hp-an1302_making radiated and conducted compliance measurements with emi receivers

8/14/2019 HP-AN1302_Making Radiated and Conducted Compliance Measurements With EMI Receivers

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Making Radiated an d Conducted

Compliance Measu remen ts w ithEMI Rece ive rs

Applica t ion Note 1302


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1.0 Introduction to compliance measurements . . . . . . . . . . . . . . 3

2.0 The compliance measurements process . . . . . . . . . . . . . . . . . 4

3.0 Compliance EMI receiver requirements . . . . . . . . . . . . . . . . 6

3.1 Requirement s above 1 GHz . . . . . . . . . . . . . . . . . . . . . . . . . . 8

4.0 Preparing for conducted emissions measurements . . . . . . . . 8

4.1 Condu cted test setu p . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

4.2 Configur ing the receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

4.3 Performin g conducted emissions measu remen ts . . . . . . . . . 11

5.0 Preparing for radiated emissions measurements . . . . . . . . 14

5.1 Open sit e requ iremen ts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

5.2 Rad iated em issions test set up . . . . . . . . . . . . . . . . . . . . . . . 16

5.3 Measu rin g rad iated em issions . . . . . . . . . . . . . . . . . . . . . . . 18

5.4 Ambient signal measu remen ts . . . . . . . . . . . . . . . . . . . . . . 18

5.5 Pla cement of EU T for maximu m signa ls . . . . . . . . . . . . . . . 19

5.6 Ambient plu s EUT m easu rem ent s. . . . . . . . . . . . . . . . . . . . 20

5.7 Eva lua tin g measu rem ent r esult s. . . . . . . . . . . . . . . . . . . . . 22

6.0 Report d evelopmen t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

6.1 Using the HP 85878A report generator software. . . . . . . . . 23

7.0 Usin g softwa re to impr ove

ra diated E MI test th roughput . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Appendix A

Line imped an ce stabilization n etwork s . . . . . . . . . . . . . . . . . . . . 28

Appendix B

Anten na factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Appendix C

Basic electr ical r elat ionsh ips . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Appendix D

Detectors u sed in E MI mea su rem ent s . . . . . . . . . . . . . . . . . . . . . 33

Appendix E

EMC regu lat ory agen cies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Glossary of acronymsan d defin itions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Table of Conte nts


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Note: In this application note, detailed measurement procedures are

provided for HP 8542E and 8546A EM I receivers.

Any product t ha t u ses th e public power grid or ha s electroniccircuitry mu st pass EMC (electroma gnetic compatibility)

requiremen ts. These requiremen ts fall into four broad types of

testing: radiated and conducted emissions testing, and radiated

and conducted immunity testing.

Cond ucted emissions testing focuses on signals present on th e AC

mains th at a re generated by the equipment u nder test (EUT). The

frequency ra nge of these m easur ement s is typically 9 kHz to

30 MHz.

Radiated emissions testing looks for signals being emitted from

th e EUT th rough space. The typical frequency range for these

measu remen ts is 30 MHz to 1 GHz, although FCC regulat ionsrequire t esting up t o 200 GHz for an int entional ra diator (such

as a wireless tra nsmitt er) operat ing at a center frequency above

30 GHz.

Figure 1 illustra tes t he difference between radiated em issions,

radiated im m un ity, cond ucted emissions, and conducted immunity.

Radiat ed immun ity is the a bility of a device or pr oduct t o

withsta nd r adiat ed electromagnetic fields. Condu cted imm un ity

is the ability of a device or product to withstand electrical

distur bances on power or data lines. Immu nity testing will not

be covered in this document.

For an electromagnetic compatibility problem to occur (such as

when an electric drill int erferes with TV reception), there m ust be

a genera tor or source, a coupling path an d a r eceptor. Unt il

recent ly, most efforts t o remove EMC pr oblems h ave focused on

reducing the emissions of the source to an acceptable level.

Figure 1. Two types of EMC measureme nts.

1.0 Introdu ctionto compliancemeasurements

Emission Immunity = Susceptibility

ConductedRadiated


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Before complian ce mea sur ement s can be perform ed on a product,

some preliminary questions must be answered:

1. Where will the pr oduct be s old (i.e., th e Un ited Sta tes,Eur ope, Japan )?

2. What is the classification of the product (i.e. information

technology equipment (ITE); industrial, scientific or medical

(ISM); automotive and communications)?

3. Where will the product be used (i.e., home, commercial,

light in dust ry or h eavy indu stry)?

With th e answer s to the a bove questions, you can det ermine wh ich

testing r equirement s apply to your product by referring t o Tables

1a a nd 1b below. For example, if you h ave determ ined th at your

product is an information technology (ITE) device and you will sellit in the U .S. th en you n eed to test t he product to FCC part 15

regulations.

Table 1a. Comparison of regulatory agency requirements.

Table 1b. Major European requ irements .

2.0 The comp liancemeasuremen ts process

European norms

Equipment type

sGeneric equipment

s Residential

s Light industrial

sIndustrial

sInformation technology equipment (ITE)

sIndustrial, scientific, medical products (ISM)

EN 50081-1

EN 50081-2

EN 55022

EN 55011

Emissions

International regulations summary(Emissions)

CISPR

11

12

13

14

15

1622

FCC

Part 18

(SAE)

Part 15

Part 15

EN 55011

EN 55013

EN 55014

EN 55015

EN 55022

EN 50081-1, 2

EN's Description

Industrial, scientific and medical

automotives

Broadcast receivers

Household appliances/tools

Fluorescent lights/luminaries

Measurement apparatus/methodsInformation technology equipment

Generic emissions standards


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EN55011 (CISPR 11)

Industrial , scien tif ic and me dical products.

Class A: Used in establishmen ts other t ha n domestic area s.

Class B: Suitable for use in domestic establishments .

Group 1: Labora tory, medical, an d scient ific equipm ent .

(For example, signa l generat ors, m easur ing receivers, frequency

coun ters, spectru m a na lyzers, switching m ode power supplies,

weighing machines, and electronic microscopes.)

Group 2: Industr ial induction h eating equipmen t, dielectric heating

equipment , indu str ial microwave heating equipment , domestic

microwave ovens, medical appar atu s, spark erosion equipment

an d spot welders. (For example, metal melting, billet hea ting,

component heat ing, soldering an d br azing, wood gluing, plasticwelding, food processing, food thawing, paper drying, and

microwave therapy equipment.)

EN55014 (CISP R 14)

Electr ic motor-opera ted a nd t herm al appliances for h ousehold an d

similar pur poses, electric tools, and electric appar atu s. Depending

on the power r at ing of the item being test ed, use one of th e limits

shown below:

DOS disk file na mes

Household and similar a ppliances

(conducted) EN014-HL

Household and similar a ppliances(radia ted) EN014-HH

Motors < 700W (conducted) EN014-P1

Motors < 700W (radia ted) EN014-P4

Motors < 1000W (conducted) EN014-P2

Motors < 1000W (radia ted) EN014-P5

Motors > 1000W (conducted) EN014-P3

Motors > 1000W (radia ted) EN014-P6

Note: Th e conducted ran ge is 150 kHz to 30 MHz a nd the radiated

range is 30 MHz to 300 MH z.

EN55022 (CISP R 22)

Informat ion technology e quipment

Equipmen t with t he prima ry fun ction of dat a ent ry, storage,

displaying, retrieval, transmission, processing, switching or

cont rolling. (For exam ple, dat a processing equipm ent , office

ma chines, electr onic business equipmen t a nd telecommun icat ions

equipment.)

European norms


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Class A ITE: Not in tended for domest ic use.

Class B ITE: In tended for domest ic use .

Table 1c. FCC regu lations

Federal Communicat ions Commiss ion

FCC Part 15

Radio frequency devices-unintentional radiators

(For example, TV broadcast receivers, FM broadcast receivers, CB

receivers, scanning receivers, TV interface device, cable system

term inal device, Class B persona l computers a nd per ipherals,

Class B digita l devices, Class A digital devices an d peripher als an d

externa l switching power supplies).

Class A digita l devices ar e mar keted for u se in a commercial,

industrial or business environment.

Class B digita l devices ar e mar keted for u se in a r esidential

environment.

For assistance, call the agency for conformation of the applicable

requiremen t. (A list of phone n um bers is included in Appendix E).

3.0 Compliance EMI receive r requireme nts

There a re several requirem ents for making compliance EMI

measurements. The first is an EMI receiver that meets CISPR 161.

A CISPR 16 r eceiver mu st h ave th e following fun ctionality in thera nge 9 kH z - 1000 MHz:

Am plit ude accu r acy:

Nominally a 2 dB absolute amplitu de accura cy is r equired

Specified bandwid t hs :

CISP R specifies th e following ban dwidth s (16 dB):

Bandwidth Frequency range

200 Hz 9 kHz - 150 kHz

9 kHz 150 kHz - 30 MHz

120 kHz 30 MHz - 1000 MHz

FCC

Equipment

s Broadcast receivers Part 15

s Household appliances/tools

s Fluorescent lights/luminaries

s Information technology equipment (ITE)

s Industrial, scientific, medical products (ISM) Part 18

s Conducted measurements: 450 kHz - 30 MHz

s Radiated measurements: 30 MHz - 1000MHz, 40 GHz

FCC

(Federal Communications Commission)

1. Comite International Special des Perturbations Radioelectriques


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The frequency response of the filters mu st a lso fall within a

ma sk defined by CISP R 16.

Specified detectors: Peak, quasi-peak, and average (see

Appendix D for a description of these detectors).The charge, discha rge time and m eter const an ts of th e

quasi-peak detector are specified.

Specified input impedance, nominal value of 50 ohms;

deviat ions specified as VSWR.

Pass product immunity in a 3 V/m fie ld .

Abil ity to pass the CISPR pulse t es t.

Other specific harmonic and intermodulat ion requirements .

The CISP R pulse t est consists of broadband pulses of a d efined

spectra l intensity of varying repetition frequen cy present ed to th e

EMI receiver. The quasi-peak detector m ust measu re th ese pulses

at a specific level within a specified accuracy. In order to meet this

pulse test, it is implied, but n ot specified, that th e receiver mu st

have:

Preselect ion: Preselect ion is achieved by input fi lters that

tra ck the receiver tun ing to reduce broadband n oise

overload a t t he front end mixer.

S en sit ivit y a n d dyn a mic r a nge

The EMI receiver must have a noise floor low enough to

measure signals at low PRFs.

Note: although high sensitivity a nd dynam ic range capabilities are

im plied to m eet th e CISPR pulse test, actual nu m bers for these

param eters are n ot specified.

A recommended feature for ensuring accura te measu rements is

overload detection. To make an accur ate m easur ement , the

receiver must be in linear operat ing mode and n ot be in sat ur ation

at th e front -end m ixer because of large na rr owband signals or

broadband em issions. A useful overload det ection scheme will

alert the user to overload conditions in all frequency ran ges and in

all modes of operation. An advanced overload detection and

measu remen t scheme will au toran ge, or a utoma tically put in

enough attenuation prior to the first mixer to measure the signal

in n on-overload conditions

The HP 8542E a nd 8546A were independently certified to meetthese CISPR-16 requirements by the German BZT1. These

receivers a lso contain au toran ging capa bilities an d overload

detection in a ll frequency ra nges a nd modes of operat ion.

1. Bundesamt fr Zulassungen der Telekommun ikution, the german appeals office for

telecommunications


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3.1 Requirements above 1 GHz:

FCC regulat ions a nd pr oposed CISPR regulat ions r equire a 1 MHz

bandwidth for measurement s above 1 GHz. The HP 8542E and8546A receivers also meet th ese requirements.

In a ddition, no quasi-peak detector is required for m easur ement s

above 1 GHz. The CISP R pulse test is not required a bove 1 GHz,

but high sensitivity in the measuring system is important to

achieve sufficient dyna mic range to perform th e measu remen ts.

According to cur rent FCC regulat ions, th e maximum test

frequen cy is th e fifth h ar monic of the h ighest clock frequ ency for

an un intent iona l radiat or (for exam ple, a compu ter) an d th e

tent h ha rm onic for a n inten tional radiat or (such as, a cellular

phone or wireless LAN).

4.0 Preparing conducted emiss ionsmeasurements

Emissions testing is divided into condu cted emissions an d ra diated

emissions t esting. Follow these steps t o set up t he equipment an d

the equipment un der test .

4.1 Conducted test setup

ANSI C63.4 describes a specific test setup for conducted emissions.

FCC Pa rt 15 deta ils th e limits for th ese tests. Figure 2 shows a

setup for a personal compu ter, requiring a t est t o CISPR 22 or

FCC pa rt 15 (Class B):

Figure 2: Side view of conducted test se tup. The LISN output conne cts tothe receiver.

ANSI C63.4 conducted emissions

test layout for desktop equipment

0.8 m

Keyboard

Non-conducting table

Peripheral

Computer

Monitor

Excess length of all power cordsto floor outlets is draped on floor

Metal floor (or ground plane) surfacedwith 0.3 cm of insulating material

LISN Junction box

Shielded powercable to line filter

LISN and junction boxes bonded to ground plane

All peripherals fed from floor outlets;monitor connected to outlet on computer.

(side view)

(CISPR 22 describes layout for ENs)


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Scroll down and highlight the required limit line (for example,

EN022_BC is the conducted limit for class B products for

EN55022). Press . (See Figure 4). The EN022_BC

conta ins both t he EN 55022 quasi-peak an d average limits.

Figure 4: Loading limit l ines for an EN55022 conducted test.

3. Next, correct the LISN by pressing the following keys:

[SETUP], , , ,

.

Scroll down t o LISN or LISN10A, depending on t he LISN you ar e

using. These files can be edited for your custom use.

Pr ess . (See Figure 5).

Figure 5: Loadin g correction factors for a LISN.


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After loading the LISN correction factors and limit lines, your

display should look like Figure 6:

Figure 6: Display corrected for a LISN and limit l ines on (no inputconnected to the receiver). The top l imit i s the qu asi -peak l imit and thebottom l imit i s the average l imit .

4.3 Performing condu cted emiss ions measuremen ts

At this point t he E MI receiver is set u p with all the corr ect

par am eters, including ban dwidth, frequen cy ran ge, LISN

compensa tion an d limit line. There is one more t hing t o consider

before star ting condu cted measu remen ts, wh ich is th e effect of the

am bient environm ent on th e results. The power cable between th e

LISN and t he EUT can act as a n a ntenna , which can cause falseEUT r esponses on th e display. To test th at th is phenomenon is not

occur ring, switch t he E UT off and check the display to insur e th at

the noise floor is at least 6 dB below the limit line. (See Figure 7).

Figure 7: A conducted test in an ambient environment.


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Switch the power to th e EUT on and observe the display. If there

ar e no signals above th e limit line, th en your job is done a nd your

product passes th e conducted emissions limit. Dat a a nd signals

close to the limit m ay n eed to be collected for your report .Remember th at l ine and n eutral mu st be tested. If there ar e

signals above the limit, closer analysis is needed.

Figure 8: Conduc ted failure

Condu cted em issions u sua lly occur in th e lower en d of the ban d.

One of th e ways to ta ke a closer look a t t he lower en d of th e ban d

is to switch to log frequency sweep. Log sweep expands the lower

decades.

Press [FREQUENCY],

In Figure 9, the display is in a log frequency format. Since log

frequency sweep expan ds th e lower decades, the signals at t he

lower frequencies are m ore clearly shown tha n in t he linear

frequency mode.

Figure 9: Log sweep for conducted test


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The next step is to perform a qua si-peak m easur ement on signals

above th e limit line. One method is to use th e measu re at ma rk

function.

Before measur ing, make su re you h ave enabled th e correct

detectors. P ress [SETUP ], , ,

Pr ess until the corr ect detectors are

un derlin ed; i.e., peak (PK), quasi-peak (QP) and Avera ge (AVG).

To measur e th e peak, qua si-peak an d avera ge level of a signal,

perform th e following:

1. Pr ess [CTRL] in th e Windows section t hen u se and to zoom in on th e signals of

interest in th e active trace. (See Figure 7).

Figure 10: Window s functio n, zooming in on signals

2. Pr ess [TEST]

3. Use the kn ob or the up/down keys to place th e mark er on a

signal of int erest.

4. Pr ess . After t he mea sur ement is

completed, the s igna l frequency and amp litu de will appear inthe box above the display.

5. Pr ess to add your signal to th e receiver

internal signal list.

Repeat the measurement procedure until all the signals above the

limit line have been measu red.


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The HP 8542E and 8546A can a utomatically measure all signals

above the limit or m ar gin with t he au tomeasur e function. P ress

[TEST], , , . These signa ls will

be stored in the signal list.

At t his point, all the measured signal values are in the intern al

list of the EMI receiver. To view the list and determine which

signa ls qua si-peak levels are a bove th e limit:

Pr ess [TEST]

Press un til QP limit 1 is sh own. (See F igure 11).

Figure 11: Sign al list

If there ar e no quasi-peak values a bove the qua si-peak limit

(positive values), and a verage values a bove the avera ge limit, th en

your product passes, or if there a re no quasi-peak values above the

average limit, then your product passes.

Remember th at a ll lines (i.e. line and neu tra l) mu st be tested.

If some of th e values ar e above the qua si-peak level using th e

quasi-peak detector a nd a lso above th e average limit with th e

average det ector, th en some t roubleshooting a nd r edesign is

required.

5.0 Preparing for radiated e miss ionsmeasurements

Performing radiated emissions measurements is not as straight-

forwar d as performin g conducted EMI measu remen ts. There is the

added complexity of the open a ir am bient environment , which can

interfere with t he emissions from the device under test.

Fortu na tely, there a re met hods to different iate between signals in

th e am bient en vironm ent (for example, TV, FM an d cellular rad io).


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5.1 Open site requireme nts

EUTs ar e measu red in a n open a rea test site (OATS). ANSI C63.4

an d CISP R 16 specify the requ irements for a n OATS, including: Preferred measurement distances of 3, 10 and 30 meters .

Antenna pos it ioning a t 1 to 4 meter he ight s

An area called the CISPR ellipse of major diameter 2X and

minor diameter 3 X, where X is the measu remen t dista nce.The ellipse mu st be free of an y reflectin g objects.

A meta l ground plane for the measurement a rea

Figure 12: The CISPR ellipse

The OATS must pass a normalized s ite at tenuat ion test ,

or NSA. The NSA is a test th at determines what value a wa ve from

a t ran smitting antenna (the E UT) is att enuated by th e receiving

an tenn a located on th e ant enna tower, referenced to a signaldirectly tra nsm itted (via cable). Note tha t wha t is received at t he

receiving ant enna is a combina tion of direct waves an d r eflected

waves. The wave att enua tion of th e OATS mu st fall with in a

specified accur acy band. The t est is perform ed at a dista nce where

the compliance tests will be performed.

Figure 13: NSA procedu re schematic, horizontal polarization

15

Major diameter = 2X

Antenna EUTX

Minor diameter = 3 X

Site attenuation test

(Horizontal polarization shown)(ANSI C63.4, 1992)

1 m*

Signalgenerator

EMIreceiver

Ground plane

Maximumreceived

signal

4 meters

1 meter

Broadbandantenna

R = 3, 10, or 30 meters

Signal source ofknown amplitude

*(1.5 m forvertical)

Broadbandantenna


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For complete deta ils on OATS requ irement s, see CISPR 16 an d

ANSI C63.4., an d ANSI C63.7. ANSI C63.7 describes OATS

construction.

Note: 10 m eter anechoic cham bers an d GT EM cells can also be

used for radiated compliance m easurements.

5.2 Radiated emissions test setup

Note: Th e followin g sequence of steps for m ak ing a com plian t

measurement with the analyzer assumes that the measurement

setup is com pliant w ith th e applicable stand ard.

1. Arra nge the antenn a, EUT and E MI receiver as shown

in Figure 14. Separat e the ant enna a nd th e EUT by 3 meters

(10 meters if the regulat ion calls it out). CISPR an d ANSI

require your EUT to be in worst case mode of operation (i.e.att ached cables, monitor, scrolling Hs across the m onitor, etc.)

Figure 14: Rad iated test setup .

2. Use Table 1 (page 4) to determine the regulat ion tha t your

product must be tested to.

3. Set up the EMI receiver for the correct span, antenna

correction factors, and limit line with a mar gin. In th is case,we are t esting to the F CC part 15, class B 3 meter limit. Load

in th e appr opriate limit line using t he following steps:

Pr ess [SETUP], , , and .

Scroll down t o the r adiat ed emissions limit det ermined in Table 1

(i. e., FCC15B3M).

16

CISPR radiated EMI test setup

Equipmentunder test

Antenna

EMI

receiver

Ground plane

1-4 meters aboveground plane

Table is 80 cm high,non-conductive

3608546A546A

EMIRECEIVERM RECEIERDEMODEMOD

EMCM

WINDOWSDO

STATE

EMCFUNCTION

MARKERRKER CONTROL

DATA

INPUT2INPUT1PUT

TG

OUTPUTTUT

TG 300MHz00 z ALC PROBEPOWER

T G 3 00 M Hz00 z ALC

OVERLOADBYPASS

RFFILTERF TRSECTIONECTON


17/44

Figure 15: Loading FCC 3-meter c lass B limit.

4. Pr ess

5. Load th e appropriate an tenn a correction factors. The

HP 8542E/8546A series ha ve two preset ra diated emissions

test ba nds, 30 MHz to 300 MHz an d 300 MHz to 1 GHz. The

30 MHz to 300 MHz ban d uses a biconical anten na a nd t he

300 MHz to 1 GHz band uses a log periodic an tenn a. There is

also a broadban d ant enna (HP 11966P), which covers 30 MHz

to 1 GHz.

Pr ess [SETUP], , , , .

Scroll down t o the an tenn a you wish to use with t he kn ob or

the up/down arrows.

Figure 16: Loading correction factors for a biconical antenna.

Pr ess .

17


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Typical a nt enna factors a re n ow loaded into th e EMI receiver. The

display is now corrected for the loss of the an tenn a an d th e level is

measu red in dBV/m, which is a field str ength measu remen t. (See

Appendix B for m ore inform at ion on field str engt h.) So far, youhave arr anged the equipment with the EU T 3 meters from the

antenna, chosen the appropriate limit line and corrected the

display for ant enna loss.

5.3 Measuring radiated emission s

The next st ep is to evalua te th e rad iated emissions from your

product. With th e EU T off, sweep th e frequency range of inter est.

This gives you a good idea of the ambient signal levels. The ideal

situa tion is to have all th e am bient signals below th e limit line. In

ma ny cases they ar e not, so its a good idea to measu re th em an d

place the results in th e intern al list of the EMI receiver.

Figure 17: An ambient environment for radiated emissions. Ambients canoften be above your l imit l ine .

5.4 Ambient signal meas ureme nts

The pr ocess for measu ring t he a mbient signals is as follows:

1. Perform a maximum hold on th e signa ls in th e band by

pres sing [TRACE], . (This fun ction cap tu res

most signals, including low P RF signals)

2. Tur n on t he WINDOW function on by pr essing [CTRL]

under t he WINDOWS area.

3. Adjust t he with t he k nob to display n o more

th an 20 signa ls above the limit line on th e bottom a ctive tra ce.

18


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4. Use the au tomeasur e fun ction to automat ically measu re

th e signals above th e limit line (above the m ar gin if it was

initiated). To enable a ma rgin on th e limit line, perform th e

following:

Press [SETUP], ,, , , then en ter your m ar gin, which t ypically is 6 dB. Margins ar e

useful when considering the entire measurement uncertainty of

your t est setup (including an tenn as, cables, preamplifiers and t he

receiver.)

Pr ess [TEST], , , t o perform

the automeasure.

At this point, th e EMI r eceiver is performing a peak, qua si-peak

an d avera ge measur ement on all signals above the limit line or

ma rgin (if these detectors were ena bled). The signa ls measu red ar e

th e am bients (signa ls produced by other sources) with th e EU T off.

These signals are placed in th e intern al list.

Move the zone ma rker to the n ext group of signals on t he top tr ace

using the function a nd r epeat th e aut omatic

measurements in step 4 above. Make sure tha t a ll the signals that

ar e above the limit on t he broad tr ace are measu red. Press [CTRL]

un der th e WINDOW area to view the menu cont aining . Press and use the knob to move the

zone ma rker to the n ext group of signals.

5.5 Placeme nt of EUT for maximum sign als (manualmeasuremen t process)

Radiated emissions from electronic devices are not uniform. The

str ongest emissions m ay be from th e rear pan el or front pan el or

slots in th e shielding. To insu re th at you ar e measu ring th e worst

case em issions from your device, do th e following:

1. With t he E MI receiver adjusted to view the span of interest ,

move the EU T th rough a 360-degree rotation in 45-degree

increments.

2. At each 45-degree step, note the am plitude of th e largest

signals. With a print er conn ected t o the I/O port, press [COPY]

to obtain a screen dump at each step.

3. On each screen dum p, mark t he position of th e EUT.

After a ll the screen dum ps ha ve been captur ed, compare th em to

find the position of the worst-case emissions. In some cases, you

ma y find th at th ere ar e worst -case emissions for different

frequencies at different positions. For example, you may find

worst -case for 100 MHz emissions a t 90-degrees and at 270

degrees for 200 MHz. In th is case, th e emissions t ests mu st be

19


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20

perform ed at both positions. If you a re not su re whet her the signa l

you ar e looking at is an ambient or E UT signal, switch the E UT

off. An ambient signal will not change. Worst case emissions must

be found for both horizontal and vertical polarizations.

5.6 Ambient plus EUT measu remen ts

With t he EU T tur ned on and oriented to the worst case position,

perform au tomat ed tests a gain as follows:

1. Press [NEXT] un der [WINDOW]. This activates th e upper

tra ce to capt ur e the a dditiona l emissions from th e EUT. Press

[NEXT] again to activate the lower window.

2. Adjust th e with th e knob to display no

more th an 20 signa ls above th e limit line on th e bott om active

trace. This gives the best frequency accuracy.

3. Use th e au tomeasur e fun ction to au tomat ically measu re

th e signals above th e limit line (or a bove the m ar gin if it was

initiated): Press [TEST], , , .

To captur e the signals over th e rest of th e band, repeat th e signa l

measu remen t pr ocess (5.5) to captur e all the signa ls above th e

limit. At t his point , the E MI receiver is performing a peak, qua si-

peak a nd a verage on a ll signals above the limit line or ma rgin

within t he zone span a rea. If necessary, move the zone span to the

next group of signals a bove the limit or ma rgin an d perform

another au tomeasure. The signals measured a re the a mbients plus

th e EUT signals. These signals ar e also placed in the int erna l list.

Now that you have the ambient signals from the first test and the

am bient signals plus th e EUT signals from the second group of

tests you can perform a sort on t he list, looking for d uplicat es (the

am bient signals). To remove th e am bient signals, perform the

following:

Press [TEST], , , ,

, , and .


21/44

Figure 18: Marking and de leting ambie nts from your list

At this point, most of th e am bient signals ha ve been deleted from

your list. Some am bients ma y have been pr esent for one of the

aut omatic measurements but not for th e other m easurement. It

would n ot h ave duplicat e signals an d would not be deleted. The

signals in the list are t he peak, qua si-peak a nd a verage values of

the EUT emissions and remaining ambient signals.

Next, find signa ls tha t a re a bove the limit. To do this, sort t he list

by quasi-peak values, with t he h ighest levels at t he top of th e list:

Press [TEST], , , , .

Next, switch on th e column tha t indicates th e value of th e quasi-

peak measur ement versus th e limit l ine.

Press [TEST], ,

Press un til VIEW QP LIM 1 is indicat ed at t he

top of th e right column see Figure 19).

Figure 19: Final EUT signal l ist

21


22/44

5.7 Evaluating measurement results

If all the values in the right hand column are negative, then the

product emissions a re below th e limit a nd your product passes t hera diated emissions r equirement s. If some of the values ar e

positive, then the quasi-peak measurements are above the QP

limit and the product fails the radiated emissions measurements.

To be sure th at a signal is not ambient, it should be remeasur ed

an d th e demodulation fun ction u sed to listen to th e signal. AM/FM

demodulation is a good t ool for determ ining wheth er or n ot a

signal is an ambient.

To listen to a signa l, do the following:

Press [TEST], ,

With th e signa l list on, highlight t he signal of interest with th e

up/down keys.

Pr ess [SELECT] in t he DE MOD section

Pr ess,

Adjust th e volume t o listen to the signal. If the signal is a local

AM, FM, TV or cellular phone tr an smission, t he dem odulation

function will ena ble the operator to hear th e audio part of th e

tr an smission by dwelling at th e ma rker for a specified length of

time (usually 500 msec).

If there is any doubt about the signal being an ambient or an EUT

signal, remove the power to the E UT an d observe the signal. If the

signal remains, it is an ambient.

Note: It m ay not be convenient t o rem ove th e power from th e EUT.

In th is case using the dem odula tion fun ction m ay be th e preferred

m ethod of identifying am bients.

If you have determined that a signal is an ambient, then you need

to delete the signal.

Press [TEST], , , , high

light t he am bient signal to be deleted an d press .

After t he a mbient signals h ave been deleted from th e list, a r eport

can be d eveloped.

22


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6.0 Report deve lopmen t

The end r esult of the a bove testing is a report. The r eport is used

by the design engineer to correct a ny problems tha t a re foun ddur ing the t est pr ocess. You can assemble a r eport using th e

[OUTPUT] functions. The report can include a list of signals a

graph ical represen tat ion of the signa ls and u p to two pages of text,

which can be generat ed using a common PC k eyboar d tha t

connects to the rear of the EMI receiver.

6.1 Using the HP 85878A EMI report generator software

The HP 85878A report generator software comes with each

HP 8546A or 8542E EMI receiver purchase. The HP 85878A can

be used to capt ur e data from your receiver an d au tomat ically

generat e r eports.

Figure 20: Capture the data you want with a few mous e c l icks using theHP 85878A.

The HP 85878A uses object linking and embedding (OLE)

technology, so you can easily dra g an d dr op your captu red da ta in

Microsoft Word . Each da ta session you perform is stored in a

database for search and retrieval.

23


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Figure 21: Data icons ca n be dragged a nd droppe d to Microsoft Word.

Using Microsoft Word an d m acros, you can au tomatically genera te

large r eports. Your da ta icons ar e bookmark ed an d a ut omatically

inserted int o your report.

Figure 22: Cu stom report template s allow fast generation of reports tocompliance authorit ies and for engineering archives.

7.0 Using so ftwa re to imp rove radiate d EMI testthroughput

Softwar e packages tha t a ut oma tically control the movements of

towers and t ur nta bles, capt ur e emissions and find worst-case

emissions ar e available. In a ddition to generat ing compat ible

reports, the HP 85876B commer cial radiat ed EMI software also

perform s t hese functions.

For example, the HP 85876B has a n icon set tha t can be used to

set up your equipment path and automatically import your

corr ection factors.

24


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Figure 24: The HP 85876B can set up your equipment and importcorrect ion factors to correct for your measurement path .

Pr edefined, edita ble test pr ocedures enable you t o automat e your

test process.

Figure 25: Test proce dures a nd con trol.

The softwar e ena bles you t o control your receiver an d a dd

additional signa ls to your signal list with a m ar ker add t oactive list function.

25


26/44

Figure 26: Software receiver control

Other signal ma ximization an d cont rol tools assist you in finding

your worst case emissions. Th e softwar e enh an ces r epeata bility,

and improves th roughput.

Figure 27: Tower control panel

Below is a polar plot a nd a height/azimu th plot of a m easur ed

signal. The near-omnidirectiona l radiat ion pa tter n of th e signa l

could signify tha t it is an ambient .

26


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Figure 28: Maximization an d graphical tools assist you in performingyour f inal measurement.

The H P 85876B allows you t o save files as *.rtf (rich t ext files) for

easy import int o popular word p rocessing programs. Gra phics can

be saved as *.wmf (Windows Metafile) for quick pasting into many

Windows-based applications.

Figure 29: HP 85876B reporting capabilities

27


28/44

A1.0 purpo se o f a LISN

A line impedan ce sta bilization net work serve th ree purpose:

1. The LISN isolates the power mains from the equipmentun der test . The power supplied to th e EUT mu st be as clean

as possible. Any noise on th e line will be coupled to th e EMC

analyzer and interpreted as noise generated by the EUT.

2. The LISN isolates an y noise genera ted by the EUT from

being coupled to the power mains. Excess noise on the power

main s can cause inter ference with th e proper opera tion of

other devices on the line.

3. The signals generated by the EUT ar e coupled to the

EMC an alyzer using a h igh pass filter which is part of the

LISN. Signa ls which a re in th e pass ban d of th e high pass

filter see a 50 load which is the input to the EMCanalyzer.

A1.1 LISN op erati on

The diagram in Figure A-1 below show the circuit for one side of

the line relative to earth ground.

Figure A-1. Typical LISN circuit diag ram.

28

Appen dix A

Line impedancestabi l izat ion networks

Line impedance stabilization

network (LISN)

605040302010

.01 .1 1 10 100

impedance(ohms)

frequency (MHz)

0.1 F

1000W

From powersource

ToEUT

ToReceiver or EMC Analyzer

(50 )

50 H

1 F


29/44

The 1 F capacitor in combinat ion with th e 50 H inductor is thefilter th at isolates th e mains from th e EUT. The 50 H indu ctor

isolates th e noise generat ed by the EU T from th e mains. The 0.1

F couples the n oise generated by th e EUT to the E MC ana lyzeror receiver. At frequencies above 150 kHz, the EUT signals are

presented with a 50 impedance.

The chart in Figure A-1 above represent s th e impedance of the

EUT port versu s frequency.

A1.2 Types of LISN s

Figure A-2. Three different types of LISNs.

The most common t ype of LISN is the V-LISN. It m easur es th e

asymm etric voltage between line a nd ground. This is done for bothth e hot an d th e neut ra l lines or for a thr ee-pha se circuit in a Y

configur ation, between each line an d ground. Ther e ar e some

other specialized types of LISNs. A delta LISN m easur es the line

to line or symmetric emissions voltage. The T-LISN, sometimes

used for telecommu nications equipment , measur es the

asymmetrical voltage, which is the potential difference between

th e midpoint potential between two lines an d ground.

A2.0 Transien t l imiter operation

The pu rpose of the limiter is to protect t he inpu t of the EMC

an alyzer from lar ge tran sients when connected to a LISN.

Switching EUT power on or off can cau se large spikes gener atedin the LISN.

The HP 11947A tran sient l imiter incorporat es a l imiter, high pass

filter, an d an a tt enua tor. It can withsta nd 10 kW for 10 sec an d

ha s a frequency ra nge of 9 kHz t o 200 MHz. The high pa ss filter

reduces th e line frequencies coupled to th e EMC a na lyzer.

29

V-LISN:-LISN:

T-LISN:

Asymmetric emissions (line-to-ground)Symmetric emissions (line-to-line)Asymmetrical emissions (mid point line-to-line)

V-LISN Vector diagram

V symmetric

Ground

H N

V1 asy

mmetricV2

asymmetric

1/2Vsymmetric 1/2Vsymmetric

V asymmetric

1

V asymmetric2

V asymmetric


30/44

B1.0 Field strength units

Radiated EMI emissions measurements measures the electric

field. The field strength is calibrated in dBV/m. F ield st rength indBV/m is der ived from t he following :

P t = total power radiat ed from a n isotropic radiator

PD = the power density at a dista nce r from the isotropicradiator (far field).

PD = Pt /4r2 R = 120

PD = E2/R

E2 /R = Pt /4r2

E = (Pt x 30)1/2 /r (V/m)

Fa r field* is consider ed t o be >/2

*Far field is the m inimum distan ce from a r adiat or where th e field

becomes a plana r wa ve.

B1.1 Ante nn a factors

The definition of antenna factors is the ratio of the electric field in

volts per meter present at the plane of the an tenna versus th e

voltage out of th e an tenn a conn ector. Note: antenn a factors a re n ot

the same as antenn a gain.

Figure B-1. Typical anten na factor shape s.

30

Appen dix B

Anten na factors

Linear Units:

dB/m

Frequency, MHz

5

10

15

20

25

0 200 400 600 800 1000

Biconical@ 10m

Log Periodic@ 1m

AF = Antenna Factor (1/m)E = Electric Field Strength (V/m)

V = Voltage Output from Antenna (V)

Log Units: AF(dB/m) = E(dBV/m) - V(dBV)

E(dBV/m) = V(dBV) + AF(dB/m)

AF = EinV out

30


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B1.2 Types of antenn as use d for commercial radiate d

measurements

Figure B-2. Antennas used in EMI emissions measurements.

There ar e thr ee types of an tenn as u sed for commercial ra diated

emissions measurements.

Bicon ica l a nt en na : 30 MH z t o 300 MH z

Log periodic an ten na : 200 MHz to 1 GHz (The biconical

an d log periodic overlap frequen cy)

Broadband an t enna : 30 M Hz t o 1 GHz (Lar ge r for m a t

than the biconical or log periodicantennas)

31

Blah

Log Periodic Antenna

Biconical Antenna

Broadband Antenna

(30 - 300 MHz)

(30 - 1000 MHz) (200 - 1000 MHz)


32/44

The decibel is used extensively in electromagn etic measur ement s.

It is t he log of the ra tio of two amplitudes. The am plitudes ar e in

power, voltage, amps, electric field units, and magnetic field units.

dec ibel = dB = 10 log (P 2/P 1)

Data is sometimes expressed in volts or field str ength un its.

In this case, replace P with V2/R.

If the impedan ces are equ al, the equa tion becomes:

dB = 20 log(V2/V1)

A unit of measure used in EMI measurements is dBV or dBA.The r elationsh ip of dBV and dBm is a s follows:

dBmV = 107 + P dBmThis is tru e for a n impeda nce of 50

Wave length (l) is determined using the following relationship:

= 3x108 / f (Hz) or = 300/f (MHz)

32

Appen dix C

Basic electricalrelat ionships


33/44

D1.0 Peak detector

Initial EMI measurements are m ade using th e peak detector.

This mode is much fast er th an quasi-peak, or a verage modes of

detection. Signals a re n ormally displayed on spectru m a na lyzersor EMC ana lyzers in peak m ode. Since signa l measur ed in peak

detection m ode always have am plitude values equa l to or h igher

th an quas i-peak or a verage detection modes, it is a very easy

process to take a sweep and compare th e results t o a limit line.

If all signals fall below the limit, th en t he product passes a nd n o

further testing is needed.

D1.2 Peak d etector operation

The EMC an alyzer h as a n envelope or peak detector in th e IF

chain which h as a t ime constan t such th at t he voltage at the

detector outpu t follows the peak value of th e IF signa l at all times.

In other words, t he det ector can follow t he fast est possible chan ges

in th e envelope of th e IF signal, but not th e instan ta neous value of

th e IF sine wave. (See Figure D-1)

Figure D-1. Peak detector diagram.

33

Appen dix D

Detec tors used in EMImeasurementspeak,

quasi -peak, an daverage

Output of the envelope detectorfollows the peaks of the IF signal


34/44

D2.0 Quasi-peak dete ctor

Most ra diated an d conducted limits ar e based on qua si-peak

detection mode. Quasi-peak detectors weighs signals according toth eir repetition ra te, which is a way of measu ring th eir ann oyan ce

factor. As the r epetition r at e increases, th e qua si-peak detector

does not ha ve time to discha rge as mu ch resulting in a higher

volta ge outpu t. (See Figur e D-2 below.) For cont inu ous wa ve (CW)

signals the peak and t he quasi-peak are t he same.

Since the quasi-peak detector a lways gives a rea ding less th an or

equal to peak detection, why n ot use qua si-peak d etection a ll the

time? Wont th at m ake it easier t o pass E MI tests? Its tru e tha t

you can pa ss the t ests easier, however, quasi-peak measu remen ts

ar e mu ch slower by 2 or 3 orders of magn itude compa red t o using

th e peak det ector.

Figure D-2. Quasi-peak detector respon se diagram.

D2.1 Quasi-peak detector operation

The quasi-peak detector has a char ge rate much faster than the

discha rge rate ther efore the higher th e repetition ra te of the

signal the h igher th e out put of th e quasi-peak detector. The qua si-

peak detector a lso responds to different amp litu de signals in a

linear fashion. High am plitude low repetition ra te signals couldproduce the same output as low amplitude high repetition rate

signal.

34

Quasi-peak detector output

varies with impulse rate

t

Peak responseQuasi-peak

detector readingQuasi-peak

detector response

t

Test Limit

Test Limit


35/44

D3.0 Average detec tor

The average detector is required for some conducted emissions

tests in conjunction with using the quasi-peak det ector. Also,radiated emissions measurements above 1 GHz are performed

using avera ge detection. The average detector outpu t is always

less tha n or equal t o peak d etection.

D3.1 Average detec tor o peration

Average detection is similar in m an y respects to peak detection.

Figure D-3 below shows a signal that has just passed through the

IF a nd is a bout to be detected. The outpu t of the envelope detector

is th e modulation envelope. Peak detection occur s when th e post

detection bandwidth is wider than the resolution bandwidth.

For avera ge detection to take place, the peak det ected signal

must pass th rough a filter whose bandwidth is mu ch less than the

resolut ion ban dwidth. The filter a verages the h igher frequency

components, su ch as noise, at th e output of th e envelope detector.

Figure D-3. Average detection respons e diagram.

35

A

t

Envelope Detector

Filters

Average Detector


36/44

The following is a listing of address and phone numbers for

obta ining EMC r egulation informa tion.

IE CCISPR

Sales De partmen t of the Central Office of the IEC

PO Box 131

3, Rue de Verem be

1121 Geneva 20, Switzerland

CCIR

ITU, Gene ral Secretariat , Sales S ervice

Place de Na tion

1211 Geneva, Switzerland

Australia

Austral ia Electromecha nical Committee

Standa rds Association of Austral ia

PO Box 458

North Sydney N.S.W. 2060

Teleph on e: +61 2 963 41 11

Fax: +61 2 963 3896

Belgium

Comite Electrotechnique Belge

3 Galerie Ravenstein, Boite 11

B-1000 Bruxelles

Teleph on e: +32 2 512 00 28

Fax: +32 2 511 29 38

Canada

Standa rds Council of Canada

Standards Sales Divis ion

350 Sparks Street, Suite 1200

Ottawa, Ontar io K1P 6N7

Teleph on e: 613 238 3222

Fax: 613 995 4564

Canadians Standa rds Association (CSA)

178 Rexdale Boulevard

Rexdale (Toronto), Ont ar io MSW 1R3

Teleph on e: 416 747 4044Fax: 416 747 2475

Denmark

Dansk Elektroteknisk Komite

Stran dgade 36 st

DK-1401 Kobenhavn K

Teleph on e: +45 31 57 50 50

Fax: +45 31 57 63 50

36

Appen dix E

EMC regu latoryagencies


37/44

37

France

Comite E lectrotechnique Fr an cais

UTE CEdex 64

F-92052 Pa ris la DefenseTelep hon e: +33 1 47 68 50 20

Fax: +33 1 47 89 47 75

Germany

VDE CERLAG GmbH

Austieferungsstelle

Merianstr asse 29

D-6050 OFFE NBACH a.M.

Telep hon e: + 49 69 8306-1

Fax: + 49 69 83 10 81

India

Bureau of Indian Standards , Sales De partmentManak Bhavan

9 Bahadur Sh ah Zafar Marg.

New Delh i 110002

Telep hon e: + 91 11 331 01 31

Fax: + 91 11 331 40 62

Italy

Cometato Eletrotecnico Ital iano

Viale Monza 259

1-20126 Milan o MI

Teleph on e: + 39 2 25 77 31

Fax: + 39 2 25 773 222

Japan

Japane se Standards Associat ion

1-24 Akasa ka 4

Minato-Ku

Tokyo 107

Teleph on e: + 81 3 583 8001

Fax: + 81 3 580 14 18

Netherlands

Nederlands Normalisatie-Instituut

Afd. Verdoop en Informa tie

Kalfjeslaan 2, PO Box 5059

2600 GB DelftNL

Teleph on e: + 31 15 69 03 90

Fax: + 31 15 69 01 90

Norway

Norsk Elektroteknisk Komite

Ha rbizalleen 2A

Postboks 280 Skoyen

N-0212 Oslo 2

Teleph on e: + 47 2 52 69 50

Fax: + 47 2 52 69 61


38/44

38

South Africa

South African Bureau o f Standards

Electronic Engineering Department

Pr ivate Bag X191Pretoria

0001 Republic of South Africa

Spain

Comite Na cional Espa nol de la CEI

Fr an cisco Gervas 3

E-28020 Ma drid

Teleph on e: + 34 1 270 44 00

Fax: + 34 1 270 28 55

Sweden

Svenka Elecktr i ska Kommiss ionen

PO Bow 1284S-164 28 Kista -Stockh olm

Teleph on e: + 48 8 750 78 20

Fax: + 46 8 751 84 70

Switzerland

Swiss Electromechanical Committee

Swiss E lectr omechan ical Associat ion

Seefeldstrasse 301

CH-8008 Zur ich

Teleph on e: + 41 1 384 91 11

Fax: + 41 1 55 14 26

United Kingdom

British Standards Institution

BSI Sales Departm ent

Lin ford Wood

Milton Keynes MK14 GLE

Telep hon e: +44 908 22 00 22

Fax: +44 908 32 08 56

Briti sh Defence Standards

DEF STAN

Ministr y of Defence

Northumberland House

Northu mberlan d AveLondon WC2N 5 BP

Teleph on e: + 01 218 9000

United S tates of America

America National Standards Institute Inc.

Sales Dept.

1430 Broadwa y

New York, NY 10018

Teleph on e: 212 642 49 00

Fax: 212 302 12 86


39/44

39

FCC Rules and Re gulations

Technical Standards Branch

2025 M Street N.W.

MS 1300 B4Washington DC 20554

Teleph on e: 202 653 6288

FCC Equipme nt Autho rization Branch

7435 Oaklan d Mills Road

MS 1300-B2

Columbia, MD 21046

Teleph on e: 301 725 1585


40/44


41/44

Auxil iary equipment

Equipment not under test that is nevertheless indispensable for

setting u p all the functions a nd a ssessing the corr ect performan ce

of th e EUT du ring its exposur e to the distur bance.

Balun

A balun is an an tenn a balan cing device, which facilita tes use of

coaxial feeds with symm etrical ant enna such a s a dipole.

Broadband emiss ion

Broadband is the definition for an int erference amp litu de when

several spectral lines ar e within the RFI r eceivers specified

bandwidth.

Broadband interference (measurements)

A distur bance that h as a spectral energy distr ibution sufficiently

brad, so tha t th e response of the measu ring receiver in use does

not var y significan tly when tu ned over a specified num ber of

receiver bandwidth s.

Conducted interference

Int erference resulting from condu cted radio noise or un want ed

signals ent ering a tr an sducer (receiver) by direct coupling.

Cross coupling

The coupling of a signal from one channel, circuit, or conductor to

an other, where it becomes an un desired signa l.

Decoupl ing network

A decoupling n etwork is an electrical circuit for p reventing t est-

signals which ar e applied to th e EU T from a ffecting other devices,

equipment, or systems th at are n ot u nder test . IEC 801-6 states

th at th e coupling an d decoupling network systems can be

integrat ed in one box or they can be in separat e networks.

Dipole

1. An anten na consisting of a str aight condu ctor usu ally not more

th an a ha lf-wavelength long, divided at its electrical cent er for

conn ection to a tr an smission line.

2. Any one of a class of an tenn as producing a radiat ion pa tter n

appr oximating tha t of an elementar y electric dipole.

Electromagne tic com patibi l i ty (EMC)

1. The capability of electr onic equipm ent of system s to be opera ted

within a defined mar gins in of safety in th e intended operat iona l

environment at designed levels of efficiency without degradation

due t o int erference.

2. EMC is the ability of equipm ent t o function sat isfactorily in its

electroma gnetic environment without introducing intolerable

disturbances into that environment or into other equipment.

41


42/44

Electromagnetic interference

Electr oma gnetic inter ference is the impairm ent of a want ed

electroma gnetic signa l by an electr omagnetic disturba nce.

Electromagnet ic w ave

The r adian t en ergy produced by th e oscillat ion of an electr ic

charge characterized by oscillation of the electric and magnetic

fields.

Emission

Electr oma gnetic energy propagated from a source by radiation or

conduction.

Far field

The region wher e the power flux density from an a nt enna

appr oximately obeys an inverse squar es law of the distan ce. For a

dipole this corresponds t o dista nces greater t ha n l/2 where l is th e

wave length of the r adiat ion.

Ground plane

1. A condu cting surface of plat e used as a common reference

point for circuit r etur ns an d electr ic or signal potentials.

2. A meta l sheet or plate used as a common reference point

for circuit ret urn s a nd electrical or signal potentials.

Immunity

1. The property of a receiver or any other equipmen t or system

enabling it to reject a rad io distur bance.

2. The ability of electr onic equipment t o with sta nd r adiat ed

electr omagnetic fields without producing un desirable responses.

Intermodulation

Mixing of two or more signals in a nonlinear element, producing

signals at frequencies equal t o the su ms a nd differences of integra l

multiples of the original signals.

Isotropic

Isotropic mean s h aving properties of equal values in a ll directions.

Monopole

An an tenn a consisting of a st raight conductor, usually not more

th an one-quart er wave length long, mounted immediat ely above,

an d norma l to, a ground plan e. It is connected to a tr an smissions

line at its ba se an d behaves, with its image, like a dipole.

Narrowband emiss ion

That which h as its principal spectr al energy lying with in th e

bandp ass of the m easur ing receiver in use.

42


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Open area

A site for radiated electr omagnetic interference measu remen ts

which is open flat t erra in at a dista nce far enough awa y from

buildings, electric lines, fences, trees, underground cables, andpipe lines so that effects due to such are negligible. This site

should have a sufficiently low level of ambient interference to

permit testing to the required limits.

Polarization

A term used t o describe th e orientat ion of the field vector of a

ra diated field.

Radiated interference

Radio inter ference resulting from radiat ed noise of unwan ted

signals. Compare radio frequency interference below.

Radiation

The emission of energy in the form of electromagnetic waves.

Radio frequency interference

RFI is t he h igh frequency int erference with ra dio reception. This

occur s wh en un desired electr omagnetic oscillat ions find en tr an ce

to the h igh frequen cy input of a r eceiver or an tenn a system .

RFI source s

Sources are equipment a nd systems a s well as t heir components

which can cau se RFI.

Shie lded enclosure

A screened or solid meta l housing designed expressly for the

pur pose of isolat ing the int erna l from th e externa l

electroma gnetic environment. Th e pur pose is to prevent outside

ambient electromagnetic fields from causing performance

degradat ion an d to

prevent emissions from cau sing int erference t o outside activities.

Stripl ine

Parallel plate transmission line to generate an electromagnetic

field for testing purposes.

Susceptibi l i ty

Susceptibility is t he cha racteristic of electronic equipment th atpermits u ndesirable responses when s ubjected to electr oma gnetic

energy.

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For more informat ion aboutHewlett-Packard test and measure-ment products , appl i cat ions ,serv i ce s , and for a current sa l e s

of f i ce l i s t ing , v i s i t our we b s i t e ,http :/ /w ww.hp .com/go/tmdir . Youcan also contact one of the followingc e n t e r s a n d a s k f o r a t e s t a n dmeasurement sales representative .

United States:Hewlett-Packard CompanyTest and Measurement Call CenterP.O. Box 4026En glewood, CO 80155-40261 800 452 4844

Canada:Hewlett-Packard Canada Ltd.5150 Spectru m WayMississauga, OntarioL4W 5G1(905) 206 4725

Europe:Hewlett-PackardEuropean Marketing CentreP.O. Box 9991180 AZ Amst elveenThe Netherlands(31 20) 547 9900

Japan:Hewlett-Packard J apan Ltd.Measurement Assistance Center9-1, Takakura-Cho, Hachioji-Shi,Tokyo 192, JapanTel: (81) 426-56-7832Fax: (81) 426-56-7840

Latin America:Hewlett-PackardLatin American Region Headquarters5200 Blue La goon Dr ive, 9th F loorMiami, Florida 33126, U.S.A.(305) 267 4245/4220

Australia/New Zealand:Hewlett-Packard Australia Ltd.31-41 Joseph St reetBlackburn, Victoria 3130, Australia1 800 629 485

Asia Pacific:Hewlett-Packard Asia Pacific Ltd.17-21/F Shell Tower, Times Square,1 Math eson Street, Causewa y Bay,

Hong KongTel: (852) 2599 7777Fa x: (852) 2506 9285

hp-an1302_making radiated and conducted compliance measurements with emi receivers

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