section having a dielectric waveguide slab with a frequency conversion structure; [Figure 11]2 is a schematic diagram of one embodiment of a measurement device illustrating the loss experienced by a signal between an antenna and a radio frequency component; [Figure 12a] FIG. 11 is a comparison of different measurement devices. [Figure 12b] FIG. 2 is a schematic diagram of a measurement device having a frequency conversion structure. [Figure 12c] FIG. 1 is a schematic diagram of a measurement setup having a frequency conversion structure in a dielectric waveguide slab. [Figure 13] FIG. 13(a) compares transmission from a patch antenna to a frequency conversion structure with and without a dielectric waveguide slab, and FIG. 13(b) is a schematic diagram of a portion of a measurement setup having a slab with an antenna transmitting a signal in the direction of the frequency conversion structure. [Figure 14a] 1 is a schematic diagram of a portion of an embodiment of a measurement device including a frequency conversion structure that transmits a frequency converted signal that is guided through a dielectric waveguide slab, through a waveguide transition, and to a radio frequency component. [Figure 14b] FIG. 13 shows a simulated electric field of a signal transmitted to a radio frequency component by a frequency converted structure in a measurement device without a dielectric waveguide slab. [Figure 14c] FIG. 13 illustrates a simulated electric field of a signal transmitted to a radio frequency component by a frequency converted structure in a measurement device having a dielectric waveguide slab. [Figure 14d] FIG. 11 compares the transmission coefficient curves of a measurement setup with and without a dielectric waveguide slab, and a scaled version of the transmission curve of a measurement setup without a dielectric waveguide slab. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0054] Different embodiments and aspects of the invention are described below, and further embodiments are defined by the appended claims.

[0055] It should be noted that any embodiment defined by the claims may be supplemented with any of the details, features and functionality described herein, and the embodiments described herein may be used individually or may be optionally supplemented with any of the details, features and functionality contained in the claims.

[0056] It should also be noted that the individual aspects described herein may be used individually or in combination. Thus, details may be added to each of the individual aspects without adding details to another one of the individual aspects. It should also be noted that the present disclosure explicitly or implicitly describes features that can be used in a measurement device or automatic test equipment (ATE). Thus, any of the features described herein may be used in a measurement device context or an automatic test equipment context.

[0057] Moreover, features and functionality disclosed herein in relation to a method may also be used in an apparatus configured to perform such functionality. Moreover, any feature, functionality disclosed herein in relation to an apparatus may also be used in the corresponding method. In other words, any feature, functionality of a method disclosed herein may be supplemented by any of the features and functionality described in relation to an apparatus.

[0058] The present invention will become more fully understood from the following detailed description and the accompanying drawings of embodiments of the invention, which should not be construed as limiting the invention to the particular embodiments described, but are merely for purposes of illustration and understanding.

[0059] (Embodiment according to FIG. 1) FIG. 1 shows a schematic diagram of one embodiment of a measurement device 100 for characterizing a radio frequency device 110 comprising multiple antennas 120 .

[0060] The measurement apparatus includes a dielectric waveguide slab 130 having a plurality of frequency conversion structures 150 disposed within or on the dielectric waveguide slab 130 .

[0061] The measurement device further comprises a plurality of waveguide transitions 140 arranged at different locations of the waveguide slab 130, e.g., along a circumference, and coupled to respective radio frequency components 160. The radio frequency components 160 are configured to transmit and / or receive radio signals 133, 136.

[0062] A frequency conversion structure 150 of the dielectric waveguide slab 130 is associated with each antenna of the plurality of antennas 120. These associations are represented by arrows 125 in FIG.

[0063] The frequency conversion structure 150 is configured to perform a frequency conversion on the received signal 133, resulting in a frequency converted signal 136. The frequency conversion structure 150 is further configured to couple each antenna 120 with the dielectric waveguide slab 130 in a frequency conversion manner, thereby establishing a frequency conversion coupling between the antenna 120 and the plurality of waveguide transitions 140, and providing a frequency conversion coupling between the antenna 120 and a radio frequency component 160.

[0064] Thus, the measurement device 100 is configured to use frequency conversion coupling between the antenna 120 and the radio frequency component 160 to characterize, for example, the antenna 120 and / or a radio frequency device 110 or radio frequency configuration comprising a radio frequency front end connected to the antenna 120.

[0065] A signal 133 transmitted by the antenna 120 is received and frequency converted by the frequency conversion structure 150. The frequency converted signal 136 is re-radiated into the dielectric waveguide slab 130. The dielectric waveguide slab 130 directs the frequency converted signal 136 from the frequency conversion structure 150 through a waveguide transition 140 to a radio frequency component 160. The measurement device 100 characterizes the radio frequency device 110 by evaluating the frequency converted signal 136 received by the radio frequency component 160.

[0066] Another option for characterizing the radio frequency device 110 by the measurement device 100 is shown in Fig. 2, where signals are transmitted in the opposite direction. The signals are transmitted by the radio frequency component 160 and mixed and / or frequency converted by the frequency conversion structure 150. The mixed and / or frequency converted signals are received by the antenna 120. The measurement device 100 characterizes the radio frequency device 110 by evaluating the mixed signals received by one or more of the antennas 120.

[0067] An advantage of the measurement device 100 of the present invention is that it allows testing large antenna arrays 110, such as communication or radar antennas. The measurement device 100 also has a compact setup and is suitable for production environments, since a reasonable number of test channels can be operated in parallel. Also, by using test probe adapters specific to the antenna 120 or antenna array 110 of the DUT, the measurement device can be manufactured in a moderately low complexity technology, which keeps production costs low and increases the number of potential manufacturers. A further advantage of the measurement device 100 is that the number of radio frequency (RF) circuits, such as radio frequency components 160, which are mainly transceivers, is not proportional to the number of antennas 120 or radiators in the antenna array 110, except for the frequency conversion structure 150, which is a passive sensing and / or re-radiating element, required per radiator or antenna. Thus, the measurement device 100 may require only a few millimeter wave hardware.

[0068] Because the number of radio frequency components, in some embodiments, is not proportional to the number of antennas of the DUT, the complexity, size and cost of the measurement equipment remains low compared to the increasing number of antennas.

[0069] (Embodiment according to FIG. 2) Figure 2 shows a schematic diagram of an embodiment of a measurement device 200 similar to the measurement device 100 of Figure 1. The measurement device 200 is configured to characterize a radio frequency device 210 comprising multiple antennas 220.

[0070] The measurement apparatus 200 further comprises a dielectric waveguide slab 230 having a plurality of frequency conversion structures 250 disposed within or on the dielectric waveguide slab 230 .

[0071] Along the circumference of the dielectric waveguide slab 230 are a number of waveguide transitions 240 that couple the dielectric waveguide slab 230 to respective radio frequency components 260 .

[0072] A frequency translation structure 250 is associated with each antenna of the plurality of antennas 220. These associations are represented by arrows 225 in FIG.

[0073] Figure 2 shows optional additional elements compared to Figure 1. The measuring device 200 of Figure 2 comprises, in addition to the elements of Figure 1, an evaluation circuit 270 and a laser diode or light emitting diode 280, while the additional enlarged area 252 illustrates, by way of example, the components and function of a frequency conversion structure 250.

[0074] The evaluation circuit 270 is coupled to the radio frequency component 260 and / or to the antenna 220 of the radio frequency device 210 and / or is coupled to a receiver unit of the radio frequency device 210. The signal evaluation circuit 270 is configured to evaluate signals received by (or using) either the antenna 220 or the radio frequency component 260 of the radio frequency device 210 in order to characterize the radio frequency device 210.

[0075] The frequency conversion structure 250 is further described in the enlarged area 252. The frequency conversion structure 250 comprises an antenna structure 258, one or more nonlinear elements 254, and a mode coupler or mode launcher 256.

[0076] The antenna structure 258 is coupled to an associated antenna 220 of the radio frequency device 210 and one or more nonlinear elements 254, such as diodes, which perform a frequency conversion on the received signal. The nonlinear elements 254 are also coupled to a mode coupler 256 to couple the frequency conversion structure 250 with the dielectric waveguide slab 230.

[0077] In other words, the signal is received by the antenna structure 258 or the mode coupler 256 , frequency converted by the nonlinear element 254 , and re-radiated by the mode coupler 256 or the antenna structure 258 .

[0078] The one or more nonlinear elements 254 of the frequency conversion structure 250 can comprise, for example, Schottky diodes and / or photodiodes. The measurement device 200 also optionally comprises, for example, one or more laser diodes or light emitting diodes 280 that allow for selectively illuminating the nonlinear elements 254, such as photodiodes.

[0079] Light 290 from a laser diode or light emitting diode 280 can bias the frequency conversion structure 250 providing a frequency converted signal, for example, to reduce or minimize conversion losses in the frequency conversion structure 250. The light 290 can also be modulated with a modulation frequency, for example, such that the modulation frequency of the light 290 determines the frequency conversion of the frequency conversion structure 250.

[0080] The measuring device 200 characterizes the radio frequency device 210 by evaluating a signal received by the antenna 220 of the radio frequency device 210 or a receiver circuit of the radio frequency device 210. The signal 233 is transmitted by the radio frequency component 260 through the waveguide transition 240 to the dielectric waveguide slab 230. The transmitted signal 233 is received by the mode coupler 256, frequency converted by the nonlinear element 254, and re-radiated by the antenna structure of the frequency conversion structure 250. Depending on the transmitting radio frequency component 260, the frequency conversion structure 250 mixes (e.g., upmixes or downmixes) the received transmitted signal 233, since the simultaneously transmitted signals 233 may have different frequencies. The mixed signal 236 transmitted by the frequency conversion structure 250 is received by the associated antenna 220 of the radio frequency device. The evaluation circuit 270 of the measurement device 200 characterizes the radio frequency device 210 by evaluating the mixed signal 236 received by the antenna 220 of the radio frequency device 210 .

[0081] The operation of the measurement device 100 in Fig. 1 and the measurement device 200 in Fig. 2 is different as the signal direction is reversed. That is, the upward radiating antenna 120 (in the direction of the waveguide slab or toward the waveguide slab in the z direction or direction) of the patch antenna 110 in Fig. 1 is weakly sensed in the reactive near-field with a small loop or small antenna structure of the frequency conversion structure 150. The sensed or received signal is frequency doubled (or frequency converted) by, for example, a nonlinear element and re-radiated with a mode launcher or a z-directed dipole to the dielectric waveguide slab 130 in the substrate plane (xy plane) direction.

[0082] In contrast, the operation of the measuring device 200 of Fig. 2, the so-called receive case, is more tricky. Instead of frequency doubling, the sensing element or frequency conversion structure 250 realizes a frequency difference at the patch receive frequency f from two incident signals, for example at 1.5f and 2.5f. For example, signals at frequencies 1.5f and 2.5f may be provided by one or more of the radio frequency components 260, and the frequency conversion structure may re-radiate a signal with the difference frequency at f.

[0083] In practical implementations, a calibrated transmit test, such as the test shown in FIG. 1, is probably more important and practical than a full receive test, such as the receive test shown in FIG.

[0084] It should be noted that the sensing element or frequency conversion structure 150 or 250 of Figure 1 or Figure 2 is disposed in or on the dielectric waveguide slab 230 without metal transmission or bias lines, which are largely metal-free and nearly transparent to electromagnetic fields. The dielectric structures associated with the radio frequency units of the device under test can be quite bulky and are easily machined or 3D printed.

[0085] (Conventional measurement method related to FIG. 3) Figure 3a shows a photograph of a conventional far-field radiation pattern measurement setup 310. It contains a mmWave OTA test chamber 315 for design verification testing. Figure 3a also shows a close-up photograph of the test chamber 315.

[0086] Traditionally, antenna arrays are tested in an anechoic chamber / box environment by probing them at large distances or in the far field, which can be slightly less than a meter up to several meters. These measurements are slow and the equipment is large, making this method unsuitable for clean production environments.

[0087] Figure 3b shows a conventional compact range radiation pattern measurement setup 320 and its schematic diagram 330. A more compact measurement setup 320 is achieved by using a reflective element 335 to reduce its size.

[0088] Measurement of modules containing small arrays, such as 4-8 elements, can be done with a small number of absorbers and tested over short distances, such as about 0.5 meters. This is quite suitable for a production environment, but it is time consuming as many array elements are tested in sequence.

[0089] (Conventional measurement method related to FIG. 4) FIG. 4 shows a schematic diagram of another conventional far-field test or measurement setup 400. A patch antenna for probing or testing and a single radiator of the DUT antenna array are at a far-field distance from each other. This distance may be smaller than the far-field distance of the entire DUT antenna array, but the radiator elements of the DUT antenna array are activated sequentially. The measurement setup remains slow and therefore the applied method is not suitable for clean production environments.

[0090] (Conventional measurement method related to FIG. 5) Figure 5 shows a schematic diagram of a conventional measurement approach for measuring modules containing small arrays, such as 4-8 elements, with a probe adapter for probing the antenna elements in the reactive near-field. This measurement setup is very compact and allows parallel measurements of antenna elements of an antenna array, and is therefore well suited for production testing. The measurement setup has further variants for measuring substrate edge radiating dipoles and a probe-in-ground device for eWLB packaging embedded antennas.

[0091] A drawback of this measurement setup is that for a given array topology, a dedicated probe adapter is required which can be quite complex, with the complexity increasing as the number of antenna elements in the antenna array increases.

[0092] (Radio frequency device according to FIG. 6) Fig. 6 shows a schematic diagram of an exemplary radio frequency device 600 of a possible future handheld device to be measured in the measuring device 100 of Fig. 1 or the measuring device 200 according to Fig. 2. The radio frequency device 600 comprises a number of antennas 620. The radio frequency device 600 comprises 14x26 antennas 620 arranged for radiation or dual pole radiation in the z-direction, and refers to a corresponding coordinate system 630.

[0093] For best connectivity and energy efficiency during its operation, it is envisioned, by way of example, that future handheld device forms will be completely covered with antennas. For example, at 30 GHz, a 7 cm x 13 cm area of ​​radio frequency device 600 can contain 364 dual pole radiators or antennas 620.

[0094] As FIG. 7 shows, characterization of envisioned future handheld devices having, for example, more than 100 antennas 620, will be difficult to achieve with conventional measurement equipment suitable for production environments, such as measurement equipment 500 of FIG. 5.

[0095] However, in embodiments according to the present invention, characterization may be easily performed if, for example, one or a small number of frequency conversion structures can be associated with each of the antennas 620 .

[0096] (Measuring device according to FIG. 7) Figure 7 shows a schematic diagram of a virtual measurement setup 700 for characterizing a hypothetical radio frequency device 710 of a future handheld device, similar to the measurement (or radio frequency) setup 600 of Figure 6. The radio frequency device 710 is characterized in a conventional reactive near-field test setup 720, similar to the near-field test setup 500 of Figure 5. The virtual measurement setup 700 illustrates the shortcomings of the conventional reactive near-field test setup 720.

[0097] The near-field measurement device 720 allows very localized measurements, but the number of test needles required exceeds the number of antennas. For example, one dual linearly polarized radiator, e.g., a patch or antenna of the radio frequency device 710, requires up to eight test needles.

[0098] Furthermore, while highly parallel measurements are possible, the number of mmWave components may need to scale with the number of antennas, i.e., many mmWave components are needed for radio frequency (RF) signal synthesis and test channel receivers.

[0099] A further drawback is that the layout of the RF circuitry and test needles must be highly customized.

[0100] In other words, a 7 cm x 13 cm area of ​​a radio frequency device 710 similar to the radio frequency device 600 of Figure 6 operating at 30 GHz can contain 364 dual pole radiators or antennas, thus requiring 2912 test needles and many RF circuits. As the operating frequency increases, the number of radiators or antennas is expected to increase as their physical size decreases, thus worsening the situation. For example, at 60 GHz, the number of test needles required is four times that at 30 GHz.

[0101] Looking at the virtual measurement device 700, it becomes apparent that the concept of a conventional near-field measurement device 720 has reached its limits and characterizing the radio frequency device 710 with a conventional measurement device having a near-field probe becomes impractical.

[0102] (Embodiment according to FIG. 8) 8a and 8b show a schematic diagram of one embodiment of a test apparatus 800. The measurement apparatus (or test apparatus) comprises a radio frequency apparatus 810 similar to the radio frequency apparatus 600 of FIG. 6, comprising a number of antennas 820. The measurement apparatus 800 further comprises a dielectric waveguide slab 880 having a number of waveguide transitions 840 located around the circumference of the dielectric waveguide slab 880. The waveguide transitions couple the dielectric waveguide slab 880 with a radio frequency component 860. The frequency conversion structures of the dielectric waveguide slab 880 coupled to the respective antennas 820 of the radio frequency apparatus 810 are not shown in FIGS. 8a and 8b to avoid cluttering up FIGS. 8a and 8b.

[0103] Both Figures 8a and 8b show the same measurement device 800. Therefore, the structural description of Figure 8b is the same as the structural description of Figure 8a.

[0104] 8b shows that a radio frequency device 810 or large antenna array is probed circumferentially in the xy plane with several, in this case six, test transceivers 860. For example, a single antenna 825 of the antenna array 810 transmits a signal 829 that is guided through a waveguide slab 880 and a waveguide transition 840 to a radio frequency component 860 such as a transceiver 860.

[0105] In another example, several, in this case six, test transceivers 860 transmit signals simultaneously and coherently through the waveguide transition 840 into the waveguide slab 880. The signals interfere constructively at the highlighted location of the single receive antenna 825 of the radio frequency device 810.

[0106] The radio frequency device 810 is characterized, for example, by evaluating the signal 829 transmitted by the antenna 820 (or by a single one of the antennas 820) and received by the radio frequency component 860. Information used to characterize the radio frequency device 810 is, for example, radiation strength, which may be derived from amplitude and / or phase information (e.g., of the signal received by the radio frequency component 860), as well as the location of the patch or antenna element, which may be determined by or derived from triangulation, for example.

[0107] Parallel characterization of the antennas is also possible, for example by obtaining code division multiple access (CDMA) signal encoding. For example, triangulation can be used to determine whether a frequency conversion structure signal received by one or more of the components occurs. Alternatively or additionally, individual frequency conversion structures can be selectively enabled and disabled, for example using selective illumination.

[0108] Alternatively or additionally, each frequency conversion structure may be modulated with a different modulation signal, thereby allowing differentiation of signals radiated from the different frequency conversion structures.

[0109] Therefore, signals originating from different frequency conversion structures can be distinguished.

[0110] (Frequency conversion structure according to FIG. 9) Figure 9a shows a schematic diagram of an embodiment of a measurement device 900 for characterizing a radio frequency device 930, similar to the measurement device 800 of Figure 8b. The measurement device 900 comprises a frequency conversion structure 950 mounted in the near field region of an antenna.

[0111] FIG. 9a further illustrates frequency conversion structures 950 and their mounts 960 within the area 910 illustrated and enlarged at 910 in FIG. 9b.

[0112] FIG. 9b shows that the frequency conversion structure comprises an antenna structure 952, one or more nonlinear elements 954, and a mode launcher 956. The antenna structure couples to the field of each of the multiple antennas. The one or more nonlinear elements are coupled to both the antenna structure and to the mode coupler. The one or more nonlinear elements are configured to perform frequency conversion. The mode coupler is configured to excite radiation, for example omnidirectionally, in the xy plane.

[0113] An antenna of a radio frequency device, for example, transmits a signal mainly in the z-direction (see the orientation of the coordinate system 920). A part of this signal is picked up by the antenna structure 952 of the frequency conversion structure 950. The frequency of the received signal is converted by the nonlinear element 954 of the frequency conversion structure 950 and transmitted by the mode coupler in the xy plane.

[0114] 9b also shows a mount 960 for the frequency conversion structure 950. The portion of the signal that is not received by the frequency conversion structure 950 is absorbed, for example, by an absorber 980.

[0115] Because the frequency conversion structure 950 is attached to the dielectric posts 970, the mount 960 can be considered an inferior alternative to a dielectric waveguide slab. Manufacturing multiple dielectric posts 970 is more complicated and expensive than manufacturing a dielectric slab. The use and advantages of a dielectric waveguide slab are explained in the following figures.

[0116] (Dielectric Waveguide Slab According to FIG. 10) 10a and 10b show schematic diagrams of one embodiment of a measurement setup section 1000 similar to measurement setup 100 of FIG. 1, with a dielectric waveguide slab 1030 being part of the measurement setup.

[0117] Both Figures 10a and 10b comprise a patch antenna array or radio frequency device 1010 similar to the radio frequency device 110 of Figure 1. The single antennas 1010a-c of the patch antenna array 1010 are, for example, configured to transmit signals primarily in direction z. A dielectric slab 1030 is disposed in the reactive near-field of the antenna array 1010. An absorber 1070 is (optionally) located on the other side of the dielectric slab 1030 opposite the patch antenna array 1010.

[0118] FIG. 10a shows that the dielectric slab 1030 is (almost) transparent to the signals 1090 of the antennas 1010a-c of the patch antenna array 1010 because the thickness of the dielectric slab is, for example, less than half the free space wavelength of the signals 1090 transmitted by the antenna elements 1010a-c.

[0119] 10a also shows that the dielectric slab 1030 does not reflect (or does not significantly reflect) the signals 1090 of the antennas 1010a-c. Thus, the dielectric slab 1030, located in the reactive near-field of the antenna array 1010, does not affect (or does not significantly affect) the antennas 1010a-c or the radiator elements.

[0120] Figure 10b has a similar layout, i.e. the measurement apparatus section 1000 comprises a patch antenna array 1010 having three antenna elements 1010a-c, a dielectric slab 1030 within the near field range of the antennas 1010a-c, and an (optional) absorber 1070 located on the opposite side of the dielectric slab 1030, opposite the patch antenna array 1010.

[0121] Compared to FIG. 10a, the dielectric slab 1030 of FIG. 10b comprises an additional frequency conversion structure 1050. In FIG. 10b, it is shown that the antenna element 1010b transmits a signal 1090 in the z-direction. A part of the transmitted signal is received by the antenna structure of the frequency conversion structure 1050. The frequency conversion structure 1050 operates similarly to the frequency conversion structure 950 of FIG. 9. The antenna structure is coupled to a nonlinear element configured to perform a frequency conversion of the received signal. The nonlinear element is coupled to a mode coupler such that the frequency converted signal 1080 is coupled to a mode in the dielectric slab 1030. The frequency converted signal 1080 in the dielectric slab is, for example, an omnidirectional signal propagating in the dielectric slab 1030. In other words, the frequency conversion structure 1050 or the frequency conversion device locally excites a slab-guided surface wave. However, the slab-guided surface wave may also be directed in one or more directions. The slab guided waves can be received, for example, at the circumference of the dielectric slab, using appropriate radio frequency components.

[0122] (Signal transmission loss according to Figure 11) Figure 11 shows a schematic diagram of one embodiment of a measurement device 1100 similar to the measurement device 100 of Figure 1, illustrating the losses experienced by a signal between an antenna 1120 and a radio frequency component 1160. The measurement device 1100 comprises an antenna 1120 and a dielectric slab 1130 having a frequency conversion structure or sensor 1150 within the near field range of the antenna 1120. The measurement device 1100 further comprises a waveguide transition 1140 coupled to the dielectric waveguide slab 1130 and the radio frequency component 1160.

[0123] 11 shows that a patch antenna 1120 is transmitting a signal 1170 having a frequency f0. At the distance between the patch antenna 1120 and the dielectric waveguide slab 1130, the signal experiences a transmission loss, denoted by Loss1.

[0124] The frequency conversion structure 1150 in the dielectric waveguide slab 1130 converts the frequency f0 of the received signal 1170 to a frequency converted signal 1180 having a higher frequency, such as 2f0, which doubles the frequency of the transmitted signal 1170. The signal undergoes a frequency conversion loss, denoted by mixLoss.

[0125] The frequency conversion structure 1150 couples the frequency converted signal 1180 to the dielectric slab 1130, where it is guided through the waveguide transition 1140 to the radio frequency component 1160. Over the distance between the frequency conversion structure 1150 and the radio frequency component 1160, the frequency converted signal experiences a transmission loss of Loss2.

[0126] The total transmission loss between the antenna 1120 and the radio frequency component 1160 is the sum of the above losses, i.e., Loss1+mixLoss+Loss2. The cascaded loss contributions are added as expected in a logarithmic scale, such as decibels (dB). Clearly, for a linear scale, the cascaded loss contributions increase.

[0127] It should be noted that the total loss is found to be acceptable over a wide range of topologies so that reliable characterization of the DUT is typically possible.

[0128] (Comparison of measuring devices related to FIG. 12) Figure 12a shows a diagram 1230 comparing different measurement setups. In particular, the diagram compares a measurement setup with multiple frequency conversion structures in or on a dielectric waveguide slab (see the measurement setup in Figure 12c), a measurement setup with frequency conversion structures that do not include a dielectric slab (see the measurement setup in Figure 12b), and a measurement setup with neither a dielectric waveguide slab nor frequency conversion structures (this measurement setup is not shown in either figure).

[0129] 12a shows a diagram 1230 illustrating the reflection coefficient at the input port of an antenna element or patch by different measurement devices. As shown in diagram 1230, the different measurement devices are compared at a frequency of 28 GHz, and the measured reflection coefficient is -25 to -32.5 dB.

[0130] Figures 12b and 12c show schematic diagrams of two of the compared measurement devices. Figure 12b shows a measurement device 1210 with an input port 1250 coupled to an antenna patch 1240, a frequency conversion structure 1260 or sensor, and a radio frequency component or probe 1270.

[0131] The antenna element 1240 transmits the signal to a frequency conversion structure 1260 which receives a portion of the signal, converts the frequency of the signal to a higher frequency, and transmits the frequency converted signal in the xy plane which combines the signal with a radio frequency component 1270. Another portion of the signal is reflected back towards the antenna element. The reflection coefficient indicates how much the reflected signal of the transmitted signal affects the antenna itself.

[0132] 12c shows a measurement device 1220 similar to the measurement device 1210 of FIG. 12b with an additional dielectric waveguide slab 1280. The dielectric waveguide slab 1280 includes a frequency conversion structure 1260 that couples the frequency converted signal to the dielectric slab 1280. The dielectric waveguide slab 1280 directs the frequency converted signal from the frequency conversion structure 1260 to a radio frequency component 1270.

[0133] From the comparison or in diagram 1230, it can be seen that the measurement device with the frequency conversion structure or sensor and the dielectric waveguide slab has the highest reflectivity, and the measurement device with the frequency conversion structure without the dielectric slab has the lowest reflectivity. Clearly, the disturbance caused by the slab and / or frequency conversion structure is small.

[0134] (Transmission comparison between the antenna according to FIG. 13 and the frequency conversion structure) 13(a) shows a plot 1310 comparing the transmission from a patch antenna to a sensor or frequency conversion structure with and without a dielectric waveguide slab. There is about a 7.5 dB difference between the transmission coefficients of the measurement device with and without the dielectric slab.

[0135] Diagram 1310 also shows that the measurement device with the dielectric waveguide slab has a 7.5 dB higher transmission coefficient when compared to the measurement device without the dielectric waveguide slab, which means that in the measurement device with the dielectric waveguide slab, a larger portion of the transmitted signal is received by the frequency conversion structure when compared to the measurement device without the dielectric waveguide slab.

[0136] In other words, this difference is due to the larger electrical length of the sensor antenna in the dielectric waveguide slab compared to free space (ε r =6).

[0137] A schematic diagram of a portion of a measurement setup with a slab 1320 is shown in Figure 13(b). The measurement setup portion 1320 comprises an antenna 1330 that transmits a signal 1340 in the direction of a frequency conversion structure 1350 within a dielectric waveguide slab 1360. Figure 13(b) illustrates the transmission from the antenna to the frequency conversion structure.

[0138] (Transmission comparison between the frequency conversion structure according to FIG. 14 and the radio frequency component) Figure 14a shows a schematic diagram of a portion 1400 of a measurement device comprising a frequency conversion structure 1410 transmitting a frequency converted signal 1420 that is guided through a dielectric waveguide slab 1430, through a waveguide transition 1450 to a radio frequency component 1440. Figure 14a illustrates the transmission from the frequency conversion structure 1410 to the radio frequency component 1440.

[0139] FIG. 14b shows the simulated absolute value of the electric field of the signal transmitted by the frequency converted structure to the radio frequency component in a measurement setup without a dielectric waveguide slab.

[0140] FIG. 14c shows the simulated absolute value of the electric field of a signal transmitted to a radio frequency component by a frequency converted structure in a measurement setup with a dielectric waveguide slab.

[0141] Comparing the simulations of Figures 14b and 14c, a larger portion of the transmitted frequency converted signal remains guided within the slab in the measurement setup with a dielectric waveguide slab.

[0142] Similar results are provided by diagram 1470 in FIG. 14d. FIG. 14d shows a diagram comparing the transmission coefficient curves of two measurement devices, one without a dielectric waveguide slab and the other with a dielectric waveguide slab. Diagram 1470 further includes a simulated transmission coefficient curve that is a scaled version of the curve of the measurement device without the dielectric waveguide slab. Placing the sensor antenna in free space shortens its electrical length and radiates less power. To fairly compare the sensors, they are scaled to have the same electrical length in free space as they would in the dielectric waveguide slab.

[0143] As shown in both Figures 13(a) and 14d, when a dielectric waveguide slab is used, the transmission coefficient of the signal transmitted from the antenna elements of the patch antenna array to the radio frequency component is highest. This transmission increase can be significant. For example, the total transmission increase in the examples of Figures 13(a) and 14d is about 30 dB.

[0144] Thus, accurate characterization of the device under test is possible.

Claims

1. 1. A measurement device for characterizing a radio frequency device comprising multiple antennas, comprising: a dielectric waveguide slab having a plurality of frequency conversion structures disposed within or on the dielectric waveguide slab; a plurality of waveguide transitions disposed at different locations of the dielectric waveguide slab and coupled to respective ones of a plurality of radio frequency components; the plurality of radio frequency components are configured to transmit and / or receive radio signals; the plurality of frequency conversion structures are associated with respective antennas of the plurality of antennas; the plurality of frequency conversion structures are configured to perform frequency conversion on a received signal to obtain a frequency converted signal; the plurality of frequency conversion structures are configured to couple each of the plurality of antennas to the dielectric waveguide slab in a frequency conversion manner, thereby establishing frequency conversion couplings between the plurality of antennas and the plurality of waveguide transitions to provide frequency conversion couplings between the plurality of antennas and the plurality of radio frequency components; the measurement device is configured to use the frequency conversion couplings between the plurality of antennas and the plurality of radio frequency components to characterize the radio frequency device; the plurality of radio frequency components are configured to simultaneously transmit signals at two different frequencies that are mixed by the plurality of frequency conversion structures; The measurement device is configured to evaluate a mixed signal obtained based on the simultaneously transmitted signals in order to characterize the radio frequency device.

2. 1. A measurement device for characterizing a radio frequency device comprising multiple antennas, comprising: a dielectric waveguide slab having a plurality of frequency conversion structures disposed within or on the dielectric waveguide slab; a plurality of waveguide transitions disposed at different locations around a periphery of the dielectric waveguide slab and coupled to respective ones of a plurality of radio frequency components; the plurality of radio frequency components are configured to transmit and / or receive radio signals; the plurality of frequency conversion structures are associated with respective antennas of the plurality of antennas; the plurality of frequency conversion structures are configured to perform frequency conversion on a received signal to obtain a frequency converted signal; the plurality of frequency conversion structures are configured to couple each of the plurality of antennas to the dielectric waveguide slab in a frequency conversion manner, thereby establishing frequency conversion couplings between the plurality of antennas and the plurality of waveguide transitions to provide frequency conversion couplings between the plurality of antennas and the plurality of radio frequency components; The measurement device is configured to use the frequency conversion couplings between the plurality of antennas and the plurality of radio frequency components to characterize the radio frequency device.

3. the measurement device comprising a signal evaluation circuit coupled to the plurality of radio frequency components and configured to characterize the radio frequency device by evaluating the signals received by the plurality of radio frequency components; 3. The measurement device of claim 1 or 2, wherein the signals received by the plurality of radio frequency components are based on signals transmitted by the plurality of antennas and frequency converted by the frequency conversion coupling between the plurality of antennas and the plurality of radio frequency components.

4. The measurement device of claim 3 , wherein the signal evaluation circuitry is configured to determine the location of a transmitting antenna using triangulation.

5. the measurement device comprising a signal evaluation circuit configured to characterize the radio frequency device by evaluating signals received by the multiple antennas; 5. The measurement device according to claim 1, wherein the signals received by the plurality of antennas are based on signals transmitted by the plurality of radio frequency components and frequency converted by the frequency conversion coupling between the plurality of antennas and the plurality of radio frequency components.

6. the plurality of radio frequency components are configured to simultaneously transmit signals at two or more different frequencies; 6. The measurement device of claim 5, wherein the measurement device is configured to simultaneously test separate branches of the radio frequency device using different signals at the different frequencies.

7. 7. The measurement apparatus of claim 1, wherein the dielectric waveguide slab has a thickness of less than half a free space wavelength of the signal transmitted by one or more antennas of the plurality of antennas or by one or more radio frequency components of the plurality of radio frequency components.

8. 8. The measurement device of claim 1, wherein the dielectric waveguide slab comprises one or more layers.

9. 9. The measurement device according to claim 1, wherein one or more layers of the dielectric waveguide slab are made of silicon and / or quartz and / or polymers and / or ceramics.

10. 10. The measurement apparatus of claim 1, wherein the plurality of frequency conversion structures are positioned in the near field of respective associated antennas of the plurality of antennas.

11. Each of the plurality of frequency conversion structures comprises: an antenna structure configured to couple to a field of each of the plurality of antennas; a mode coupler configured to couple the plurality of frequency conversion structures with the dielectric waveguide slab; one or more nonlinear elements; the one or more nonlinear elements are coupled to the antenna structure and to the mode coupler; 11. The measurement device of claim 1, wherein the one or more nonlinear elements are configured to perform frequency conversion.

12. The measurement device of claim 11 , wherein the antenna structure of the frequency conversion structure is smaller than an associated antenna of the plurality of antennas.

13. 13. The measuring device according to claim 11 or 12, wherein the antenna structure or the frequency conversion structure of the frequency conversion structure is arranged in the vicinity of a radiating edge of an associated antenna of the plurality of antennas.

14. 14. The measurement device according to claim 11, wherein the one or more nonlinear elements of the frequency conversion structure are made of silicon and / or gallium arsenide.

15. 15. The measurement apparatus of claim 11, wherein the one or more nonlinear elements of the frequency conversion structure comprise Schottky diodes.

16. 16. The measurement apparatus of claim 11, wherein the one or more nonlinear elements of the frequency conversion structure comprise a photodiode configured to bias the frequency conversion structure when illuminated.

17. The measurement device of claim 16 , wherein the photodiode is configured to reduce conversion losses in the frequency conversion structure when illuminated.

18. 18. The measurement device of claim 16 or 17, wherein the photodiode is configured to selectively activate the frequency conversion structure when illuminated.

19. 19. A measurement device according to any one of claims 16 to 18, wherein the photodiode is configured to generate an alternating signal when illuminated with modulated light.

20. The measurement device is configured to irradiate the photodiode with light modulated at a modulation frequency; 20. The measurement apparatus of claim 19, wherein the frequency conversion structure is configured such that a frequency difference between a frequency of an input signal of the frequency conversion structure and a frequency of an output signal of the frequency conversion structure is determined by the modulation frequency.

21. 20. The measurement device of claim 16, comprising one or more laser diodes or light emitting diodes configured to illuminate the photodiodes of one or more corresponding frequency conversion structures.

22. 22. The measuring device according to claim 1, wherein the frequency of the signal and / or the frequency converted signal is between 30 GHz and 300 GHz.

23. 23. The measuring device according to any one of the preceding claims, wherein the signal and / or the frequency converted signal is a chirp signal.

24. An automatic test equipment comprising a measuring device according to any one of claims 1 to 23, An automatic test equipment configured to place a device under test having a plurality of antennas in proximity to the measurement apparatus.

25. A method for characterizing a device under test comprising multiple antennas using a measurement apparatus according to any one of claims 1 to 23, comprising the steps of: establishing a frequency conversion coupling between at least one of the plurality of antennas of the device under test and the plurality of waveguide transitions disposed at different locations of the dielectric waveguide slab, to provide a frequency conversion coupling between the plurality of antennas and the plurality of radio frequency components; performing the frequency conversion on the received signal by the plurality of frequency conversion structures disposed within or on the dielectric waveguide slab; using the frequency conversion couplings between the plurality of antennas and the plurality of radio frequency components to characterize the device under test.

26. 26. A method for characterizing a device under test according to claim 25, comprising the steps of: The method performs the characterization by evaluating the signals transmitted by the multiple antennas, frequency converted by the frequency conversion couplings between the multiple antennas and the multiple radio frequency components, and received by the multiple radio frequency components.

27. 26. A method for characterizing a device under test according to claim 25, comprising the steps of: The method performs the characterization by evaluating signals that are transmitted by the plurality of radio frequency components, frequency converted by the frequency conversion couplings between the plurality of antennas and the plurality of radio frequency components, and based on signals received by the plurality of antennas.

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