Sub-THz frequency systems are getting more and more attention. Addressing this migration, Rohde & Schwarz, in collaboration with Innovations for High Performance Microelectronics (IHP), claimed the first full 2D/3D antenna characterization of transceiver modules operating in the D-Band. Antenna systems and RF transceiver modules for next-generation mobile communications standards or automotive radar applications have a wide frequency range, a greater number of antenna elements, and a lack of conventional external RF connectors, demanding testing over-the-air in a shielded environment.
Migrating successfully into the sub-THz range, the companies demonstrated the first full 2D/3D over-the-air measurements of a radar module at D-Band frequencies. 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, targeting 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 near-field to far-field 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 characterization verified the wider bandwidth provided by the stacked patches than that by the single patch.
The performance of the various DUTs was characterized 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.