Presentation from San Diego Test Equipment Symposium 2019

1. ©2019 ETS-LINDGREN
©2019 ETS-LINDGREN
Antenna Calibrations for Electromagnetic
Compatibility (EMC) Testing: SAE ARP 958D, ANSI
C63.5-2017, CISPR 16-1-6:2017, & YOU!
By Doug Kramer, Chair of ANSI C63.5 Working Group,
Director, Lab Services,
ETS-Lindgren Inc, Cedar Park, TX, USA
douglas.kramer@ets-lindgren.com
12 November 2019
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What’s Happening?
• 2017, TWO (2) NEW/revised documents were published
• ANSI C63.5-2017, American National Standard for Electromagnetic
Compatibility--Radiated Emission Measurements in Electromagnetic
Interference (EMI) Control--Calibration and Qualification of Antennas (9
kHz to 40 GHz)
• CISPR 16-1-6:2014+AMD1:2017, Specification for radio disturbance
and immunity measuring apparatus and methods - Part 1-6: Radio
disturbance and immunity measuring apparatus - EMC antenna
calibration
• SAE ARP 958D, still there and in revision
Let’s review them all!
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Antennas and EMC
• Antenna – Transducer that converts the guided electromagnetic
energy of the feed line into a radiated wave in space and vice
versa.
• Antenna Factor – ratio of the electric field strength of a plane
wave, incident from the direction corresponding to the main axis
of the antenna, to the voltage induced across a specified load
connected to the antenna, measured in a free-space
environment, based on the antenna gain
Regulatory Limits are historically in terms of Field Strength at given distances
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The Goal
• Traceability - Unbroken chain of comparisons to the SI units, all having stated
uncertainties
NMI
You, the
Consumer
Inaccurate
Measurements
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Applications
Different applications = Different Calibration Methods
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Rod Antenna
MIL-STD 461, CISPR 25, C63.4, CISPR 22, 32…
In general, ALL applications
• Generally, 10Hz to 50MHz
Method = Equivalent Capacitance Substitution Method
(ECSM)
CISPR 16-1-6 and C63.5 are the same
SAE ARP 958D is different, but only slightly
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ECSM
• Mono-pole antennas
• Typically 10 Hz to 50 MHz
• Capacitor used to couple energy
• Value based on the length and diameter of the antenna element
• This can vary between manufacturers and models
• Correction value added to measurement
• THIS IS HARMONIZED between ANSI and CISPR
• not SAE
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ECSM
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ECSM
• Summary:
• Different standard documents call out different capacitance.
• Same general calibration circuit:
You MUST verify the height and radius of the antenna to make
certain the correct Dummy antenna is used.
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MIL-STD, Automotive, Aerospace
• METHOD = SAE ARP 958D
1 meter separation distance, 3 meters high
Two Identical Antenna or Three Antenna method (TAM)
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ARP 958D Two Identical Antenna
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Requires that the 2 antenna be identical
make and model, having the same physical
dimensions.
Applies to all types of antenna,
except rods and loops.
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TAM - general
• 3 antenna method over a reference ground plane
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ARP 958D, Loops Loop Antenna
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ARP 958D, Loops Loop Antenna
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Consumer products, Industrial
• Radio devices, ISM, ITE, Multi-media
• Almost anything that isn’t MIL-STD, Automotive, Aerospace
• METHOD = CISPR 16-1-6 or ANSI C63.5
• Depends on the market…
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ANSI vs CISPR
• But which one do you use?
• Whichever the standard you are testing to requires
A calibration lab can’t read your mind, nor your customer’s
• Presently both are considered equivalent,
• if you use the SSM < 1000 MHz
• AND the CISPR site is a REFTS
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Site Validations
• ACS - A site used to calibrate antennas. The site requirements are
divided into two frequency ranges, i.e., 30 MHz to 1000 MHz and 1
GHz to 40 GHz
• NSA - The minimum relative insertion loss measured between two polarization-
matched antennas located on a test site when one antenna is moved vertically over a
specified height range divided by the free-space antenna factors (all in linear units) of
the transmit antenna and the receive antenna, and corrected by the geometry-specific
correction factors (GSCF) if available.
• CALTS - calibration site with a metallic ground plane and tightly
specified site insertion loss in horizontal e-field polarization
• REFTS - test site with metallic ground plane and tightly specified site
insertion loss in both horizontal and vertical e-field polarizations
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Site Validations
• ANSI, ACS
• NSA with in ±2dB of an ideal site and meet statistical criteria (σ)
• Horizontal polarization: <0.3 dB; Vertical polarization: <0.6 dB
• Matched antenna pairs
• CISPR, CALTS
• Measured SIL compared to theoretical using Calculable dipoles
• Horizontal polarization only
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Standard Site Method (SSM)
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SSM
• ANSI C63.5: 2017 requires the Antenna Calibration Site (ACS) meet
a Normalized Site Attenuation (NSA) specification of +/- 2dB.
• CISPR 16-1-6: 2017 requires the calibration site meet the Calibration
Test Site (CALTS) requirements as specified in CISPR 16-1-5: 2016.
• Since these two sets of criteria are distinctly different, the antenna calibration
site used must meet both site requirements and the applied antenna
calibration method must be the SSM.
• Under these circumstances one calibration can be performed
resulting in one antenna factor that can be used for product testing to
both ANSI C63 and CISPR product standards.
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General Comparison of Methods
• Standard Site Method (SSM), Reference site method, 3
antenna method (TAM & 3AM)
• Standard antenna method (SAM), Reference antenna method
(RAM), Substitution antenna method
• Loops…
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Method for > 1 GHz
• For > 1000 MHz
• TAM
• Free-space conditions
• Antenna calibrated in such a way that the antenna polarization does
not impact the results
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Symmetry & VSWR
• SAME INTENT, slightly different process
• C63.5, 4.4.3
• 30MHz to 300MHz, H=1m
• 16-1-6, 6.3.2
• See 16-1-4:2010, 4.5.4
• No frequency range specified, H=1.5m
• “In general, log-periodic dipole array antennas do not exhibit
significant DM/CM conversion and the following check applies to
dipoles, biconical antennas and hybrid antennas.”
• Makes mention of the need to know VSWR (CISPR contains some
measurement details)
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Differences
• Site Validations
• Loops
• Antenna Factor Definitions
• Patterns
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Site Validations
• CISPR 16-1-6, for >30 MHz, two types of sites are used
• Over metal ground plane
• Free-space (absorbing material on the ground)
• CISPR 16-1-5, measurement procedure
• Calculable dipoles
• CALTS (SSM), REFTS (SIL measurement antenna)
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Site Validations
• C63.5, Annex J
• At least five SA measurements shall be made for each measurement
geometry, using the antenna pair positions; d = 10m (shown) or 3m; r=
1.5 m.
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Loops
• C63.5, Annex N (taken from IEEE 291)
• Standard receiving loop
• Substitution
• Standard transmitting loop
• Known field
• CISPR 16-1-6, 5.2
• TEM Cells
• Predeterministic field
• Shielded loops only
• Helmholtz Coils
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Antenna Factors
• ANSI C63.5, near free-space, free-space
• CISPR 16-1-6, provides multiple methods for determining free-space AFs
or height-dependent AFs used for product emissions measurements.
• Fa and Fa: antenna factor and antenna factor for a monopoles calibrated in plane
wave conditions
• Fac: antenna factor for monopoles, ECSM
• Fa(h,p) and Fa(h): height and polarization dependent factors
• FaH: magnetic antenna factors
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Patterns
• ANSI – No patterns, see IEEE 149 for this effort
• CISPR 16-1-6, Annex I (normative)
• Site validation process
• Simplified uncertainty budget
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Patterns
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Similarities
• ECSM – Equivalent Capacitance Substitution Method
• SSM – Standard Site Method <1GHz
• TAM >1GHz (free-space)
• Symmetry & VSWR (well, almost the same)
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Conclusion
• MAKE SURE TO SPECIFY THE CALIBRATION YOU NEED
• Be specific on method
• KNOW your measurement application
• MAKE SURE TO SPECIFY THE CALIBRATION YOU NEED
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MAKE SURE TO SPECIFY THE CALIBRATION
YOU NEED
Which of the following 4 statements of calibration requests
are most likely to get it correct?
“Calibrate the same as last time”
“Calibration in accordance with the SSM of ANSI 63.5:2017 from
30MHz to 1GHz in 5MHz steps; VSWR from 30MHz to 1GHz in
5MHz steps; Antenna Symmetry from 30MHz to 300MHz in
5MHz steps”
“Do a CISPR 16 calibration”
“CISPR 16-1-6:2017 SSM on a CALTS from 30MHz to 1GHz in
5MHz steps”
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And…..
• Documents are in the process of being updated
• ANSI C63.5:2020????
• CISPR 16-1-6 Amendment 2: 2020????
• SAE ARP 958D….
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References
Questions?
ANSI C63.5-2017, American National Standard for
Electromagnetic Compatibility--Radiated Emission
Measurements in Electromagnetic Interference (EMI)
Control--Calibration and Qualification of Antennas (9 kHz to
40 GHz)
CISPR 16-1-6:2014+AMD1:2017, Specification for radio
disturbance and immunity measuring apparatus and
methods - Part 1-6: Radio disturbance and immunity
measuring apparatus - EMC antenna calibration
CISPR 16-1-4:2010+AMD1:2012+AMD2:2017,
Specification for radio disturbance and immunity measuring
apparatus and methods - Part 1-4: Radio disturbance and
immunity measuring apparatus - Antennas and test sites for
radiated disturbance measurements
CISPR 16-1-5:2014/AMD1:2016, Specification for radio
disturbance and immunity measuring apparatus and
methods - Part 1-5: Radio disturbance and immunity
measuring apparatus - Antenna calibration sites and
reference test sites for 5 MHz to 18 GHz
ANSI C63.4: C63.4-2014, American National Standard for
Methods of Measurement of Radio-Noise Emissions from
Low-Voltage Electrical and Electronic Equipment in the
Range of 9 kHz to 40 GHz
SAE ARP 958D-2003, Electromagnetic Interference
Measurement Antennas; Standard Calibration Method
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