Advertorial
Master the challenges of OTA calibration
Integrating antennas to the radio
frequency chipset without connectors
is increasingly common with both
low cost IoT devices and especially in
highly integrated 5G mobile communication
equipment operating at mmWave
frequencies. This makes testing a device
under test (DUT) over the air (OTA)
mandatory. To tackle the challenges of
OTA testing it is key to understand the
demands of antenna measurement and
chamber setup.
Calibration is an important first step in
the preparation for OTA testing. The
measurement results of a DUT should
not be setup-depended, requiring
a calibration for each measurement
setup. The OTA link adds a significant
amount of attenuation to the measurement
setup due to the free space path
loss (FSPL), in addition to the losses
from cables and other connected components.
Unlike with cables, a stable
measurement distance and perfect
mechanical alignment is crucial for
OTA measurement accuracy in order to
avoid differences in attenuation caused
by positioning errors.
Port calibration, for example by using a
network analyzer, cannot be conducted
to an air interface. Therefore, another
type of calibration is required. Commonly,
antenna gain measurements are
conducted by comparing an unknown
antenna to a reference antenna. Following
this principle, an antenna with
known gain is required to identify the
calibration information of the OTA test
setup and store these calibration data
either on the measurement instrument
or some external software controlling
the measurement setup.
The high FSPL, longer cables due to the
required measurement distance as well
as the use of high frequencies require
excellent dynamic range from the test
and measurement equipment.
To address these different challenges,
to calibrate OTA test setups and to
carry out OTA measurements, Rohde
& Schwarz has a diverse portfolio
of vector network analyzers like the
R&S®ZNA, vector signal generators,
such as the R&S®SMW200A and signal
and spectrum analyzers such as the
R&S®FSW. Rohde & Schwarz also
offers complete OTA test solutions,
such as the R&S®ATS1000 antenna
test chamber. Combined with Rohde &
Schwarz test instruments, it is the ideal
environment for 5G antenna characterization
throughout the entire process
from R&D to production for both active
and passive devices.
For more information,
visit www.rohde-schwarz.com/5G
www.mwee.com March - April 2019 MW 11
/5G
/www.mwee.com
/5G
