S VSWR S VSWR—Site Voltage Standing Wave Ratio Site Voltage Standing Wave Ratio g g g g Site evaluation above 1 GHz Site evaluation above 1 GHz Validation of OATS and Semi-anechoic Chamber Validation of OATS and Semi Validation of OATS and Semi anechoic Chamber Validation of OATS and Semi anechoic Chamber anechoic Chamber Peter Berquist Peter Berquist Emissions Test Consulting, LLC Emissions Test Consulting, LLC 1736 Stove Prairie Circle 1736 Stove Prairie Circle Loveland Colorado 80538 Loveland Colorado 80538 C 970 970- -667 667- -2451 2451
Presentation Outline Presentation Outline � Introduction Introduction � SVSWR Measurement Definition SVSWR Measurement Definition � SVSWR Procedures SVSWR Procedures � Results Results � Precautions Precautions � Summary Summary 2
SVSWR SVSWR- -Introduction Introduction � 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 free The test environment is reflection free—no no groundplane groundplane— —removed by absorbers removed by absorbers � CISPR 16 CISPR 16- -1 1- -4:2007 4:2007- -4 is the applicable standard 4 is the applicable standard � Applies to test sites for testing to CISPR 22:2005 Applies to test sites for testing to CISPR 22:2005 � CISPR 22: 2005 Amendment 1 defines the test � CISPR 22 2005 A CISPR 22 2005 A CISPR 22: 2005 Amendment 1 defines the test d d t 1 d fi t 1 d fi th th t t t t limits and frequency range limits and frequency range— —1- -6 GHz 6 GHz � The FCC defines the measurement upper limit of The FCC defines the measurement upper limit of The FCC defines the measurement upper limit of The FCC defines the measurement upper limit of 5 times internal clock frequencies 5 times internal clock frequencies— —up to 40 GHz up to 40 GHz 3
SVSWR SVSWR- -Introduction Introduction � CISPR 22:2005 Amendment 1 Implementation CISPR 22:2005 Amendment 1 Implementation d t d t date date— —October 1, 2011 O t b O t b October 1, 2011 1 2011 1 2011 � VCCI Japan Implementation Date VCCI Japan Implementation Date— —April 1, 2010 April 1, 2010 However members have the option of waiting However members have the option of waiting However, 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 GHz above 1 GHz Note: VCCI will require telecommunication port Note: VCCI will require telecommunication port measurements as of April 1, 2010 measurements as of April 1, 2010 4
SVSWR- SVSWR -Introduction Introduction � 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 adequate adequate if it meets adequate if it meets adequate if it meets NSA if it meets NSA NSA Some logic!! NSA. . Some logic!! Some logic!! Some logic!! � However, Section 4.1.5.4 However, Section 4.1.5.4- -note specifies a note specifies a reflection free reflection free environment, environment, well indirectly well indirectly- -the the reflection is considered an ERROR reflection is considered an ERROR � ANSI C63.4:2009 is the optional requirement ANSI C63.4:2009 is the optional requirement calls for meeting CISPR 16-1-4-SVSWR to 18 GHz calls for meeting CISPR 16 calls for meeting CISPR 16-1-4-SVSWR to 18 GHz calls for meeting CISPR 16 SVSWR to 18 GHz SVSWR to 18 GHz � OR OR � Alternatively covering a minimum area of 2.4 by Alternatively covering a minimum area of 2.4 by y y g g y y 2.4 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 material material material material � The FCC accepts either standard The FCC accepts either standard 5
SVSWR SVSWR- -Introduction Introduction � ANSI C63 Subcommittee 1 has been working on ANSI C63 Subcommittee 1 has been working on and promoting the much and promoting the much maligned TDR method d d ti ti th th h h maligned TDR method li li d TDR d TDR th d th d for site validation for site validation � Does not simulate the EUT environment Does not simulate the EUT environment � � The The TDR method TDR method, as proposed, is wrought with , as proposed, is wrought with enormous enormous errors and inadequacies errors and inadequacies 6
SVSWR Measurement Definition SVSWR Measurement Definition � Foreword Foreword SVSWR is a new method for site validation of a free SVSWR 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 1- measurements from 1 -18 GHz. 18 GHz. A free A free- -space environment is radio frequency reflection space 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 Earth This may be a little impractical here on Mother Earth � SVSWR SVSWR-What is it? SVSWR SVSWR-What is it? What is it? What is it? The term VSWR comes from analogous term used in VSWR comes from analogous term used in The term transmission line theory. transmission line theory. � VSWR VSWR-is an acronym VSWR VSWR is an acronym is an acronym-Voltage Standing Wave Ratio is an acronym Voltage Standing Wave Ratio Voltage Standing Wave Ratio Voltage Standing Wave Ratio 7
SVSWR Measurement Definition SVSWR Measurement Definition VSWR W VSWR Wave simulation i l i F:\VSWR\Reflection_file\reflection.htm G:\Applets Physics\ph14e\stwaverefl.htm G:\Applets Physics\ph14e\stwaverefl.htm 8
SVSWR Measurement Definition SVSWR Measurement Definition When a transmission line is terminated with an When a transmission line is terminated with an impedance, Z , that is not equal to the impedance, Z , that is not equal to the impedance, 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 of back so that phase addition and subtraction of back 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). 9
SVSWR Measurement Definition SVSWR Measurement Definition Instead of the reflection of a mismatch source and Instead of the reflection of a mismatch source and l l load of a cable, the reflection is from an object on load of a cable, the reflection is from an object on d d f f bl bl th th fl fl ti ti i i f f bj bj t t 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: � Groundplane Groundplane � Exposed Ferrite Tile Exposed Ferrite Tile � Antenna mast Antenna mast � Antenna feedlines Antenna feedlines � Chamber Walls Chamber Walls � Absorbers Absorbers— —in some cases in some cases 10
SVSWR Measurement Definition SVSWR Measurement Definition Reflections 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). 11
SVSWR Measurement Definition SVSWR Measurement Definition � As the frequency increases, the wavelengths decrease. � The two differing path lengths cause a in-phase or out-of-phase condition condition—adding and subtracting from the direct path propagation adding and subtracting from the direct path propagation Reflections from Groundplane on OATS Two EMCO 3115 Horn Antennas 45 40 35 dB 30 25 20 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) Horizontal-No Absorbers Horizontal--Absorbers 12
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