Aerospace & Defense Technology - February 2022 - 26

RF & Microwave Technology
High-frequency 50-Ω RF/
microwave coaxial interconnection
solutions for military
avionics systems must be
light in weight and small to
fit the high-density requirements
of modern airframes
and avionics systems. Avionics
applications typically
range in frequency from DC
to 12 GHz, including such
applications as 4-GHz radar
altimeters, distance measuring
equipment (DME), a satellite-based
Global Positioning
System (GPS) receiver, a
microwave landing system
(MLS), and a Traffic Alert
and Collision Avoidance
System (TCAS). Driven by
demands for smaller SWaP
equipment requirements,
avionics systems are being
mounted within smaller airframes and
equipment housings, requiring coaxial
assemblies to maintain reliable electrical
and mechanical interconnections in
tight spaces and under the most severe
operating conditions.
0.7
0.6
0.5
0.4
0.3
0.2
0.1
200
FREQUENCY (GHz)
400
600
800
tems can function as antennas
and generate electromagnetic
interference (EMI) within the
system, affecting components
or subsystems such as receivers
susceptible to excess levels of
EM emissions. RF/microwave
coaxial cables and connectors
for military or civil avionics
applications should provide
minimum required levels of
EM compatibility (EMC) and
EMI suppression to enable
interference-free operation of
avionics systems within tightly
packed housings.
Figure 1. MilTech® Lightweight (MTL) hermetically sealed RF/microwave
cables are designed to provide high performance and reliability in densely
packed military avionics systems.
For example, the limited physical
room for military avionics systems results
in tight spacing that invites unwanted
coupling between RF/microwave transmission
lines such as coaxial cables. If
not adequately shielded, RF cable assemblies
within an aircraft's avionics sysTracking
Trends
Modern military avionics
systems with greater functionality
from smaller spaces reach
higher frequencies to provide
the bandwidth for more subsystems.
A military avionics range that
once reached 12 GHz is being extended
to 18 GHz and higher, even into the
millimeter-wave (mmWave) frequency
range (30 GHz) and beyond. Tight
spaces for multiple avionics subsystems
Miltech 130
Miltech 160
Miltech 210
Miltech 230
Miltech 270
Miltech 330
Miltech 440
1000
1200
1400
1600
1800
2000
Cable
MT 130
MT 160
MT 210
MT 230
MT 270
MT 330
MT 440
Cable Diameter
(In./mm.)
0.13/3.3
0.16/4.1
0.21/5.3
0.23/5.8
0.270/6.9
0.34/8.6
0.435/11.0
Loss@ 18 GHz
(dB/ft.)
0.65
0.65
0.44
0.36
0.29
0.22
0.13 (@10 GHz)
Minimum Bend Radius
(In./mm.)
Mass
0.65/16.5
0.65/16.5
0.95/24.1
1.03/26.2
1.25/31.8
1.75/44.5
2.50/63.5
0.020lb/ft (30g/m)
0.021lb/ft (31g/m)
0.030lb/ft (45g/m)
0.037lb/ft (55g/m)
0.049lb/ft (73g/m)
0.068lb/ft (101g/m)
0.135lb/ft (201g/m)
Figure 2. The loss of flexible coaxial cables such as the MTL cables increases with frequency and decreases with larger diameter.
26
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Aerospace & Defense Technology, February 2022
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Aerospace & Defense Technology - February 2022

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