IREAP
Update on the HPM Source and
Effects Program at UMD
John
Rodgers,
Mike
Holloway (DEPS Scholar),
Dr.
Zeynep
Dilli
,
Mi Jung Jun,
Bisrat
Addissie
and
Bipin
Gyawali
Institute for Research in Electronics and Applied Physics
University of Maryland
College Park, MD 20742
rodgers@umd.edu
IREAP
Outline
1.
State of the UMD HPM Effects Research Group post

MURI
2.
New Capabilities:
a.
System for studying EM field and coupling statistics in
complex cavities (AFOSR DURIP)
b.
New sources:
•
7 kW pulsed L

band TWT w/ arbitrary waveform
generator
•
MW wideband (chaotic), pulsed L

band source
3.
New Efforts:
a.
Radiation Studies
b.
Mitigation Strategies
c.
HPM Source Development
IREAP
State of the UMD HPM Effects Group
•
Full time faculty:
Profs. Vic
Granatstein
,
Ido
Waks
Kristine
Rosfjord
, Dr.
John Rodgers (PI)
•
Postdoc
: Dr.
Zeynep
Dilli
•
Graduate Students: Mike Holloway
•
Undergrads:
Mi Jung Jun (EE),
Bisrat
Addissie
,
Bipin
Gyawali
•
Funding: AFOSR $100k/year, SNL $100k, DURIP $270k
(2008)
•
Notable increase in student interest in advanced EM & HPM
research
IREAP
New Experimental Systems & Capabilities
Q

configurable test chamber and 7 kW
pulsed TWT rack for radiation studies
Pyramidal RF test chamber for
coupling studies
IREAP
New Experimental Systems & Capabilities
Upgraded RF probe station for studies
of effects in electronic circuit boards
WB MW HPM Source
IREAP
Research Goals
•
HPM Effects
:
D
eterministic or hopelessly stochastic
processes?
•
Circuit Effects (deterministic)
:
–
Investigate nonlinear (overdriven), high frequency (out

of

band) response of devices, circuits & networks
–
Develop deterministic effects models that scale with
process technology
•
Modeling (combination):
–
EM Statistical
: Large

scale (rooms, buildings, vehicles,
etc) require statistical electromagnetic approach (RCM)
–
EM Finite Element
: Circuit

level coupling, parasitic
effects, HF resonances
•
Future Prospect
: A comprehensive, scalable approach to
modeling HPM effects.
IREAP
Scope of
Work
HPM Sources
(multi

frequency)
EM Coupling
Cavity Fields
Circuit Effects
Device Effects
Physical Models
IREAP
Prof. Steve
Anlage
One Statistical Approach: RCM
•
Solves field statistics based on GOE
(time

reversal symmetric) of chaotic
ray trajectories
•
Has been benchmarked for High

Q,
ideal structures
•
Minimal information about the target
required: estimates of volume & Q
•
Fast: 30

60 sec. execution time.
Q: What about non

ideal (realistic) structures?
•
High Loss, large variations in boundary conditions
•
Examples: aircraft cockpit, vehicle compartments, rooms.
IREAP
Test RCM for Non

Ideal Cavities with 20 < Q < 500
•
Configure test chamber
with many irregular
scattering surfaces
•
Place non

uniform loss
along boundaries
•
Measure EM statistics
IREAP
Results: Q ~ 200
Experiment
RCM
IREAP
Results: Q ~ 100
Experiment
RCM
Short

orbit effects
IREAP
Results: Q ~ 50
Experiment
RCM
Short

orbit effects
Characterization
of E
lectronic Enclosures
LAN switch with coaxial RF ports
PC with waveguide port
•
Most electronic systems
contain
modular components
and
standardized
form factors (4U, 19” bays, ATX, etc.)
•
Deterministic or statistical EM method?
•
The enclosures are clearly natural microwave
resonators with
~ D
.
Results of S

parameter measurements in
a
LAN switch
•
Port #1 is a dipole launching antenna and port #2 is connected to the main
+12 VDC power bus on the motherboard
Port #1
Port #2
•
Strong resonances are observed across L

band (~1

2 GHz)
RF Surface Current Density for Various TEM
Eigenmodes
on the Motherboard
f= 1.284 GHz
f= 1.502 GHz
f= 1.654 GHz
f= 1.591 GHz
Power
Supply
Power Bus
EMI Gasket
Results from Upset Studies in a LAN Switch
•
At upset, the RF caused the switching power supply to either completely
shut down or output the incorrect voltage for times that were 100
–
1000
times the RF pulse width.
•
This forced the microcontroller to completely reboot the system.
IREAP
Schematic of
LAN switch
power
regulator
Rectified RF voltage at
the feedback pin fools
the comparator into
detecting an over

voltage condition. It
then sends a shutdown
signal to the power
controller via an opto

isolator
The power controller feedback is
designed to shutdown the system (~
30 sec) even if the “fault” is
momentary (microseconds).
IREAP
The EM characteristics of electrically small (d<
)
features (IC packaging leads, bonding wires, etc.) can
be extracted and modeled as lumped elements.
IREAP
Parasitic elements are then coupled to nonlinear
circuit models
Bond wire and
package model
Nonlinear IC model
IREAP
HPM Effects in Sensors & Detectors
Applications:
Communications, Imaging, Ranging, Detection, Encoding
IR PIN Photo Detector
Hall Effect Sensor
Nonlinearity in TWT’s (1

D Model)
RF field on helix
Modulated electron beam
Equation of Motion
Continuity
Gauss’s Law
Wave Equation
Over

modulation
of the beam
increases space

charge forces
which saturate
the amplifier.
Numerical Results Using Quadratic Saturation Model
2.
V. Dronov, M. Hendry, T. M. Antonsen, Jr., and E. Ott,
Chaos,
Vol. 14, No. 1, pp. 30

35, 2004.
Surface of Section
Return Map
System
Parameters:
IREAP
Characteristics of 276HA
TWT
Amplifier
for Satellite Communications
Phase becomes periodic for large input amplitudes!
Frequency:
3

4
GHz
Output Power:
0.6 W
Gain:
35 dB
Bandwidth:
1 GHz
Efficiency:
70
%
TWT Loop Gain
= 1.60
IREAP
Development of Novel Wideband HPM Test Sources
Power
1

2 MW
Frequency
0.9

1.4 GHz
Pulse Width
100

500
m
s
Helix terminated by plasma
column produces dynamic
EM boundary condition.
The helix

plasma
dispersion generates
wideband chirps and hops
in the output radiation.
IREAP
Frequency (MHz / 10)
Time (
m
s)
Loop Gain = 15 dB
Frequency (MHz / 10)
Loop Gain = 5 dB
Time (
m
s)
HPM source with chirp

hop output frequency
IREAP
Evolution of HPM
Power and
Frequency
100
m
s
500 MHz
Total Power 1 MW
IREAP
Conclusions
•
RF rectification by ESD protection diodes and parasitic resonances have
been identified as major susceptibility issues.
•
The RF characteristics of these devices can be accurately described
using lumped

element circuit models with simple high

frequency diode
parameters.
•
Upset can be easily predicted in terms of the high

frequency transfer
characteristics of the circuit and the RF voltage, frequency and
modulation at the circuit terminals.
•
In systems, the problem requires an EM or RCM treatment.
•
Power controllers with feedback have been identified as a major and
universal problem.
•
An informed basis for developing effects sources:
–
L

band
–
Wideband or chaotic modulation
–
10

100 MW Power levels
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