Testing the D-band for 6G and car radar
Wireless comms test expert Rohde & Schwarz, in collaboration with the research facility IHP GmbH (Innovations for High Performance Microelectronics), has performed the industry’s first full 2D/3D antenna characterisation of transceiver modules operating in the D-Band.
The D-Band, ranging from 110 GHz to 170 GHz, is a candidate for beyond 5G and 6G mobile communications as well as for future automotive radar applications. But D-band antenna systems and RF transceiver modules share 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 have transferred their current 5G test methods into the sub-THz range. The test setup consists of the R&S ATS1000 antenna test system, the R&S ZNA43 vector network analyzer and the R&S AMS32 antenna measurement software from Rohde & Schwarz.
The R&S ATS1000 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 GmbH, 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 analyze the effect of the finite on-board reflector area on the radar sensor FoV (field-of-view).
Gerhard Kahmen, managing director of IHP, says: “Sub-THz frequency systems are getting more and more attention in research and many fields of application. The Rohde & Schwarz OTA test system, extended to D-Band, provides an excellent way to characterise radiation patterns of the complex antenna structures, realised in our D-Band radar chips, in a time efficient and precise way.
For IHP, these measurements are valuable to understand the physics of the antenna structures and to further improve their performance. The very successful cooperation with an industrial partner leading in the field of wireless and mmWave communication shows the benefit of close interaction between research and application.”
Alexander Pabst, VP of systems and projects at Rohde & Schwarz says: “We are excited to work with such an excellent partner as Innovations for High Performance Microelectronics on advancing our industry-leading test solutions for over-the-air testing. These joint efforts will help researchers and key industry players to test and characterise antenna systems and transceiver modules for future automotive radar applications and wireless communication standard, that we eventually call 6G.”
