Rohde & Schwarz is advancing its pioneering sub-THz research in the D-Band and
has reached important milestones. In collaboration with the Berkeley Wireless
Research Centre (BWRC), the test and measurement expert has successfully
characterized a TX/RX multi-antenna chip (CHARM) operating at up to 140 GHz,
using their D-Band over-the-air (OTA) test chamber. Academia and industry leaders
agree that the 110 GHz to 170 GHz frequency range, known as D-Band, is critical for
beyond 5G and 6G mobile communications and future automotive radar
applications.
TX/RX multi-antenna chip (CHARM) from BWRC operating at sub-THz
frequencies inside the R&S ATS1800C OTA antenna test system.
June 13, 2024 — Devices supporting mmWave frequencies, antenna
systems and RF transceiver modules for future mobile communications standards or
automotive radar applications will share the same characteristics that make them
challenging to test. The wide frequency range, greater number of antenna elements and
lack of conventional external RF connectors will require testing over-the-air in a shielded
environment.
Doctoral candidates Ethan Chou and Hesham Beshary of Professor Ali Niknejad’s Berkeley
Wireless Research Center (BWRC) at the University of California, Berkeley, in collaboration
with test experts from Rohde & Schwarz, recently conducted tests using the new Rohde &
Schwarz D-band over-the-air (OTA) characterization chamber. The tests took place at the
Rohde & Schwarz lab in Coppell, TX, where the group evaluated the chips and application
boards, they designed and fabricated.
The test setup consisted of the R&S ATS1800C OTA antenna test system, the
R&S FSW50 signal and spectrum analyser, the R&S SMW200A vector signal generator,
the R&S SMB100A signal generator for PLL reference, the R&S NGP800 and NGL200
power supplies, and the R&S AMS32 antenna measurement software.
The R&S ATS1800C is a compact and mobile shielded chamber solution for OTA and
antenna measurements based on a compact antenna test range (CATR) ideal for 5G
mmWave applications. To cover the D-Band frequencies, the R&S FE170SR was installed
at the rear of the OTA chamber as an external frontend to the R&S FSW50. The R&S
FE170SR integrates easily with the signal and spectrum analyser, sending calibrated signal
data back to it. This setup does not require any mechanical modifications or additional RF
cabling to the antenna test system.
The setup measures the amplitude and phase coherent response of the device under test
(DUT) radiating in the D-Band. Thanks to the R&S AMS32 software option, which
calculates the nearfield-to-farfield transformation, and the high-precision positioner, fully
automated 3D-pattern measurements including post-processing can be performed in short
time.
The BWRC researchers provided a TX/RX multi-antenna chip (CHARM) mounted on a
power board with FPGA interface. A laptop connected to the FPGA via USB was used to
configure the chip in either TX/RX mode, number of antennas, power settings, etc. An
appropriate phase shift between the antennas was applied to configure the beam steering
direction.
The EIRP performance of the TX configuration was characterized by spherical
measurements in both H and V polarizations. Initially, a continuous sweep was conducted,
but more stable results were obtained from discrete-step positioner angles every 5
degrees. Full 3D maps were conducted at 130, 135, and 140 GHz for both 1 and 4 antenna
configurations. A total of 20,805 discrete data points were acquired in one day of testing.
System path loss was accounted for by calibrating the empty chamber with a known
antenna. Additional test included broadside 8 antennas and 4 antennas with 30-degree
beam-steering using two phase-offset IQ channels of the R&S SMW200A and continuous
sweep data with finer (1 degree) resolution.
Prof. Ali Niknejad, Faculty Director of BWRC, said: “The OTA chamber gives us the ability
to accurately characterize the performance of our D-band modules operating over-the-air.
Not only the 3D antenna pattern, but also the EVM and EIRP performance of the module in
various spatial configurations is a unique capability, giving us important insights into the
beamformer performance.”
Dr. Philipp Weigell, Vice President of the Industry, Components, Research & University
Market Segment at Rohde & Schwarz says: “We are excited to work with BWRC students
and faculty to address the challenges of over-the-air testing at sub-THz frequencies. These
efforts will help researchers and key industry players test and characterize antenna
systems and transceiver modules for 6G wireless communication standards, massive
MIMO testbeds, future automotive radar applications and more.”
At IMS 2024, Rohde & Schwarz will present a demonstration of the characterization of the
TX/RX multi-antenna chip (CHARM) operating at up to 140 GHz using the D-Band OTA
test solution. Trade show visitors can see the demo at the Rohde & Schwarz booth #1521
in Washington, D.C., from June 18 to 20, 2024.
For further information on antenna research using cutting-edge OTA test solutions from
Rohde & Schwarz, visit www.rohde-schwarz.com
