Over-the-air test is successful in sub-THz range

Continuing its sub-THz research efforts with focus in this frequency range, in collaboration with IHP, Rohde & Schwarz has performed the industry’s first full 2D/3D antenna characterisation of transceiver modules operating in the D-Band.

Similar to 5G networks and devices supporting mmWave frequencies, antenna systems and RF transceiver modules for future mobile communications standards or automotive radar applications will share the same features that make their testing a challenge.

Their wide frequency range, a greater number of antenna elements and the lack of conventional external RF connectors will demand testing over-the-air in a shielded environment.

Rohde & Schwarz and IHP (Innovations for High Performance Microelectronics) have transferred this test method successfully into sub-THz range.

The test setup consists of the R&S ATS1000 antenna test system, the R&S ZNA43 vector network analyser and the R&S AMS32 antenna measurement software from Rohde & Schwarz.

The antenna test system is a compact and mobile shielded chamber solution for OTA and antenna measurements, ideal for 5G mmWave applications.

To cover the D-Band frequencies, extensions from Radiometer Physics, a Rohde & Schwarz company, are used in the setup, which allow direct frequency conversion at the probe in both transmit and receive directions.

No mechanical modifications or additional RF cabling to the antenna test system is necessary. The setup can measure the amplitude and phase coherent response of a DUT radiating in the D-Band.

Fully automated 3D-pattern measurements including post-processing can be performed in short time thanks to the R&S AMS32 software options for nearfield to farfield transformation and the highly accurate precision positioner. 

IHP provided four different devices under test (DUT), based on the same D-Band radar transceiver chipset but with different antenna structures, including on-chip single and stacked patches with air trenches and an on-chip antenna array. The over-the-air characterisation verified the wider bandwidth provided by the stacked patches than that by the single patch.

The performance of the various DUTs was characterised by spherical measurements, using two different setups.

By increasing the angular theta step-size from 1 degree to 5 degree, the total test times for a DUT could be reduced from 70 minutes to 12 minutes.

By comparing the different DUT designs based on the obtained measurement data, researchers of IHP were able to analyse the effect of the finite on-board reflector area on the radar sensor FoV (field-of-view).