FIELD OF THE DISCLOSURE

Embodiments of the present disclosure relate to an over-the-air measurement system for testing a device under test.

BACKGROUND

In the state of the art, over-the-air (OTA) measurement systems for testing a device under test are known. Typically, so-called compact antenna test ranges (CATRs) are used to test the respective device under test, wherein the compact antenna test range has a testing chamber, e.g. an anechoic chamber also called RF-shielded chamber, in which the device under test is placed for testing purposes. The measurement system provides a quiet zone within the testing chamber, wherein the quiet zone is associated with a testing location at which the device under test is placed during the testing. In compact antenna test ranges, at least one reflector may be used that is located in a beam path established between the test location and a respective feed antenna, also called measurement antenna, in order to increase the travelling distance of the electromagnetic waves, thereby ensuring (indirect) far-field (IFF) conditions at the test location located within the quiet zone.

The respective devices under test typically comprise dual-polarized antennas so that it is necessary to make a minimum of four measurements with four different measurement polarizations in order to measure axial ratio and maximum power of the respective device under test. For instance, the devices under test use dual-polarized electromagnetic waves. Hence, the devices under test may relate to FR1 and/or FR2 base stations, FR2 user equipment and radar devices.

In the state of the art it is known to use two separately formed feed antennas and a mechanical feed switcher that mechanically moves the feed antennas in order to test the four different measurement polarizations.

In other words, the feed antennas are changed mechanically, namely moved, which however increases the overall costs of the over-the-air measurement system. In addition, the overall measurement time is relatively high due to the fact that the measurement has to be interrupted when moving the feed antennas.

Therefore, there is a need for a cost-efficient way to perform the respective tests.

SUMMARY

Embodiments of the present disclosure provide an over-the-air measurement system for testing a device under test. In an embodiment, the over-the-air measurement system comprises at least two orthomode transducers and at least two antennas. Each of the antennas is connected to a dedicated orthomode transducer respectively, thereby establishing at least two measurement modules. The at least two orthomode transducers are rotated relative to each other, thereby providing different measurement polarizations of the at least two measurement modules with respect to a common reference plane.

The main idea is that the at least two measurement modules having the orthomode transducers are rotated relative to each other such that they provide different measurement polarizations simultaneously when testing the device under test due to their relative rotated arrangement. In other words, the orthomode transducers are positioned with respect to each other such that a respective polarization reference plane associated with one of the orthomode transducers is tilted with respect to the other one due to the relative rotation.

In general, the at least two measurement modules are rotated with respect to each other such that the polarizations of their antennas are inclined accordingly, for example with respect to the common reference plane.

Since the at least two measurement modules are fixedly arranged, e.g., not moved with respect to each other during the testing, an orthomode transducer assembly is provided.

The orthomode transducer assembly comprises the at least two measurement modules that are stationary or rather static during the testing of the device under test. The measurement modules can include, for example, one or more circuits.

Therefore, the different measurement polarizations are obtained due to the respective (static) arrangement of the at least two measurement modules with respect to each other rather than due to a movement of the at least two measurement modules with respect to each other.

An aspect provides that each of the at least two antennas is a dual-polarized antenna. Therefore, the dual-polarized antennas each provide two different measurement polarizations simultaneously. The two different measurement polarizations per antenna are tilted with respect to each other due to the relative rotation of the orthomode transducers with respect to each other.

For example, the at least two antennas together provide four different measurement polarizations in total. Since each of the at least two antennas provide two different measurement polarizations and both antennas are rotated with respect to each other, four different measurement polarizations are obtained. These different measurement polarizations are required for testing dual-polarized devices under test appropriately, for example dual-polarized antennas under test or rather devices under test with dual-polarized antenna(s).

Another aspect provides that the at least two orthomode transducers are arranged relative to each other such that the different measurement polarizations are offset from each other by 45° with respect to the common reference plane. Accordingly, the corresponding polarization reference plane of at least one orthomode transducer is tilted by 45° with respect to the one of the other orthomode transducer, which may be parallel to the common reference plane, e.g., a horizontal plane.

Therefore, both dual-polarized antennas provide polarizations at 0° and 90° (first dual-polarized antenna) as well as at −45° and +45° (second dual-polarized antenna). Therefore, four different measurement polarizations are provided simultaneously. In other words, four different measurement polarizations can be obtained without the necessity to move or rather rotate one of the antennas or rather one of the orthomode transducers due to their specific static arrangement, which already ensures four different measurement polarizations.

Accordingly, the measurement time can be reduced significantly, as it is not necessary to move or rather rotate a component during the testing in order to ensure to test the device under test by means of four different measurement polarizations at least.

A further aspect provides that the number of antennas is equal with the number of orthomode transducers. In some embodiments, each orthomode transducer is connected with a dedicated antenna, e.g., a measurement antenna, also called feed antenna. Each orthomode transducer is connected with a dedicated output interface as well as two input interfaces via which differently polarized signals are received, e.g., orthogonally polarized signals like horizontally polarized signals and vertically polarized signals.

Moreover, the at least two orthomode transducers and/or the at least two antennas and/or the at least two measurement modules are construed identically. Therefore, the respective components of the orthomode transducer assembly are similar. Hence, the respective additional measurement polarizations are solely obtained due to the relatively rotated arrangement of the orthomode transducers, for example the relatively rotated arrangement of the measurement modules. The relatively rotated arrangement means that the respective components of the orthomode transducer assembly are located stationary or rather fixedly positioned with respect to each other, but their polarization reference planes are tilted or rather inclined with respect to each other, e.g. by 45°.

Another aspect provides that an antenna phase center separation is below 2 cm. Therefore, it is not necessary to re-position the device under test during testing, as the resulting shift of the quiet zone is minimized when changing the antenna for testing purposes. Accordingly, the measurement modules of the orthomode transducer assembly are positioned with respect to each other such that the output interfaces of the measurement modules to which the antennas are connected are located in proximity with each other, resulting in the antenna phase center separation of less than 2 cm, for example less than 1.8 cm, preferably (about) 1.6 cm.

In addition, the over-the-air measurement system comprises at least one reflector. The reflector can be used for increasing the travelling distance of the electromagnetic waves along a beam path between the antenna(s) and the device under test, thereby ensuring (indirect) far-field (IFF) conditions. Therefore, the device under test can be tested under real conditions, namely under far-field conditions.

The at least two antennas may be located substantially at a focal point of the at least one reflector. Since the phase centers of both antennas are separated by less than 2 cm, it can be ensured that both antennas are located substantially at the focal point of the at least one reflector such that a quiet zone shift is minimized.

Further, each of the at least two measurement modules may comprise a housing that accommodates the respective orthomode transducer. The orthomode transducer is located inside the respective housing to which the antenna is connected, for example an output interface provided at an outer side of the housing.

Each of the at least two measurement modules may comprise two input ports and one output port, wherein the respective antenna is connected with the output port. The ports provide the respective interfaces for interconnecting waveguides and/or the antennas. Hence, the ports may be located at outer surfaces of the respective housing such that the respective waveguide(s) and/or antenna(s) can be connected easily to the respective measurement module.

In addition, an RF-shielded chamber may be provided. The RF-shielded chamber ensures that interfering or disturbing signals can be shielded appropriately such that the testing conditions are improved, yielding more reliable characterizations of the device under test.

In addition, the over-the-air measurement system comprises a measurement equipment. The measurement equipment may provide the respective differently polarized signals forwarded to the orthomode transducer assembly, for example its input ports. Thus, the measurement equipment may comprise a signal generator, wherein the measurement equipment is connected with respective waveguides that are connected with the input ports such that the signals generated are forwarded to the orthomode transducer assembly, namely the differently polarized signals.

Furthermore, analysis equipment may be provided that is connected with the orthomode transducer assembly and/or the device under test in order to receive signals to be analyzed to characterize the behavior of the device under test during the testing.

Moreover, a positioner system for the device under test may be provided. The positioner system may be used for rotating the device under test during the testing in order to characterize the device under test sufficiently, for example in several directions. In some embodiments, the positioner system may be a three-dimensional (3D) positioner system, for instance a phone positioner and a tablet positioner in case of testing a mobile phone or rather a tablet.

In general, the positioner system ensures highly accurate azimuth and elevation positioning of the device under test, for example within the quiet zone(s).

In some embodiments, total radiated power (TRP) measurements can be performed accurately and fast.

The over-the-air measurement system may be a far-field system. In some embodiments, direct far-field conditions may be provided due to the distances ensured between the antenna(s) and the device under test.

In other words, the over-the-air measurement system may be a compact antenna test range (CATR) system. The compact antenna test range system comprises the reflector that is used for increasing the travelling distance of the electromagnetic signals, thereby ensuring (indirect) far-field conditions for testing the device under test under far-field conditions.

In general, a compact multi-band orthomode transducer assembly is provided that has two or more orthomode transducers, for instance three orthomode transducers. The input interfaces associated with one orthomode transducer provide differently polarized signals, e.g., orthogonal polarized signals like horizontally polarized signals and vertically polarized signals. Each orthomode transducer of the multi-band orthomode transducer assembly may split a respective signal received via the output interface into two components that are polarized orthogonally with respect to each other, wherein the components are forwarded to the input interfaces. Further, each orthomode transducer is also configured to combine orthogonally polarized signals received via the input interfaces to a combined signal that is forwarded to the output interface.

