Over-the-air power measurement to 75 GHz for 5G and wireless gigabit

November 10, 2016 // By Graham Prophet
Rohde & Schwarz' NRPM OTA power measurement solution is presented as 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 R&S NRPM OTA power measurement solution from allows 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 27.5 GHz to 75 GHz and therefore covers the 28 GHz band currently being discussed for 5G as well as the frequency range from 55 GHz to 66 GHz for WLAN in line with IEEE 802.11ad and frequencies above 66 GHz in line with IEEE 802.11ay.

 

The NRPM OTA power measurement solution consists of two core components: the antenna module and the three-channel sensor module. The R&S NRPM A66 antenna module is a simple, polarized Vivaldi antenna with an integrated diode detector for power measurements. 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. 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 is available for evaluating and processing the measurement data. It can be used to visually monitor measurements on up to twelve channels