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Lab: Naval Research Laboratory
4556 Overlook Avenue S.W.
Washington, DC, 20375
Phone: 202-767-3083 ext.
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FUNCTION: The NRL advanced technology
chamber (ATC) is a welded aluminum
shielded room (5.33 × 4.64 × 2.73
m). The ATC has two purposes: (1) as a
mode stirred chamber to assess the
electromagnetic (EM) susceptibility or
emissions of electronic equipment and
interfaces that might be installed on U.S.
Navy ships or aircraft, and (2) as a
research tool for investigating mode
DESCRIPTION: The ATC configured as a mode stirred
chamber (MSC) excites a large number of different
modes that characterize the distribution of the electric
and magnetic fields from 200 MHz through 40 GHz.
Mode stirring is accomplished by rotating a 1.0-m
long aluminum stirrer that is situated just below the
ceiling. The excitation of these large number of modes
is the result of the changing boundary conditions on
the rotating stirrer surfaces. The large number of
modes provide a randomly polarized EM environment.
The EM field within the chamber exhibits statistical
uniformity for repeatability in measurements. Extremely
large electric field intensity levels are achievable with
modest amounts of input power due to the large Q
factor (in excess of 50,000) that is presented by the
aluminum cavity. Mode-stirred chambers have found
wide acceptance for electromagnetic compatibility
(EMC) susceptibility and emissions testing among the
automotive and medical as well as the DoD communities.
Recently, there has been a great deal of interest in
electronic in place of mechanical stirring methods to
expedite the measurement process. NRL is currently
investigating a phase stirring approach where the
excitation phases of three orthogonal wires are varied
with respect to one another. An NRL patent (Application
No. 82,622) has been applied for.