SGS Helps Mobile Device Manufacturers Get Ready for 5G

Expected to hit the market in 2019/2020, 5G is the next evolution in mobile wireless technology. It will move beyond 4G mobile internet, facilitating the world of the internet of things (IoT). Alongside greater speed, the new wireless networks will permit communication between a wide range of smart devices and thereby create a massive IoT ecosystem.

To benefit from the introduction of this new technology, manufacturers must ensure their products are compatible with the requirements for target frequencies above 24 GHz and the RF requirements as specified in the OTA standard. To achieve this, these need to use the applicable metrics (EIRP: Effective Isotropic Radiated Power, TRP: Total Radiated Power, and EIS: Effective Isotropic Sensitivity).

To test RF requirements at high frequency (f > 24 GHz), the following methodological aspects apply:
• OTA measurement is the testing methodology for UE RF at high frequency (f > 24 GHz)
• Permitted test methods are Direct Far Field (DFF), Indirect Far Field (IFF), Near Field to Far-field transform (NFTF), that meets the equivalence criteria to the far field environment in an anechoic chamber

There are three different measurement setups for the different permitted test methods – DFF, IFF and NFTF.

The DFF measurement setup of RF characteristics for f > 24 GHz is capable of center and off-center beam measurements. This setup can be simplified for center of the beam measurements, and the measurement antenna and the link antenna can be combined so that a single antenna is used to steer the beam and to perform RF measurements.

The minimum far field distance R for a traditional far field anechoic chamber can be calculated based on the following equation:

R > 2D2
---------
λ

Where D is the diameter of the smallest sphere that encloses the radiating parts of the Device Under Test (DUT).

A problem does exist with this method, since the distance could be very great when testing larger antenna sizes with higher frequencies. These would require extremely large chambers, which may be prohibitively expensive. Methods may, therefore, be required to reduce the measurement distances for the compact antenna testing range and near field testing range.

The IFF measurement setup of RF characteristics for f > 24 GHz is capable of center and off-center beam measurements. This method creates the far field environment using a transformation with a parabolic reflector. This is also known as the Compact Antenna Test Range (CATR) – a collimator system in which the spherical wave is transformed into a plane wave (uniform amplitude and phase), within the desired quiet zone.

Quiet zone size would mainly depend on the reflector, feed taper, and anechoic chamber design. Quiet zone quality can be impacted by amplitude uniformity, phase planarity and polarization purity. The CATR system does not require a measurement distance of 2D2/λ to achieve a plane wave as in a standard far field range. The far field distance R is seen as the focal length, distance between the feed and reflector, which can be calculated as shown below (as a rule of thumb although it can vary depending on system implementation):

• D = X [m]
• Size of reflector = 2 x D
• R = focal length = 3.5 x size of reflector = 3.5 x (2xD)

There is a plane wave with no space loss from the reflector to the quiet zone.

Finally, the NFTF measurement setup of RF characteristics for f > 24 GHz is capable of center and off-center beam measurements. This system measures the amplitude and phase on a surface (spherical in this case) around the DUT. A circular probe array can measure the full 3D pattern with a rotation in azimuth only. Through use of electronic switching between the probe array elements the points in elevation can be measured without rotating the DUT in the elevation plane. The 3D far field pattern is obtained by using a modal spherical wave expansion.

The NFTF is based on the Huygen’s principle. A direct solution to the Helmholtz equations is found by applying boundary conditions on the surface at an infinite distance away from the DUT. From the tangential fields over the surface, the modal coefficients can be determined using the orthogonality of the modal expansion. The NFTF method computes the metrics defined in far field by using the near field to far field transformation. Radiated near field beam patterns are measured and based on the near field to far field mathematical transform, the final metric such as EIRP is the same as the metric for the baseline setup.

As 5G wireless technology comes online in 2019/2020, manufacturers of wireless phone devices need to be ready with compliant products to readily access this new market – products must conform to OTA standards. It is therefore important for manufacturers to understand the methodology associated with RF Testing for 5G mmWave OTA.

To learn more about SGS OTA Testing: (www.sgs.com/en/consumer-goods-retail/electrical-and-electronics/it-and-telecommunication/certification/ota)

For more information, please contact:

Dr. Peter Liao
Global OTA Technical Leader
Wireless Laboratory
Tel: +886 2 2299 3279 ext 1562
Email: crs.media@sgs.com
Website: www.sgs.com/ee

About SGS
SGS is the world’s leading inspection, verification, testing and certification company. SGS is recognized as the global benchmark for quality and integrity. With more than 95,000 employees, SGS operates a network of over 2,400 offices and laboratories around the world.

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This release was published on openPR.