Tech Briefs Magazine - May 2022 - 22

Hypersonic Threats
ly steered radar to prototyping a phased
array, or an electronically scanned array
(ESA), radar. Ultimately, rapidly prototyping
new algorithms with software defi
ned radios could allow researchers and
systems engineers to deliver critical new
capabilities faster.
Agility
Unlike traditional ballistic missile deOne
key challenge facing radar developers
is that an S-Band radar detecting a
hypersonic threat moving at Mach 10
will see a Doppler shift of approximately
35 MHz. Narrowband instrumentation
will not be suffi cient for measuring this
change in frequency, nor for emulating
targets at hypersonic speeds in a hardware-in-the-loop
test system.
Test strategies must then be adapted to
accurately mimic hypersonic threats. Relying
on technologies like wideband,
modular multichannel fi eld programmable
gate array (FPGA)-based instrumentation
is going to be critical in emulating a
realistic high-Doppler shift and getting
real-time responses with a low-latency
FPGA. This technology is critical in prototyping
and testing these types of systems.
Power
The dynamic nature of hypersonics
means that detection radars must be distributed
across different platforms on
land and sea. Remotely located and mobile
radar systems will need considerable
power to operate, for example, from a
giant military truck running a generator.
So, the game becomes how best to get
the most out of the power available. For
that we need Gallium nitride (GaN) amplifi
cation technology for the radio frequency
(RF) transmitters.
Utilizing GaN means radars can increase
transmit power and extend detection
range required to detect hypersonic
missiles, without a signifi cant increase in
supplied power. This amplifi er technology
is still relatively young and is expected
to see considerable power effi ciency improvements
over the upcoming years.
The GaN supply chain currently has low
volume and high prices, making it
cost-prohibitive to deploy into a large
22
channel count distributed radar confi guration.
To lead to higher volume production
and lower prices, this technology
needs more adoption across industries.
For test engineers, using GaN is an exercise
in extreme precision. It requires
more capable test equipment than previous
power amplifi er technology. Since
GaN has lower leakage than other power
amplifi ers, measurement tools must be
meticulous. High bandwidth and great
sensitivity are essential. There is an increased
need for testing inspection for
safety-critical reliability requirements.
Stealth
Hypersonic vehicle technologies
are
hard to detect via radar as they have a low
radar cross section (RCS), which measures
how detectable an object is by radar.
There are a few approaches radar developers
can take to overcome this challenge.
The fi rst is to further incorporate GaN
technology to boost radar transmit power
to improve the probability of detection.
To detect an object that has low RCS like
one of these stealthy objects, you need a
higher power, since these hypersonics
are designed with sharp edges in such a
way that it will refl ect very little of the
power back to the radar trying to track it.
In this context, GaN can act as a more
effi cient technology that will get more
out of the semiconductor for those applications.
Another route to overcoming
stealth is implementing improved algorithms
for detecting targets and distinguishing
those targets from other objects.
Radar developers will then
need to experiment with new waveforms
and system architectures to
rapidly adapt as threats evolve.
For example, that might look
like going from mechanicalwww.techbriefs.com
Tech
Briefs, May 2022
livery systems, hypersonic vehicles can
be considerably more agile and thus a
challenge to track. This requires radars
to employ ESA technology rather than
relying on systems with mechanically
steered, single-beam antennas, which
adds a layer of complexity.
Testing ESAs presents several challenges
due to the multichannel nature
requiring precise synchronized, phase
coherent measurements. Although they
offer unprecedented performance and
wideband multifunctionality, radar developers
are expected to quickly adapt
and demonstrate new capabilities in the
real world, placing a demand on reliable
test solutions, especially when it comes
to transitioning from simulation to testbed
to fi elded system.
While rapidly deploying advanced capabilities
will not be a simple task, it's crucial
to be able to test systems in realistic
scenarios to evaluate system-level performance.
Supporting radar developers and
engineers as they work toward spectrum
superiority, the NA scalable RF solution
for ESA test offers a single toolchain to
do the most common parametric tests for
RF and perform advanced radar pulse
measurements for ESA systems.
Cost
Since hypersonic vehicles can be extremely
complex in their movement and
speed, radars that can track them are very
expensive. To get fi nal system approval, defense
teams often require a live
fi re open range test
to assess the
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Tech Briefs Magazine - May 2022

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