75GHz OTA power measurement for 5G

13th November 2016

Mick Elliott

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Datasheet

The R&S NRPM OTA power measurement solution is claimed to be the first solution for measuring transmit power over the air interface for 5G and wireless gigabit components. The solution enables users working in development and production to calibrate the output power of the antenna on a DUT and to test the DUT's beamforming function.

Base stations, access points, wireless devices and radio modules use phased array antennas to transmit 5G and wireless gigabit radio signals. Beamforming is used to control the direction of radiation of the transmit antenna in order to maximize the power level at the receiver.

The OTA power measurement solutionallows users to measure and calibrate the output power of a DUT as well as test its beamforming function ‒ all with a single, simple test setup. The solution works in the frequency range from 27.5GHz to 75GHz and therefore covers the 28GHz band currently being discussed for 5G as well as the frequency range from 55GHz to 66GHz for WLAN in line with IEEE 802.11ad and frequencies above 66GHz in line with IEEE 802.11ay.

It consists of two core components: the antenna module and the three-channel sensor module.

The R&S NRPM A66 antenna module is a simple, polarised Vivaldi antenna with an integrated diode detector for power measurements. Thanks to its high linearity, it measures the relative power with a measurement accuracy better than 0.2 dB.

Because the power is measured directly on the antenna, the user does not need any additional RF cables, which also eliminates complex compensation for cable loss. With a single antenna module, the user can calibrate the output power on a DUT, for example.

With several spatially offset antenna modules, it is possible to test a DUT's beamforming function.

The R&S NRPM3 three-channel sensor module processes measurements from up to three antenna modules. If more than three antennas are needed for a test setup, users can operate any number of sensor modules in parallel.

The additional measurement points increase the measurement resolution during beamforming tests.

The free R&S Power Viewer Plus PC software from Rohde & Schwarz is available for evaluating and processing the measurement data. It can be used to visually monitor measurements on up to twelve channels and, for example, to determine the average power.

For measurements in its R&S TS7124 19in shielded chamber, Rohde & Schwarz also offers the R&S NRPM-ZD3 cable feedthrough with integrated feedthrough filter. This allows users to acquire signals in a shielded measurement environment for measurement results that are always reproducible.