Over-the-air test apparatus

Abstract

The disclosure pertains to an over-the-air test apparatus for characterizing a device under test (DUT) at mm-wave frequencies, the apparatus comprising a measurement chamber enclosing a measurement space; a testing chamber enclosing a testing space, the testing chamber being arranged in the measurement chamber, and structured to accommodate the device under test; an environmental setting unit structured to establish set a conditioned environment in the testing chamber; wherein the testing chamber is made from a material, which is at least transparent to electromagnetic radiation.

Description

[0001] TITLE

[0002] Over-the-air test apparatus.

[0003] TECHNICAL FIELD

[0004] The present disclosure relates to over-the-air testing technology for characterizing electromagnetic structures and materials, also denoted as a device under test (DUT) at various frequencies over wide temperature, relative humidity and climate ranges.

[0005] BACKGROUND OF THE DISCLOSURE

[0006] The wireless community is reacting to governmental institutions imposing more severe qualification of wireless devices over wide temperature, relative humidity and climate ranges. Test / standards for antennas, wireless communication devices and radars are expected to become only more stringent. As a use case: radars deployed in cars are currently tested under optimal circumstances but should be able to operate between a temperature range of -40°C / +85°C, in humid climates and with adverse atmospheric conditions (e.g. rain, snow, fog, etc.) demonstrating a guaranteed longevity during field use.

[0007] So far, some over-the-air (OTA) measurements have been performed outside to account for weather influences. However, the weather environments can not be controlled and thus at this moment repeatable and reliable measurements cannot be performed this way.

[0008] Accordingly, it is a goal of the present disclosure to provide an improved over-the-air testing technique, which allows for characterizing electromagnetic structures and materials, also denoted as a device under test (DUT) at mm-wave frequencies under controlled and reproducible climate conditions.

[0009] SUMMARY OF THE DISCLOSURE

[0010] According to a first example of the disclosure, an over-the-air test apparatus for characterizing a device under test (DUT) at various is proposed, in particular but not limited at mm-wave frequencies. The apparatus comprises a measurement chamber enclosing a measurement space as well as a testing chamber enclosing a testing space. The measurement chamber functions as an over-the-air measurement facility such as an radio frequency (RF) anechoic chamber, hybrid chamber or a reverberation chamber.

[0011] In all examples, the testing chamber is placed within the measurement chamber, and it is structured to accommodate the DUT. In addition, the apparatus comprises an environmental setting unit, which is structured to establish or set a conditioned environment within the testing space of the testing chamber. Moreover, the testing chamber is made from a material, which is at least transparent to electromagnetic radiation.

[0012] Herewith, an environment or climate-controlled testing chamber is created from RF-transparent material, which is used for testing or characterizing electromagnetic structures and materials, in general denoted as devices under test, at mm-wave frequencies. The testing chamber encloses a testing space, which allows for the forming of a climate e.g. temperature, humidity, air pressure, rain, fog, snow, etc. inside the testing space, which climate or environment is different from the space outside of the testing chamber and without them influencing each other.

[0013] The wall forming the testing chamber and enclosing the testing space behaves like an isolator and at the same time. The testing chamber material ensures that it is invisible to electromagnetic waves used by wireless applications. The device or material under test that is placed in the testing chamber can be characterized under the different climatic conditions.

[0014] In an example, a mount is positioned inside the testing chamber, the mount being structured to accommodate the DUT and wherein the mount is made from a material, which is at least transparent to electromagnetic radiation. This ensures that the whole construction of the testing chamber and mount is virtually invisible for the DUT.

[0015] Further, at least one environmental sensor is provided for contactless sensing a characteristic of the conditioned environment in the testing chamber. Preferably, the at least one environmental sensor is accommodated in the testing chamber and is connected with a sensing unit positioned outside the testing chamber. The environmental sensor or sensors are intended to monitor the environmental or climatic conditions (e.g., temperature, humidity, pressure) in the testing chamber and in the environmental setting unit. Also, the temperature of the DUT will be monitored using the contactless environmental sensors.

[0016] In a further example, the test apparatus further comprises at least one reference measuring device accommodated in the measurement space and / or the testing space. This reference measuring device is part of and attached to the over-the-air measurement facility such as an RF anechoic chamber, hybrid chamber or a reverberation chamber. In a first application of the testing apparatus according to the disclosure, the at least one reference measuring device is accommodated in the measurement space of the measurement chamber yet outside the testing space of the testing chamber. This functionality serves to perform device / material characteristics measurements.

[0017] In a second application of the testing apparatus according to the disclosure, the at least one reference measuring device is accommodated in the measurement space of the measurement chamber and inside the testing space of the testing chamber. In this application, the testing chamber encloses both the DUT t as well as the at least one reference measuring device of the testing apparatus. This allows for performing so-called propagation channel measurements, wherein the reference measuring device is attached to the testing chamber as well as to the testing apparatus.

[0018] For both the first and second application, the at least one reference measuring device may be movable with respect to the device under test.

[0019] In the second application, the reference measuring device - whilst being displaced or moved by a suitable displacement or moving unit - will scan around the device under test and accordingly the wall of the testing chamber surrounding the testing space will not be static and will displace together with the reference measuring device. This displacement of the at least one reference measuring device can be achieved by a suitable moving unit, that is made of the same material as the testing chamber. An example of a moving unit can e.g. be a conveyer belt system, which ensures that the testing chamber is kept separated from the outside environment, such that the climatic environment stays inside the testing chamber as intended to.

[0020] For effectively creating the desired conditioned climate or environment under which the device under test is to be characterized or tested, the environmental setting unit comprises an environment preparation chamber for preparing the conditioned environment. The conditioned environment is thus created outside the testing chamber. In effect, the environment preparation chamber is in fluid communication with the testing chamber, allowing for an effective transfer of the conditioned climate or environment thus created from the environment preparation chamber into the testing space of the testing chamber. For example, the environment preparation chamber can be in fluid connection with the testing space of the testing chamber via an environment transfer pipe, this transfer pipe contains one or more valves, which can be effectively controlled (opened and closed) in order to transfer the conditioned climate or environment thus created from the environment preparation chamber into the testing space.

[0021] In yet a further example, the environmental setting unit of the over-the-air test apparatus according to the disclosure may further comprise a gas supply unit, which is in fluid communication with the environment preparation chamber, for example by means of a gas supply pipe.

[0022] In yet further example, the over-the-air test apparatus according to the disclosure comprises a liquid supply unit, which is in fluid communication with the testing chamber. Likewise, a supply pipe is provided connected with the liquid supply unit, wherein a free pipe end of the supply pipe is supendable into the testing chamber.

[0023] With the gas supply unit and the liquid supply unit it is possible to create different climatic environments for measurements to be performed in the testing space. For example, the humidity within the testing can be influenced through the liquid supply unit, whereas the gas supply unit allows for measurements using different gases, e.g. argon, nitrogen, etc.

[0024] In order to effectively prepare the testing chamber for a particular climate- controlled measurement, it is advantageous to testing space relief means are present for relieving the testing space of the testing chamber. In particular, the testing space relief means comprises a relief valve which is in fluid communication with the testing chamber. More in particular, the relief valve is configured as a venturi, which allows to relief the testing space under the influence of an under pressure created in the testing space.

[0025] In an advantageous example of the test apparatus according to the disclosure, a control unit is provided for controlling the environment preparation chamber and / or the gas supply unit and / or the testing space relief means and / or the sensing unit and / or the liquid supply unit. The control unit allows for a proper temperature and humidity control within the testing space, dependent on the type of measurements to be performed.

[0026] In order to excite a signal to the device under test, other than conventional methods, also a feed-through of RF and DC signals using a probe station can be present dependent on the type of measurements to be performed.

[0027] BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The disclosure will now be discussed with reference to the drawings, which show in: Figures 1-5 various stages of a first example of an over-the-air test apparatus according to the disclosure;

[0029] Figures 6-10 various stages of a second example of an over-the-air test apparatus according to the disclosure.

[0030] DETAILED DESCRIPTION OF THE DISCLOSURE

[0031] For a proper understanding of the disclosure, in the detailed description below corresponding elements or parts of the disclosure will be denoted with identical reference numerals in the drawings.

[0032] As outlined in the introductory part of this application, it is known in the prior art to perform over-the-air (OTA) measurements outside a test facility into the open atmosphere in order to account for weather influences. As indicated, these weather environments in the outside can not be controlled and thus a device under test can not be subjected to repeatable and reliable measurements.

[0033] The present disclosure provides an improved over-the-air testing technique, which allows for characterizing electromagnetic structures and materials, also denoted as a device under test (DUT) at various frequencies, in particular but not limited at mm-wave frequencies, under controlled and reproducible climate conditions.

[0034] Two examples of such improved over-the-air testing apparatuses are described here below, with the first example of the over-the-air test apparatus 100i being described in various stages in Figures 1-5 and the second example of the over-the-air test apparatus IOO2 being described in various stages in Figures 6-10.

[0035] Both examples embody a similar construction with the main difference that in the configuration of the second example the reference measuring device - whilst being displaced or moved by a suitable displacement or moving unit - is accommodated in the testing chamber together with the device under test and will scan around the device under test and accordingly the wall of the testing chamber surrounding the testing space will not be static and will displace together with the reference measuring device.

[0036] In both the first example and the second example, reference is made to Figures 1-10. The over-the-air test apparatus 100i (IOO2) is suitable for characterizing a device under test (DUT) at various, e.g. mm-wave frequencies. In all Figures the device under test is denoted with reference numeral 1. The apparatus 100i (IOO2) comprises a measurement chamber 10, which encloses a measurement space 10z. The measurement chamber 10 functions as an over-the-air measurement facility, such as an RF anechoic chamber, hybrid chamber or a reverberation chamber. In the drawing the measurement chamber 10 functions as an RF anechoic chamber.

[0037] Inside the RF anechoic chamber 10 a testing chamber 11 is accommodated. The testing chamber 11 encloses a testing space 11z which is thermally isolated from the measurement space 10z surrounding the testing chamber 11. As depicted in all Figures 1-10, the testing chamber 11 is arranged or placed within the measurement chamber 10. The functionality of the testing chamber 11 is to accommodate a device under test 1.

[0038] In an example, a mount 13 is positioned inside the testing chamber 11 , and the mount 13 serves as a support platform on which the device under test 1 can be accommodated. The testing chamber 11 and in particular its chamber wall 11a surrounding the testing space 11z is made from a material, which is at least transparent to electromagnetic radiation, more in particular electromagnetic fields and waves at mm- wave frequencies.

[0039] Accordingly, an environment or climate-controlled testing chamber 11 is created from RF-transparent material, which is used for testing or characterizing electromagnetic structures and materials, in general denoted as devices under test 1 , at mm-wave frequencies. The testing chamber 11 encloses a testing space 11z, which allows for the forming of a climate e.g. temperature, humidity, air pressure, rain, fog, snow, etc. inside therein. In particular, the climate or environment within the testing space is different from the space outside of the testing chamber, for example the space 10z of the RF anechoic chamber 10 and the outside environment outside of the RF anechoic chamber 10. This environmental isolation between the testing space 11z and the space 10z ensure that both environments do not influence each other.

[0040] The wall 11a forming the testing chamber 11 and enclosing the testing space 11z behaves like an isolator and at the same time, the material of which (the wall 11a of) the testing chamber 11 is manufactured ensures that it is invisible to electromagnetic waves used by wireless applications. The device or material under test 1 that is placed on the mount 13 in the testing chamber 11 can be characterized under the different climatic conditions.

[0041] In a similar manner, the mount 13 may be manufactured from a material, which is at least transparent to electromagnetic radiation like the wall 11a forming the testing chamber 11. This ensures that the whole construction of the testing chamber 11 and the mount 13 is virtually invisible for the device under test (DUT) 1.

[0042] For sensing a characteristic of the conditioned environment in the environment or climate-controlled testing chamber 11 at least one environmental sensor is provided, which is denoted with reference numeral 14. Preferably, the at least one environmental sensor 14 is accommodated in the testing chamber 11 and is in contactless communication with a sensing unit 15 positioned outside the testing chamber 11.

[0043] It is possible to implement a number n of environmental sensors 14n, each capable of sensing a particular characteristic of the conditioned environment in the environment or climate-controlled testing chamber 11. The characteristics or environmental I climatic conditions to be monitored can be e.g. a temperature, a humidity, a pressure, a gas composition, a radiation level, etc. etc. which exist in in the testing chamber 11 and in the environmental setting unit 17 (described further in the detailed description). Also, the temperature of the device or material under test 1 can be monitored using the contactless environmental sensors 14n.

[0044] Reference numeral 16 denotes at least one reference measuring device which is accommodated in the measurement space 10z (first example or application as shown in Figures 1-5) and / or the testing space 11z (second example or application as shown in Figures 6-10). In the first application of the testing apparatus 100i according to the disclosure, the at least one reference measuring device 16 is accommodated in the measurement space 10z of the measurement chamber 10 yet outside the testing space 11z of the testing chamber 11. This functionality serves to perform device / material characteristics measurements.

[0045] In the second application of the testing apparatus IOO2 according to the disclosure, the at least one reference measuring device 16 is accommodated in the measurement space 10z of the measurement chamber 10 yet also inside the testing space 11z of the testing chamber 11. In this application, the testing chamber 11 encloses both the device or material under test 1 as well as the at least one reference measuring device 16 of the testing apparatus. This allows for performing so-called propagation measurements, wherein the reference measuring device 16 is attached to the testing chamber 11 as well as to the testing apparatus IOO2.

[0046] For both the first and second application, the at least one reference measuring device 16 may be movable with respect to the device under test 1. This displacement of the at least one reference measuring device 16 within the the measurement chamber 10 is depicted in the various Figures 1-10 by means of the alternative positions denoted with 16’ and 16”. This displacement is also denoted by means of the arced arrows, and can be achieved by means of a moving unit 28 for the first example of Figures 1-5. For the second application, the displacement of the reference measuring device 16 and hence the displacement of the testing chamber 11 can be achieved by a suitable moving unit denoted with reference numeral 27. Preferably the moving unit 27 is made of the same material as the testing chamber 11.

[0047] In the second application, as an example of a moving unit 27, a conveyer belt system is proposed, which ensures that the testing chamber 11 is kept separated from the outside environment 10z, such that the climatic environment stays inside the testing chamber 11 as intended to. The moving unit 27 ensures that the testing chamber 11 is sealed of from the outside environment 10z whilst the testing chamber 11 is displaced during measurements due to the movement of reference measuring device 16.

[0048] In the second application, depicted in Figures 6-10, the reference measuring device 16 is located inside the testing space 11 and will scan around the device under test 1 and accordingly the wall 11a of the testing chamber 11 surrounding the testing space 11z will not be static and will displace together with the reference measuring device 16.

[0049] For effectively creating the desired conditioned climate or environment under which the device under test is to be characterized or tested, reference numeral 17 denotes an environmental setting unit. This environmental setting unit 17 is structured to establish or set a conditioned environment within the testing space 11z of the testing chamber 11. The environmental setting unit 17 comprises an environment preparation chamber 17z for preparing the conditioned environment. The conditioned environment is thus created outside the testing chamber 11. In effect, the environment preparation chamber 17z is in fluid communication with the testing chamber 11 , allowing for an effective transfer of the conditioned climate or environment thus created from the environment preparation chamber 17z into the testing space 11z of the testing chamber 11. In the examples, the sensing unit 15 is mounted inside the environment preparation chamber 17z as it may also be capable of sensing one or more characteristics of the desired conditioned environment in the environment preparation chamber 17z.

[0050] For example, the environment preparation chamber 17z can be in fluid connection with the testing space 11z of the testing chamber 11 via an environment transfer pipe 18, which transfer pipe 18 contains one or more valves 19a- 19b, which can be effectively controlled (opened and closed) in order to transfer the conditioned climate or environment thus created from the environment preparation chamber 17z into the testing space 11z.

[0051] The environmental setting unit 17 may further comprise a gas supply unit 20, which is in fluid communication with the environment preparation chamber 17z, for example by means of a gas supply pipe 21. The gas supply unit 20 allows for the transfer of different gases, e.g. argon, nitrogen, etc. into the environment preparation chamber 17z in order to establish a particular conditioned climate or environment within the environment preparation chamber 17z and the subsequent testing of the device under test 1 within the testing chamber 11 by subjecting the device under test 1 to that particular gaseous climate or environment thus created.

[0052] In a similar fashion, a liquid supply unit 24 can be provided, which is in fluid communication with the testing chamber 11. A supply pipe 25 is provided which is connected with the liquid supply unit 24 and a free pipe end 25a of the supply pipe 25 ends into the testing chamber 11. As with the gas supply unit 20, the liquid supply unit 24 allows to create different climatic environments with varying humidities within the testing space 11, and thus allows for humidity measurements to be performed. Further, environments containing weather conditions such as fog, rain, snow etc. can be created using the liquid supply unit 24.

[0053] In order to effectively prepare the testing chamber 11 for a particular climate-controlled measurement, testing space relief means 22 are used for relieving the testing space 11z of the testing chamber 11 from the environment, humidity, gas or air already contained therein.

[0054] In both examples 100i and IOO2, a particular conditioned climate or environment is prepared within the environment preparation chamber 17z, see Figures 3 and 8. The conditioned climate or environment is to be transferred into the testing chamber 11 via an environment transfer pipe 18, which transfer pipe 18 contains one or more valves 19a-19b, which can be effectively controlled (opened and closed) in order to transfer the conditioned climate or environment thus created from the environment preparation chamber 17z into the testing space 11z.

[0055] In order to effectively transfer the particular conditioned climate or environment thus prepared from the environment preparation chamber 17z into the testing space 11z, the latter has to relieved in advance in order to allow the transfer.

[0056] To this end, with the valves 19a and 19b in closed position thus preventing any fluid communication between the environment preparation chamber 17z and the testing space 11z via the environment transfer pipe 18, the testing space relief means 22 comprises a pump unit (not shown) and a relief valve 23 which is in fluid communication via a small relief pipe 23a with the testing chamber 11. More in particular, the structure containing the testing space relief means 22, the relief valve 23, and the small relief pipe 23a is configured as a venturi 23. By blowing air through the relief pipe 22 towards the relief valve 23, an under pressure is created in the testing space 11z and the testing chamber 11 is relieved by removing any air contained in the testing space 11z through the small relief pipe 23a and the relief valve 23 in a relief container 22z. This situation is disclosed for both examples 100i and IOO2 in Figure 2 and 7 respectively. Depending on the application, the relief container 22z might or might not be present. The relief container 22z is detachable.

[0057] Accordingly, an under-pressure is created in the testing chamber 11. The subsequent opening of the valves 19a and 19b (see Figure 4 and 9) ensures that the under-pressure present in the testing chamber 11 sucks the conditioned climate or environment from the environment preparation chamber 17z into the testing space 11z of the testing chamber 11. This suction phenomenon creates a homogeneously distributed climate in the testing chamber 11 without any adverse effects of air flow.

[0058] On both examples a control unit 26 is provided for controlling the environment preparation chamber 17z and / or the gas supply unit 20 and / or the testing space relief means 22 and / or the sensing unit 15 and / or the liquid supply unit 24 as well as processing the various signals obtained from the various environmental sensors 14. The control unit 26 allows for a proper temperature and humidity control within the testing space 11, dependent of the type of measurements to be performed.

[0059] In both examples 100i and IOO2, depending on the application, the device under test 1 can be excited by means of a probe (not shown).

[0060] LIST OF REFERENCE NUMERALS USED

[0061] I device under test (DUT)

[0062] IOO1-IOO2 over-the-air test apparatus (first and second embodiment)

[0063] 10 measurement chamber

[0064] 10a measurement chamber wall

[0065] 10b RF absorber

[0066] 10z measurement space;

[0067] I I testing chamber

[0068] 11a testing chamber wall

[0069] 11z testing space

[0070] 13 mount

[0071] 13z signal excitation

[0072] 14nenvironmental sensor

[0073] 15 sensing unit

[0074] 16 reference measuring device

[0075] 16’-16” positions of movable reference measuring device

[0076] 17 environment setting unit

[0077] 17z inner space or inner chamber of environment preparation unit

[0078] 18 environment preparation chamber conduit

[0079] 19a environment preparation chamber valve

[0080] 19b testing chamber valve

[0081] 20 gas supply unit

[0082] 21 gas supply unit conduit

[0083] 22 testing space relief means

[0084] 22z relief collection space

[0085] 23 relief valve I venturi

[0086] 23a venturi pipe

[0087] 24 liquid supply unit

[0088] 25 supply pipe

[0089] 25a free pipe end

[0090] 26 control unit

[0091] 27 moving unit for movable testing chamber

[0092] 28 moving unit for reference measuring device

Claims

CLAIMS1. An over-the-air test apparatus for characterizing a device under test (DUT) at various frequencies, the apparatus comprising: a measurement chamber enclosing a measurement space; a testing chamber enclosing a testing space, the testing chamber being arranged in the measurement chamber, and structured to accommodate the device under test; an environmental setting unit structured to establish a conditioned environment in the testing chamber; wherein the testing chamber is made of a material, which is at least transparent to electromagnetic radiation.

2. The over-the-air test apparatus according to claim 1 , wherein a mount is arranged inside the testing chamber, the mount being structured to accommodate the device under test and wherein the mount is made of a material, which is at least transparent to electromagnetic radiation.

3. The over-the-air test apparatus according to claim 1 or 2, wherein the test apparatus further comprises at least one environmental sensor for sensing a characteristic of the conditioned environment in the testing chamber.

4. The over-the-air test apparatus according to claim 3, wherein the at least one environmental sensor is accommodated in the testing chamber and is in contactless communication with a sensing unit arranged outside the testing chamber.

5. The over-the-air test apparatus according to any one or more of the claims 1-4, wherein the test apparatus further comprises at least one reference measuring device accommodated in the measurement space and / or the testing space.

6. The over-the-air test apparatus according to claim 5, wherein the at least one reference measuring device is movable with respect to the device under test.

7. The over-the-air test apparatus according to any one or more of the claims 1-6, wherein the environmental setting unit comprises an environment preparation chamber for preparing the conditioned environment, the environment preparation chamber being in fluid communication with the testing chamber.

8. The over-the-air test apparatus according to claim 7, wherein the environmental setting unit comprises a gas supply unit being in fluid communication with the environment preparation chamber.

9. The over-the-air test apparatus according to any one or more of the claims1-8, wherein the environmental setting unit comprises testing space relief means for relieving the testing space of the testing chamber.

10. The over-the-air test apparatus according to claim 9, wherein the testing space relief means comprises a relief valve being in fluid communication with the testing chamber.

11. The over-the-air test apparatus according to claim 10, wherein the system containing the relief valve, testing space relief means, and the small relief pipe are configured as a venturi.

12. The over-the-air test apparatus according to any one or more of the claims1-11 , wherein the test apparatus further comprises a liquid supply unit being in fluid communication with the testing chamber.

13. The over-the-air test apparatus according to claim 12, wherein the liquid supply unit comprises a supply pipe having a free pipe end which is suspendable in the testing chamber.

14. The over-the-air test apparatus according to any one or more of the claims 1-13, wherein the test apparatus further comprises a control unit for controlling the environment preparation chamber and / or the gas supply unit and / or the testing space relief means and / or the sensing unit and / or the liquid supply unit.

15. The over-the-air test apparatus according to any one or more of the claims 1-14, wherein the test apparatus further comprises a probe station for applying RF and DC signals.

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