or parts thereof,
8092 Zurich, Switzerland.
Honorary Patron:
Sponsor:
Organized by:
stitute of Technology Zurich
international Radio Consultative Committee (CCIR), IEEE Elec-
tromagnetic Compatibility Society, IEEE Switzerland Section,
Association of Polish Electrical Engineers (SEP), Committee AE-4
on Electromagnetic Compatibili ty of the Society of Automotive
Engineers (SAE), Information Technology Society of the SEV (ITG)
Organizing Commlttee:
Prof. Dr. P. Leuthold, Zurich (Symposium President); E. Diinner, Zurich
(Vice-President); Prof. Dr. F. L. Stumpers, Eindhoven (Vice-President);
Dr. T. DvoNk, Zurich (Organizing Chairman); Prof. Dr. R. M. Showers,
Philadelphia (Technical Program Chairman); H. K. Mertel, San Diego
(Workshops Program Chairman); U. Welte, Zurich (Exhibition Chair-
man); B. Szentkuti, Berne (Publicity Chairman); Dr. M. lanovici,
Lausanne (Joint Events Chairman); R. Bandle, Zurich; R. Danieli, Zug;
G. Meyer, Stafa; J. @rum, Zurich (Chairpersons, Local Arrangements);
G. Georg, Allenwinden (Treasurer); Mrs. E. Danieli, Zug; Mrs. V.
Szentkuti, Berne (Ladies Program).
Chairman: Prof. Dr. R. M. Showers
Prof. Dr. P. Degauque, Villeneuve-d’Ascq; Dr. T. Dvorak, Zurich (Pro
ceedings Editor); Prof. Dr. C. Egidi, Turin; Dr. J. J. Goedbloed,
Eindhoven; Prof. Dr. S. Lundquist, Uppsala; Dr. A. D. Spaulding,
Boulder; Dr. R. Sturm, Munster; Dr. A. Whitehouse, London; Prof.
Dr. F. Zach. Wien.
Advisory CommIttee:
H. Bachmann, Noordwijk; Prof. Dr. F. E. Gardiol, Lausanne (Swiss Na-
tional Committee of the URSI); Ft. Gressmann, Bruxelles (EBU); J.
Hamelin, Lannion; J. S. Hill, Springfield (IEEE EMCS); G. A. Jackson,
Leatherhead; R. C. Kirby, Geneva (CCIR); J. L. Moe, Fort Worth (SAE
AE-4); Prof. Dr. J. J. Morf, Lausanne; W. Moron, Wroclaw (SEP); Prof.
Dr. J. Neirynck, Lausanne (IEEE Switzerland Section); Prof. Dr. R.
Sato, Sendai; Ch. Scherrer, Berne (BAUEM); Prof. Dr. Ft. Struzak,
 
Symposium Patrons 1975.1995:
Program Chairman:
Workshops Program Chalrman: H. K. Mertel (19751985)
Sponsoring organlsatfons 19751965:
Swiss Electrotechnlcal Association
Organfslng tnstitutlons 1975.1965:
Montreux Tourist Office, Netherlands National Committee of the IEC in
cooperation with the Institute of High Frequency Electronics of the Federal
Institute of Technology Zurich, Institute for Communication Technology of
the Federal Institute of Technology Zurich
Cooperating organlsations 19751985:
International Union of Radio Science (URSI), Convention of the National
Societies of Electrical Engineers of Western Europe (EUREL), International
Radio Consultative Committee (CCIR), International Special Committee on
Radio Interference (CISPR), Region 8 of the IEEE, IEEE Switzerland Section,
IEEE Electromagnetic Compatibility Society, Association of Polish Elec-
trical Engineers (SEP), Committee AE-4 of the Society of Automotive
Engineers (SAE), Nachrichtentechnische Gesellschaft im Verband
Deutscher Elektrotechniker (NTGIVDE), Information Technology Society of
the SEV (ITG)
Certificates of Acknowledgement:
(for outstanding support of the Symposium)
J. S. Hill (1977), H. K. Mertel (1977), J. C. Toler (1977).
Prof. Dr. F. L. Stumpers (1983)
Some data on past svmposia
I Year
Attendance
 
Montreux 1971:
1. ex aequo, in alphabetical order of the first author):
. W. p. King, G. S. Smith: “Electrical field probes and their application
in EMC”
*V. P. Pevnitsky, L. V. Tigin: “A stochastic model of a cumulative. pro-
cess of man-made radio interference and objective evaluation of srgnal
distortions produced by these interferences”
craft”
vironment - Facts models, trends”
4. R. Cortina, F. Demjchelis, W. Serravalli: “Anew type of 500kHzmeasuring
instrument for long-term recording of radiointerferencefrom power lines”
Montreux 1977:
voltages measured with a CISPR measuring set”
*A. D. Spaulding: “Optimum reception in the presence of impulsive
noise”
. J. Hasler: “The measurement of external immunity of domestic
receivers-some problems and their solution”
‘R. G. Struzak: “CISPR auasi-oeak measurino channel with extended
.
dynamic range”
P. Groenveld, A. de Jong: “A simple r.f. immunity test setup”
P. G. Galliano: irlmpulsive disturbances on car electric circuitry”
Rotterdam 1979:
2. (ex aequo, in alphabetical order of the first author) :
*I. L. Gallon: “EMP coupling to long cables”
“J. Hamelin, B. Djebari, R. Barreau, J. Fontaine: ‘Electromagnetic field
resulting from a lightning discharge, surges induced on overhead lines,
mathematical model”
“J. G. Tront, J. J. Whalen: “Computer -aided analysis of RF effects in
operational amplifiers”
3. (ex aequo, in alphabetical order of the first author):
W. Hadrian: Reduction of electromagnetic disturbances ‘in buildings
caused by lightning using conductive facades”
A. P. Kalmakov: “Possibilities of reduction of volume of measurements
when checking the sources of clicks for compliance with CISPR limits”
T. Takagi, t-t. Echigo, R. Sato: “Some characteristics of electric discharge
as a noise source in EMC problems-recent studies in Japan”
Zunbh 1981:
1. (ex aequo, in alphabetical order of the first author):
‘C. R. Paul: “Adequacy of low-frequency crosstalk prediction models”
*F. M. Tesche, T. K. Liu: “Recent developments in electromagnetic field
couolina to transmission lines”
2. . ‘Bersier: “Measurement of the immunity of TV receivers to AM RF
fields in the 3 to 30 MHz range, including the influence of connected
cables”
4. M. L. Crawford: “Options to open-field and shielded enclosure elec
tromagnetic compatibility measurements”
5. M. Borsero, E. Nano: “Comparison between calculated and measured at-
tenuation of the site recommended by IEC for radiation measurements”
6. B. Demoulin, P. Degauque, M. Cauterman: “Shielding effectiveness of
braids with high optical coverage”
Zurich
1983:
1. “J. J. Goedbloed, K. Riemens, A. J. Stienstra: “Increasing the RFI im-
munity of*amplifiers with negative feedback”
2. ‘T. G. Dalby: “Linear antenna near-field decoupling using a radial
transmission line”
through an interruption of the shield of a coaxial cable”
4. K. Bullough, A. Cotterill: “Ariel 4 observations of power-line harmonic
radiation over North America and its effect on the magnetosphere”
5. L. E. Varakin: “Electromagnetic compatibility of cellular mobile com-
munication systems with pseudo-noise signals”
6. J. J. Max, A. V. Shah: “Distributed lowpass filters for EMI filtering”
* ecipients of monetary awards
1Al
2A2
3A3
4A4
An overview.
Automated immunity measurements.
test facility for spacecraft.
surements on major systems.
24~4
ments in the understanding of coupling paths
of ESD through a metallic cabinet.
7B3 L.Inzoli, Honeywell ISI, Milano, Italy: ESD
-
peripheral printers.
25~5
26~6
zerland: Fast discharge mode in ESD-testing.
F, Li ght ni ng l ect r omagnet i c ul se
C, Tr i gger ed i ght ni ngEMP
WI H.Kikuchi, Nihon University, Tokyo, Japan:
A new model of triggered lightning.
I@2 The St.Privat d'Allier Research Group, Fran-
ce: Applications of triggered lightning in
France:
analysis of the lightning - CN tower inter-
action.
magnetic fields on the ground due to light-
ning strokes triggered with rockets and a
tall chimney.
UDl
14D2
15D3
16D4
17D5
18W
IBM Corp., Austin, TX: Electromagnetic wave
propagation in a semi-anechoic chamber.
M.Kanda,
evaluating microwave anechoic chamber measu-
rements.
tortions in a TEM cell.
J.H.Davis, W.C.Cockerill, IBM Corp., Austin,
TX: Chamber quality assessment.
broadband EM1 using a spectrum analyser.
U.Raicu, G.U.Sorger, Eaton Corp., Sunnyvale,
CA: Broadband YIG-tuned preselector for VHF
and UHF.
the difficulties encountered.
density using a double loaded loop antenna.
E. Pr i nt ed ci r cui t boar d EMC
ZEl
2232
B.Danker,
ted circuit boards.
circuits.
NJ: Controlling EM1 by proper printed wiring
board layout.
a ground grid to reduce printed circuit bo-
ard radiation.
J.P.Charles,
zona,
Tucson,
then, Neubiberg,
Lannion, France: Radiation characteristics,
lightning.
models for comparison of lightning, nuclear
and electrostatic discharge spectra.
Baum, D.J.Andersh, Kirtland AFB, NM: Compa-
~-
D.Jaeger, R.Rode,
for modern aircraft equipment.
Prediction of lightning-induced interference
in similar installations.
port,
Impulse current and voltage propagation in
underground telecommunication cables.
G, EMwave i nt er act i onw t h bi ol ogi cal
syst ems
China:
on and discussion of safety thresholds.
37~2 T.S.Tenforde, C.T.Gaffey, M.S.Raybourn, Uni-
versity of California, Berkeley, CA: Influ-
_... -.
-
 
Electrotechnical Faculty, Belgrade, YUgOSla-
tablishment of antibiotic bactericidal action.
communication, Tokyo, Japan: Balloon and sa-
A.J.Berteaud, CNRS, Thiais, France: Specific
tellite observation of power line radiation
mechanisms of microwave power dissipation in
over northern Europe.
ratory,
fic absorption rate in a full-size man model
SJI J.K.Breakall, G.J.Burke, E.K.Miller, Lawren-
near a 10.67-m monopole antenna/ground plane
ce Livermore National Laboratory, Livermore,
system at 2.101 MHz.
G.d'Ambrosio, A.Scaglione, F.De Martino, R.
5752 D.J.Bem, J.Janiszewski, R.Zielidski, Techni-
Pennarola, University of Naples, Italy: Ku_
cal University of Wroclaw, Poland: Computer-
.
aided analysis of electromagnetic compatibl-
42~7 D.W.Griffin, N.Davias, University of Adelai-
lity in VHF-FM broadcasting networks.
de, Australia: Wideband evaluation of micro-
58J.3 A.Farrar,
wave intensity near the eyes with scattering
dels for determination of satellite power-
structures present such as safety spectacles.
flux-density limits.
5qJ4 K.Hirasawa,
- -
, St at i st i cal spect s of noi se and l i m t s
Japan: Computer programs for calculating
bounds of interference between arbitrarily
43Hl
shaped wire antennas.
of noise and limits.
A.C.D.Whitehouse,
~
bility in time domain.
B.Audone,
rino,
Italy: Statistical evaluation of the of thin cylindrical antennas loaded by non-
EMC safety margin at system level. linear impedances.
R.Bersier, Swiss PTT, Berne, Switzerland: The
-
45H3
46H4
47H5
48H6
of man-made radio interference and their use
63~2
Q.Chen, Y.C.Zhu, CARIS, Beijing, China: The
application and development of EMC in China.
64~3
ew of the past decade.
J.G.Tront, Virginia Polytechnic and State Uni-
versity,
RF1 susceptibility of several typical IC
pin drivers/receivers.
herst, NY: Demodulation RF1 in inverting and
non-inverting operational amplifier circuits.
I , EMPhenomena n Power t r ansm ssi on nd
di str i but i on
4911
5012
5113
5214
5315
L. Nucl ear el ect r omasnet i culse imoact
65~1 .Dafif, C.Bardet,
E.Jecko, University of Li-
66~2 .-D.Briins, D.KBniqstein, Hochschule der Bun-
deswehr, Hamburg,
in EMP simulators.
National De-
68~4 M.E.Gruchalla,
A.J.Bonham, J.Gibson, P.G.
-
Carlo-optimization to guarantee the compati-
bility of inductively coupled line systems.
W.MachczyAski,
ried cable exposed to electromagnetic effects
of a power line under fault condition.
J.L.ter Haseborq, H.Trinks, Technical Univer-
sity Hamburg-Harburg; R.Sturm, NBC Defence
GFR: Coupling and propagation of transient
currents on multiconductor transmission li-
nes.
wire illuminated by an inhomogeneous plane
wave.
moges, France: Time domain scattering by thin
wire structures above a homogeneous ground.
Johnson,
log-weighted peak-level recorder for direct-
.___
bounds.
Kimberley Communications Consultants, Notting-
tures using transmission-line modelling.
France;
EMP calculation methods using the response
of an aerial cable to a lightning stroke.
M Power and dat a l i ne t r ansi ent s
EMI W.T.Rhoades, Xerox Corp., El Segundo, CA:
Characteristics of unusual power main tran-
sients.
The development of an IEEE guide on surge
testing for equipment connected to low-vol-
tage AC power circuits.
ton, MA: Changes to classic surge-test waves
required by back-filters used for testing
powered equipment.
by current surges.
MA; F.D.Martzloff, GEC Comp., Schenectady,
NY: Characterization of disturbing transient
waveforms on computer data communication li-
nes.
& St at i st i cal heor y of EMC
78Nl D.Middleton,
and parameter estimation in non-Gaussian EMC
environments.
optimum and sub-optimum detector performan-
ce in non-Gaussian "broadband" and "narrow-
band interference environments.
vironment control on the basis of system mo-
dels with random structure.
communi cat i ons
Houston,
indoor power lines using spread spectrum
techniques.
L.E.Varakin,
The efficiency of the cellular spread spec-
trum radiotelephone.
efficiency of CDMA and FDMA mobile radio
systems.
tawa, Canada: Interference analysis of a
land mobile cellular radio system.
8606 K.Fisher, Department of Trade and Industry,
London,
8707 B.BeriE, Federal Radiocommunication Directi-
on, Belgrade, Yugoslavia: Comparison of fi-
eld strength measurements and computer pre-
diction in land mobile service.
8808 A.Golas, Telecommunication Research Centre,
New Delhi, India: Compatibility of TV and
UHF communications antennas mounted on the
same tower.
lishment, Madras, India: Design of compatible
equipment for land mobile vehicles.
WPl
91P.2
92P3
93p4
94P5
!%P6
96P7
Attenuation of electromagnetic radiation
metallic surface combined with magnetic re-
sistive sheets and absorbers.
Austria: Low-frequency magnetic shielding
effectiveness of steel-reinforced oncrete
to electromagnetic shielding.
reduction inside a spherical magnetic shield.
H.Rahman, St.Louis University, Cahokia, IL;
J.Perini, Syracuse University, NY: EMP enclo-
sure penetration and cable coupling.
B.Demoulin, P.Duvinage, P.Degauque, Lille
surements of transfer parameters of shielded
cables at frequencies above 100 MHz.
K.H.Gonschorek, Siemens AG, Erlangen, GFR:
Magnetic stray fields of twisted multicore
cables and their coupling to twisted and non-
twisted two-wire lines.
Solbiati, SIRTI S.p.A., Milano, Italy: Pro-
-
EMC point of view.
Systems, Basel,
EMC tests.
Austria: A new pulse width modulation control
for.line commutated converters minimizing
the mains hacmonics content.
lysis of the RF1 voltage generation by small
commutator motors.
reduction of spurious emissions from small
DC to DC power converters.
 
ry, Spies, Switzerland: High current fast
pulse measurement with a Rogowski coil.
103Q7 V.Nikiforova, All-Union Research Institute
of Energetics, Moscow, USSR: Electromagnetic
compatibility of electrical equipment in po-
wer and industrial supply systems.
R, Key Pr obl emsof spect r umuse
l@Rl K.Olms,
spectrum management.
squeeze - A selective look at ORB-85/88.
l&R3 A.H.Wojnar,
land: Deformable lattices for efficient fre-
quency management.
England: The prediction of field strength in
the frequency range 30-1000 MHz and its in-
fluence on spectrum management.
Communications, Ottawa, Canada: Optimum fre-
quency assignment strategies for radio cellu-
lar
tawa, Canada: A second generation mobile spec-
trum monitoring system.
u@l H.Cichofi, .Trzaska, SARU Region 1 EMC Wor-
king Group, Poland: Selective interference
in home entertainment electronic devices.
US2 I.Oka, K.Ishida, I.Endo, University of Elec-
tro-Communications, okyo, Japan: Co-channel
lite.
cal Laboratories; Y.Noguchi, Nippon Electric
Company, Tokyo, Japan: Relation between APD/
CRD of automobile ignition noise and resul-
tant TV picture degradation.
Takagi, Tohoku University, Sendai, Japan:
Electromagnetic radiation caused by silver
palladium alloy contact switching.
Neher Laboratories PTT, Leidschendam, Nether-
lands: On the characteristics of the electro-
magnetic field generated by video display
units.
land: Overvoltage protection circuits.
lecommunications, oscow, USSR: Iterative
two FM signals.
mated EMC measurements and the current tech-
nology.
to understanding the strengths and weaknesses
of current technology and needs for future
development. A present-day computer-controlled
described.
Introduction
Background
found its inception in the decade of the 1950's
with the greatest incentive arising, perhaps,
from the plethora of measurements mandated by
military EMC standards on military communica-
tions and electronics equipment. The problem
most pressing at the time could be summarized
as too many measurements to be made resulting
in too much data to analyze all in too short
a time. From this apparent need arose mechani-
cal attachments for the manual radio noise
meters of the day to tune them automatically
over their available tuning ranges while driv-
ing the X-axis of an X-Y plotter with a volt-
age proportional to the position of the me-
chanical tuning mechanism and the Y-axis with
the envelope voltage from the indicating
instrument drive circuitry. Although these
"automatic"
quently inaccurate,
usable graphical form than could be provided
by a human operator tuning, reading an indi-
cator,
by-point basis.
tuned instrument by providing electronic tun-
ing, more responsive detector functions, large
dynamic measurement range by use of AGC or
logarithmic amplifiers, and untuned wide band
antennas and transducers. To this day such
instruments are still widely used to make
measurements in accordance with MIL-STD-461/
462 [4, 51 and other military standards, Dur-
ing this same time,
tually come to be used for some EMC measure-
ments.
engineers and instrument manufacturers saw ad-
EMC test instruments. The computer could oper-
ate the test instruments; record data; apply
antenna, transducer, cable loss, instrument
calibration, and other correction and conver-
sion factors to the data; and plot this reduced
data on multi-decade plots for ease in compar-
ing the performance of equipment under test
with the limits in the technical standards.
Many such systems for measuring interference
emissions are in use today.
While much automation has been achievedwith
interference emissions tests, automation of
interference immunity (susceptibility) tests
for this has been the more complicated nature
of immunity tests.
Purposes and Objectives
introduce this session on automated EMC meas-
urements by giving an overview of the session,
and by discussing the philosophy of automated
EMC measurements.
present some details on an automated radio
noise (EMI) measuring system incorporating
both self- and computer-controlled test capa-
bilities. The objectives are to bring out some
of the strengths and weaknesses of automated
EMC tests,
The scope of this session is to address the
issues associated with the use of computer-
controlled or self-controlled automatic and
semi-automatic test equipment and techniques
to make EMC measurements* Both halves of the
EMC test question will be addressed, i.e.,
both emissions (interference) and immunity
(susceptibility) measurements. Some of the
automated EMC measurement issues to be raised
and discussed are:
neering and development;
or disturbance being measured or simulated,
a mixture of signals and noise, and the
characteristics of sources on EMC measure-
ments;
 
cial requirements (import licensing, type
approval, etc.); and
tion for automated EMC measurements versus
that traditionally used in manual EMC
measurements.
answer a number of questions. Some of these
questions are:
What are the strengths and weaknesses of
the present technology?
mated EMC measurement technology?
the need to ask others, we must understand the
sometimes conflicting requirements of EMC meas-
urement standards and regulations. What do the
technical standards of such bodies as IEC,
CISPR, ANSI, ISO, VDE, FCC, CSA, JASO, SEV, and
many others, and the military establishments
of several countries have in common and where
do they differ? Can an automated system be
made to adequately deal with the differences?
Should tasks that a thinking human operator can
do easily be automated for an unthinking com-
puter controller to do poorly, e.g., click
measurements [a]?
This question was basically answered in the
introduction,
these days.
degree of automation in EMC measurements, the
growth of the use of electronics with its con-
comitant growth of EMI causes the problem men-
tioned earlier of "too many measurements, too
much data,
needing either more and better automation of
EMC measurements or fewer EMC measurements to
make. The latter choice would tend to imply
less or poorer control of radio noise andelec-
tromagnetic interference, and, thus, a worsen-
ing lack of compatibility among our uses of the
electromagnetic spectrum and electrical and
electronic appliances and equipment. Even now,
some regulatory agencies are reducing the
amount of testing for compliance with their
regulations in attempts to achieve a more
acceptable balance between the amount of test-
ing needed and the degree of EMC obtained,with
the economics of both issues being a major
consideration,
A complete answer to this question is beyond
the scope of this paper; however, an outlineof
the answer would obviously include both inter-
ference emissions from equipment and interfer-
ence immunity (susceptibility) of equipment.
Also, both conducted and radiated interference
emissions and immunity measurements would be
included.
of what to measure,
the various EMC measurement standards and
regulations along with the current and pre-
dicted EMC problems in the geographical area
of interest. The fact that geographical areas
are an important factor is obvious if the in-
terference regulations of high population den-
sity, high technology areas are compared with
those of low population density, high tech-
nology areas.
Measurements
measurements uses desk-top calculators and
small computers to operate the test instru-
ments,
bration, plot results, and even write test
reports. At its present state, the technology
has both advantages and disadvantages. Some
of the advantages are summarized by Mr. D.N.
Heirman of AT&T in his paper [l] in this
session:
as an engineering tool and not as a replace-
ment for the engineer who must determine
compliance with either regulatory or corpo-
rate EMC criteria. As a tool, automation if
hood of measurement error due to operator
inattention, test instrumentation misad-
test conditions on a repeatable basis. The
cost of automation must also be weighed
against the increased test time normally
associated with manual operations."
tems seem to be abundant, but they also have
serious disadvantages. Automation of EMC
tests now often provides us with much more
incorrect data faster. It is difficult to make
the computer think and understand what is
being measured,
can think and understand can't make measure-
ments as fast and tends to record data incor-
rectly or lose it entirely. However, a major
reason for the incorrectness of the automated
data lies in the typical understanding of the
state-of-the-art many years ago. Many an EMC
engineer is so happy to have the measurements
done quickly with less labor that he or she
has forgotten that many measurement error-
producing compromises were the state-of-the-
art years ago and are still present andaffect
the correctness of the data taken by modern
strength measurements.
which the electromagnetic fields to be meas-
ured are not homogeneous, but the antennas
used to make the measurements are calibrated
for and operate properly only in homogeneous,
planewave fields which might be found in free
space many wavelengths from their sources.
Mixed signals and noise can pose particular-
ly difficult problems. An example of this may
be seen in testing a vehicle for ignition
noise emanations.
the vicinity of sensitive receivers for long
wave,
tions, broadcasting,
ignition noise must meet stringent limits from
10 kHz to 1 GHz. The vehicle is large and the
testing organization has no large shielded
chamber in which to test it, so it must be
tested outside.
nals throughout the required test frequency
range, and most of these signals are so large
that they produce indications in the EMI ana-
lyzer or radio noise meter far above the limit
specified for the ignition noise emanations
from the vehicle under test!
Current EMC Instrumentation Technology
are the primary factor that determines if the
ignition noise in the above example can be
measured throughout the range of frequencies
from 10 kHz to 1000 MHz. The regulatory re-
quirements [4, 5, 6, 71 are secondary factors
in the accurate and successful measurement of
EMI in such a non-ideal real-world measure-
ment situation.
set to produce a level of 52 dB(uV/MHz) which
simulates the vehicle ignition noise; 2) A
pulse generator operating at 50 kHz producing
a pulse amplitude of 0.0025 ~VS [68 dB(uV/MBz)]
which simulates low frequency industrial noise
in the vicinity of the test site; and 3) Two
cw signal generators set to produce signals at
22 kHz and 8 MHz at levels of 64 dB(pV) and
49 dB(llV),
cast signals also in the ambient of the test
site. A thinking,
well-trained and experienced
but this appears to be an almost impossible-
to-solve problem using a computer-controlled
radio noise meter unless it and the control
computer software have capabilities that ex-
ceed those usually found in "standard" EMI
analyzers or radio noise meters and control-
lers. In the 10 kBz to 150 kHz frequency
range, the standard CISPR radio noise meter
[2] has a bandwidth of 200 Hz and the standard
ANSI radio noise meter [3] has bandwidths of
200 Hz, 1 kHz, and 10 kHz. In a 200 Hz band-
width the impulse generator produces a level
of -22 dB(!.N),
he pulse generator produces
a level of -6 dB(pV), and the 22 kHz cw gen-
erator produces a level of 64 dB(UV). In a
1 kHz bandwidth these levels become -8 dB(lN),
+8 dB( Jv) ,
10 kHz bandwidth, the levels become +12 dB(uV),
+28 dB()N), and 64 dB(BV), respectively. The
simulated ignition noise (the impulse genera-
tor) which must be measured is far below the
interfering signals and may be below the im-
pulse sensitivity of the radio noise meter in
a 200 Hz bandwidth. As can be seen from the
above data, when the bandwidth of the radio
noise meter is made larger to bring the simu-
lated ignition noise UP to a level where it
can be easily measured, the bandwidth is so
wide that the 22 kHz narrowband signal begins
to override the simulated ignition noise in
the skirts of the radio noise meter selec-
tivity characteristic. This effectively pre-
vents the detector in the radio noise meter
from properly responding to the simulated
ignition noise, It may be seen that theprob-
lem of relative noise levels continues on
above 50 kHz,
on the radio noise meter output may be able to
make some satisfactory measurements, given
enough time. A computer-controlled analyzer
would need to be extremely sophisticated to
do as well as the human operator.
perhaps the
would be to determine that no satisfactory
broadband noise measurement could be made in
this frequency range under these conditions,
and so inform the operator. Because of prob-
lems such as this, the US Air Force has seen
fit to issue an application note [61 recom-
mending that "official" measurements be made
in one bandwidth and compared against one limit
no matter what the nature of the EMI, broad-
band or narrowband. The United Kingdom is in
the process of issuing regulations to this
effect [7]. Both of these documents assume that
measurements can always be made in a low am-
bient noise environment, such as a shielded
enclosure,
In the current technology, CISPR and ANSI
instruments are specified in such a manner as
to imply that manual EM1 measurements are to
be made. At the same time, the military pre-
sumes 153 that some form of automated measure-
ments will be made,
and test laboratories per-
tary standards are generally making automated
measurements. Also, automation has begun to
pervade EMI measurements made to comply with
standards and regulations, such as those of
the VDE [8] and FCC [9], covering consumer
electronics equipment.
measurement of EMI, but similar instrumenta-
tion problems exist in making interference
immunity (susceptibility) measurements. From
respect to making immunity measurements since
few regulations exist covering these measure-
ments. This allows those who wish to make im-
munity measurements much freedom to develop
instrumentation and methods that are timely
and appropriate. Mr. Heirman demonstrates this
in his Paper CU. This does not mean that auto-
mated immunity measurements are intrinsically
any easier to make or more reliable than auto-
mated emissions measurements. Immunity meas-
urements will be addressed by other papers
in this session.
was investigated further with the objective of
finding a way to automate the measurements and
yet obtain valid results. First, the needed
attributes of the system are discussed, then
ways one might manually measure the various
signals and noises are investigated, and fi-
nally a method combining hardware and software
is realized.
kBz to 150 kHz frequency range, but similar
problems exist in,
signals are properly measured, the automated
system must be able to make several decisions
without manual intervention by the operator.
First the system must be able to identify all
 
discriminator which recognizes these signals
easy to do by monitoring the FM video output
of the receiver for a D.C. shift in the output
level. Once the presence of the cw signal is
determined, a more difficult decision must be
made: Is there a significant impulse level
superposed on the cw signal? Since all NIL-STD
type measurements must be made with a peak de-
tector, the level of the cw signal read in-
cludes any additive impulse level; the problem
is to isolate the impulsive signal and measure
its level.
of the radio noise meter output level, a high
level cw signal can almost entirely mask an
impulsive signal.
a situation where one finds a narrowband sig-
nal present at 15 kHz at a relatively high
level, 60 dB(uV). A typical source of such a
narrowband signal would be switching regulated
power supply operating at a switching frequen-
cy of 15 kHz. The narrowband signal is one
line, the fundamental, of the spectrum of many
harmonics created by the rectangular switching
waveform, and appears in the 4 kHz bandwidth
of the radio noise meter as a cw signal. In
addition to this signal, there is an impulsive
signal at a level of 50 dB(uV/MHz). Since the
radio noise meter impulse bandwidth (6.31kHz)
is a relatively large fraction of the tuned
frequency (15 kHz),
sent at the start of the frequency range (10
kHz).
away resides the high level second harmonic of
the switching power supply frequency.
Contrasting the above narrowband signal is
the 50 dE(uV/MHz) impulsive signal. Due tothe
fact that at 15 kHz we still have a 6,31 kHz
impulse bandwidth,
impulsive signal. The actual voltage level
will be approximately 6 dH(pV), as shown by
equation (1).
to
reference bandwidth can be calculated as
follows:
One can then change both levels to voltage,
add them algebraically, then reconvert their
sum back to a level in dH(uV), to find the
difference in meter indication that is caused
by the presence of both signals simultaneously.
These calculations are shown in equations
(2.1) and (2.2):
y )lv log-l(~)
60 dB(uV) using eq. (2.2), y = log-1(60/20),
we find 60 dB(HV) = 1000 uV.
Next let us consider the 50 dB(uV/MHz) i m
pulsive signal level, which we have already
calculated to be ~6 dB(UV) in a 6.31 kHz im-
pulse bandwidth, Using equation (2.2) again,
is =2 I-IV.
1002 uV. The next step will be to convert back
to a decibel scale to find the meter reading
of the combined signals. Using equation (2.1),
x dB(uV) = 20 log(1002), we find a level of
~60.017 dB(uV),
impulsive signal adds a meagre 0.017 dB to the
level measured with the narrowband signalonly.
d%iV)
i n Peak Posi t on
Herein lies a large part of our problem. With
the accuracy and precision of most radio noise
meters being such that a difference of 0.017
dB is insignificant,
and probably unmeasurable,
of 50 dB(uV/MHz)? Let us first consider the
options we would have in performing these meas-
urements manually, then we will try to develop
an automated method.
ability to arrive at a correct impulse level
measurement is the presence of a narrowband
signal and its associated harmonics. An ob-
vious solution, therefore, would be to elimi-
nate
with the use of a sharply tunable notch filter,
thus removing the narrowband signal from the
same fashion,
one frequency range at a time, being careful
not to take measurements on the "skirt" of the
filter characteristic, the operator could ob-
tain valid readings on the impulse level
present. This method, however, will be cumber-
some and may not yield valid results if the
encountered narrowband signals are spaced too
closely together in frequency. Generally, how-
ever, this method can be used to arrive at
reliable, valid results,
series of tunable notch rejection filters,
another method must be attempted,, he first
step would be to decrease the I.F. bandwidth
to decrease the frequency range masked by the
narrowband signal on the skirts of the radio
noise meter selectivity characteristic. The
operator must note, however, that by changing
the width of the I.F. bandwidth, he is sacri-
ficing some of the impulse sensitivity of the
 
Frequency
Tabl e I . Typi cal Radi o Noi se Meter
Speci f i cati ons
Changing to a 1.26 kHz impulse bandwidth
sacrifices approximately 4 dB of impulse sen-
sitivity, but changing to a 97 Hz impulse
bandwidth sacrifices 16 dB of sensitivity --
obviously too much. From this observation we
see that we cannot decrease the impulse band-
width to less than 1 kHz and still get reason-
able impulsive sensitivity. The operator must
note, however,
bandwidth, he must apply the appropriately
increased bandwidth correction factor to ref-
erence to a 1 MHz bandwidth. The bandwidth
correction factor calculation is shown in
equation (3).
x = 20 log(1 MHz/y)
quency range affected by the skirt of the nar-
rowband signal, he can tune to a point where
the narrowband level is a significantly lower
portion of the total signal level measured.
(The operator must note that the impulse level
will have also dropped, probably by about 14
dB, but the narrowband signal level Will have
generally dropped significantly more.) The
next step that must be performed by the opera-
tor is to identify the impulse and narrowband
portions of the signal. To do this the opera-
tor should change the radio noise meter detec-
tor function to a carrier or average detector,
tune the receiver to the lowest possible am-
plitude point on the narrowband signal, and
take an amplitude reading in d.B(HV).
dB&')
Detector i n Carr i er Posi t i on
The operator must then change the detector
function back to peak and take another reading
in dB(pV) (See Figure 3). The readings can
then be converted back to voltage levels, al-
gebraically subtracted, and reconverted into
dB(pV) and dB(pV/MHz) levels respectively. An
example of these calculations is as follows:
Receiver: NARROWBAND, PEAK
x = log'l(y/ZO)
x = log'l(-3/20)
x = log'l(-lO/ZO)
0.3917 nV. Converting the difference to dB(HV):
y = 20 log(o.3917/1)
y = -8.1 dB(HV)
equation (3),
50 dB(HV/MHZ).
: o
i
of performing these measurements in a manual
mode, we must explore a means to arrive at the
same results using an automated system, Through
experimentation it has been found that the
second manual method lends itself very well to
automation.
ing the FM video output. The system can tune
through a frequency segment, identify, locate
and measure all narrowband signals, storing
the data as it goes. Once all signals areiden-
tified in a particular segment, the computer
accesses the data it has stored, and analyzes
the signal pattern it has encountered. During
this analysis the computer locates the best
possible frequencies to attempt to gather valid
broadband readings. Once this procedure has
been completed, the computer then tunes the
receiver to the first selected position, and a
reading is attempted. A narrow bandwidth is
selected, and data is taken first with the de-
tector in the peak function, and then with the
carrier function.
checks the collected data for a measurable
difference in the peak and carrier levels to
determine if it is feasible to arrive at an
impulsive signal amplitude. Should the analysis
 
described, stores the calculated data,proceeds
to the next previously selected frequency
point, and repeats this procedure until all
such points are completed in the frequency seg-
ment. A problem arises, however, when the com-
puter analysis determines that a valid impulse
level cannot be arrived at by the previously
described algorithm, At this point the comput-
er notifies the operator that it cannotproceed
with calculations at this frequency point and
that further manual investigation is necessary,
Once the message has been noted, the computer
proceeds to the next point to be analyzed.
After all data collection and analysis have
been completed, the computer adds tranducer
factors and other correction or calibration
factors,
the desired specification limit or reference.
u
.-L____-_______J:
r’
Proceeding in this fashion, the computer
(controlled radio noise meter) can perform a
complete EMI emissions test, collecting large
quantities of data and undertaking an immense
number of mathematical calculations, in a rela-
tively short period of time. Unfortunately,
there will be situations encountered that re-
quire the judgment of the human operator, show-
ing that inquiry and development must proceed
still further, but the number of operator in-
terventions can be greatly decxeased by using
this automated procedure.
tion to that suggested by the ASD application
note ES], but it provides the correct data
under non-ideal measurement conditions. The
approach suggested by the application note
cannot provide the correct data under similar
non-ideal measurement conditions. Also, we
have not addressed the proper application of
transducers,
method requires a theoretically unsound use
of a transducer such as an antenna, we may
still be collecting much incorrect data.
References
[2] CISPR Publication 16 (1977) and Amendment
1 (1980),
Standard Specifications for Electromag-
[4] NIL-STD-461B (1980), "Military Standard,
Electromagnetic Emission and Susceptibili-
tromagnetic Interference"
Electromagnetic Interference Characteris-
tics, Measurement of"
band Emissions," Aeronautical Systems
Scientific, and Medical (IsM) and Similar
Purposes"
(1983),
Devices"
Session A
_.
 
Automation of EMC Testing should be viewed as an engineer-
ing tool and not as a replacement for the engineer who must
determine compliance with either regulatory or corporate EMC
criteria. As a tool, automation if implemented properly
decreases the likelihood of measurement error due to operator
inattention, test instrumentation misadjustments, and inabili-
ty to recreate all the test conditions on a repeatable basis. The
cost of automation must also be weighed against the increas-
ed test time normally associated with manual operations. This
paper will address the proper use of automation in immunity
testing. The areas where automation is most useful are shown
by describing a typical immunity test using a transverse
electromagnetic (TEM) cell.
Introduction
In recent years, the proliferation of a wide range of RF noise
sources from commercial broadcast stations to
microprocessor-controlled appliances have increased concern
for product susceptibility. Of course, in military systems, the
is vital for strategic and tactical systems. On the other hand,
consumer product immunity is generally designed to respond
to pressures of the market place. A too sensitive product to
the RF ambient would cause customer complaints and lead
them to purchase a competitor’s product.
The sheer magnitude of immunity testing has created much
schedules and to ensure that the product has been made
immune to all sorts of RF environments. The advantages and
in some case the disadvantages of automation of susceptibility
involved with consumer products,
Automating Engineering Evaluation Stage
Even before a product is well along towards prototype or
preproduction models, testing can be used to assess the
relative immunity of the product during the development
cycle. At this time, it is more important to get sufficient data
in a short period of time to evaluate immunity progress. This
phase is generally called engineering evaluation. Here
automation can provide a quick view of product immunity. All
the test parameters can be held constant from test-to-test,
especially when instrumentation is computer-controlled and
the product response automatica(\y recorded.
During engineering evaluation with incomplete or laboratory
models, it is generally more important to see if there is any
immunity response at all with the minimum test time. Typical-
ly, levels higher than the anticipated RF ambient are applied
with a frequency scan rate faster than that for a full response
of the equipment under test (EUT). The higher field, faster
scan is traded for a lower (and perhaps closer to the design
immunity limit) level and slower scan for full response. Here
automation is a requirement since an operator may not be able
to keep up with all the necessary instrumentation settings and
EUT monitoring. Response algorithms based on scan rate and
frequency response can be written to guide the chosen scan
speed. These algori thms can be used and evaluated to
ensure that the final compliance test is truly respresentative
of the product immunity.
fabricate sensing hardware and to adapt automation software
to determine better the actual EUT performance degradation
as a function of applied level, scan rate, and type of applied
signal (AM, PM, FM, impulse, etc.). The need for automating
the remote operation of the EUT is also studied during this
time. Such operation might be controlled by remote computer
terminals, load simulators, or the instrumentation controller
itself. If mechanical operations are needed, pneumatics may
be used.
Recreation of the Immunity Field
The RF environment is a complex one in both time and
frequency domain. Electronic products generally respond
undesirably to certain frequencies and waveshapes, not the
aggregate. This response i s documented primarily by study-
ing interference cases or by testing to several representative
ambient signals.
tronic product performance can be expected to degrade at
some point during the life of the product. The seriousness of
the degradation may or may not warrant design or in-the-field
changes. Examples of degradation include:
1. Increased bit error rate
2. Erratic Operation
4. Audio Rectification
7. Component failure
There is always a problem with the ability of any transducer
to recreate the in-use praduct RF envlranment. The literature
in the USA shows that the vast majority of RF data taken is
associated with commercial broadcasters and other licensed
radio services.[l,2,3,4]. Hence most immunity tests attempt
to recreate these narrowband radiated fields. There &much
less data on RF conductedinto the product via the AC power
mains and other signal or interconnecting cabling.[5] There
is even less data from impulsive or aperiodic signals produc-
ed by switching transients and other localized fields such as
that from a cooling fan for a power supply. Of course, special
RF surveys can be made to better describe the actual
ambient at product locations. This requires considerable time
 
in the literature in setting up immunity test levels.
System Immunity Test
and conducted tests to include the following:
Radiated Immunity
4. Impulsive Noise
1. Direct Coupled
2. Near-field coupled
The radiated test would expose the entire product to a radiated
field. The associated peripherals, l/O cables and other
subsystems would also be simultaneously exposed. The
conducted test concentrates on powerline and signallcomm-
unications lines. The above list is not exhaustive. It is clear
that any automation to help relieve such an extensive test
program activity is highly desirable.
To focus our attention on one of the most used tests, this paper
will concentrate on automation of radiated immunity tests
where the radiated filed is a narrowband electric field typical
of AM, FM, or TV broadcast fields.
The basic instrumentation for creating broadcast fields in a
controlled chamber is comprised of an RF generator, modula-
tion source, power amplifier, and transducer (antenna). Since
broadcast transmitting antennas are generally far enough
removed so that a plane wave is incident on the product, the
presence of the product does not cause the transmitting power
to increase or decrease. However, the field in close proximity
to the product, does differ from that with the product remov-
ed. Most RF environment surveys measure the field with
antennas removed from any object that would affect the
measurement including the ground, i.e., the antenna is located
several wavelengths above ground except for AM broadcast.
This is close to measuring a free space value of field strength.
Hence, we want to recreate that fiefd in a controlled manner.
All such RF environment simulations have the potential for
errors. Immunity measurements even at open area test sites
must contend with and account for the ground reflection.
Measurements made in enclosed chambers have even more
reflections if the walls are not anechoically treated. That leaves
few choices of test facilities that readily approximated free
space. One choice is a parallel plate capacitor (stripline
antenna or a transverse electromagnetic (TEM cell). Both
provide a plane wave for frequencies within the passband of
the transducer. RF anechoically treated shielded rooms (all
six surfaces) are yet another choice for free space
measurements. However, anechoic chambers are usually
more expensive.
immunity field can be implemented. Generation of the
necessary fields are relatively straightforward and will not be
discussed further. The monitoring of these fields is not
straightforward and great care must be exercised in monitor-
ing the field around the EUT. The most popular monitoring
procedures are:
1.
2.
3.
Real time leveling using a field probe next to the EUT.
Recalling f rom controller memory signal source drive
power based on previous measurements of field strength
in the test volume with the EUT removed.
Recalling from memory the source drive to set a desired
field strength based on the calculated field using anten-
na gain, radiation pattern, and signal level input.
Item 1 has the potential for monitoring a field that is largely
affected by the EUT, especially at frequencies where the EUT
resonates. Items 2 and 3 are preferred if the EUT does not
significantly interact with the transducer to affect the calibra-
tion of the applied signal. Both of these latter items to be fully
implemented require automation to look up the calibration data
and control the signal input into the power amplifier.
A Sample Automated Susceptibility Test
To further focus on the benefits of automated immunity testing,
we describe a typical test using a TEM cell as the radiating
transducer for launching an RF narrowband electric field am-
bient. Figure 1 shows typical instrumentation. TEM cell testing
provides a passband of operation from dc to a frequency
where the dimensions of the cell are approximately equivalent
to a wavelength. For a cell with dimensions as shown, the
useful upper frequency is about 165 MHz for EUTs with
dimensions of up to 10 by 30 by 30 cm. General test guidelines
are contained in Reference 161.We now expand those guides
for this example.
First, the EUT dimensions should be kept small compared to
the dimensions of the cell’s test volume. If not, errors in the
applied test field will increase due to the capacitive loading
of the EUT. Generally the linear dimensions of the EUT should
be kept to no more than about 30 percent of the associated
test volume dimensions in either the top or bottom half of the
cell. The far field immunity level at the center of the test volume
(midway between the center conductor and ground plane) can
be calibrated by several methods with the EUT removed:
Monitoring input RF voltage using a monitoring Tee for
frequencies typically below AM broadcast frequencies.
Monitoring net power flow into cell using incident and
reflected power and a bidirectional coupler. This techni-
que can be used for all frequencies within the passband
of the cell.
The first two aproaches are accomplished external to the cell
which has distinct advantages since no cables exposed to the
high RF field. Automation is virtually a necessity to keep track
of these levels and to perform net power flow calculations as
well as repetitively calibrate the meters. The last approach
requires the most care.
In the probe approach an optic link is generally required to
not disturb the field or become a radiating or scattering
structure. The placement of the probe is also critical since at
EUT resonance, for example, the field is most perturbed and
a probe in the near or scattered field will indicate fields that
are different from the nomimal test level.
During the actual immunity test, the fields can be monitored
using the above three basic approaches. The levels will differ
from nominal due to the loading affect of the EUT. If the
dimensions of the EUT are kept to the 30 percent test volume
criteria, the level differences from nominal will be in the order
of &3- 6 dB under cell multimode frequency. The most
useful way to evaluate what is happening to the electric field
is by using an electrically short dipole or monopole probe. To
avoid the near field scatter problem at EUT resonance, these
probes can be placed in the half of the cell not occupied by
the EUT and at a point which is the mirror image (about the
cell’s center conduct) of the geometrical center of the EUT.
Above multimode, placement of the probe becomes much
more critical to remotely monitor the field at the EUT. The
differences between the nominal immunity level and what is
read by the probe significantly increases making this monitor-
ing method less useful.
Characterizing the effects of all the monitoring methods is a
useful undertaking. For example, one of the benefits of such
probing may be to extend the useful upper frequency limi t of
 
LINES INSIDE CELL.
be used above its normal upper frequency limit. In this
frequency region, the field strength is complicated by the
multimoding of the cell. Only through use of automated data
gathering techniques can the cell be properly mapped to
determine the field throughout the test volume. The mapping
would be much too cumbersome using manual techniques for
recording the orthogonal (and total) field components. In this
case automation is the only practical way to extend the test
capabilities of the cell.
The next area where automation helps is in recording perfor-
mance degradation as a function of applied field strength, fre-
quency, modulation, degradation type, EUT response time,
etc. Much of this is simple data bookkeeping. However, there
still persists those who want to visually determine performance
degradation. If degradation monitoring were constantly done
by this means, especially by viewing a CRT, errors will soon
occur due to the long, repetitious and boring nature of immuni-
ty tests. No matter how conscientious the operator, monitor-
ing of anticipated, slow to materialize, visual EUT degrada-
tion is prone to errors and lack of repeatability.
Typical automation of performance degradation would include
monitoring analog signals directly onto the IEEE 488 general
purpose bus or digital information on an RS 2326 interfaces
cable. These signals are routed to the bus by one of 2
methods:
a.
fiber optic or high impedance transmission lines.
b.
Indirectly via connection to EUT performance monitors,
external controllers, external circuitry, simulated loads, or
peripherals, all of which are not in the test chamber but
are connected to the EUT via cabling.
The former method requires several telemetry links not part
of the EUT. The latter relies solely on using part of the EUT
system that is not exposed to the high fields, except of course
for the interface cabling inside the test chamber. Proper filter-
ing of these leads through the TEM cell walls are needed to
protect the equipment outside the cell from RF on the cables
extending through the walls of the cell.
Once the degradation is recognized by the computer, pre-
programmed operations can be implemented. Some opera-
tions are shutting down the amplifier if a destructive level of
degradation is reached, sequencing to other EUT modes of
operation, and pausing on particular frequencies to evaluated
EUT response time to the applied field.
Other instrumentation activities can also be conducted while
 
10 -
there are relatively high cell Q’s above its normal upper
frequency (multimode) limit, the output of the signal source
power amplifier chain should be filtered so that the second
and higher harmonics are suppressed by at least 60 dB. This
will avoid a false EUT response at the signal source frequen-
cy when in fact the response is due to a harmonic of the
applied signal (generated by the amplifier) which is coincident
with a multimode response. Automatic switching of low pass
filters is a necessity since the test engineer is concentrating
his attention on the EUT degradation and operation and could
easily forget this switching detail.
It cannot be overemphasized the importance of spending the
extra time to automate the performance degradation monitor-
ing. The test controller can do most of this, especially if all
degradation can be sent to the controller using analog (via
an A/D converter) or digital (via the IEEE 488 bus or EIA
RS-232 telemetry) signals. The test engineer should where
at all possible take advantage of performance monitoring by
sensing signals on the same leads which remotely operate
or communicate with the EUT from outside the test chamber.
This will avoid introducing additional cabling which itself might
be vulnerable to the applied field causing a false degradation
indication.
test is performed. This test must be highly repeatable and
calibrated to judge compliance. Here automation will
significantly increase the test repeatability and ensure that
separately derived calibrations are always used. These tests
are generally longer in duration since the full range of perfor-
mance degradation is checked and recorded for the final test
report. This phase is particularly methodical and a great deal
of degradation bookkeeping is necessary. For example, the
frequency scan rate may be varied to ensure that a degrada-
tion response is not missed. The affect of the complex field
within a TEM cell above multimode has to be accounted for
here if used. It may be necessary in the multimode range to
move the EUT in the cell to expose various circuitries to the
full field gradient caused by the standing wave pattern which
can amount to field uniformity errors in the order of 10 dB or
more. Even under multimode, there are undesirable TE and
TM modes launched that at the very least should be accounted
for in the measurement error. All of these factors are best
recorded and controlled via a well thought out and planned
automation program.
This paper described the usefulness and precautious of
automation of immunity testing. Automation if used properly
is a powerful tool that can be used to produce a test with less
operational errors. However, automation which is not
periodically checked by manually performing a test, tends
to lull users into a sense that the results of such tests are
irrefutable. Periodically it pays to manually set all instruments
and see if the results are the same as that found by automa-
tion. The paper has also shown the concern for ensuring that
the EMC engineer correctly automates the immunity test to
replicate the appropriate immunity field and to monitor the
proper perform degradation.
References
PI
121
131
141
[51
PI
D. E. Janes, R. A. Tell, T. W. Athey, and N. N. Hankin,
United States,” Proceedings, IVth International Radiation
Protection Association, Vol. 2, pp 329 - 332, April 1977.
R. A. Tell and N. N. Hankin, “Measurement of Radio-
frequency Field Intensity in Buildings with Close Proximity
to Broadcast Stations,” U. S. Environmental Protection
Agency Report ORPIEAD-78-3, August 1978.
D. N. Heirman, “Broadcast Electromagnetic Interference
Environment Near Telephone Equipment,” IEEE National
Telecommunications Conference Record, Catalogue
G. Costache et al., “Electromagnetic Field Strength
Probability Profiles for Canadian Cities,” International
Electrical and Electronic Conference and Exposition,
Toronto, Canada, October 1981.
October 1, 1979.
M. L. Crawford and J. L. Workman, “Using a TEM Cell
for EMC Measurements of Electronic Equipment,”
U. S. National Bureau of Standards Technical Note 1013,
April 1979.
The purpose of this paper iS t0 give a compl-
ete overview of an Automated EMC Test Facili-
ty in operation, for Emission-, Susceptibili-
ty-
drawings with a description of different test
set-ups used for spacecraft, subassembly or
unittesting.
pects are highlighted,
output from the system are included. Conclu-
sions are drawn with respect of specifica'
tions,
ting the EMC Test Facility was conceived and
initial funding became available, the line of
thinking had changed quit a bit. Due to im-
provement of the test equipment, measuring
techniques and the budgetary constraints, the
original idea of setting up a separate system
for Emission- and Susceptibility- Testing had
to be abandoned.
way that all instrumentation performs a multi-
ple function and will be used for Radiated/
Conducted Emission and Radiated/Conducted
diagram,, Fig. 1,
Due to the fact that a broadband high power
requirement will increase the cost of the ra-
diated susceptibility part of the system by
100% or more,
accommo-
given frequency "narrowbanded", which complies
with the experience so far.
All specifications for this system are derived
from spacecraft requirements existing today
and in the near future. The system has been
designed to meet these requirements.
3. Introduction
measurements:
A)
B)
C)
quency range from 20 Hz - 40 GHz,
Conducted Emission Measurements over the
frequency range from 20 Hz - 100 MHz,
Radiated Susceptibility Measurements over
3A3
the frequency range from 20 Hz- 100 MHz,
With the possibility of injecting CW and
pulsed signals, to test power-, signal- and
commande lines.
FIG. x- TEST - FACI LI TYGENERAL SET- UP
All equipment used in this system is operated
to IEEE-488 standards or equivalent. The pos-
sibility of opto-coupler extention is provi-
ded for operation in a radiation-hazardous
area. The System Controller is a desktop
model with a large screen, so the facility
engineer is able to program it and to modify
the software during the test.
For the sweep section we stay as long as pos-
sible co-axial,
test work. However, a synthesizer is a must,
due to the frequency accuracy required. The
exact specifications of each subsystem will
be discussed separately.
have for the Low frequency range, Amplitude-
modulation, for the Megahertz range Frequen-
cy-modulation and for the Gigahertz range
Pulse-modulation.
amplifiers;
band and one from 26.5 GMz - 40 GHz - "KA"
band.
dard gain horn will have to be used for each
amplifier.
will be fed through a dual directional coupler
to the antennas.
a Dual-Sensor-Powermeter is used in order to
measure set-power and reflected power. For the
radiated- and conducted emission a front-end
receiver is used.
ssary pre-amplification over a frequency
range from a minimum of 100 Hz to 18 GHz, and
preselection below 2.4 GHz. The unit will be
used with the HP-8566 spectrum analyzer.
Blockdiagram Fig. 3.
vulnerability to overload, especially on
broadbandnoise,
and dynamic range.
ving system a broadband electric field anten-
na is used,
Apart from the existing spectrum analyzer, a
second analyzer has been introduced, partly
used for susceptibility testing. This in
order to control the injected voltage and
current on the line under test.
Due to the fact that scientific spacecraft
are low-noise, but still produce noise with
its own frequency spectrum, the susceptibility
levels to be injected are small, depending on
the applicable voltage- or currentlimit, which
can be in the order of 20 dBuR. In order to
link the system together several co-axial
switches and relays are used, positions and
number are shown in the blockdiagram of Fig.
2. To control system operations and monitor
the behaviour of the U.U.T. (unit under test)
a digital voltmeter combined with a data
acquisition unit is used.
the system,
it includes:
channel multiplexers,
Also,
grated part of the test activities. A bus
controlled oscilloscope is used for this
purpose.
gives out the test data, like: a narrowband
plot containing the narrowband signals only
includiny spec-level and frequency printout
with measured levels.
can be achieved for broadband measurements or
conducted- and radiated susceptibility mea-
surements.
complete testreport with detailed information
directly after completion of the test.
4. Description and Specifications
with reference to blockdiagram Fig. 2, and
broken down in subsections in order to have
a better overview of the system.
IF-DISPLAY SECTION
RF SECTION
:m-?
:...._..._.......__..____....................................:
4.1 Control part
that the controller can be handled and pro-
grammed by the facility engineer directly,
without having to ask for software support,
which means no loss of operating time, main-
taining and updating of a more complex system
Apart from the above,
tance that the "EMC-Engineer" on the job can
translate his EMC problems directly into the
machine,
cations of already complex problems.
The calculator has a 12" CRT and two built-in
disc-drive units for 5%" floppy disc. Memory
capability expendable up to 2 Mbytes, with
Basic,(extentions) Pascal, graphics dump and
storage. This system is also fitted with an
extra HP-IB and BCD interface. More than 4
bus expanders can be added to provide 16
additional slots for memory- and I/O cards.
In addition there is an HP-IB extender with
fibre-optic interface.
Due to the fact that in our case the system
isa combined one,
"Emission Measurements!' as "Susceptibility
to avoid unnecessarily problems due to small
beaks,
would limit the dynamic range of the equip-
ment.
porved EMC measurements quality considerably
and is now standard in our facility.
The thermal graphics printer can handle a
graphics dump from the 9836-s CRT within 10
seconds.
conds after the test, a protection against
nailbiting and nose eating customers who are
nervously waiting for the test result to be
produced,
specifications.
A- SRD-2548-C precision wideband front-end
receiver.
3. The specification is the combination of
the two instruments.
tion is obtained by pre-amplification. Above
2.5 GHz we have Yig-pre-selection.
Use of this front-end receiver in combination
with the spectrum analyzer has imporved the
sensitivity, dynamic range and instantaneous
band width of the spectrum analyzer without
losing any of its features. The system has
been set up to operate over the frequency-
range from 20 Hz - 40 GHz. However, from 20 Hz
to 100 Hz, extra care has to be taken due to
the fact that we have to work so close to the
local oscillator and having to extrapolate
the antenna factor.
noise figure of 10 dB and a dynamic range from
72 dE to 1 MHz BW.
From 18 - 26.5 GHz the ana-
lyzer is used with a harmonic mixer type HP-
11970-K and from 26.5 - 40 GHz with a harmonic
mixer type HP-11970-A. With a noise level of
approximately -110 dBm by 1 KHz. Bw. For
equipment layout see Fig. 4.
In addition to Fig. 4 we have Fig. 5. Showing
the same set up, but with the HP-11517-A Bias
Mixer. This has the disadvantage of 20 dB less
sensitivity, plus the fact that each frequency
line has to be investigated. Must be manually
adjusted.
such as antennas and current probes. The cali-
bration routines will accept and store exter-
nally derived calibration data. Another impor-
tant feature included is the overload sensing
and warning in all the critical areas of the
RF signal path.
sed in the appropriate part of the system.
In the normal remot digital control mode the
interface connects directly the receiver with
the analyzer.
trols the analyzer and the entire receiving
system need only appear as one device for pur-
poses of addressing and control. In this role
the system is both a listener and a talker.
All data transfer functions from the spectrum
analyzer display section are retained.
Fig. 5
receiver, and spectrum analyzer is the most
powerful tool for EMC measurements I have
seen sofar. It is able to step from one fre-
quency line to the next and evaluate each
data point for narrowband or broadband cri-
teria (according to Mil-STD in our case). If
necessary at the same time coherent and inco-
herent broadband noise can be separated, and
narrowband and broadband data can be graphed
on separate plots and each individual fre-
quency point can be printed out. For analyzing
the test results is this a very important
piece of information.
band emission plot will take about 30 minutes
(20 Ilz - 1 GHz)
of receiving antenna,
electric field antenna over the frequency
range from 300 Hz -
cuitry is such that the response rolls off at
the rate of approximately 20 dB per decade of
frequency below 300 Hz.
rate antennas,
yolarisation is vertical and the directivity
 
V/m,
cations.
we use the well known Solar current probe
type 6741-1,
which has a flat frequency response over the
frequency range 10 KHz - 100 MHz. Maximum
current:
50 + j 0. ohms.
ductor is not necessary, since the probe may
be opened for insertion of the conductor.
4.3 Sweep Section
required for this system, three instruments
are used:
tion Generator. 0.1 Hz-50 MHz.
B- BP-8673-D Frequency Synthesizer.
50 MHz - 26.5 GBz.
C- WJ-1204-40 Milli!meter-Wave Frequency
Extender. 26.5 - 40 GHz.
versatile function generator with good accu-
racy. Microprocessor control ensures rapid
programming amplitude output from 10 mVpp -
10 VPP,
precise signal simulation capability. The fre-
quencies are derived from a quartz crystal
time base,
providing extremely low signal sideband phase
noise. Harmonically related spurious C-60
dBc.SSB Phase noise<-80 dBc. 10 KHz offset
at 10 GHz
Leveled calibrated output to -100 dBm.
Amplitude,
>HO dB and frequency modulation maximum c
peak deviation is smaller than 10 MHz or (see
data sheet).
ting (in 0.1 dB steps).
The same synthesizer is used to feed the
Watkins-Johnson frequency extender WJ-1204-40.
excellent frequency resolution, accuracy and
stability.
As stated in the introduction,
one of the
in order to facilitate the test work. However,
one has to realize that starting from 12 or
15 GHz and going up,
the attenuation is in-
has to be payed with respect to the length of
cable, connectors etc.
it sofar.
are used for multiple purposes, such as ra-
diated- and conducted susceptibility testing,
for testing as modulation sources and also
for conducted spikes and commandline testing.
From the HP-8116-A, pulse function generator
all functions are bus controlled and provide
sinewave,
quency range 100 mHz to 50 MHz, pulse width:
10 nS - 999 mS. Amplitude 10 mVpp to 16 Vpp.
The second instrument in this
HP-8112-A, programmable pulse
the following specification:
section is the
Pulse delay
Double pulse
Source
4.5 Power Meter
HP-438A, with a frequency range from 100 KHz-
26.5 GHz, using the HP-8485-A Thermocouple
power sensor.
._/
Fig. I
transmitting antennas. Measurement modes are
A, B, A-B, B-A, A/B and B/A. The power range
is sensor dependent, dynamic range 50 dB. The
use of the power meter is entirely based on
Mil-STD testing, which implies that the elec-
tric field is calibrated with the transmit-
ting and receiving antenna one meter apart in
an empty room, the empty room being the EMC
Test Facility covered with absorbing material,
in order to reduce reflection.
Power levels are taken and stored in the cal-
culator and called up during the test to set
the levels.
the antenna is radiating, check the level and
compare the reflected power etc.
The use of electric field sensors has been
I_-
of a given object.
diagram Ref.nr. 11, 12, 13 and 14 (Fig. 2).
First instrument in sequence is the HP-8566-S,
spectrum analyzer with a frequency range from
100 Hz - 22 GHz, using external harmonic mix-
ing with a frequency range up to 40 GHz. Am-
plitude approximately from -137 dBm to +30
dBm, resolution 0.1 dB. Dynamic range
95 dB.
from 100 Hz - 22 GHz.
With internal software
The above mentioned features are a must if a
 
ELECTRIC FIELD-STRENGTH GENERRTION --
Ref.nr.
unit HP-3947-A including the extender unit.
5% digit DVM which may be programmed for 300
readings per second (3% digit mode) or 50 rea-
dings per second (5% digit). It consists of a
40 channel relay multiplexer with a power ra-
ting of 1 VA per channel (170 Vp max), relay
contact 1 Ohm, crosstalk -40 dB, 32 channel
Mercury wetted relays are added, with 100 VA
per channel (100 Vp max). Contact resistance
400...mOhm.rosstalk -30 dB. Further we have a
Dual Current D/A converter with an output from
0 to + 10 Volt.
provide a programmable test stimulus or to
control voltage programmed devices like power
supplies and VCO.
"Data Acquisition Unit" contains a real time
clock to support all data output.
With Ref.nr.
range 0.1 - 10 Volt with more than 5000 rea-
dings/set.
One of the more important functions of this
monitor sub-section is to control susceptibi-
lity testing.
tage and current and are able to plotbZ-.
To be in full control means y
u have your hand
it is,
4.7 Amplifiers/Antennas
diagram Fig. 2. The measuring set up for Rad.-
susc.
We work over the frequency range from 20 HZ -
40 GHz.
From 250 MHz - 18 GHz:
10 Watt power.
1 Watt power.
Electric field level is shown on Fig. 9. From
the diagram in Fig. 8 we can see that the EMC
Community is in great need of a much more -.
effective antenna between 30 - 100 MHz.
Nowever,
standard available power. But from project to
project it will be investigated if an effort
will be made to increase the power and field
level.
range and antennas used. For more detailed in-
formation, please refer to the data sheet.
Generally speaking we can say that amplifiers,
couplers and antennas are harmonized to the
maximum extent possible as regards frequency
range and power.
ment criteria.
lyzer settings,
Each band is scanned with 2 different band-
HPIR
HP-8165
SYNTHJGEN
Fig. 8
 
the first and second measurement are compared
with a 3 dB criterion in our case. Correction
factors are added before printing the signal
output. Fig.
Broadband noise is measured in 4 scans from
10 KHz - 22 GHz.
hold mode with a relatively wide bandwidth.
The time set to fill each "Bit!' s equal to
the data from an impulse signal with a sepa-
ration of 50 Hz. Each data point contains half
impulse bandwidth,
file,
is compared with 6 data points before
and after; if 4 3 dB (in our case) it will
be processed. Fig.
5.2 Conducted Emission
we opt for the same criteria of signal proces-
sing as we did for radiated emission. Measure-
ments are carried out on power-and synchroni-
zation lines in differential- and commonmode
in voltage and current. Data- and command I
lines are tested in bundles of wires, separa-
ted like;
due to the importance with respect to the qua-
lity of collected- or transmitted data. Furt-
her more I would like to draw your attention
to what we call a "Structure noise Test".
Fig. 12. This test supplies us with important
information,
citance, loops etc.
under test.
in the time-domain.
Frequency Domain measurement with your Time-
Domain measurements. The instruments used are
arbitrary;
scope:
use of a digital storage oscilloscope has the
advantage of good triggering possibilities
and thanks to the bus you are able to dump the
picture on the printer, including all infor-
mation.
out on Power- and Sync. lines both for CW and
Spike signals.
trolled and checked against the limits. Vol-
tage and Current injected are plotted together
with the Impedance.
susceptible-
mation to analyze the problem.
Fig. I3 shows a typical output plot from a
conducted emission test.
Fig. 13
j ec t t o conducted susceptibility testing. Due
to their important function in a "spacecraft"
a lot of our attention is devoted to test
those lines.
veloped for this purpose. Fig. 14 shows the
test set up.
the disturbance is injected via an opto-coup-
ler,
Fig. 12
and positive pulses into a "0". Together,
this enables us to determine the safety mar-
gin of the circuit. A typical advantage of
this kind of equipment set up is the ability
to supply the customer with a small box in
order to control the test. This box provides
him with the possibility of decreasing the
signal level until the susceptibility has
stopped,
susceptibility has passed.
the frequency range and the threshold level
of the susceptibility.
5.4 Radiated Susceptibility
operator has to control the frequency with
one hand, amplitude with the other, check the
modulation,
rect T.A.F.,
ceptibility criteria of the UUT.
All this control.and check functions are now
taken over by the system controller. This
provides an accurate and fully corrected,
measurement calibrated on the spot of each
frequency step.
to repeat this measurement any number of
times without the slightest diviation.
Also here the susceptibility control box can
be introduced (as discussed under cond.susc.
testing). An important aspect is that the
UUT is not unnecessarily overtested. With
manual operation we have seen errors up to
20 dB or more due either to human errors or
mismatch.
also the possibility of investigating the so
called "Window" effect by automatically in-
creasing and decreasing the power level. So-
for we have not seen this "Window" effect in
our facility. The fact that we are working
in a shielded room is the cause of other
problems like non-uniformity and antenna po-
sition this can be the subject of a calibra-
tion routine. Reflections can be controlled
through the installation of reasonably sized
anechoic
Remember that most of the requirements call
for starting at 10 KHz. Building a facility
where 10 KHz is in the far field is sheer
UTOPIA. And near f!ield odeling is a sophis-
ticated guess.
problem is to move away from Low-Frequency
Radiated Susceptibility Testing.
Fig. 8 shows the test set up used for radia-
ted susceptibility testing. The use of the
system interrupt box and dual sensor power
meter has already been explained.
5.5 Susceptibility to E.S.D.
for the schaffer-NSG-430 discharge gun apart
from normal applications like testing of
"Spacelab" equipment which is subject to dis-
charges from 10 m-joule.
during Spacelab missions.
stations or computers to detect bonding faulr
ts and ground loops. It cuts back expensive
facility time considerably.
An attempt has been made to set up a system
using commercially available equipment
ting, one is afraid to face high cost imple-
mentations. The cost can be rather limited on
the basis of "growth system". It is possible
to achieve a very sophisticated system by
planning the cost over a long period of time.
The new system should be developed in tight
cooperation with an EMC engineer, and aim for
achieving flexibility and growth capability.
Automatic measuring techniques has brought
us many additional advantages.
measurements errors, direct comparison of
test results and use the same results for
prediction. And it protects the test-facili-
ty against poor preformance.
theoretical background of the topics dis-
cussed. And a routine engineer can ask many
awkward questions. However, it is hoped that
successful innovating, will achieve what we
call "EMC".
ON MAJOR SYSTEMS
reasons of cost and efficiency, require accu-
rate prior preparation of the tests. The time
available is limited and most often it is im-
possible to resume the tests if later analysis
It is thus necessary to have an automatic
system to avoid handling errors and a control
assisting system which enables refining the
results and adapting the theoretical experi-
mental program to the actual situation.
The EMP data acquisition system consists
of 5 main elements : sensors, optical transmis-
sion lines,
2. - SENSORS
gnetic and electrical sensors, coil-type high-
impedance sensors have been used along with
built-in amplifiers and correctors and also
electronically matched high-impedance electri-
tended by a sensitivity change remote-control
system (0 to 70 dB 10 dB steps).
Figurel8indicates the main sensors as well as
their dynamic ranges (between noise and maxi-
mum saturation 1evel)passband external dimen-
sions.
2.1.1. Free space electric field sensor.
This type of sensor is used to determine the
incident field and the field within cavities.
It has a full-scale sensitivity from 2 1 V/m
to 3.16 kV/m with a total dynamic range of
120 dB (50 dB of instantaneous dynamic range
and 70 dB by switching).
It enables measuring low excitation fields
(100 V/m to 1 kV/m) .
The passband extends from 70 Hz to 150 MHz.
The sensor takes the form of a sphere with a
diameter of 106 mm.
wide passband to low frequencies and small
dimensions) were obtained by implementing the
active sensor concept.
sphexe (comprising the ground frame) surroun-
ded by two half-spheres forming the positive
and negative frames (Fig.)).
impedance 40 dB attenuators.
characteristics of free-space sensor
20 dB low-impedance attenuator, an amplifier
(gain 46 dB)and a second low-impedance atte-
nuator.
(via the optical link) and their sensitivity
is switch-selectable over a range of 70 dB by
10 dB steps.
teristics of the sensor. The spherical shape
.
of the antenna.
'electric field over the surface of the sensor.
The field, perpendicular at all points to the
surface of the sensor,
depends on the incident
sensor axis
surface of a metal hemisphere
The value of the field is given by
equation (1)
It is drawn up from two limit conditions :
-zero tangential field on the surface,
-field indentical to the incident field to
infinity. .
each half-sensor. Ch represents the capaci-
tance between the hemisphere and the internal-
sphere and Ce,
'resistance of the amplifier.
_
Q (2) within each hemisphere of radius ro :
Q =j!S EO Er. ds (2)
where s is the surface area of the hemisphere.
Taking into account the value of Er (l),
the induced charge is :
= 311r02 oEi (3)
three times that of a disk with a radius ro.
The voltage Ve at the input of the ampli-,
fier depends on this charge, Q, as well as on
the capacitance between the hemisphere and the
sphere and the input capacitance :
Ve =
Q
31Ir20scEi
height par hemisphere is :
The effective height is
(7)
The utilization of attenuators and high
impedance differential amplifiers (Re = 22 MO)
enables reducing the lower cutoff frequency to
less than 100 Hz.
- = 69 Hz (8)
the incident field is thus obtained (non-deri-
vative response).
-Dynamic range
the dynamic range depends on the effective
level (N) at the input :
S
field of 1 V/m.
frequencies,
j
frequencies,
number of turns) is required and sensor size
should be small with respect to the wave length
Moreover,
stray capacity,
flat coil shielded with a split shield.
ThistYpe of dev