Peter Berquist Peter Berquist Emissions Test Consulting, LLC - - PowerPoint PPT Presentation

S SVSWR 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 Validation of OATS and Semi anechoic Chamber anechoic Chamber Validation of OATS and Semi 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 C Loveland Colorado 80538 Loveland Colorado 80538 970 970-

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Presentation Outline Presentation Outline

Introduction

Introduction

SVSWR Measurement Definition

SVSWR Measurement Definition

SVSWR Procedures

SVSWR Procedures

Results

Results

Precautions

Precautions

Summary

Summary

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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 A

d t 1 d fi th t t CISPR 22 2005 A d t 1 d fi th t t

CISPR 22: 2005 Amendment 1 defines the test

CISPR 22: 2005 Amendment 1 defines the test 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

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SVSWR SVSWR-

• Introduction

Introduction

CISPR 22:2005 Amendment 1 Implementation

CISPR 22:2005 Amendment 1 Implementation d t d t O t b 1 2011 O t b 1 2011 date date— —October 1, 2011 October 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

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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 if it meets NSA NSA Some logic!! Some logic!! adequate adequate if it meets if it meets NSA NSA. . 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 calls for meeting CISPR 16-1-4-SVSWR to 18 GHz SVSWR to 18 GHz calls for meeting CISPR 16 calls for meeting CISPR 16-1-4-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 g y y g 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

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material material

The FCC accepts either standard

The FCC accepts either standard

SVSWR SVSWR-

• Introduction

Introduction

ANSI C63 Subcommittee 1 has been working on

ANSI C63 Subcommittee 1 has been working on d ti th h d ti th h li d TDR th d li d TDR th d and promoting the much and promoting the much maligned TDR method maligned TDR method 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

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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? What is it? SVSWR SVSWR-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.

VSWR

VSWR-is an acronym is an acronym-Voltage Standing Wave Ratio Voltage Standing Wave Ratio

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VSWR VSWR is an acronym is an acronym Voltage Standing Wave Ratio Voltage Standing Wave Ratio

SVSWR Measurement Definition SVSWR Measurement Definition

VSWR W i l i

F:\VSWR\Reflection_file\reflection.htm G:\Applets Physics\ph14e\stwaverefl.htm

VSWR Wave simulation

G:\Applets Physics\ph14e\stwaverefl.htm

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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).

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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 d f bl th fl ti i f bj t l d f bl th fl ti i f bj t load 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:

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

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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).

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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 adding and subtracting from the direct path propagation

Reflections from Groundplane on OATS Two EMCO 3115 Horn Antennas

condition—adding 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) 12

Horizontal-No Absorbers Horizontal--Absorbers

SVSWR Measurement Definition SVSWR Measurement Definition

This addition or subtraction to the direct path

This addition or subtraction to the direct path ti b lti ti b lti th ti b th ti b propagation by multi propagation by multi-path propagation can be path propagation can be responsible for: responsible for:

• Adding 6 dB

Adding 6 dB g

• OR completely canceling the direct path propagation

OR completely canceling the direct path propagation

• OR somewhere in between the above conditions

OR 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 reflector

The quality of the reflector—size, material, etc. size, material, etc.

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SVSWR Measurement Definition SVSWR Measurement Definition Omni

Omni-directional source antenna (used to simulate the directional source antenna (used to simulate the EUT) is used to illuminate all objects for 360 EUT) is used to illuminate all objects for 360° °. .

The normal measurement antenna is used to receive.

The normal measurement antenna is used to receive.

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SVSWR Measurement Definition SVSWR Measurement Definition The EUT source could exist anywhere within the test

The EUT source could exist anywhere within the test volume and radiate in any direction volume and radiate in any direction

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SVSWR Measurement Definition SVSWR Measurement Definition The receive antenna beamwidth must be sufficient to

The receive antenna beamwidth must be sufficient to encompass the test volume encompass the test volume

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SVSWR Measurement Definition SVSWR Measurement Definition

• Dual

Dual ridge Horn and Standard Gain antennas don’t comply ridge Horn and Standard Gain antennas don’t comply

• Dual

Dual-ridge Horn and Standard Gain antennas don t comply ridge Horn and Standard Gain antennas don t comply

• ANSI C63.4

ANSI C63.4-

• 2009 Specifies Only Horn Antennas for measurements

2009 Specifies Only Horn Antennas for measurements

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SVSWR Measurement Definition SVSWR Measurement Definition

• Log

Log-

• periodic antennas comply across the band but sacrifice some

periodic antennas comply across the band but sacrifice some sensitivity sensitivity

• Schwarzbeck

Schwarzbeck ESLP 9145 is an example ESLP 9145 is an example

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SVSWR Measurement Definition SVSWR Measurement Definition Sensitivity sacrifice in additional antenna factor for L

Sensitivity sacrifice in additional antenna factor for L-

• P

Dual-ridge Horn Schwarzbeck Log-periodic

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SVSWR Measurement Definition SVSWR Measurement Definition Omni

Omni-directional source antenna defined directional source antenna defined

H-

• Plane requirements shown

Plane requirements shown

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SVSWR Measurement Definition SVSWR Measurement Definition

Bi i l H Bi i l H f ibl f H f ibl f H Pl Pl

• Biconical Horn

Biconical Horn-

• performance possible for H

performance possible for H-Plane Plane

• The POD approaches perfection

The POD approaches perfection

• Schwarzbeck 9112 conforms but approaches directional

Schwarzbeck 9112 conforms but approaches directional

POD Schwarzbeck 9112

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SVSWR Measurement Definition SVSWR Measurement Definition E-

• Plane Requirements

Plane Requirements-

• dipole in nature

dipole in nature

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SVSWR Measurement Definition SVSWR Measurement Definition

E-

• Plane patterns

Plane patterns

POD Schwarzbeck 9112

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SVSWR Measurement Definition SVSWR Measurement Definition

• ETS

ETS-

• Lindgren 3183 Source Antenna

Lindgren 3183 Source Antenna

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SVSWR Measurement Definition SVSWR Measurement Definition

• A series of measurements

A series of measurements are made at different are made at different distances from the reference distances from the reference point point

• These measurements will

These measurements will define the test volume in two define the test volume in two dimensions dimensions—the area and the area and dimensions dimensions—the area and the area and height height

• Any reflecting objects that

Any reflecting objects that are illuminated by the source are illuminated by the source antenna will cause the phase antenna will cause the phase p addition and subtraction of addition and subtraction of the wave at the receive the wave at the receive antenna. antenna.

• Changing the path length,

Changing the path length, ill th t dditi d ill th t dditi d will cause that addition and will cause that addition and subtraction to change. subtraction to change.

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SVSWR Measurement Definition SVSWR Measurement Definition Side SVSWR is influenced by Rx antenna pattern

Side SVSWR is influenced by Rx antenna pattern

The pattern is changing not the SVSWR

The pattern is changing not the SVSWR-

• Typically 3 dB

Typically 3 dB

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SVSWR Measurement Definition SVSWR Measurement Definition

From the previous slide

From the previous slide-

• it can be seen that

it can be seen that

The environment near the source antenna

The environment near the source antenna matters more than the environment behind the Rx matters more than the environment behind the Rx antenna antenna antenna antenna

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SVSWR Measurement Definition SVSWR Measurement Definition With th

dditi f d ti th f With th dditi f d ti th f

With the addition of a second propagation path from a

With the addition of a second propagation path from a reflector the response will add and subtract depending reflector the response will add and subtract depending upon path length. upon path length.

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SVSWR Measurement Definition SVSWR Measurement Definition

• Free

Free-

• space conditions with the only propagation path is the direct

space conditions with the only propagation path is the direct path path

• As the source moves away from the receive antenna, the response

As the source moves away from the receive antenna, the response change is 20*LOG(D1/D2) change is 20*LOG(D1/D2) change is 20 LOG(D1/D2) change is 20 LOG(D1/D2)

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SVSWR Measurement Definition SVSWR Measurement Definition Th

fl ti th l th h d th h Th fl ti th l th h d th h

The reflecting path length changes as does the phase

The reflecting path length changes as does the phase addition and subtraction addition and subtraction

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SVSWR Measurement Definition SVSWR Measurement Definition By varying the distance of the source, the path to any

By varying the distance of the source, the path to any reflecting object changes and thus changes the standing reflecting object changes and thus changes the standing reflecting object changes and thus changes the standing reflecting object changes and thus changes the standing wave. wave.

All the measurements at different distances are corrected to

All the measurements at different distances are corrected to the first reference distance by the free the first reference distance by the free-

• space propagation

space propagation formula formula

If the test environment simulates free

If the test environment simulates free-

• space, the corrected

space, the corrected readings will be very close to the reference reading at each readings will be very close to the reference reading at each position on the test volume position on the test volume position on the test volume. position on the test volume. At each frequency, the maximum and minimum are found for At each frequency, the maximum and minimum are found for each of the six positions. each of the six positions.

The difference is found

This is the SVSWR The difference is found This is the SVSWR The difference is found. This is the SVSWR The difference is found. This is the SVSWR

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SVSWR Procedures SVSWR Procedures

• SVSWR Positions are conditional depending upon test volume

SVSWR Positions are conditional depending upon test volume

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SVSWR Procedures SVSWR Procedures

VSWR

SVSWR SVSWR S

Procedures are detailed in CISPR 16

Procedures are detailed in CISPR 16-

• 1

1-

• 4

4

Th

f i ifi d t 1 Th f i ifi d t 1 18 GH 18 GH

The frequency range is specified at 1

The frequency range is specified at 1-18 GHz 18 GHz

However

However-

• CISPR 22:2005 upper limit of test is 6 GHz

CISPR 22:2005 upper limit of test is 6 GHz

The acceptance criteria for SVSWR is 6 dB

The acceptance criteria for SVSWR is 6 dB

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SVSWR Results SVSWR Results

SVSWR-Semi-ancechoic Chamber Front-Vertical-1.5 Meter 8-22-2007 8 9 10 4 5 6 7 dB 1 2 3

1000 1250 1500 1750 2000 2250 2500 2750 3000 3250 3500 3750 4000 4250 4500 4750 5000 5250 5500 5750 6000

Frequency(MHz)

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SVSWR Precautions SVSWR Precautions

Omni

Omni-

• directional

directional antenna mast antenna mast is critical to is critical to success success

Re

Re-

• radiation off the

radiation off the feedline feedline or

• r antenna mast

antenna mast should be avoided should be avoided should be avoided should be avoided

Exposed ferrite

Exposed ferrite tile are reflectors at these tile are reflectors at these frequencies frequencies

Foam absorbers tips

Foam absorbers tips are reflectors at low angles are reflectors at low angles

• f incidence
• f incidence

Any medium other that air is a reflector at low

Any medium other that air is a reflector at low

Any medium, other that air is a reflector at low

Any medium, other that air is a reflector at low angles of incidence at these frequencies angles of incidence at these frequencies

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SVSWR Precautions SVSWR Precautions

With large test volumes,

With large test volumes, absorbers absorbers may have to may have to be placed upon the be placed upon the turntable turntable be placed upon the be placed upon the turntable turntable

Cumings

Cumings EVA EVA-

• 12 works great for continuous

12 works great for continuous handling handling— —flexible and clean from flexible and clean from Panashield Panashield

Receive antenna’s

Receive antenna’s beamwidth beamwidth must must generously generously encompass the test volume encompass the test volume— —antenna must be antenna must be the same used during emissions measurements the same used during emissions measurements g

Antennas are

Antennas are not aimed not aimed at each other as in NSA at each other as in NSA

ETS 3115

ETS 3115 is much better than ETS 3117 for a 2 is much better than ETS 3117 for a 2 meter test volume meter test volume my experience my experience meter test volume meter test volume—my experience my experience

A

A log log-

• periodic antenna

periodic antenna may be required for large may be required for large test volumes test volumes--

• - > 2 meters (

> 2 meters (for ANSI) for ANSI)

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SVSWR Precautions SVSWR Precautions

Measurement Instrumentation may have to be

Measurement Instrumentation may have to be l d l d th t th t iti it iti it placed placed near near the antennas the antennas-

• sensitivity

sensitivity

A

A preamplifier preamplifier should be used on Port 2 of the should be used on Port 2 of the network analyzer network analyzer—20 dB of head 20 dB of head-room required room required network analyzer network analyzer 20 dB of head 20 dB of head room required room required

The

The noise floor noise floor should be checked should be checked

Problematic SVSWR is an indication that there

Problematic SVSWR is an indication that there are reflection problems below 1 GHz. Those are reflection problems below 1 GHz. Those reflections will reflections will not not necessarily be found by NSA necessarily be found by NSA

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SVSWR Summary SVSWR Summary SVSWR Technique was reviewed.

SVSWR Technique was reviewed.

Thi

it lid ti ill b i d f CISPR Thi it lid ti ill b i d f CISPR

This site validation will be required for CISPR

This site validation will be required for CISPR measurements over 1 GHz. measurements over 1 GHz.

The

The ANSI C63.4:2003 ANSI C63.4:2003 only requires site validation below 1

• nly requires site validation below 1

GH t it i GH t it i GHz as an acceptance criteria GHz as an acceptance criteria

The

The ANSI C63.4:2009 ANSI C63.4:2009 calls for meeting CISPR calls for meeting CISPR 16 16-

• 1-
• 4-
• SVSWR

SVSWR

OR

OR

Alternatively covering a minimum area of 2.4 by 2.4

Alternatively covering a minimum area of 2.4 by 2.4 meters (for a 3 meter test distance) between the antenna meters (for a 3 meter test distance) between the antenna ( ) ( ) and the EUT Using RF absorbing material and the EUT Using RF absorbing material

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SVSWR Summary SVSWR Summary

The SVSWR validation provides a method to

The SVSWR validation provides a method to d t i fl ti d t i fl ti t t it t t it determine reflections determine reflections on a test site

• n a test site

While it detects the problems, there is no

While it detects the problems, there is no indication of the indication of the source location source location of the problem

• f the problem

indication of the indication of the source location source location of the problem

• f the problem

The

The reflection location reflection location can be found via TDR with can be found via TDR with two directional antennas two directional antennas— —another presentation another presentation

SVSWR does not detect anomalies in

SVSWR does not detect anomalies in propagation propagation path path loss loss— —only the presence of reflections

• nly the presence of reflections

Thank you Thank you— —Questions or comments? Questions or comments?

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