2007 Issue 2 - Raytheon

R F S Y S T E M S
Continued from page 27
completed, affirming Raytheon’s leadership
position in the development of this technology.
This testing was done at elevated temperatures
and operating conditions to simulate
performance over a much longer period
of time. Three temperature DC Arrhenius
tests of Raytheon’s 28V GaN have also been
completed, and the results predict a mean
time to failure (MTTF) of greater than 1 million
hours at a standard transistor channel
temperature of 150 Celsius. These test
results have given Raytheon customers confidence
in the use of Raytheon’s GaN for
future defense systems.
To support these efforts, RRFC is presently
transitioning the fabrication of GaN MMICs
into its high-volume 100 mm diameter wafer
production fabrication facility (see Figure 2).
This transition will make GaN available with
the quality (RF performance, reliability and
yield), quantity and affordability necessary
to support systems requirements.
Figure 2. A 100 mm diameter GaN wafer
produced at RRFC
GaN is a disruptive high-power semiconductor
technology that will enable a new class of
microwave and millimeter wave RF systems
envisioned for the near future. Raytheon is at
the forefront of GaN development, having
demonstrated outstanding microwave performance
and industry-leading reliability.
This performance gives Raytheon a strategic
advantage in the development of nextgeneration
defense systems.
Nick Kolias
nicholas_j_kolias@raytheon.com
28 2007 ISSUE 2 RAYTHEON TECHNOLOGY TODAY
onTechnology
Metamaterials:
Materials That Perform the Impossible
Imagine if you could create a
“cloaking” device by surrounding an
object with a new and special material.
How would you design an optical
system if the lenses could be any
shape and size you desired?
How could you utilize an antenna
that conforms to the shape of
an airframe?
Would a material that converts waste
heat into THz energy (with no
moving parts) be of interest to you?
These are just a few of the advanced
concepts made possible by a new technology
field that merges physics and materials
science. This wide-ranging field, called
“metamaterials,” bases macroscopic
behaviors on nano-scale building blocks.
The metamaterials field is now being studied
worldwide at universities and
companies including Raytheon.
Metamaterials are materials that gain their
properties from their periodic structure,
rather than from their composition —
particularly when the resulting properties
are not found in naturally formed substances.
For example, index of refraction,
a property used to describe how light is
bent as it passes through an interface
between two materials, is traditionally a
positive number between 1.0 and 4.0.
Metamaterials can effectively create
negative indices of refraction (so-called
“left-handed” materials). Since the index
of refraction is also directly related to
permittivity (dielectric constant) and magnetic
permeability, these same unusual
behaviors open up entirely new possibilities
in materials and structures exposed to
any form of electromagnetic energy.
Investigators have found, for example, that
creating controlled patterns of defects in
materials — where the defects are of the
same scale as the wavelengths of the
energy they wish to control — can be
used to channel energy much as waveguides
are used. Similarly, split-ring
formations etched on printed wiring
The effects of a the typical refraction of an object in a positive index of refraction material
(left) compared with the effect of a negative index of refraction material. (Courtesy of W.
Padilla, Boston College and D. Smith, Duke University)
Y E S T E R D A Y … T O D A Y … T O M O R R O W