SVSWR—Site Voltaggge Standing Wave Ratio - · PDF fileSVSWR—Site Voltaggge Standing Wave Ratio ... Applies to test sites for testing to CISPR 22 ... calls for meeting CISPR 16calls

SSVSWRVSWRSite Voltage Standing Wave RatioSite Voltage Standing Wave Ratiog gg g
Site evaluation above 1 GHzSite evaluation above 1 GHz
Validation of OATS and SemiValidation of OATS and Semi anechoic Chamberanechoic ChamberValidation of OATS and SemiValidation of OATS and Semi--anechoic Chamberanechoic Chamber
Peter BerquistPeter Berquist
Emissions Test Consulting, LLCEmissions Test Consulting, LLC1736 Stove Prairie Circle1736 Stove Prairie Circle
CCLoveland Colorado 80538Loveland Colorado 80538970970--667667--24512451

Presentation Outline Presentation Outline
IntroductionIntroductionSVSWR Measurement DefinitionSVSWR Measurement DefinitionSVSWR ProceduresSVSWR ProceduresResultsResultsPrecautionsPrecautionsSummarySummary
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SVSWRSVSWR--IntroductionIntroduction
SVSWR is CISPR method of validation of a test SVSWR is CISPR method of validation of a test site from 1 GHz to 18 GHz but limited to the site from 1 GHz to 18 GHz but limited to the maximum specified limit frequency.maximum specified limit frequency.maximum specified limit frequency.maximum specified limit frequency.The test environment is reflection freeThe test environment is reflection freeno no groundplanegroundplaneremoved by absorbersremoved by absorbersCISPR 16CISPR 16--11--4:20074:2007--4 is the applicable standard4 is the applicable standardApplies to test sites for testing to CISPR 22:2005 Applies to test sites for testing to CISPR 22:2005 CISPR 22 2005 A d t 1 d fi th t tCISPR 22 2005 A d t 1 d fi th t tCISPR 22: 2005 Amendment 1 defines the test CISPR 22: 2005 Amendment 1 defines the test limits and frequency rangelimits and frequency range11--6 GHz6 GHzThe FCC defines the measurement upper limit ofThe FCC defines the measurement upper limit ofThe FCC defines the measurement upper limit of The FCC defines the measurement upper limit of 5 times internal clock frequencies5 times internal clock frequenciesup to 40 GHzup to 40 GHz
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CISPR 22:2005 Amendment 1 Implementation CISPR 22:2005 Amendment 1 Implementation d td t O t b 1 2011O t b 1 2011datedateOctober 1, 2011October 1, 2011VCCI Japan Implementation DateVCCI Japan Implementation DateApril 1, 2010April 1, 2010However members have the option of waitingHowever members have the option of waitingHowever, members have the option of waiting However, members have the option of waiting until October , 2010 for emissions measurements until October , 2010 for emissions measurements above 1 GHzabove 1 GHz
Note: VCCI will require telecommunication port Note: VCCI will require telecommunication port measurements as of April 1, 2010measurements as of April 1, 2010
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ANSI C63.4:2003 is the current site validation ANSI C63.4:2003 is the current site validation standard for > 1 GHz. The site is deemed standard for > 1 GHz. The site is deemed adequateadequate if it meetsif it meets NSANSA Some logic!!Some logic!!adequateadequate if it meets if it meets NSANSA. . Some logic!!Some logic!!However, Section 4.1.5.4However, Section 4.1.5.4--note specifies a note specifies a reflection freereflection free environment, environment, well indirectlywell indirectly--the the reflection is considered an ERRORreflection is considered an ERRORANSI C63.4:2009 is the optional requirement ANSI C63.4:2009 is the optional requirement calls for meeting CISPR 16calls for meeting CISPR 16--11--44--SVSWR to 18 GHzSVSWR to 18 GHzcalls for meeting CISPR 16calls for meeting CISPR 16--11--44--SVSWR to 18 GHzSVSWR to 18 GHzORORAlternatively covering a minimum area of 2.4 by Alternatively covering a minimum area of 2.4 by y g yy g y2.4 meters (for a 3 meter test distance) between 2.4 meters (for a 3 meter test distance) between the antenna and the EUT Using RF absorbing the antenna and the EUT Using RF absorbing materialmaterial
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material material The FCC accepts either standard The FCC accepts either standard

ANSI C63 Subcommittee 1 has been working on ANSI C63 Subcommittee 1 has been working on d ti th hd ti th h li d TDR th dli d TDR th dand promoting the much and promoting the much maligned TDR methodmaligned TDR method
for site validationfor site validationDoes not simulate the EUT environmentDoes not simulate the EUT environment
The The TDR methodTDR method, as proposed, is wrought with , as proposed, is wrought with enormousenormous errors and inadequacies errors and inadequacies
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SVSWR Measurement DefinitionSVSWR Measurement Definition
ForewordForewordSVSWR is a new method for site validation of a freeSVSWR is a new method for site validation of a free--space space
environment used to make radiated emissions environment used to make radiated emissions measurements from 1measurements from 1--18 GHz. 18 GHz.
A freeA free--space environment is radio frequency reflectionspace environment is radio frequency reflection--free free environment, as found in space. environment, as found in space.
This may be a little impractical here on Mother EarthThis may be a little impractical here on Mother Earth
SVSWRSVSWR--What is it?What is it?SVSWRSVSWR--What is it?What is it?The term The term VSWR comes from analogous term used in VSWR comes from analogous term used in transmission line theory. transmission line theory. VSWRVSWR--is an acronymis an acronym--Voltage Standing Wave RatioVoltage Standing Wave Ratio
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VSWRVSWR is an acronymis an acronym Voltage Standing Wave RatioVoltage Standing Wave Ratio

VSWR W i l iF:\VSWR\Reflection_file\reflection.htm
G:\Applets Physics\ph14e\stwaverefl.htm
VSWR Wave simulation
G:\Applets Physics\ph14e\stwaverefl.htm
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When a transmission line is terminated with an When a transmission line is terminated with an impedance, Z , that is not equal to theimpedance, Z , that is not equal to theimpedance, Z , that is not equal to the impedance, Z , that is not equal to the characteristic impedance of the transmission characteristic impedance of the transmission line, not all of the incident power is absorbed by line, not all of the incident power is absorbed by the termination. Part of the power is reflected the termination. Part of the power is reflected back so that phase addition and subtraction ofback so that phase addition and subtraction ofback so that phase addition and subtraction of back so that phase addition and subtraction of the incident and reflected waves creates a the incident and reflected waves creates a voltage standing wave pattern on the voltage standing wave pattern on the transmission line. The ratio of the maximum to transmission line. The ratio of the maximum to minimum voltage is known as the Voltage minimum voltage is known as the Voltage Standing Wave Ratio (VSWR).Standing Wave Ratio (VSWR).
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Instead of the reflection of a mismatch source and Instead of the reflection of a mismatch source and l d f bl th fl ti i f bj tl d f bl th fl ti i f bj tload of a cable, the reflection is from an object on load of a cable, the reflection is from an object on a measurement site. a measurement site.
Some of those objects might be:Some of those objects might be:Some of those objects might be:Some of those objects might be:GroundplaneGroundplaneExposed Ferrite TileExposed Ferrite TileAntenna mastAntenna mastAntenna feedlinesAntenna feedlinesChamber WallsChamber WallsAbsorbersAbsorbersin some casesin some cases
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SVSWR Measurement DefinitionSVSWR Measurement DefinitionReflections on the site cause the addition and subtraction of Reflections on the site cause the addition and subtraction of
waves at the observation point (receive antenna). waves at the observation point (receive antenna).
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As the frequency increases, the wavelengths decrease.
The two differing path lengths cause a in-phase or out-of-phase condition adding and subtracting from the direct path propagation
Reflections from Groundplane on OATSTwo EMCO 3115 Horn Antennas
conditionadding and subtracting from the direct path propagation
40
45
25
30
35
dB
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1.0
1.5
2.0
2.6
3.1
3.6
4.1
4.7
5.2
5.7
6.2
6.7
7.3
7.8
8.3
8.8
9.4
9.9
10.4
10.9
11.5
12.0
Frequency(GHz)
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Horizontal-No Absorbers Horizontal--Absorbers

This addition or subtraction to the direct path This addition or subtraction to the direct path ti b ltiti b lti th ti bth ti bpropagation by multipropagation by multi--path propagation can be path propagation can be
responsible for:responsible for:Adding 6 dB Adding 6 dB ggOR completely canceling the direct path propagationOR completely canceling the direct path propagationOR somewhere in between the above conditionsOR somewhere in between the above conditions
The magnitude of the interference depends on:The magnitude of the interference depends on:The magnitude of the interference depends on:The magnitude of the interference depends on:The path length of the unwanted reflection with respect The path length of the unwanted reflection with respect to the direct path (wanted)to the direct path (wanted)The quality of the reflectorThe quality of the reflectorsize, material, etc.size, materia

SVSWR—Site Voltaggge Standing Wave Ratio - · PDF fileSVSWR—Site Voltaggge Standing Wave Ratio ... Applies to test sites for testing to CISPR 22 ... calls for meeting CISPR 16calls

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