NS' 0= STAND & TECH

NBSIR 75-936 aiiio? 5ao5^

NI8T

PUBLicATONS REFERENCE

THE NATIONAL ELECTROMAGNETIC MEASUREMENT SYSTEM

Robert A. Kamper

Electromagnetics Division

Institute for Basic Standards

National Bureau of Standards.

Boulder, Colorado 8C302

June 1977

loo

/977
I

0
NBSIR 75-936

THE NATIONAL ELECTROMAGNETIC MEASUREMENT SYSTEM

Robert A. Kamper

Electromagnetics Division

Institute for Basic Standards

National Bureau of Standards

Boulder, Colorado 80302

June 1977
I

1

i
NBSIR 75-936

THE NATIONAL ELECTROMAGNETIC MEASUREMENT SYSTEM

Robert A. Kamper

Electromagnetics Division

Institute for Basic Standards

National Bureau of Standards

Boulder, Colorado 80302

June 1977

U.S. DEPARTMENT OF COMMERCE, Juanita M. Kreps, Secretary

Sidney Harman, Under Secretary

Jordan J. Baruch, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Acting Director

CONTEiNTS

Page

EXECUTIVE SUMMARY 1 1. INTRODUCTION 3 2. STRUCTURE OF THE ^EASUREMB^T SYSTEM 6 2.1 Conceptual System 5 2.2 3asic Tscnnical Infrasxructure 7 2.2.1 Documentary Scecification System 7 2.2.1.1 Stanaardization Institutions 7 2.2.1.2 Sarvey of jocumentary Standards 7 2.2.2 Instrjmentation System , 7 2.2.2.1 Measurement Tools and Technicues 7 2.2.2.1.1 C'A Transmission Line Systems 7 2.2.2.1.2 Antennas 3 2.2.2.1.3 Noise 9 2.2.2-. 1.4 Time Domain 9 2.2.2.1.5 Field Strength 9 2.2.2.1.5 Lasers 10 2.2.2.2 The Instrumentation Inoustry 10 2.2.3 reference Data 10 2.2.4 Reference Material 10 2.2.5 Science and People 10 2.3 Table 2. Realized Measurement Capabilities 11 2.4 Dissemination and Enforcanent Network 13 2.4.1 Central Standara Authorities 13 2.4.2 State arc Local Offices of Weight, and "Measures 13 2.4.3 Stanaaras and Testing Laooratories ana Services 14 2.4.4 Regulatory Agencies 14 2.5 Organizational Innut-OutDut Transactions Matrix 15

2.5.1 Analysis of Suopliers and L'sers 15 2.5.2 Highlights re Major Users 15

3. IMPACT, STATUS AND TRENDS OF THE MEASUREMENT SYSTEM 18

3.1 Impact of Measurem.ents 18 3.1.1 Functional 18 3.1.2 Economic 19 3.1.3 Social 20 3.2 Status and Trends of the System 21 4. SURVEY OF MSS SERVICES • 22

4.1 The Past 22 4.2 The Present-Scooe of NBS Services 24

4.2.1 Description of NBS services 24 4.2.1.1 Guided Wave Metrology 24 4.2.1.2 Electromagnetic Sensing Metrology 24 4.2.1.3 Electromagnetic Interference/Radiation Hazards 24 4.2.1.4 Signal Waveform Metrology 25 4.2.1.5 Antenna Systems Metrology 25 4.2.2 Users of NBS Services 25 4.2.3 Alternate Sources 25 4.2.4 Funainc Sources for NBS Services 26 4.2.5 Mecnanism -or Supplying Services 26 4.3 Impact of NBS services 26 4.3.1 Economic Impact of Major User Classes 26 4.3.2 Technological Imoact of Services 25 4.3.3 Payoff from Changes in NBS Services 27 4.4 Evaluation of NBS Program 27 4.5 The Future 27

5. SU^^^ARY AND CONCLUSIONS 23 A?°ENDIX A. METHODOLOGY OF "HE STUDY (AND AC:<I^OWLEDGMENTS ) 29 APPENDIX 3. INSTRUMENT MANUFACTURERS 30 APPENDIX C. LABORATORIES AND CAPABILITIES 35

iii
LIST OF FIGURES

Page

Figure 1. Spectral distribution of electromagnetic background noise and

atmospheric transmission... 4 Figure 2. Direct measurements transactions matrix for lasers 16 Figure 3. Direct measurements transactions matrix for electromagnetics 17

LIST OF TABLES

Table 1. Common Electromagnetic Quantities 6 Table 2. Realized Measurement Capabilities 11
THE NATIONAL ELECTROMAGNETIC MEASUREMENT SYSTEM

Robert A. Kamper

Electromagnetics Division

EXECUTIVE SUMMARY

Electromagnetic technology is the practical exploitation of electromagnetic waves, propagating either in transmission lines or freely through the atmosphere, and occupying

a very wide spectrum of frequencies. It has grown up within the limitations set by nature.

In the range of frequencies below a few

hundred MHz components are cheap, most

antennas are not very directional, and the background is noisy. This part of the spectrum is very heavily used by telecommunication systems, both for business and for

pleasure. High performance brings no significant advantages to these systems, so accurate measurements of the characteristics of

components are rarely called for. The FCC keeps order among the various users of the spectrum by assigning frequencies, which are checked routinely, and power levels, which

are rarely enforced. Many electronic systems,

such as computers and servo control systems,

are unintentional transmitters and receivers

of electromagnetic radiation in this part of

the spectrum. Interference is therefore a severe problem, that calls for repeatable

measurements of complex, fluctuating quantities, to be used a the basis for the assignment of responsibility for its resolution .

An extreme case of electromagnetic

interference occurs when fields are strong

enough to injure people. This is a real danger with radio and TV transmitters and leaking microwave ovens. Exposure to haz- ardous fields is regulated by OSHA, supported

by measurements of the field levels in question.

Another aspect of electromagnetic waves

in this part of the spectrum that is not yet

fully exoloited is their ability to penetrate

to useful distances in rock, soil, concrete,

water, etc., to probe structures of these

materials to supply information for civil

engineering, mining, or agriculture. This

will require extensions in the formulation

of electromagnetic theory and the acquisition

of a base of data on the properties of materials, wnicn are the subjects of research

that is in progress now.

At frequencies in the range from about

300 MHz to 30 GHz we find a higher prepon- derance of more sophisticated systems. Here wavelengths are short enough that highly

directional antennas are quite common. The

background noise is low enough to enable

systems to operate with very weak signals.

This range of frequency is used by most of

the radar systems on which modern navigation

depends, both for ships and for airplanes.

Improved systems such as discrete address

microwave beacons are under development for air navigation. Microwave systems are under

development for landing in conditions of poor visibility. The armed services use radar for the automatic guidance of terrainfollowing aircraft and of weapons, as well

as for searching for the enemy. On the

highways, the police use radar for speed

control

.

In addition to radar, this region of the spectrum is used for telecommunications.

Most long-distance telephone traffic is carried by microwave beams between repeater

stations in direct line of sight with each

other. Satellite communications are a rapidly growing business. The driving force

in the expansion of the telecommunications

industry is the trend towards having distant

computers coirmunicate directly with one

another. In addition to demanding large

channel capacity, computers and the associated digital technology encourage a trend

towards digital communication, and separating

different messages in time rather than

frequency. This also has advantages for

transmitting the voice, in the efficiency of

use of channel capacity and the quality of

tne transmission. This is generating a new demand for time-domain measurements. The electromagnetic systems that use this part

of the spectrum tend to be expensive, but do repay their expense with very high performance if they are carefully designed and maintained. For this they require the support of accurate measurements.

The region of the spectrum from 30 GHz to 300 GHz is presently regarded mainly as an overflow for users of the crowded channels

at lower frequency. Components become much

more expensive and less efficient in this region, and the atmosphere has strong absorption bands. The most significant commercial

system, under development in several countries,

is for telecommunication at 90 GHz through

oversize circular waveguides.
There is not much commercial activity at frequencies between 300 GHz and TOO THz. There is much scientific activity in the de- velopment of lasers, and the world's most

accurate spectroscopy is done in this region.

Surely commercial or military exploitation

will follow, especially of the laser,

which can already be made to be cheap, efficient, and powerful. There is some activity

with military funding to develop it into a weapon, and the most significant measurements

to be made are of its beam profile and energy output.

The near infrared and visible parts of

the spectrum are used for all the activities

that the possession of eyesight has suggested

to us, in addition to some that had to await

the development of instruments. These

include the remote sensing of temperature by

radiometry, and all the possible applications

of visible lasers, such as alignment and measurement of linear displacement, micromachining and surgery, holography, information processing (especially Fourier trans- formation), video disc recording, and auto- matic checking of groceries at the supermarket. 'Obviously, a very diverse collection of measurements must be made to support

these activities, not the least important of

which is the measurement of power and energy

to regulate safety.

One newly developing optical technology

that has much in common with the corresponding microwave techniques is telecommunication through optical fibers and the

integrated electro-optical systems that will

be used for transmitters and receivers.

These will call for all the types of mea- surement that have been made on microwave

systems, translated to a different region of

the spectrum with different difficulties and

conveniences.

In general, electromagnetic measurements

do not attempt to attain the degree of accuracy that is possible for dc electrical measurements. Practical systems must be designed to tolerate variations of a few percent

in circuit parameters due to instability of

components and variations in operating con- ditions. Therefore measurements with uncertainty less than 0.1% are rarely called for.

Another striking feature of the electromagnetic scene is the high demand for measurements of dimensionless quantitites, such

as attenuation, phase angle, reflection

coefficient, and antenna gain. There are national standards and calibration services

for many of these, but the trend is to replace them with self-calibration techniques.

Reference to the SI base units is tem- pered by the modest requirement for accuracy. The ohm can readily be independently

realized in the form of a length of trans- mission line whose characteristic impedance

can be calculated from its geometry. The

amplitude of waves is determined by measuring power, voltage, current, electric, or magnetic field. The essential step in all these measurements is the conversion of the

quantity to be measured to an equivalent dc

quantity. Reference of the latter to the basic SI units is a trivial step at the

level of accuracy required.

The foreseeable future challenges to the National Electromagnetic Measurement System

will come from: heavier use of the "underdeveloped" parts of the spectrum, such as millimeter waves, and the infrared and visible, for communication; wider use of multimode transmission lines; the quest for opti- mum use of time division multiplexing and

the consequent need for the precise characterization of the time-domain response of

devices, systems, and materials; and the new forms of interference that all this activity

will generate.

2
1 . INTRODUCTION

Electromagnetic technology is the practical exploitation of electromagnetic waves, propagating either in transmission lines or freely through the atmosphere. These waves

are useful over a very wide spectrum of frequencies, and this section will start with

some general remarks about the characteristics of various regions of that spectrum.

It will then continue with a survey of the most significant commercial, military, and

scientific activities that use the various

parts of the spectrum, speaking particularly

to the nature and quality of physical measurements and standards that they require

for support.

For practical purposes, two of the most

important cnaracteristics of the electromagnetic spectrum are the transparency of the atmosphere and the amount of background

noise and their variation with frequency.

These are illustrated in figure 1.

The atmosphere is essentially transparent

at frequencies below about 1 GHz. In clear

weather this transparency extends somewhat

above 10 GHz, but the liquid water in falling

rain begins to show significant absorption

between 1 and 10 GHz. Between 10 GHz and

1 THz there are some very strong molecular

absorption bands, separated by "windows" of

moderate transparency. Between 1 THz and

10 THz the atmosphere is opaque, and so are most solid and liquid materials. This is the range of frequencies at which most

molecules vibrate, absorbing radiation very

strongly. At frequencies above 10 THz the molecular absorption bands become more

widely separated again until we come to the

prominent "window" through which we see visible light. Higher frequencies than this

take us into ionizing radiation, which is discussed in R. S. Caswell's report on the National Measurement System for Ionizing

Radiation (NBSIR 75-946).

At frequencies below about 100 MHz the world is very noisy, the sources being thunderstorms, the activity of the ionosphere

and the galaxy, and the activities of man.

In the range from a few hundred MHz to 10 GHz the background noise is much lower

and is associated with localized sources

such as the sun, the moon, and various radio

stars. An antenna pointed at the regions of

the sky in between these objects sees only

tne thermal noise from the cold background

of the universe, at a temperature of about

3K. At higher frequencies where the atmosphere has appreciable absorption, the background noise corresponds to thermal noise at

the temperature of the atmosphere, a few hundred K.

Electromagnetic technology has grown up within the limitations set by nature. In the range of frequencies below a few hundred

MHz, components are cheap, most antennas are

not very directional, and the background is noisy. This part of the spectrum is very

heavily used by telecommunication systems,

both for business and for pleasure. High

performance brings no significant advantages

to these systems, so accurate measurements

of the characteristics of components are rarely called for. When they are required,

the components in question are usually parts

of microwave systems. The FCC keeps order

among the various users of the spectrum by

assigning frequencies, which are checked

routinely, and power levels, which are rarely enforced. Many electronic systems, such

as computers and servo control systems, are unintentional transmitters and receivers of

electromagnetic radiation in this part of

the spectrum. Interference is therefore a severe problem, that calls for repeatable measurements of fluctuating quantities, to be used as the basis both for agreement on

the assignment of responsibility for its resolution and for changes in engineering

design to reduce its effects.

The extreme case of electromagnetic in- terference occurs when fields are strong

enough to injure people. This is a real danger with radio and TV transmitters and

leaking microwave ovens. Exposure to hazardous fields is regulated by the Radiation

Control for Health and Safety Act (PL90-602),

and the Occupational Health and Safety Act

(PL91-596), which require supporting mea- surements of the field levels in question.

Another aspect of electromagnetic waves

in this part of the spectrum that is not yet

fully exploited is their ability to pene- trate to useful distances in rock, soil,

concrete, water, etc. They may therefore be

used to probe structures of these materials

to supply information for civil engineering,

agriculture, or mining. However, this will

require extensions in the formulation of

electromagnetic theory and the acquisition

of a base of data on the properties of

materials. These are the subjects of

research that is in progress now.

At frequencies in the microwave range,

from about 300 MHz to 30 GHz, we find a higher preponderance of more sophisticated

systems. Here wavelengths are short enough

that highly directional antennas are quite

common. The background noise is low enough

to enable systems to operate with very weak

signals. This range of frequency is used by most of the radar systems on which modern

navigation depends. Radar sets are carried

3
ATMOSPHERIC TRANSMISSION

CLEAR

ABSORPTION

BANDS

BLACK

ABSORPTION

BANDS

CLEAR

BACKGROUND NOISE

NOISY VERY QUIET QUIET NOISY

' FREQUENCY, Hz

Figure 1. Spectral distribution of electromagnetic background

noise and atmospheric transmission.

4
by ships and airplanes to give warning of

potential collisions and severe weather.

They are also placed at stations on the

ground to determine the positions of aircraft

to supply information for traffic control. More sophisticated microwave beacons are under development for air navigation.

Microwave systems are under discussion and

development for landing in conditions of

poor visibility. The armed services use

radar for the automatic guidance of terrainfollowing aircraft and of weapons, as well

as for searching for the enemy. On the highways, the police use radar for enforcing

the speed limit.

In addition to radar, the microwave

region of the spectrum is used for telecommunications. Most long-distance telephone

traffic is carried by microwave beams between

repeater stations in direct line of sight

with each other. Satellite communications

are a rapidly growing business. The most

coimon frequencies are 4 GHz and 6 GHz, and

development work is in progress to use higher frequencies. One of the driving

forces in the expansion of the telecomnunications industry is the trend towards having

distant computers communicate directly with

one another. This enables large corporations

to operate branch offices very efficiently,

and specialized companies are being formed

to serve this market. In addition to demanding large channel capacity, computers and

associated digital technology encourage a trend towards digital communication, and separating different messages in time rather

than frequency. This also has advantages

for transmitting the voice, in the efficiency

of use of channel capacity and the quality

of the transmission. The trend towards

digital communication is generating a new demand for time-domain measurements.

The major scientific uses of this part of

the spectrum are in radio astronomy and molecular ana solid state spectroscopy.

The electromagnetic systems that use the microwave part of the spectrum tend to be expensive, but the favorable natural conditions in which they operate enable them to repay their expense with very high perfor- mance if they are carefully designed and

maintained. For example, satellite communication systems are very expensive to install.

An orbiting satellite costs about S3G million, and is designed to last about 5 years, and the cost of a ground station

varies in the range from S2Q0 thousand to S5 million. Nonetheless, the channel capacity

of the system can be large enough to offer

communication services at very competitive

prices. Furthermore, since the cost of transmission is indeoenaent of distance, the economics of long distance telecommunications

are drastically altered. These systems call for accurate measurements of the electromagnetic characteristics of components, both

during manufacture and acceptance and for

routine maintenance.

The next region of the spectrum, from

30 GHz to 300 GHz, is presently regarded

mainly as an overflow for users of the crowded channels at lower frequency. Components become much more expensive and less efficient in this region, and the atmosphere

has strong absorption bands. These absorption bands are seen as an advantage for some military short-range systems that can use

the attenuation of the atmosphere to avoid

detection and interference from greater

distances. The most significant commercial

system, under development in several countries,

is for telecommunication at 90 GHz through

oversize circular waveguides, which minimize

the effect of atmospheric attenuation.

There is not much commercial activity at frequencies between 300 GHz and 100 THz. There is much scientific activity in the development of lasers, and the world's most accurate spectroscopy is done in this region. Cormiercial or military exploitation

are expected to follow, especially of the

CO2 laser, which can already be made to be cheap, efficient, and powerful. There is some activity with military funding to develop it into a weapon, and the most significant measurements to be made are of

its beam profile and energy output.

The near infrared and visible parts of

the spectrum are used for all the activities

that the possession of eyesight has suggested

to us, in addition to some that had to await

the development of instruments. These

include the remote sensing of temperature by

radiometry, and all the possible applications

of visible lasers, such as alignment and measurement of linear displacement, micromachining and surgery, holography, information processing (especially Fourier trans- formation), video disc recording, and auto- matic checking of groceries at the super- market. Obviously, a very diverse collection of measurements must be made to support

these activities, not the least important of

which is the measurement of power and energy

to regulate safety.

One newly developing optical technology

that has much in common with the corresponding microwave techniques is telecommunication through optical fibers and the integrated electro-optical systems that will be used for transmitters and receivers. These

will call for all the types of measurement

that have been made on microwave systems,

translated to a different region of the spectrum with different difficulties and conveniences

.
2. STRUCTURE OF THE MEASUREMENT SYSTEM

2.1 Conceptual System

A complete description of an electromagnetic wave would have to specify the magnitudes of the three components each of electric and magnetic field, their distribution

in space, and their variation with time.

This is too much information either to obtain

or to use for most practical purposes, so more specialized measures have been defined

to convey more limited information about the wave and its interaction with devices and

materials. Table 1 is a list of the electromagnetic quantities that are most commonly

measured, and their units.

Table 1: Common Electromagnetic

Quantities

Quantity

Electric field

Electric Displacement

Magnetic Field

Magnetic Flux Density

Voltage

Current

Power Complex Impedance

Complex Admittance

Components of the Complex

Scattering Matrix

Impulse Response Function

Unit

Vm

'

Asm' Am

Vsm

VA

U

n

•1-2

1

dimension! ess

dimension! ess Complex Reflection Coefficient dimensionless

VSWR dimensionless

Attenuation dimensionless

Gain dimensionless

Phase Shift dimensionless

Q-Factor dimensionless

Antenna Gain dimensionless

Antenna Pattern dimensionless

Efficiency dimensionless

Noise Temperature K Noise Figure dimensionless

1 Spectral Density

Frequency*

Wavelength

Rise Time

Complex Relative

Pemi tti vi ty

*Frequency is discussed in A. S. Risley's

report on the National Measurement System

for Time and Frequency (NBS Soecial Publication 445-1 (1976)).

WHz

Hzm

s dimensionless

Quantity

Complex Relative

Permeabil ity

Dielectric Loss Tangent

Conductivity

Reflectivity

Unit

dimensionless

dimensionless

n'^m"^ dimensionless

It is obvious that there is a high degree

of redundancy even in this list, even though

it excludes many quantities that are only

occasionally used.

In general, electromagnetic measurements

do not attempt to attain the degree of accuracy that is possible for dc electrical mea- surements. The basic reason for this is that

the reflections from connectors and bends in transmission lines, and variations in atmo- sheric conditions and the movement of reflecting objects, all cause variations of a few

percent in the characteristics of parts of a system during normal use. With very few ex- ceptions practical systems are designed to tolerate errors of comparable magnitude, so measurements with uncertainty less than 0.1%

are rarely called for.

Another striking feature of the electromagnetic scene is the high demand for measurements of dimensionless quantitites, such as attenuation, phase angle, reflection coefficient, and antenna gain. These are the quantitites that determine the ability of a sys- tem to transmit electromagnetic energy. There are national reference standards and

calibration services for many of these dimensionless quantities, but the trend is to replace them by self-calibration techniques.

The impedance of transmission lines and

the amplitude of electromagnetic waves re- quire reference to the basic units of the Systeme International (SI). In practice,

the ohm can be realized independently with

sufficient accuracy in the form of a uniform

transmission line whose characteristic im- pedance can be calculated from its linear dimensions and the permittivity of the dielectric (usually air). This is a convenient

standard to which to refer the impedance at the ports of devices by measurements of re- flection. The amplitudes of v/aves are de- termined by measuring power, voltage, current, electric field, or magnetic field,

whichever is most convenient. The essential

step in all these measurements is the con- version of the quantity to be measured to an equivalent dc quantity that can be comoared

directly with the realized SI electrical

units. In practice, the final step of ref- erence to the national electrical standards

is trivial at the level of accuracy required.

It is often left to the manufacturer of an instrument such as a digital voltmeter.
2.2 Basic Technical Infrastructure

2.2.1 Documentary Specification System

2.2.1.1 Standardization Institutions

In this section we consider voluntary spec- ifications, or "paper standards," as distinct from physical standards and enforced

regulations. These voluntary specifications

cover topics such as definitions of technical terms and symbols, recommended test and measurement methods, and the performance,

reliability, compatibility, and safety of

produces. They make a significant contribution to greasing the wheels of commerce.

The dominant international organization

is the International tlectrotechnical Com- mission (I EC). This draws its members from

National Committees in each of the member

countries. (The International Bureau of

Weights and Measures (3IPM) keeps physical

standards that have very little direct in- fluence on electromagnetic measurements).

In addition to the National Committees of the

lEC, each country has a plethora of standardizing institutions that may or may not share

members with one another and the lEC. One

such institution of particular significance

is the European Committee for Electrical

Standardization (CENELEC), which speaks for

all the members of the European Comnon Market.

In the United States, the institution with

the greatest influence is the Department of Defense. It is the largest purchaser of electromagnetic equipment and the leader in developing the technology, so most commercial

products are designed to conform with the Military Specifications (MIL-S?ECs). Other

significant standardizing institutions are: the Institute of Electrical ana Electronics

Engineers (IEEE); tne Instrument Society of America (ISA); the Electronic Industries

Association (EIA); the Society of Automotive

Engineers (SAE); the Aerospace Industries

Association of America (AIAA); the American

Society for Testing and Materials (AST?*!); and

the American National Standards Institute

(.AfJSI). There appears to be little formal coordination of these organizations, and activities seem to be taken ud by one or another on the principle that 'nature abhors a vacuum."

The National Bureau of Standards takes some part in writing specifications, usually

in collaboration with one of the institutions listed In the previous oaragraoh, and especially wnen pnysical measurement metnoas

must be specified. This activity is increasing at oresent. The regulatory agencies

also write many specifications, which will

be spoken to in section 2.4.4.

2.2.1.2 Survey of Documentary Standards

The various organizations listed in section 2.2.1.1 tend to emphasize somewhat different types of standards. These can be sunmarized as follows:

* MIL-SPECs are standards of performance and

physical compatiblity of one device with

another. They often specify testing methods,

some of which need improvement.

* The professional societies, such as IEEE,

SAE, and ISA, tend to write standards of

terminology and engineering practice. These

often include testing methods. They also

write standards for physical compatibility.

* The trade associations, such as EIA and

AIAA, emphasize those standards that are of

mutual advantage to all the companies com- peting in their respective parts of the market.

* ASTM is concerned mainly with methods of

testing materials. It does cover electromagnetic prooerties of materials and laser

damage.

* ANSI covers a wide range of standardizing activities, including certifying pro- ducts for quality, performance, and safety.

It also attempts to coordinate the efforts

of the other standardizing institutions,

esoecially in the international arena.

2.2.2 Instrumentation System

2.2.2.1 Measurement Tools and Techniques

2.2.2.1.1 CW Transmission Line Systems

These comprise various active or passive

components connected together by uniform

transmission lines, which can be coaxial

lines, strip lines, or singly connected

waveguides. Until quite recently, it was almost universal practice to choose trans- mission lines that would support only a single mode of oropagation at the operating

freauency. The objectives of the measurements to be made are to determine the phase

and amoiituae of the electromagnetic waves traveling in either direction along the transmission lines, and the effect on these

Quantities of interaction with the components at the ends of the lines.

/
A great deal of useful information is conveyed by the n-dimensional scattering

matrix that specifies the relationship be- tween the waves passing into and out of the

n ports of one of the components and the connecting waveguides. In their usual form,

the coefficients of the scattering matrix are dimensionless quantities. They are measured

by measuring the relative amplitude and phase

of waves in different parts of the system.

The simplest way to compare amplitudes is to assume the linearity of a detector that converts each signal to dc that can be measured with a digital voltmeter. This is adequate if errors of a few percent and a somewhat restricted dynamic range can be tolerated. Greater accuracy and dynamic

range are attained by using reference standard attenuators, or with a heterodyne system

to convert both signals to a lower frequency

at which they may be compared with a ratio

transformer.

The measurement of phase angle requires

more trouble and expense than almost any other quantity. The phase angle between the

signal of interest and a coherent reference

signal must be measured. This can be done

by allowing the two signals to combine in an adjustable bridge and seeking a balance at which they cancel. A more elaborate way

that is commonly used in automatic systems

is to use mixers and a local oscillator to convert both signals down to an intermediate

frequency that is low enough to permit the use of phase-sensitive detectors to compare

phases directly. The most recent and sophisticated method employs the mathematics of

scattering theory, recognizing that measurements of the amplitude of the signals ai; four properly chosen points in a transmission line network supplied with two conerent

signals contain enough information to determine the relative phase and amplitude of

the two signals. A simple calibration technique and a small computer to perform the necessary matrix manipulations comprise the

remainder of a practical measuring system.

This is known as a e-porv system.

At the level of accuracy generally re- quired for microwave measurements (0.1%), it

is comparatively straightforward to make an independent realization of the ohm, in the form of a uniform coaxial transmission line

whose characteristic impedance Z may be calculated from the radii of the inner and outer conductors and the permittivity of the dielectric (usually air) between them. The

impedance Z at the port of a component con- nected to this line is referred to Z by

measuring the complex reflection coefficient

r, and using

Z = ZQ-(l+r)/(l-r).

When the characteristic impedance of the line

is known, the amplitudes of electromagnetic

waves can be referred to the SI units by measuring the power absorbed in an approximately

matched (i.e., ref lectionless) termination of

a transmission line. The device commonly

used is a bolometer, with which the heating

effect of the absorbed wave is compared with

that of a direct (or low frequency) current

flowing through the same resistive element,

thereby converting the measurement to one of

dc (or low frequency) current and voltage.

Corrections must be made for: residual re- flections; absorption of some rf power in parts of the bolometer other than the in- tended resistive element; and differences

between the spatial distributions of the heating effects of the dc and rf currents. Calibration of a bolometer consists of the evaluation of these corrections. It is interesting to note that although calorimetry is employed in the process, the results

are expressed as dimensionless ratios. It is

a dc calibration that carries the burden of

the reference to the SI units. RF voltage is measured by a device that is similar to a bolometer but severely mismatched to the transmission line (it has a very high impedance) .

These basic principles are applied in systems that fall in a wide range of sophistication, accuracy, and cost. There has been a constant evolution from simple bridge

circuits that must be manually tuned up and

balanced at each operating frequency, through

self-balancing bridges, to fully automatic

systems controlled by computers that electronically switcn the frequency and other

ooerating parameters, measure the transmission properties of the system both with and

without the device under test inserted in it, and compute the desired scattering parameters of the device under test from the stored

information obtained by these operations.

2.2.2.1.2 Antennas

At frequencies above about 1 GHz, antennas of moderate size have linear dimensions that encompass several wavelengths.

The consequence of this is that the angular

distribution of radiated power is usually

very anisotropic, with distinct "lobes" of strong radiation and sensitive reception.

This can be a nuisance or it can be exploited

by the designer of a radar or communication

system striving for high performance, but

in either case it must be measured.

8
The quantity of interest is the distribution of radiated power and polarization in the "far-field," at distances greater than

d /\ where emitted radiation can be regarded

approximately as a plane wave, (d is the

aperture of the antenna and x is the wavelength.) Early methods of making these measurements required large antenna ranges. Although these are kept as clear as possible

of obstructions, unwanted reflections from

the ground, buildings, etc., still set a limit to attainable- accuracy. Recently,

techniques have been developed to use near- field scanning combined with a mathematical

reconstruction of the far field. There is also a somewhat simpler extrapolation technique which can measure just the gain of the antenna in one direction. The workhorse of antenna standards is the "standard gain

horn," a simple antenna with a calculable

radiation pattern.

2.2.2.1.3 Noise

Noise sets the lower limit to the power

level at which a radar or communication system can work. In the microwave range, where

the background noise is very low and the atmosphere is transparent, the limiting noise

is apt to be within the system itself. The

ultimate lower limit is the thermal noise

power P(T), described by Nyquist's formula

P(T) = / kTdf

where k is Boltzmann's constant, T is the

absolute temperature, f is the frequency, and

the limits of integration are set by the pass

band of the system. The primary standards of

noise are matcned (reflectionless) terminations of transmission lines maintained at controlled temperature. These are often used

as working reference standards also, together

witn gas discharge tuoes, semiconductor

diodes and radio stars. All these must be calibrated against a primary standard. The

instrument used to compare a noise source with a reference standard is a radiometer.

The most commonly used type is the Oicke

radiometer, which simply switches the two sources rhythmically to a sensitive detector

and records the component of the detected

signal ai tne switcning frequency with a synchronous detector. The weaKness of this

system is the switcn, wnich may be eliminated

by more sophisticated correlation techniques.

2.2.2.1.4 Time Domain

which is at present a more primitive art

than the corresponding measurements in the frequency domain. The traditional tool is the real-time oscilloscope, but it has limited

speed ana accuracy. Better performance can

be obtained by sampling techniques, especially with repetitive waveforms. The basic

tool for this is the sampling oscilloscope,

that samples successive parts of the waveform from each repetition. A more sophisticated system digitizes the information

in these samples, and stores and manipulates

it in a computer. In combination with a suitable signal source, a system like this

can be used to characterize the response and

transfer functions of transmission line

networks to impulsive signals. Such a system is known as a time domain network

analyzer. Work is in progress to increase

the operating range of these systems, par- ticularly in the resolution of short pulses,

and to develop the transducers required to make these measurement techniques accessible

to optical pulses.

2.2.2.1.5 Field Strength

The most important reason to measure electromagnetic field strength is to control

electromagnetic interference (EMI) and the exposure of people to hazardous fields. The

fields to be measured are therefore usually

random and impulsive in nature, and often in the near-field zones of their sources. The

best measuring devices at microwave and radio

frequencies are small dipole antennas, con- nected to receivers by lines that are designed

to minimize the perturbation of the field to be measured. These instruments need to be calibrated in standard fields, which can be set up with standard antennas inside anechoic

chambers at frequencies above 1 GHz. Below

1 GHz, the transverse electromagnetic (TEM) cell can be used. These facilities are also

well adapted for investigating the effects

that EMI and hazard probes are meant to guard

against. A great deal of such testing is done in undamped screened enclosures, and is prone to large errors because of the presence

of standing waves.

The instruments available at present lack

the full dynamic range and frequency range, and particularly the speed of resDonse,

that is needed. Work is in progress to remedy this, and to develop probes for baseband

impulse fields.

The current trend towards digital communication and time division multiplexing is increasing tne importance of the characterization of waveforms in the time domain.

9
2.2.2.1.6 Lasers

The quantities that characterize a laser

beam are: average power (long term);

"instantaneous" power (averaged over a specified interval of time controlled by the measuring equipment); energy (in a pulse);

frequency (or wavelength) spectrum; spatial

beam profile; and temporal pulse shape. Measurement of frequency is included in

A. S. Risley's companion report on the

National Measurement System for Time and

Frequency (NBS Special Publication

445-1, 1976). Of the other quantities, only

power and energy are the subjects of an organized measurement system. The basic measurement tools are calorimeters that com- pare the energy received from a laser beam in

a controlled interval of time with an equivalent amount of energy supplied electrically.

Imperfections such as backscatter and differences between optical and electrical

efficiency are usuallly calculated with some support by auxiliary measurements. Photodiode detectors (usually silicon) are used

when short response time or sensitivity to low power levels are needed. They can be calibrated against calorimeters with the

aid of a calculable attenuator consisting

of a thin prism in which a laser beam suffers multiple internal reflections, dividing

its energy according to Fresnel's formula.

2.2.2.2 The Instrumentation Industry

There is a healthy instrumentation in- dustry that supplies the bulk of the equip- ment needed for testing and tuning up working electromagnetic systems. The most clearly "electromagnetic" part of the total market is that which covers microwave test and

measuring instruments. This is projected to amount to SI 45 million in sales in the U.S.

in 1976. Appendix 8 is a list of U.S. man- ufacturers of this equipment, categorized

by the quantities it is intended to measure.

The giant among the customers of this

industry is the Department of Defense, which

develops and uses the most advanced radiofrequency and microwave systems. A large

quantity of test and measuring equipment is needed for maintenance of these systems.

2.2.3 Reference Data

the first three volumes of a series of Me- trology Guides, that give a systematic expo- sition of all available techniques for measuring a given quantity. There is a need

for more of these, and also for a classic

text summarizing the whole field of electromagnetic measurements, explaining the general principles and their application to spe- cific problems. Ginzton's book "Microwave Measurements" filled this need in its time,

but that was 20 years ago, and the field

has matured considerably since then. A successor is needed.

2.2.4 Reference Material

There is at present no organized source

of reference materials for electromagnetic

measurements. It will be necessary to create

one to support full use of remote electromagnetic sensing. The U.S. Department of

Agriculture may well become the repository

for the first certified reference materials

for dielectric measurements.

2.2.5 Science and People

The dominant professional society in the field of electromagnetic measurements is the Institute for Electrical and Electronic

Engineers (IEEE). It publishes journals

(including IEEE Proceedings, IEEE Transactions

on Microwave Theory and Technique, IEEE Transactions on Instrumentation and Measurement), writes standards of practice and performance, and sponsors professional meetings. The National Conference of Standards

Laboratories (iNCSL) also provides a forum for exchange of metrological philosophy and technique at its conference and in its Newsletter. Other societies with some interest in the field are the Instrument Society of

America (ISA), and the U.S.. National Com- mittee of the International Scientific Radio

Union (URSI). Both of these organizations

sponsor conferences.

The most important conference devoted to electromagnetic measurements is the biennial

Conference on Precision Electromagnetic Measurements. This conference is sponsored

jointly by NBS, IEEE, and URSI. The Proceedings are published in the following

December issue of the IEEE Transactions on Instrumentation and Measurement.

Very few reference data are used in electromagnetic measurements, and most of them

are round in regular engineering and mathematical handbooks. Descriptions of techniques and methods are usually found in pro- fessional society journals and other publications of the same kind. NBS has published

10
2.3 Table 2. Realized Measurement Capabilities

QUANTITIES

Impedance

RANGES

Attenuation

TYPE Or MtASUREMENT

Frequency Dynamic

ACCURACi'

Res i Stance 30 kHz -

1 MHz

i 010^ ohms0.2 - 15%

250 f*z

20 - 5x10"* ohms

0.2 - 15

inuucxance

10 MHz

1 u

1 henries

U.I -

uapacitdnce

2 terminal

U.J - 250 MHz

-7

" 10 farads

U.I - liU.3

1 MU 7 10 ' farads

U.I - \ ,0

3 terminal 100 kHz

- 1 MHz 10-}^ - 10" farads

0.05 - 10%

Q 1000 Hz - 10 MHz

10-2 . 2 - S%

1000 Hz - 250 MHz

10-2 . >103

2 - 100%

Magnitude including

(VSWR of 1 to 4)

0.1 - 8 GHz

20 - 200

ohms

0.1=^ - 10%

Phase Angle 0.1 - 8 GHz 0 - 90° 0.1 - 10%

Phase Shift 1 - 8 GHz 0 - t/2

radians

0.4% - 10%

Coaxial Impedance 8 - 18 GHz 20 - 200 ohms

0.3% - 10%

Coaxial Phase of

Impedances

8 - 18 GHz 0 - 90° 0.3% - 10%

Length of equivalent

airl ines

0.1 - 8 GHz 5 - 30 cm 0.005 cm - 0.1 cm

Ref 1 ection

Coefficient

2.6 - 40 GHz 40 - 100 GHz0 - 0.2

0 - 0.2

1 - 10%

1 - 10%

Insertion Loss 1 MHz - 18 GHz

0 - 100 dS 0.C2 - 1 dB

18 - 40 GHz

C - 70 dB 0.2 - 1 dB

40 - 100 GHz

0 - 60 dB 0.05 - 2 dB

11
Table 2, continued

QUANTITIES TYPE OF MEASUREMENT

RANGES ACCURACY

Frequency Dynamic

Phase Shift 0.1 - 18 GHz

0 - 360° 0.1 - 3°

18 - 100 GHz

0 - 360° 3°

Delay 0.1 - 18 GHz

10-12 . 10'^ sec

0.5 - 1%

Power Instantaneous, CW,

Average, Effective

Efficiency

Coax

10 MHz - 17 GHz1 mW - 100 W 10-12 .

1 mW

1 - 10"»

5 - 20%

Waveguide

dn-Q"! GH7

1 Itln

1 w

1 mW - 1 W

7 - 1 fT" . / I U '0

3 - 10%

Peak Pulse 50 MHz - 18 GHz

0.1 mW - .10 kW2 - 10%

Vol tage Instantaneous, CW,

RMS, Average

30 kHz -

1 GHz

1 GHz - 2.5 GHz

30 kHz - 2.5 GHz

1 mV - 200 V

1 mV - 20 V Below

1 mV

0.01 - 15:

1 - 15%

=20%

Current No Known Needs

Noise Noise Temperature

[or in Excess Noise

Ratio above 290 K where applicable]

Coax:

lU nnz

18 GHz

Waveguide:

1 . 3 unz - 18 GHz and

18 GHz - 100 GHz

77 K - ju,uuu ^

77 K

- oU , UUU N

10,000 K

- 30,000 K

5-15%

10 - 25%

Impulse Noise Coax:

10 MHz - 18 GHz

0-120

dS above

1 yV/MHz

25 - 300%

Waveguide:

18 GHz - 40 GHz

0 - 140

dS above

1 uV/MHz

25 - 300%

Baseband Gaussian

Noise

10 Hz -

1 GHz

- 120 dBW

- 0 dBW ±0.2 dB

Amplitude and Phase NoiseCarrier:

1 MHz - 18 GHz Sideband Offset -165 dBc

10 Hz - per Hz 100 MHz Resolution

zl dB

12

1-
Table 2, continued

QUANTITIES TYPE OF MEASUREMENT

RANGES

Frequency Dynamic ACCURACY

Waveform

EM Fields

Laser Output

Transition Time

Pulse Amplitude

Field Strength

Antenna Gain

Power

-n

s -

Energy

2.4 Dissemination and Enforcement Network

2.4.1 Central Standard Authorities

The only central authority in this field

for physical standards in the U.S. is the National Bureau of Standards (NBS), which

maintains an Electromagnetics Division to provide standards and measurement services

in electromagnetic quantities. Intercomparison of electromagnetic standards with

other national laboratories does occur

occasionally, but it plays a very minor role

in maintaining statistical control of the measurement system. There is almost no interaction with BIPM connected with electromagnetic measurements. Although the SI electrical units are subject to frequent

international intercomparisons , these have

very little influence on the electromagnetic

measurements that are referred to them

because of the comoarati vely low level of accuracy that is called for.

The most sophisticated and highly organized part of the National Electromagnetic

Measuring System is that which serves the Department of Defense and its industrial contractors. Control of errors is maintained there by requiring that all measurements

10 Hz - 100 GHz

10 kHz - 100 GHz

28 THz

280 THz - 750 THz 280 THz - 750 THz

28 THz

280 THz - 750 THz

10

1 s

1 mV - 100 V 10-^.

10"* Volt/ meter

0 - 60 dB

50 mW

- 100 kW

1 nW -

1 mW

0.3 mW - 22 W

15 J - 7 MJ

10 mJ - 200 J

=0 - 50%

1 - 20%

3 - 20%

.25 - 2 dB

3/0

CO/ 3 10

1%

5%

'3<V

must be traceable to physical standards kept

at NBS. Army Regulation 750.25, Air Force Regulation 74-2, and Navy Regulation SEC

NAV 4355.14 require that the standards for

calibration of all military measuring instruments must be traceable to NBS. Similar re- quirements are imposed upon industrial de- fense contractors by the Military Specification MIL-C-45562A.

Professional societies such as the IEEE

and the SAE do publish recommendations for measuring techniques, but the physical standards to support these all reside at NBS.

2.4.2 State and Local Offices of and Measures

Weight,

State and local governments hold no formal electromagnetic standards. In California,

there is some talk of offering the calibration services of private comoanies under a state license, but this is more likely to be done for quantities that are more directly

subject to state regulation. It is conceivable that California and other State governments may take a more active interest in measurements of electromagnetic interference in the future.

13
2.4.3 Standards and Testing Laboratories

and Services

There are many private and federal govern- ment laboratories that are capable of electromagnetic measurements and calibrations. Appendix C is a list of these laboratories taken from the 1976 Directory of Standards Laboratories, published by the National Conference of Standards Laboratories (NCSL), an organization of which many of the listed laboratories are members.

Many of these laboratories serve either

the Department of Defense or defense contractors, and are therefore subject to the DoO regulations requiring traceability to NBS. At present, there is no formal mechanism

for assuring the compatibility of measurements and calibrations made by the remainder

of the laboratories on the list with national standards. In an attempt to remedy this

deficiency, the Department of Commerce has announced a National Voluntary Laboratory

Accreditation Proaram (see the Federal

Register, 40FR20092-95 and 41 FR8163-68)

.

This program is intended to cover all laboratories that request accreditation, but it

is in a very early stage of development. So far, one private company has applied for

accreditation to measure microwave power and

attenuation, and it will probably take at least two years to organize the necessary

inspection, certification, and connection to national standards.

2.4.4 Regulatory Agencies

Most of the regulatory agencies that use electromagnetic measurements do so to control the effects of excessive radiation:

either the direct hazard to people or interference with the functions of electronic

control and communication systems.

The Radiation Control for Health and

Safety Act of 1968 (PL 90-502) set limits

to the electromagnetic field strength that may be radiated by electronic products.

The classes of people most likely to be exposed to hazardous field strengths are the owners of leaking microwave ovens and people

who work near radio and TV transmitters.

The Bureau of Radiological Health (BRH) tests samples of the microwave ovens on the market for leaks, when they are new and also

after many openings and closings of their

doors. The Occupational Safety and Health

Administration (OSHA, authorized by PL 91-596)

inspects work places for hazards including

those from electromagnetic radiation in places where they are likely to be found.

The safety of lasers is also controlled

by BRH and OSHA. Following a standard published by ANSI (Z 136.1-1973), BRH classifies

lasers into four classes that are defined

according to the hazard of exposure to the direct beam that is accessible outside the case of the instrument. Class I lasers are regarded as perfectly safe under all conditions: one can stare directly into the beam with impunity. Class II is restricted

to visible, continuous wave lasers that

present a hazard similar to that of the sun: the direct beam is capable of damaging our

eyes but we instinctively avert them before

damage is inflicted. Class III includes

lasers from which our instinct is not sufficient to protect our eyes from damage:

the power is too great or the beam is pulsed

or the radiation is not visible. Class IV lasers can burn the skin. The ANSI stan- dard assigns boundaries to these classes

according to wavelength, average power, or

the energy and duration of pulses. BRH re- quires labelling of all commercial lasers

to specify which class they belong to. OSHA is in the process of defining the safety

precautions that industrial employers must

provide for workers exposed to the various

classes of lasers, and Executive Order 11807

will extend the OSHA regulation to the Federal Government.

The control of electromagnetic interference (EMI) by fields below the human hazard

level is a much more diffuse responsibility

that simply has not been properly organized

yet. The Federal Communication Commission

(FCC) issues licenses for transmitters,

which can be revoked when a nuisance is proven. However, some of the sources of interference are perfectly legitimate users of

the electromagnetic spec-rum, and some are unintentional emitters from equipment such

as internal combustion engines that are

not regulated directly by the FCC. In Canada, the Radio Act was recently amended

to cover emission of interference by such

equipment. In a series of dockets (20654,

20718, and 20780) the FCC has announced its intention to follow suit in the U.S. At

present, manufacturers of automobiles in the

U.S. all observe a voluntary standard, SAE J-551d, but there are many other kinds of gasoline-powered machines that do not con- form to it.

Motor vehicles can be victims of EMI as well as sources. The National Highway

Transport Safety Administration recently set

a standard for the braking performance of

trucks and buses (FMVSS-121) that can be met only by using an electronic servo system

14
to prevent locking and skidding of wheels.

These devices proved to be susceptible to interference from Citizens' Band radio

transmitters, and no doubt the regulation

•will need to be modified to specify a rea- sonable degree of immunity to this problem.

The principle of regulating the victim

rather than the often inaccessible source

of EMI is carried further in bills introduced into the Congress by Charles Vanick

(HR 7052) and into the Senate by Barry

Goldwater (S 3033). Among other provisions,

these bills would require equipment such as 7/ sets to have filters to make than rea- sonably insensitive to the parts of the electromagnetic spectrum outsiae tne bands

they are designed to respond to. It is expected that Federal Drug Administration

(FDA) will be required to set limits to the susceptibility to interference of acceptable

medical electronic devices, such as heart

pacemakers and diagnostic equipment.

The Federal Aviation Administration

(FAA) maintains radio navigation aids such

as airport radar, VOR, and ILS. It therefore needs to make the measurements necessary to keep these systems working with

tolerable accuracy and also to conform to the OSHA regulations controlling the exposure of its employees to the fields generated by the associated transmitters. The

U.S. Coast Guard has similar responsibilities for marine navigation aids such as LORAN-C.

Finally, if any gaps are left in the pro- tection of the public from nuisance and haz- ard from electromagnetic radiation by these

various regulatory agencies, the Environmental Protection Agency (E?A) stands ready

to fill them. At present, it is engaged in

a survey of backaround fields throuchout

the U. S.

Althougn all these agencies have legal

responsibilities that require measuring

very complex electromagnetic fields, the necessary techniques are not yet fully de- veloped throughout the range in which they are needed. Work is in orogress, at NBS and elsewnere, to remedy this deficiency.

2.5 Organizational Input-Output

Transactions Matrix

2.3.1 Analysis of Suopliers and Users

The two essential components of an ac- ceptable measurement system are: a set of measurement techniques, supported by

available equioment and a complete understanding of sources of error; and a set of

accessible reference standards to enable

different people, measuring the same quantity by different techniaues, to make sure

that their results are consistent.

Electromagnetic measurement techniaues

are generally aeveloped by metrology

engineering laboratories (including the Electromagnetics Division of NBS), by

universities, and by the manufacturers of

instruments. They are passed on to the users by publications in professional journals (such as the IEEE Transactions on Instrumentation and '-leasurement and the

IEEE Transactions on Microwave Theory and

Tecnnique), at professional conferences

sucn as the Conference on Precision Electromagnetic Measurements, and by the de- tailed reporting that is usually reauired

to fulfill development contracts. The

major users at present are the Department

of Defense, the aerosoace industry, and

the teleconmunications industry. The trans- portation industry and the regulatory agencies are becoming significant users as they

face growing problems of interference with

electronic controls and radiation hazard to people. State and local government agencies are conspicuous by their absence from

the electromagnetic scene.

2.5.2 Highlights re Major Users

The Department of Defense and the Aerospace Industry tnat supolies it use electromagnetic tecnnology for surveillance,

navigation, guidance of weaoons and terrainfollowing aircraft, and communication.

They have developed very sophisticated

systems for these purposes, and these systems

reauire tne best available electromagnetic

measurements to ensure the comoatibi ity of components made by different manufacturers

and to maintain performance after they are installea. Control of this part of the 'iat- ional Measurement System is maintained by

requiring all calibrations of instruments to

be traceable to standards at NBS. To make

this possible the three armed services have

a hierarchy of calibration laboratories.

Laboratories at each level of this hierarchy

receive transfer standards from laooratories

at the next higner level. The too laboratories are the primary m.etrology centers at Newark, Ohio (Air Force); San Diego, California 'Navy); Washington, D. C. (Navy); and Huntsville, Alabama (Army). These laooratories have their reference standarcs calibrated by NBS. The manufacturers suoolying

the eauipment are left to fina their own paths

15
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KEY TO MATRIX E.'ITRIES lyPCRTA'lCE OF TRANSACTIONS

T = Purely convenience

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3 - RATE OF CHANGE

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17
for traceability to NBS. They do it partly

by having their own reference standards calibrated at NBS and partly by buying calibrated

test instruments from manufacturers who, in their turn, use reference standards calibrated at NBS.

The measurement system for high energy

COj lasers is now entirely controlled by the

DoD. These devices are being developed for weapons, and early disagreements on measuring their performance led to the formation

of an ad hoc committee among the armed

services, which assigned to NBS the task

of developing standard calorimeters to measure the energy delivered by these devices. At first the NBS calorimeters were taken

to the testing ranges for evaluation by NBS personnel. When they had been established as a measuring system under good

statistical control, they were transferred

to the custody of Newark Air Force Station,

where the service begun by NBS is being

continued.

Commercial airlines and ships use electromagnetic aids to navigation that are gen- erally derived from technology developed by the Department of Defense, but make lower

demands on performance.

The Te 1 ecommun i cations Industry serves

the home entertainment industry, emergency

services, and common carriers of information

such as telephone conversations and digital

data. The first two of these make very low direct demands on measurement technique.

They mostly use frequencies below about

200 MHz, so that performance is limited by

background noise rather than the engineering

of the equipment. However, these services

are an important part of the electromagnetic

interference problem, both as sources and as victims. The solution of this problem will

require regulations based on sound measurement techniques. The common carriers operate at a much higher level of technical

sophistication, and so demand good measurement techniques to maintain oerformance.

They must respond to a rapidly growing

demand for channel capacity as the direct

communication of digitized information

between computers is added to the already

vigorous telephone traffic. To meet this

demand, communication along wires has been

supplemented by multiplexed communication

along coaxial lines and 1 ine-of-signt ter- restrial microwave links. Large numbers of

microwave links via orbiting satellites are being added to these at present, and in the future fiber optic links will become importan

The giant among the common carriers is the American Telephone and Telegraph Company,

which is almost completely self-sufficient

in its measurement system, as it is in all its operations. Independent companies are appearing to take advantage of new types of

traffic, such as the direct communication of

data between computers, and new technology

such as satellite comnuni cation. These

companies must maintain close ties with the

overall U.S. National Measurement System,

because they buy their equipment from a variety of independent manufacturers.

The Regulatory Agencies depend heavily on measurements to set regulations and to enforce them. Their measurements must be able to survive challenges in court. They

usually derive their measurement techniques

from the sources described in section 2.5.1. They need national measurement standards

maintained at NBS for independent proof of

their accuracy.

3. IMPACT. STATUS AND TRENDS OF THE MEASUREMENT SYSTEM

3.1 Impact of Measurements

3.1.1 Functional

There are three fields in which electromagnetic measurements of high accuracy and

reliability are required in order to make

complex systems function. They are: military avionics; satellite communications; and remote sensing.

Since the time of World War II, the U.S. Department of Defense has been the world

leader in the development of rf and microwave

technologies applied to: early warning

radar; side-looking radar; the guidance of

terrain-following airplanes; the guidance of

weapons; navigation; and telecommunication.

Our national security and our national

bargaining position in international affairs

depend in no small measure on our leadership

in these technologies. The systems that

have been developed are very complex, and are assembled from components and subsystems procured from a wide variety of

manufacturers, both large and small, that

comprise the U.S. aerospace/defense industry.

All these components and sub-systems must be compatible with one another and must meet stringent specifications for performance.

This can be accomplished only if the three

armed services and the industry that serves

them have a unified system of physical measurements for the Quantities that specify

operating characteristics and performance.

18
The formal mechanism for setting up such a system of measurement is to require all measurements made by the three armed services

and their inaustrial contractors to be referred to standards that are traceable to the national standards maintained by "IBS. A close cooperation betiveen the electromagnetic measurement and standards program at

NBS and the Department of Defense has existed since 1958 and has contributed significantly to the success of the technology

it serves.

Satellite communications were developed

during the '5Cs, by a combination of the

Department of Defense and the National

Aeronautics and Space Administration, followed in due course by the CCMSAT Corporation,

which was formed when the time was propitious

for comm.ercial ization. This form of telecommunication depends on the reliable reception of very weak signals. This becomes

very obvious as one contemplates tne large

dish antennas that are used. The highest

performance is required of all comoonents

of the system, particularly the antennas. There is therefore a demand for accurate

measurements, both for "tuning up" the sys- tem and for acceptance of components from

their various manufacturers. One of the payloads that are planned for the 'JASA space

shuttle is an orbiting standards platform,

loaded with instruments to test satellite

communication systems. This will be used to calibrate ground stations, which in turn can then measure tne performance of flying sat- ellites. The whole of a satellite communication system must be monitored constantly to maintain reliable performance.

Remote sensing with rf and microwave ra- diation is a technique that has been developing slowly and is still a long way from

reaching its full potential. It depends on deducing variations in the dielectric proo- erties of unseen objects by measuring the scattering of electromagnetic radiation,

either in the form of snort pulses or in the form of continuous radiation with variable

frequency. The required information is ob- tained from quite small variations in the scattered radiation, and when dielectric

anomalies are founa, a connection must be estaolished .vith variations in comoosition

or structure before the information becomes

useful, aood electrom.agnetic measurement

techniaue is recuired, ccupleo with a data

base to aid interpretation. The most imcortant aopli cation of this technicue will be

to the aetecticn and measurement of moisture

in soil, ccncreta, grain, etc. It has also

oeen acolieo to maoping reck strata (incl'jcing coal seams), finding underground pipes

and voids, detecting plastic land mines, ano measuring tne depth of glaciers anc sea ice.

3.1.2 Economic

Of the three fields mentioned in the previous section, military avionics and satellite communications support large industries,

the latter of wnich is growing at a raoid

rate. If remote electromagnetic sensing ful- fills its promise as an aid to water management in farming, its direct economic effect

will be enormous. Another field that may develop a large economic significance in the next few years is the regulation of electromagnetic interference. Sales of the products

of various industries will depend upon proving compliance with regulations that are in the process of oeing written now.

The total 'J.S. military procurement of

electronic equipment was 514 billion in 1975, of which 34 billion was spent on avionics and missile guidance systems. In addition a large amount is spent on measurements to support maintenance of equipment

that is already in use. The Air Force alone

has about 160 field calibration centers

(PMELS) to maintain its measuring instruments.

Satellite communication systems serve a market of about SI billion per year, of

whicn half is civilian and half is military.

It is growing at the rate of 12!^ per year.

In the period from 1975 through 1983, there

are plans to launch 51 new satellites and

build at least 2900 new commercial ground

stations: 51 for the Intelsat system, 53 for

U.S. domestic use, 200 for shipboard use as part of the MARISAT program, and 25C0 in Brazil for a new communications network.

The Intelsat ground stations cost about S5 million each, the MARISAT terminals will cost about $20K each, and the others range from

$200K to 32M. Performance is at a premium,

and contracts bet,veen satellite users ano venders usually have incentive clauses which

pay 5 to 10"^ extra for radiated power exceeding an agreed minimum value and up to 35'i for lifetime of per^'ormance up to specification. The measurements required to determine

the payment of incentive bonuses are at the limit of attainable accuracy, and they

control the vendors' profit margins. Measurements required just to ootimize performance can become quite expensive. The antenna range to test Intelsat 4 cost S550K, and Intelsat 3 will require 10,000 times as many measurements as were needed by Intelsat 4.

The real economic promise of remote electromagnetic sensing is in water management

in agriculture, a field in which it has yet

to be oroven and adopted. In particular, accurate methods are needed for measuring

the moisture content of grain and the distribution of water in the soil, and electromagnetic techniques are under development

19
for both of these. The annual grain harvest

in the U.S. is about 10 billion bushels, and

it sells for an average price of about S3 per bushel. This price is reduced by U for every %X by which the water content exceeds

13% in wheat or 15% in corn, and the determination depends on sampling and using in- struments with errors of about 2 or 3%.

If the moisture in corn is allowed to exceed

18%, then moulds can grow and make it inedible. In 1970, 1% of the U.S. corn crop was affected this way. In 1975 it was 11%. It requires 10,000 Btu per bushel to dry grain

from 20% to 13% moisture. An even greater

problem in Western fanning is the control of

irrigation. Water itself is scarce. If too little is used the crop dies. If too much

is used it washes out salts from the soil and concentrates them in places where a shallow water table encourages evaporation.

Already 150,000 acres in Montana have been

lost to agriculture because of this "saline

seep," and another 10,000 acres per year are

going. Electromagnetic measurements may not solve all the measurement problems associated with water management, but they appear to offer the best hope at present.

In October 1975, Canada passed an Amend- ment (SOR 75-629), to the Canadian Radio Act requiring the enforcement of much more re- strictive laws governing the emission of

electromagnetic radiation from all manner of

devices, excluding legal transmissions for

communications. The Act now stipulates that

such devices will be equipped with EM noise

suppression equipment by the manufacturer

who, in turn, must maintain records of proof

of testing, ensuring that such devices are compatible with the limits set by the Act. The Act covers equipment "generating electromagnetic noise" such as: spark ignition

systems of vehicles and other devices equipped with internal combustion engines, electric motors, medical equipment, industrial

sources, computers, welding equipment, process controls, etc. It also covers radiation

conducted back into power transmission lines

from equipment, especially television receivers. This far-reaching Act applies to a substantial U.S. export market, e.g., the internal combustion engine powered products

market which in 1974 amounted to S3.5B.

In the U.S. the FCC is acutely aware of

the growing EMI problem and is seriously

considering further regulatory actions to meet the problem. Accordingly, the FCC plans

to update regulations Parts 18 and 15; the former deals with industrial, scientific,

and medical equipment while the latter deals

with low-power intentional radiation (e.g.,

wireless intercoms), and with unintentional

radiation (e.g., electronic and video games).

To this end the FCC has looked at the amended

Canadian Radio Act and has proposed changes

to Part 15 (Docket 20780), and to Part 18 (Docket 20718), to include interference

from broadband sources such as ignition systems (Docket 20654). The impact of FCC actions will be substantial, affecting the following products (1972 Department of Com- merce data): motor vehicles - S39B, con- struction machinery - S3. 88, electric motors - $2.48, farm machinery and equip- ment - SI .88, electronic computing equipment - 34. 68, household appliances - S3. 98,

industrial controls - SI. 48, etc.

The FCC prefers requiring U.S. manufacturers to make their products EMI proof;

i.e., control the susceptibility of products

to EM interference. Currently, FCC has no legal authority to require such; however,

if the action of Senator Goldwater (S. 3033)

and Congressman Vanik (H.R. 7052) succeeds

in amending Section 302 of the Communications

Act then the FCC may indeed make reasonable

regulations governing: (1) the interference

potential of devices that can cause harmful

interference to communi"cations , and (2) the use of protective components in audio and

visual electronic equipment to reduce susceptibility. This would make the whole con- sumer electronics market ($7.58 in 1976)

depend upon meeting regulations based on fairly sophisticated electromagnetic measurements .

The industrial part of the laser market

was S384M in 1976, and is growing at the rate

of 22% PA. The use of all these lasers will

be controlled by OSHA regulations, based on the BRH classification.

3.1.3 Social

The most important direct social consequence of electromagnetic measurements is in the enforcement of safety regulations covering direct radiation hazard and, to a lesser

extent, electromagnetic interference with

control systems. It is a somewhat negative

benefit: our lives are not threatened by the electromagnetic technology that serves

us. The particular threats from which we are protected include microwave ovens, radar systems, TV and radio transmitters,

and industrial rf equipment.

20
3.2 Status and Trends of the System

Most of the National Electromagnetic Mea- surement System is under good statistical

control because the dominant user - The

Department of Defense - has insisted on the traceability of all essential measurements

to national standards. Adequate measurement

and calibration services are available to support most of the electromagnetic equipment in use at present. The challenges for

the future are: to support the maturing

parts of the technology more efficiently;

to develop measurement techniques and standards to support new technology that is being

developed now and will become commercially

important during the next. few years; to develop a measurement base for the regulation

of radiation hazard and interference without

unnecessary restriction of electromagnetic

activities; and to fully exploit the possibilities of remote electromagnetic measurement.

A trend of the recent past that is maturing now is the use of the mini -computer to improve the efficiency of the measurement

process. Early microwave measurement systems depended for their accuracy on very accurately made components, whose residual errors were tuned out for each frequency

with stub tuners. This is not necessary

when a computer is available to perform ma- nipulations of scattering matrices. Instead,

the effects of imperfect components are measured using a set of check standards. The

information is stored by the computer and automatically applied as a correction to subsequent measurements. With the aid of a programmable signal generator it becomes

possible to repeat a set of measurements rapidly at many different frequencies without

any retuning. Systems that use this principle are the Automatic Network Analyzer,

that compares the pnase and amplitude of

incident and reflected waves at t//o measuring ports, and the more recently invented

5-port coupler, that uses interference

between signals in different branches of a network to derive the same information from measurements of power only at four measuring

ports

.

Both these systems have the added advantage of allowing much greater flexibility in the choice of reference standards. In particular, they lend themselves very conveniently

to self-calibration procedures that can eliminate the need for f^any -;f the reference

standards for dimensionless ratios that are

still used very heavily in electromagnetic

metrology. As automatic systems take a more prominent part in metrology, the supporting

organization of national standards and calibration services can become more compact

than it is at present.

The computer has had a similarly profound

influence on antenna measurements, where it can be used to transform measurements of the near field of an antenna, that are relatively

easy to make, into a map of the far field,

which is the region of greatest interest.

Of the developing technologies that will

require new measurement techniques to support

them, telecommunication will make the greatest foreseeable demands. The desire for di- rect communication at a very high bit rate between computers is causing a great increase

in the demand for channel capacity. It is also leading a trend to use pulse code modulation to carry information instead of the familiar relatively narrowband modulation

of a continuous carrier wave. It is coming

to be recognized that this digital mode of

communication also makes the most efficient

use of channel capacity for audio and video

information. Thus, many of the new systems

will call for a much heavier emphasis on time domain measurements, which are generally

in a more primitive state than the available

techniques for frequency domain measurements.

Satellite communications systems will call for measurements at very low power levels,

and for the accurate characterization of

very large and elaborate antennas. The fre- quencies used are spreading into the milli- meter wave region, limited only by the absorption of the atmosphere.

A new coirmuni cation system that is essentially fully engineered but not yet deployed

uses millimeter waves propagating in oversize circular waveguide. It has the characteristic that it offers a very high chan-

•

nel capacity for a cost that is competitive

with other systems only if all the channels

are used. The system does not have the flexibility to offer a lower capacity at a proportionately lower cost, so its future is uncertain in the face of competition from

fiber-optic systems.

Other, mostly military, applications of

millimeter waves are under development.

The measurements they will require for sup- port will differ from present-day microwave measurements in that there will probably be much more call to characterize transmission

systems that will support multiple modes of

propagation at the operating frequency. In- convenient physical size will also limit the

use of some of the techniques presently used

for microwave measurements.

21
The future of optical fibers as a trans- mission medium appears to be more certain.

They have the advantage that single fibers

offer moderate channel capacity at moderate

cost, but are very compact so that higher

capacity can easily be achieved by cabling.

This flexibility will permit the testing of many experimental systems and an orderly

progression to greater complexity, without

the barrier of having to design an expensive

system with inadequate experience of the per- formance of components in the field. The

technical problems of the manufacture of

low-loss fibers, and sources, modulators and

detectors with acceptable reliability, are

being solved. Reasonable projections of the cost of fiber-optic systems look attractive.

Therefore, it is reasonable to expect them

to come into widespread use in the next few years. Experimental systems are already

being installed for short-range communication

within cities (e.g., cable TV links) and for

transmitting control signals in aircraft.

The present size of the market is small ($25M per year) but the rate of growth is Wo per year. The measurements and stan- dards required to support fiber-optic com- munication systems will probably be similar

to those required by microwave systems: power, scattering parameters of components, and

dispersion of transmission lines. Measurements of the index profile of fibers will be important to the manufacturers, but system

design and trade in components are more

likely to depend on measurements of performance; i.e., dispersion and attenuation.

These techniques and standards have yet to be developed.

Much work remains to be done in the de- velopment of definitions, standards, and measurement techniques for electromagnetic

interference and radiation hazards, especially

as regulations in the process of being written could cause unnecessary confusion and restriction of activities unless they are

based on sound measurement techniques that

allow a unique determination of compliance.

Methods of measuring the interaction (both

emission and susceptibility) of devices with

interfering fields, and probes with which

to measure ambient fields, all exist but need development to cover a wider range of

frequency, field strength, and response

time. This last is particularly important

because of the random, impulsive nature of

interfering fields. More work must also be done to define realizable measures of interfering fields that can accommodate their

statistical fluctuations.

Finally, the full exploitation of remote electromagnetic measurements will require the compilation of a base of data on the dielectric properties of materials and their variation with physical condition. It will also

require a systematic exploration of the limits of detectabi 1 ity and interpretation

of dielectric anomalies in various conditions. This is a field that needs a theoretical framework on which to organize a lot of empirical observations.

4. SURVEY OF NBS SERVICES

All NBS electromagnetic measurement and

calibration services, and the standards that

support them, are developed and maintained

by the Electromagnetics Division in Boulder,

Colorado. The basic electrical standards,

and electrical measurements that are not significantly affected by the dynamics of

propagating waves, are the province of the Electricity Division, in Gaithersburg,

Maryland.

4.1 The Past

The NBS Electromagnetics Division traces

its origin to two primary sources. The first

is the work within the National Bureau of

Standards on radio communications, which

began in 1904. The second is the Electronic

Calibration Center, which was set up within

the Bureau in 1957, in response to urgent

needs arising within the Department of

Defense.

On the radio side, the first work associated with the Bureau was under Dr. Louis

W. Austin, a guest worker who was investigating, for the U.S. Navy, the practical ap- plication of radio-telegraphy. From 1908

to 1932, Dr. Austin headed the U.S. Naval Radiotelegraphic Laboratory at the Bureau.

In 1911, the Bureau itself entered the radio

field, when J. Howard Dellinger was assigned

the problem of calibrating a "wavemeter."

Soon thereafter, Dellinger became Head of a new Section in the Electrical Division

called "Radio Measurements."

The Bureau was very active in the entire

field of radio during both World Wars. It supported the development of commercial

radio during the 1920' s, and was closely

connected with the establishment of the Federal Radio Commission, later renamed the Federal Communications Commission. War-time

needs during World War II stimulated heavy

Bureau involvement in radio propagation

22
ressarch and the formation at the Bureau of

the Interservice Radio Prcpacation Laboratory.

From 1925 to the end of World War II, the Bureau was engagea in studies of the ionosphere and in radio engineering projects,

including aeronautical raaio guidance systems,

a blind landing system, the raaiosonde, and

early develocments of zhe oroximity fuse. With a single important exception (new

precise frequency measurenents ) , raaio

standards work went into an eclipse in that

period.

Following World War II, the Radio Section

(which included the Interservice Radio Propagation Laboratory) was renamed the Central

Radio Propagation Laboratory (CRPL) and became the central agency of the nation for basic research in the propagation of radio

waves. CRPL had division status and was organized into nine sections. Its ooerations included all the research and standards functions of the former Radio Section

of the Bureau's Electrical Division.

Research in the lower frequencies was extended into the ultrahigh frequency and .nicrowave

regions, for the new fields of television,

FM broadcasting, and military and corrmercial radar. In 1954, CRPL moved to the new Bureau site at Boulder, Colorado, in order

to find a more favorable radio environment

than that existing in the Washington, D.C., area, and as a part of a general move to disperse Government facilities in response

to the nuclear bomb threat.

After tne move from the east coast, the Radio Standards Division was formed within

CRPL. In 1961 it was separated from CRPL

and became the Radio Standards Laboratory

(RSL). In 1965, CRPL ^as transferred from

NBS into the newly created Environmental

Sciences Services Acministration.

In 1962, RSL was divided into two Divisions - Radio Physics ana Circuit Standards. In 1967, a third Division, Time and

Frequency, was added, and the names of the existing Divisions were changed to Radio

Standards Physics and Radio Standards

Engineering, respectively. By this time

all three Divisions were part of the 'IBS Institute for Basic Standaras. In 1970,

the name of the Raaio Stanaaras Engineering

Division was cnangea to Electromagnetics,

that of Raaio Standaras Physics to Quantum

Electronics; and for tne first time in sixty-six years, the Bureau had no organizational unit affiliated with it bearing

the name ''Radio. '

Meanwhile, during the 1950's, the growing

complication and sophistication of the electronic equipment used by the military was leading to increasing problems in connection

with iiiai ntenance and repair and with the standards supporting the maintenance and repair test equipment. In 1951, the Air

Force took initial steps in requesting that

a new and large-scale facility be established

in the Bureau to meet an increasing need for calibration of its electronic standards in order to obtain "traceability" to the

national standards. Soon thereafter, the

Army and Navy made similar requests.

In 1957-58 these recuests culminated in the establishment of the Electronic Calibration

Canter at the Boulder Laboratories. This

facility was grafted onto the ongoing work

of the Radio Standards Division.

While the basic mission of developing

standards and measurement techniques for

electromagnetic measurements continued,

two significant changes occurred between

1968 and 1974. A new and major emphasis

upon applied metrology began. For examole,

the Division's basic measurement expertise

was applied to problems such as measuring

the electromagnetic noise in coal mines so that the Bureau of Mines could obtain suitable communication equipment. The second

change was that major work was begun on automated measurements. The Division had

had several small efforts on automated measurements, but finally funds were accumulated

and programs redirected so that a concentrated effort could begin.

Today automated measurement systems have

arrived, and are expected to play a prominent part in the consolidation of the rf and

microwave calibration services to imorove

their efficiency and rationalize their scope. Vigorous development is in progress to create measurement tecnnicues and standards for: millimeter wave and fiber optic systems;

comolex antennas and otner comocnents of

satellite communication systems; transient

waveforms; electromagnetic interference;

hazardous fields; and remote electromagnetic

sensing. Responsibility for laser power and energy measurements was transferred to the Division in 1974, when tne Quantum Electronics

Division was abolisned and its personnel

divided between the Electromagnetics ana Time and Freauency Divisions.

23
4.2 The Present-Scope of NBS Services

4.2.1 Description of NBS Services

The Electromagnetics Division of NBS has recently been drastically reorganized in response to a reordering of priorities.

This description will speak to the Division

in its new form. The new Electromagnetics

Division is divided into five programs:

1 . Guided Wave Metrology

2. Electromagnetic Sensing Metrology

3. Electromagnetic Interference/Radiation

Hazards

4. Signal Waveform Metrology

5. Antenna Systems Metrology

The following five subsections will com- prise brief descriptions of the services offered by these five programs.

4.2.1.1 Guided Wave Metrology

This program provides standards and mea- surement services for the basic quantities

describing waveguide systems and continuous

waves propagating through them: power, voltage, attenuation, dispersion, and reflection coefficient. At present, there is a comprehensive calibration service for transfer standards of these quantities, both in coaxial line and in the various standard

waveguides at appropriate frequencies. The

frequency ranges covered are from 30 kHz to

1 GHz for voltage, and roughly from 10 MHz

to 65 GHz (with a gap from 40 GHz to 55 GHz) for the other quantities. These services

are in process of being cut down to the minimum that is considered essential for maintaining the traceability of the National

Electromagnetic Measurement System to stan- dards maintained by NBS. This will be discussed in section 4.5.

In addition to these services, work is

in progress to develop new standards and measurement techniques. These include the 6-port coupler, which is expected to play

a prominent role in the rationalization of

microwave measurements as well as providing

the most promising approach to millimeter

wave measurements. The Superconducting

Quantum Interference Device (SQUID) is being

developed as a way of measuring rf power

at very low levels. Development of fiber

optic standards and measurement techniques

is beginning. Preliminary work is in pro- gress on the measurement of power and dispersion in optical fibers.

4.2.1.2 Electromagnetic Sensing Metrology

This program develops the mathematical

foundation for systematic use of remote sensing of dielectric anomalies, as well as

a data base correlating the dielectric

properties of materials with other physical

properties. Much of the work is done in collaboration with other government agencies

that need to use remote sensing techniques,

so as to maintain the discipline of solving

real problems while developing the basic

tools. Work is in progress to develop

electromagnetic measurement techniques for: moisture in grain (with the Department of

Agriculture); the structure of coal layers

above mines (with the Bureau of Mines); the structure cf soil in potential landslide areas

(with the Geological Survey and the Federal

Highway Administration); the distribution of water in soil (with several Western State governments); and the progress of curing con- crete (as part of a larger program in other

parts of NBS). Measurements are being made

of the dielectric properties of moon dust, to assist remote monitoring of the radiation

temperature of the moon's surface. A system

has been developed for the Army to use to detect plastic land mines. All these projects'

will expand the body of available technology

to be applied to other problems as well as solving the problems of primary interest to the cooperating agencies.

4.2.1.3 Electromagnetic Interference/

Radiation Hazards

This program develops techniques for measuring the strength of interfering fields over a wide range of frequency, time, and

amplitude, and the emission of and response

to these fields by devices to be tested.

These techniques are then made available

through workshops, seminars, and voluntary

standard-setting committees. The goal is to cover the range of frequency from

10 kHz to 30 GHz, with response times down

-8

to 10 s, and at power densities from

-10 2 2 10 W/cm to 1 W/cm . The measuring devices

under development include anechoic chambers

(for frequencies above 1 GHz) and TEM cells

and field synthesizers (for frequencies below 1 GHz) to measure emission and susceptibility and to calibrate field probes.

Probes to measure various combinations of

the components of electric and magnetic

field are also under development. Part of

the desired range is already covered, but much remains to be done before complete

coverage will be available.

24
4.2.1.4 Signal Waveform Metrology

This program develops techniques and standards for measuring waveforms (both

transient and repeating) in the time domain.

Both optical (envelope) and electrical waveforms are being worked upon, and the ulti- mate goal is to attain a time resolution

-12 of 10 s. A calibration service is of- fered for the transition times of pulse

generators and filters in the range above

10'^^ s, and for the spectrum of impulse

generators in the range 5 MHz to 6 GHz.

Measurement Assurance Programs are offered for laser power and energy in various

ranges for Hetie, fld-YAG, and lasers.

4.2.1.5 Antenna Systems Metrology

This program develops techniques for measuring the performance of the large antennas

used for satellite communication and advanced

radar systems. It also maintains noise

standards to test the performance of the associated receivers. Special measurement

services are performed, including: determination of the radiation patterns of antennas by scanning the near field on a planar,

cylindrical, or spnerical surface (whichever

is most appropriate); determination of the gain on axis by an extrapolation method; and determination of the performance of complete

satellite ground stations using radio stars for reference. Also, a regular calibration

service is offered for standard noise sources. This group provides consultation on an- tenna problems, such as the design of the proposed Orbiting Standards Platform and the testing of the Global Positioning System,

and is developing new measurement techniques

such as a system to test the response of

small antennas to impulsive fields.

4.2.2 Users of N3S Services

The direct services provided by the NBS Electromagnetics Division may be divided

into three categories: researcn and development of new standards and measurement

techniques; special testing and measurement

services; and calibration of transfer standards.

Researcn and development account for 50" of the total. Over 65;= of this is performed

for the various branches of rhe Department

of Defense. Most of the remaining 3S'c is performed for other agencies of tne Feceral Government, mostly regulatory agencies.

Special testing and measurement services account for about 30%. Over 80-;^ of this is for the Department of Defense, the remainder

being also mainly for regulatory agencies of

the Federal Government.

Calibration is the smallest category,

accounting for less than 20% of the total. One half of this is done for the Department

of Defense, almost exclusively for the four

Metrology Centers of the armed services.

Nearly all of the remainder is for defense

contractors in private industry, in fulfillment of requirements for traceability

to NBS.

4.2.3 Alternate Sources

The four large Metrology Centers of the Department of Defense, and the calibration

laboratories of many large aerospace and

instrument corporations, are all capable of

performing electromagnetic measurements and

calibrations under good statistical control

although none offer so comprehensive a service as NBS. The maintenance of statistical control relies heavily on the concept

of traceability to NBS, so there is no serious alternative to using NBS as the central reference point of the National Measurement System. However, a question

that is open to debate is how wide a variety

of transfer standards needs to be calibrated

at NBS, and how far the users should carry

the burden of converting quantities to be measured into a form that can be referred

directly to the national standards.

Negotiations are in progress to cut down

the transfer standards calibrated by NBS for the Department of Defense to the minimum set that is essential to maintaining

traceability. Similar discussions will be held with the aerospace industry, but the opportunity to bring about a significant

reduction in calibrations there is less obvious

.

Another method by which a large part of

the load of routine calibrations can be moved away from NBS is by commercial laboratory accreditation. Accredited laboratories would offer calibration services

that are inspected by NBS so as to give some degree of assurance of their quality. An invitation to interested organizations to seek accreditation was published in the Federal Register of February 25, 1975, pages 3163-8158. This document describes

the procedures for setting up an accrediation

program for any class of measurements. So far, there has been only one formal application for accreditation in electromagnetic

25
measurements. Since the whole accreditation

program is in its early stages of development, it will be at least two or three years

before proper arrangements can be made.

4.2.4 Funding Sources for N8S Services

Section 4.2.2 describes the distribution

of direct users of MBS services in electromagnetic measurements and standards. These

users pay for the services they receive,

and this accounts for 45% of the funding of

the N8S Electromagnetics Division. The

remaining 55;i comes from direct appropriation for research and development in anticipation of future needs.

4.2.5 Mechanism for Supplying Services

The direct services were described in section 4.2.2. In addition, staff members

of the MBS Electromagnetics Division are active in several voluntary standards com- mittees, publish monographs on the techniques

for particular types of measurement

(e.g.. Metrology Guides), publish papers in professional journals, organize workshops

for the detailed discussion of various measurement problems, and occasionally

organize conferences such as the Laser

Damage Symposium and the Conference on Precision Electromagnetic f'leasurement.

4.3 Impact of NBS Services

4.3.1 Economic Impact of Major User Classes

The major users of NBS services in electromagnetic m.easurements are: the Depart- ment of Defense; the aerospace industry

(serving defense, civil aviation, and sat- ellite communication); and the federal reg- ulatory agencies. The economic significance of these users was discussed in section 3.1.2 of this study.

To summarize, our national defense relies

heavily on surveillance with sophisticated

radar systems to give early warning of attack,

and possession of airplanes and missiles

with electromagnetic guidance systems, all of which need NBS services to support the measurements needed for acceptance and maintenance. Satellite communications need the most accurate available measurements for adjusting complex systems for optimum perfor- mance and to determine the paymem: of perfor- mance bonuses. The regulation of electromagnetic interference and radiation hazard

could inhibit commerce significantly unless

it is based on sound testing methods that

determine compliance unamoiguously.

4.3.2 Technological Impact of Services

The technological impact of NBS services

is greatest when the technology they serve

is in the early stages of being made to work. As technologies mature the support

they receive from measurement services is more for maintenance than development, and

the measurement services themselves should

evolve so as to improve efficiency rather

than accuracy.

Twenty years ago the NBS services in basic

rf and microwave measurements made an essential contribution to the development

of the military radar and guidance systems

that are part of the defensive posture we

enjoy today. As these systems have matured,

so have the measurement services supporting

them. The old manual measurement systems,

which were capable of great accuracy but

required much skilled labor, are being re- placed by computer-controlled systems that

are no more accurate but a great deal more efficient in their use of time, although the operators they require are if anything more

skilled than before.

The rapidly developing electromagnetic

technologies of today still include radar

systems, using complex phased-array antennas,

as well as satellite communications, remote electromagnetic sensing (of nearby objects),

and electronic servo control of vehicles and processes.

Near-field scanning methods for measuring

the radiation patterns of antennas have proven to be particularly useful with phasedarray antennas, which are used for both

radar and satellite communications. The near-field information itself is valuable in determining the adjustments required by

individual elements of an array. The use of radio stars as standard noise sources

also provides a valuable tool for testing

the performance of complete satellite com- munications ground stations, that can be used when putting a new station into service.

Measurement services connected with electromagnetic interference can save a great

deal of trouble if they are used to test and correct prototype servo control systems,

before the design is "frozen" and becomes

expensive to change. The major automobile

manufacturers in the U.S. are now using

riBS-designed TEM cells for this purpose, following unfortunate experiences with

early electronic servo systems in auto- mobiles, trucks, and buses.

26
4.3.3 Payoff from Changes in NBS Services

The automation and consolidation of the basic rf and microwave calibration services

have already been discussed. The benefit

to the users is that computer-controlled

systems can give much better coverage of

the effects of changing frequency and power

level for the same cost. The benefit to NBS is that manpower can be taken from this

work and used to develop the measurement

services that are expected to be needed in the future.

The payoff from the development of measurement services for millimeter waves and fiber

optic systems, and for fast transient waveforms, is obvious. These are the services

that will be in demand in a few years time,

and now is the time to develop them.

The most fundamental change in the form of

NBS services is the adoption of Measurement

Assurance Programs as a replacement for most

of the calibration services. This change is in progress now and will take about two years

to complete. A measurement assurance program

is designed to test the user's overall measurement system. It makes maximum use of check

standards (that do not require calibration

at NBS) to maintain statistical control. The'

connection to national standards maintained

at NBS is through a set of transfer standards

that are sent to all the users in turn, at quite long intervals of time that are determined by the stability of the users' measurement systems as monitored by the check standards.

Measurement Assurance Programs require

just as much highly skilled manpower as the calibration services did, but they are capable of keeping tne National Measurement

System in much tighter statistical control

simply because they test the whole measurement process rather than allowing the re- sponsibility of NBS to stop at the calibration of transfer standards.

4.4. Evaluation of NBS Program

The NBS program in electromagnetic

metrology is revie>wed by the NBS Executive

Soard at the annual Base Program Review, wnere priorities are assigned to the various

programs throughout NBS. It is also reviewed

annually by an Evaluation Panel organized by the National Academy of Science. This panel

consists of nine exoerts in the field drawn

from universities and private corporations.

In the Spring of 1976s the NBS Executive

Board determined that the Electromagnetics

Division (which employed about 130 people

full time) was larger than was warranted by the priority of its work relative to other

responsibilities of NBS. Consequently, the

10 programs in the Division were consolidated into 5, with the elimination of 31 positions. At the same time, the calibration services were reduced in scope so as

to retain only those services that are essential to the maintenance of traceability

of the National Electromagnetic Measurement

System to NBS, as discussed earlier in this

report. The Evaluation Panel generally

approved of the reorganization with some reservations about parts of the program that were not completely settled at the time of

its examination. Judgement about perfor- mance is reserved until the wounds from the reorganization have had a chance to heal.

Public reaction to the curtailment of

calibration services, expressed in the professional journals, showed that the users

of these services had been satisfied with

them in the past and were uneasy about the possible consequences of reducing them and

dissipating the resources that supported

them. However, when questioned directly

about the adequacy of the remaining services,

'most of the users (both in the OoD and in private industry) seemed to be willing to accept the changes. Only experience will

tell if further adjustments will be necessary.

4.5 The Future

The status and trends of the National

Electromagnetic Measurement System were discussed in section 3.2. NBS must respond to those trends, of which the most significant

are:

1) the rapid expansion of satellite com- munications, both military and commercial,

to form a world-wide system;

2) the rapid expansion of electro-optic

technology, for applications ranging from

control functions within an airplane to inter-city communications;

3) the full exploitation of electromagnetic

remote sensing, particularly in agriculture;

^) increasing reliance on electronic servo

control of industrial processes and vehicles;

5) worsening of the problem of electromagnetic interference, as a consequence of item

(4) coupled with a proliferation of CB radios

and the like, leading to stricter regulations;

27
6) increasing public exposure to non-ionizing

radiation hazard, which may be accompanied by

a lowering of the permissible exposure to a level nearer that which is used in Eastern

Europe.

The response of NBS has' been to reorganize

the Electromagnetics Division into five programs :

1) Guided Wave Metrology

2) Electromagnetic Sensing Metrology

3) Electromagnetic Interference/Radiation

Hazards

4) Signal Waveform Metrology

5) Antenna Systems Metrology

The scope of these five programs, and their relationship to the technological

trends mentioned above, were discussed in section 4.2.

Overall, the development and dissemination of electromagnetic metrology is declining in priority as new calls are made on the limited resources of NBS to attend to matters

that are regarded as more urgent. The Electromagnetics Division recently suffered a 25%

reduction in staff. This was accompanied by

a 50% reduction in the volume of calibrations.

Services essentval to maintaining statistical

control of the National Electromagnetic Measurement System will be maintained,

together with the basic standards that they

require. Indeed, new services will continue

to be developed to meet future needs,

but with shrinking resources a strong sense

of priorities must be exercised.

The only program that may experience significant expansion in the near future is the development of measurement techniques and

standards for electromagnetic interference.

As the urgency of this problem comes to be generally recognized, it may receive priority comparable with the other new tasks

that are being assigned to NBS.

5. SUMMARY AND CONCLUSIONS

In the past, the National Electromagnetic Measurement System made an essential contribution to the development and maintenance

of the military systems for early warning

radar, side-looking radar, the guidance of

terrain-following airplanes, the guidance

of weapons, navigation, and telecommunications on which our defensive posture relies

very heavily. As usual, commercial tech- nology has followed the military lead, so that today six trends can be seen that will

determine the develooment of electromagnetic

measurements and standards in the next few years:

1) the rapid expansion of satellite commu- nications into a world-wide system;

2) the rapid expansion of electro-optic

technology, particularly fiber-optic commu- nication systems;

3) the full exploitation of electromagnetic

remote sensing, particularly in agriculture;

4) increasing reliance on electronic servo

control of industrial processes and vehicles; •

5) worsening of the problem of electromagnetic interference, leading to stricter

regulation of both sources and victims;

6) increasing public exposure to non- ionizing radiation hazard.

In response to these trends, the NBS Electromagnetics Division is being reorganized into five programs:

1) Guided Wave Metrology, which provides

the basic rf and microwave measurement and

calibration services, and develops stanards

and measurement techniques for millimeter

wave systems and fiber optics;

2) Electromagnetic Sensing Metrology, which

performs the research and development nec- essary to enable electromagnetic waves to be used for remote sensing and characterization

of inaccessible dielectric anomalies;

3) Electromagnetic Interference/Radiation

Hazards, which develops standards and mea- surement techniques to determine the emission and susceptibility of devices of and

to interfering fields, and the strength of

fields to which people and equipment are exposed;

4) Signal Waveform Metrology, which develops

standards and measurement techniques to characterize transient and modulated waveforms,

and systems designed to transmit them, in the time domain;

5) Antenna Systems Metrology, which develops measurement techniques and provides measurement services to characterize complex antennas and associated systems used for satellite

communications

.

This reorganization is a direct response

to information collected for this study of

the National Electromagnetic Measurement

System.

28
APPENDIX A - METHODOLOGY OF THE STUDY

(AND ACKNOWLEDGMENTS)

The first source of material for this study was an earlier description of the National

Electromagnetic Measurement System by Francis X. Ries and Wilbur J. Anson (unoubl ished,

July 25, 1975). In particular, the list of realized measurement capabilities (section 2.3),

the history of NBS services (section 4.1), and the list of instrument manufactures

(appendix B) were all taken directly from that report. Additional material was collected

by Ramon C. Baird, Arthur J. Estin, Paul A. Hudson, and Charles K. S. Miller, by visiting

representatives of eleven parts of the Department of Defense, three other agencies of the Federal Government, and fourteen private companies in the aerospace and telecommunications

industries. A one-day meeting was held at NBS at which representatives of NBS and the four

metrology centers of the Department of Defense discussed the future of the maintenance of

traceability of electromagnetic measurements to NBS. Most of the material on laser measurements was contributed by Richard L. Smith. The two organizational input-output matrices

were taken from a ccnsisient set published by Raymond C. Sangster (NBSIR 75-943).

I thank all these people for their contributions to this report.

29
APPENDIX B

- INSTRUMENT MANUFACTURERS

These lists were compiled from the 1973 "Electronic Engineers Master"

(EEM). The data is presented to illustrate the large number of instrument manufacturers facilitating the measurement of the parameters supported

by the Electromagnetics Division of NBS. The parameter breakdown is

impedance, attenuation, phase shift, power, voltage, current, waveform,

noise, EM fields, and materials properties.

WAVEFORM OF VOLTAGE, CURRENT & POWER

MEASUREMENT INSTRUMENTATION

1-Analyzers 4-lndicators

2- Calibrators 5-Oscilloscopes

3-Generat6rs 6-Recorders

MANUFACTURERS

Active Control Instrumentation: 5 Accutronics, Inc.: 2 A. D. Data Sys., Inc.: 1 AIL, Div. Cutler-Hammer, Inc.: 1 Alden Elctrn. t Impulse Record

Equip . : 1 Areriean Astrionics: S Anerican Elctrn. Labs., Inc.: 1, 5 A-nerican Time Products: 3 A. P . Circuit Coro . t 1 Ar-nlied Maqnetics Corp.: 5 Acnlied Microwave Lap.: 3

' AUL Instrs., Inc.: 1, 5 Au3 tron . Inc . : 1 Automated Meas . : 5 B t F Instrs . , Inc. : 5 3 s K Instrs.: 1 Saf CO, Inc. : 1 Paaanoff Assocs., Inc.: 1 ?all3ntir.e Laboratories: 5, 6 Sarry Sescn. Corn.: 1 ?ecitman Instrs., (AISSD) : 1, 5 ?ehlman 3iv. , California Instrs.: 5 Bell 4 Howell Co. : 5, 6 3er)5elev Nucleonics Core: 3 ?icron rictrns., Co.: 3 riocon. Inc. : 5 Jiomation Corr.: 6 BLH jrictrns . , Inc . : 5 3owraar/ALI. Tnc. : 1 Pow~ar Instr., Corp.: 1 Calico Div., California Instrs. Co.: 5 California Instrs., Co.: 3 CrLCO: 1 C^ronetics, Inc.: 3 Chuo Electronics Co., Ltd.: 1, 3 Ci rcon Core . ; 5 Clavier Coro. : 1, 5 Cober Elctrns., Inc.: 3 Collins Radio Co.: 1 Colorado Video, Inc. : 1 Ccraltest: 3 Ccnnor-Wintield Corp.: 3 Crown Int ' 1 . : 1 race Instr . Co., Inc.: 4 Damon Corp . : 1 lata Disc Inc.: 6 Data Dynamics Div.: 3 Disc Instruments, Inc.: 3 Dixson , Inc . : 5 Draneti Snorg. Labs.: 1, 3, 4 Dumont Oscilioscooe Labs., Inc.: 5 Dynair Elctrns. Inc.: 1 Dynascan Corp . : 5 Eastern Delta Coro. : 4 E G S G, Inc. : 3 E-H aescft. Labs., Inc.: 2, 5, 6 Electro/Data, Inc.: 1 Electro-Sumer ICS : 4 Electro-Ootical : 1, 5 Fndevco: 6 "nqdahl Enterprises: 6 Essential Elctrns. Corp.: 5 Esterlme Angus Div.: 5 Exact Elctrns., Inc.: 3

t-Z Hook, Test Prods.: 5 Fairchild Electro-letrtcs : 1 Federal Sci. Corp.: 1 Feedback, Inc.: 1 General Microwave Corp.: 3 General Radio Co.: 1, 3 Ceo Space : 5 Gordon Alan Fntprs.: 5 Gould, Inc.: 5, S Gralex Inda., Inc.: 3 Hallmaric Standards, Inc.: 3 Harshaw Chem. Co.: 1 Heat.h Co. : 5 Hewlett-Packard: 1, 3, 3 Hickok Elect. Instr.: 5 Honeywell: 1, 5 Hughes Aircraft Co.: 1 ILC, Inc.: 3 Ind'l. Control Co.: 1 Infadex, Inc. : 5 Inter-Computer Elctrns.: 1 Interstate Elctrns. Corp.: 3 IP.D "lechanal/sis , Inc.: 1 ITI Electronics, Inc.: 5 James Elctrns., Inc.: 1 Jodon Fngrq. Assocs.: 1 Kay Elemetrics: 1 Kenton Fngrg. Corp.: 6 Kikusui Elctrns. Corp.: 2, 3 Kikusui Elctrns. Inc.: 5 Lab Electro-Acoustique : 1 Labqear, Ltd.; 1 Leader Instruments Corp.: 3, 5 Lecroy Resch. Sys. Corp.: 5, 6 London Co. : 1 Loral Flctrn. Sys.: 1 Magnetic Elctrns.: 3 Marconi Instrs.: 1 MB Elctrna/Textron Co.: 1 MCG Electronics Inc. : 4 Medistor Instr. Co.: 2 Meguro Cenpa Sokki K..K.: 1 Meloy Laboratories: 2 Metra Instrs., Inc.: 3 MFE Corporation: 5 Micro Instr. Co.: 1, 4, 6 Micro-?el Corp.: 1 Microwave Control Co.: 3 Miles Reproducer Co., Inc.: 6 Millen, James Mfg. : 5 Multimetric I.-idustries . : 1 Nano Fast , Inc. : 2 Nelson Ross Elctrns.: 1 Micolet Instr., Corp.: 1 Nort-hern Sci., Inc.: 1 Sovatronics, Inc.: 1 Nuclear-Chicago: 1 Nuclear Data: 1 Nuclear Equip. Chem. Corp.: 1 Nuclear Meas. Corp.: 1 Optics Technology; 1 Packard Instrument Co., Inc.: 1 Panametrics, Inc.: 3 Philips Elctrn. Instrs.: 3, 5 Photron Instr. Co.: S

Pioneer Magnetics: 1 Polarad Elctrn. Instrs.; 1 Precision Apparatus: S Precision Standards Corp.: 5 Princeton Applied Pesch. Corp.; 1 Projects Unlimited, Inc.; 5 Ouan-Tech: 1 Railway Comm.: 1 Raytheon Instrs.: 5 RCA Elctrns. Co. : 5 Rockland Sys. Corp.; 1 Rohde i Schwarr Sis.: 1 Schoeffel Instr. Corp.; 1 Scientific Measurements.: 3 Servo Corp. A-merica; 1 ."^lenens Corp . : 1 Signal Analysis Inds. Ccrr.: 1 Siqna tron , Inc . ; 1 Simoscn Flee. Co.: 5 Simulation Prods. Div.; 1 Singer Instru.mentatir-n, Los Angeles, Oner. : 1, 3 Singer Ins tru-Tenta t ion , Palo Alto Oper. ; 1 Sol tec Corp. ; 1 , 3 Spectra- Phys ICS , Inc.; 1 Spectral Dynamics Corp.: 1 Spectran Elctrns.; 1 Soectrum Instrs., Inc.; 1 Sprengnether , w. F. Instr., Cc.

,

Inc.; 6 Stoddart Electro Sys.: 1 Systems Resch. Labs.; 1, 5 Sys tron-Conner Ccrp.; 1, 3 Systron-Donner Datapulse Div.; 1, 3 Systron-Oonner Kruse Elctrns.

Sub. ; 1, 3 Systron-Donner Microwave Civ.; 1, 3 Takeda Riken Industry Ltd.; 3 Tasker Inds . : 1 Technical Research 4 Mfg. Co.; 1 Tektronix, Inc.; 1, 2, S Teldyne Geotech; Telonic Inds., Inc.; 5 Tennelek , Inc . ; 1 Texscan Corp.; 1, 5 Transducer Controls Corp.; 1 Universal Ad-Vu Elctrns., Inc.; 1 Vanan Aerograph ; 5 Varian Data Machines: 5 Vari-L Co. , Inc. ; 1 %*ector Engrg.: 5 Vega Precision Labs.: 3 Velonex: 3 Vibration Instrs. Co.; 1 Vi z Mf g . Co . ; 3 Voiceprint Laboratories: 1 Voltex Co. , Inc. ; 3 Vu-data Corp.; 1, 3 Wandel s Goltermann; 1 Weston Instruments, Inc.: 1 Westronics, Inc.; 6 Wolff Industries; 5 Yewcec Corporation: 5 Zonic Tech. Labs.; 6 ?oomar , Inc . ; 1
VOLTAGE

MEASUREMENT INSTRUMENTATION

1-Calibrators 3-Monitors

2 -Meters 4 -Standards

Active Control Instruswntation: 3 Airoax Elctrns.: 3 Allied Elctrna., Corp.: 3 Anerican Aerospace Controls: 3 >iYT Electrical Prods.-. 3, 4 Ajncrobe Instr.: 3 Analogic: 1. 4 Analogic Co. : 1, 4 A. O.I. P.: 4 Astro Cons. Lit. : 2

Atri. Instrs., Inc.: 4 Autottatic Switch Co.; 3 Autronies Corp.: 3 S 4 K Instrs. , Inc. : 2 ?ali3ntine Laboratories: 1, 2, 4 3ecHr--an I.-.strs., (AISSO) : 4 Pecknan Instrs.: 1, 4 3eede Electrical Instrs., Co., Inc.: 2 3endix: 2 Setamite Electronic Devices: 3 ?iddle, Jaires 3.: 4 31onder-Tono'-e Labs., Inc.: 2 Soonton Elctrns.: 2 Sulova Watch Co., Servo Prods. Elctrns., :iv.: 3 CALEX : 3 California Instrs., Co.: 2 CEA: 4 Chicaqo Condenser Corp.: 1 Coax levices Inc. : 1 Collins, G. L. Corp.: 4 Como'j- Systems Co.: 1 Cono-jier Diode: 1, 4 Co-nouter Test Corp.: 1 Conner-Wmf iald Corp.: 4 Constant Voltage Co.: 1 Controlotron Coro.: 3 * Diversified Elctrns.: 3 ?oric Sci. Corp.: 1, 3 Dranetz E.ngrg. Labs.: 3 Oynaae: 4 Dynax.ic Controls Corp.: 3 Eicon Sys . : 2 Electrical Instr. Svc, Inc.: 1, 2, 4 Electro/Data, Inc.: 2 Electro-'lecfianics Co.: 2 Electronic Dev. Corn.: 1, 4 Elctrns. Ltd. : 3 Elctrn. Navigation Inds.. Inc.: 2 Electro-Cotical Inds., Inc.: 1 Electro Soi. Inds.: 1, 4 Eneroency 3eacon Corp.: 2 Etc ley Lab., Inc.: 4 Fsterlme Angus Div. : 3, 4 Eairchild Electro-Metrics: 2 rluice, John Mfg., Co., Inc.: 1, 2, 4

MANUFACTURERS

Oenacal Microvava Corp.: 1, 2, 3, 4 Seneral Radio C'-i . : 2 General Resistance, Inc.: I, 4 Glentronics, Div. Sawyer Inds.: 4 Gralex Inds., Inc.: 3 Guidalin* Instrs., Inc.: 1, 4 Hallmark Standards, Inc.: 1, 2, 4 Haatti Co. : 2 Hewlett-Packard: 1, 2, 4 HI-G: 3 Hiram Jonas: 2 Molt Instr. Labs. : 1, 4 Honeywe 11: 2 Horex Elctrns., Inc.: 1 Hoyt Elec. Instr. Works: 2 Idalee Elctrns., Corp.: 1, 4 Ideal Precision Meter Co., Inc.: 2 Industrial Inventions, Inc.: 3 Ind'l. Test Equip.: 1, 4 I.-.strulab, Inc.: 4 Instrs. for I.nd., Inc.: 2 International Rectifier: 4 ITT Jennings Eastern "'egional Office: 2 ITT Jennings, Instr. t Systems: 2 ITT Jennings, Vacuum Elctrn. Prods.: 2 ISC Magnetics Div.: 3 Jerrold Electronics Corp.: 2 J-Omega Co. : 3 Julie Research Lab., Instruments

Div.: 1, 4 Keit.Mey Instrs., Inc.: 1 Kepco, Inc.: 1, 4 Kilovolt Corp. : 4 Kistler Instr., Co.: 1 Kratos: 2 Lab. Electro-Acoustique: 2 Leader Instruments Coro. : 2 LFE Corp. : 3 Logitek, Inc.: 3 Lorch-Adret Corp, : 1. 4 Mag-Con Engrg. Co.: 3 Marconi Instrs.: 2 MCG Electronics Inc.: 3 Medistor Instr., Co.: 1, 4 Megavolt, Inc. : 4 Meguro Denpa Sokki K.X.: 1 MFE Corporation: 3 Micro Instr., Co.: 2, 3 Microlab/FXR: 3 Millen, Jzunes Mfg. : 2 Monroe Elctrns., Inc.: 1, 4 Mura Corp. : 2 fIZS, Inc.: 3 MH Research, Inc.: 3, 4 North Atlantic Inds.: 4

North Hills Elctrns., Inc.: 1, 4 Ohio Seraitronics: 3 Pacific Meas., Inc.: 2 PECO Corp. : 3 Pioneer Magnetics: 1 Polarad Elctrn. Instrs.: 2 Power Designs: 1, 4 Precision Standards Corp.: 1, 4 Princeton Applied Rescn. Corp.: 2, 3 Quan-Tech : 2 Q.V.S., Inc.: 2 Radiation Devices Co. : 2 Pai Iway Comm. : 2 RCA Elctrns. Comps.: 2 Reeve Elctrns., Inc.: 2 RFL Inds., Instr. Div.: 1, Rohde i Sc.'-.warz Sis.: 2 Rosa Engrg. Corp.: 1, 2 P.ystl Elctrns. Corp.: 2 Sawyer Inds . : 4 Sensitive Researcf: Insrrs.: 2, 4 Shurite Meters: 2 Sigma Instrs., Inc.: 3 Simpson Elec. Co.: 1, 2, 4 Singer Instrumentation, Lcs Angeles Oner . : 2 Solar Elctrns. Co.: 2 Spectral Dynamics Corp.

San Diego: 2 Soectrum Control, Inc. : 2 SRC Div. : 3 Stoddart Electro Sys.: 2 Strut.hers-Dunn , Inc.: 3 Systron-Donner Alpha Scientific

Sub.: 1, 4 * Systron-Donner Corp.: 1 Takeda Riken Industry Co.. Ltd.: 4 Tektronix, Inc.: 1, 3 TSI-COM, Inc.: 1 Trio Labs , Inc. : 3 Triplett Elec. Instr., Co.: 2 United Sys. Corp.: 1 Velonex: 4 Vidar Corp. : 3 Volcex Co. , Inc. : 3 Wandel i Goltermann: 2 WeinsCiel Engrg. Co. : 4 Hestberg Mfg.' Co.: 2 Westmghouse Elec. Corp., Computer

i Instr. Div. : 2, 3 Weston Instruments, Inc.: 1, 2, 4 Westronics, Inc.: 1, 3 Yewtee Corporation: 4

CURRENT

MEASUREMENT INSTRUMENTATION

1-Sources 2-Meters

- » " Electrical Inst.: 2 \-ez:z3r. Aeroscace Controls: 1 "allanrine Laboratories: 1, 2 ~r-.ruter Test Corn.: 1 riectrical Instr. Svc, Inc.: 1, 2 T'.ez-rznic "ev. Coro.: 1 -frrar.t; Ltd.: 2 "•.j<e ."cr.r. -^fc. Co., Inc.: 1 "enera^ Resistance, Inc.: 1 "uidelme Instrs., Inc.: 1

MANUFACTURERS

Hallmark Standards, Inc.: 2 Holt Instr. Labs. : 1 Ideal Precision "etsr Co., Inc.: Ind'l. Test Eauionent: 1 Julie Research Lab. , Instru- ments Div . : 1 Keithley Instrs., Inc.: 1, 2 LEE Coro. : 2 North Hills Elctrns., Inc.: 1 Q.V.S., Inc.: 2

PEL Inds. . :ns-.r. Div. : 1 Sensitive Research :.-.strs.:

2 Simoson Elec. Co. : 2 Sunshine 3ci. Instrs., :.-.c. : Systrcn-Donner Ma'-.a Sci- entific Sub. : 1 TriDlett Elec. Ir.str. Co. : 2 rnited Svs . Coro. : 1 Westir.ghouse Elec. Ccrr.: : Weston Instruments, Inc.: 2 Yewtec Corooration: 2

31
POWER

MEASUREMENT INSTRUMENTATION

1- Bridges

2-Calorimeters

3- Bolometers

4 -Mounts

5 -Monitors

6- Probes

7-Meters

Ai rcom , Inc. : 4 , 6 Airerican Clctrn. Laba., Inc.: 4 A.O.r.P.:

AVL Ir.strs., Inc.: 1. Aviel Electronics Inc.: 5 Pallantme Laboratories: "> ^ell, F. W., Inc.: Bend IX : C, 5, 7 Siddle, James 0 . : 1 ?ird rictrn. : 1 , 2, 5 , T 3ooncon Clctrns.: 6, 7 Centralafc, Elctrns.: 4 rzs rictrns. : 4, € C'e-ialloy rictrns.: 2 Clarke Hess: " Jcax "^e'-icas Inc.: 3. 4 Cr'lins 'adio Co.: 5 Cond 1 1 , rnc. : r .-.t- '.c Cors. : " ^ataliaht Ir.c: 5 TM : ttrore-Treinuth Corn.: 4,, 6 rrake, =.. 1., Cc.

--i.;. Inc.: 1, 5 riertncal Ir.str. Svc. , Inc.: ^ rlectro Innulse, Inc.: 1, 2, 7 Flcrrn. r.'aviaation Inds., Inc.:

? lertroenys ICS Ccro.: 5 r-ener.cy Reacon Corn.: f rsterlme A-ous Div. : ' '".iirc^iili Flectro-"etrtcs : 7

'"ar.r.on electric: 5 "erranti Elec, I.-.c: "erranti ltd . : 7 "Ijxe, Jchn "Ifa. Co., Inc.: 7 "rea•^enc^' FncrT. labs.: 7 "atnel Elctrns. Coro.: 4 -fl^-a Sci . : "pnera 1 Flee . : ' "oneral Elec. Co., Elctrn, Compf '. s . Pept . : General 'licrowave: 1, "General Radio: 6, 7 3, 4, 5, S, 7

MANUFACTURERS

nuida Inds., Inc.: 4, 5, 6, 7 Hadron Inc. : S Hallaark Standards, Inc.: 7 Halraar Elctrns., Inc.: 7 Heath Co. : 7 Hewlett-Packard: 1, 2, 4, 5, S, 7 Hickok Elect. Instr.: 7 Honeywall, Apparatus Controls: 4 I'uahes Aircraft Co.: 4, 5 Ind'l. Test Equip.: 7 Instruffient Displays: 7 International Light: 5 ISC Magnetics Div.: 7 Jodon Fnqrq. Assocs . : 5 Kahl Scientific Instr. Corp.: 2 Kraeos: " Larson Instr. Co., I.-c. : 7 LFE Coro. : 7 'Tarconi Instrs . : '' '^aury 'licrowave Corp.: 3, 4, 5, 6, VCS Coro.: 4, 6, 7 '.icrodot Inc . : 7 "^icrof lect Co . : 4 Micro Instr . Co. : 7 •'tcroiab/FX?: 2, 3, 4, 6, 7 .'Ucrowave Assccs., I.nc: 4 Microwave Labs. Anerica: 4, 6 Microwave Sys. Co.: 4 Mobil Elctrns., Inc.: 7 Molectron Corp. : 5 Multi-Amo Coro.: Varda "icrowave Corn.: 1, 2, 3, 4, 6, New-Troni03 Corp.: 1, 7 NH Research, Inc.: 7 Ohio Semitronics: 7 Clektron Corp . : 1 Omeqa Labs., Inc.: 4, 6 OMNI Soectra: 3 Pace Div. : 1 , 5 Pacific Meas., Inc.: 5, 7 Polarad Elctrn. Instrs.: 7 PRO Elctrns., Inc.: 1, 2, 3, 4, 5, 5, PHASE SHIFT

Premier Microwave: 4, 6, 7 Quantronix Corp.: 5 Q.V.S., Inc.: 7 Radiation Int'l., Ire: 6 Rafec Elctrns'. 5 Raytheon Co . : 2 , 5 RCA Corn . : 7 Peeve Elctrns., Ire: 2, Republic Flctrn. Irds.. !r.c.: RF Corununications , Inc.: 7 RFL Inds . : 4 Pohde i Schwarz 5iS.: " Scientific Columbus: ' Scientific flducaticnal rr-is. Sensitive Research ir.strs.: Shiaoto Inds. : 7 Simcson Clec. Cr, . : Struthers Elctrns. C:.r::.: 1, 6, Sunshi.-.e Sci . Irstrs., Ir.c: Systron-Dcrner Ccrr.: Systrcn-Donner Satj^ulie Z.:. Syscron-Ior.ner Fruse rlctrr.3. ?ystrcn-:3onr.er Microwave Telonic Inds., Inc.: 5, TRG ProUs . : 2 , 3 Triolett Elec. Irstr. Co.: ' TPV; Instrs. : 5 ITion Carbide: 5 L'nited Detector Technoir.jy: " Varian Assccs . : ? Variar Assocs. "lectror. TjJ;e

i Device ^roup: 2 Vari-L Co . , Ire. : 5 , " Vector Industries: 4 wavelme. Inc.: 4, 6,

" Kemschel Er.qrg. Cc: 1, 3, 4 Western Reserve rictrns Westinghouse Elec. Corp Heston Instruments, Inc yewtec Corporation: 7

MEASUREMENT INSTRUMENTATION

1-Analyzers

2-Meters

3- Standards

4- Sources

5-Monitors

6-Loads

7-Load Stretchers

A i room. Inc. : 6 , 7 Alford Mfo. Co. : 2, 6, 7 American Elctrn. Labs., Inc.: 7 American Microwave Inds., Inc.: AMF Electrical Prods.: 4 Arra Inc. : 7 Associated Resch. : S Aus cron. Inc. : 2 , 3 Automated Meas.: 1 Automatic Switch Co.: 5 Baaanof Assocs., Inc.: 1 3is ler Flee. Co. : 5 aowmar/ALI, Inc.: 1 r i A Products, Inc.: 4 res Elctrns. 6 Chesterfield Prods. Inc.: 2, 5 c; ar'<e-Hess : 2 "cax "devices Inc.: 6, Collins Radio Co.: 2 Columbia Elec. Mfq. Co.: 4 Co-outer Conversions Corp.: 2 ror.trcl "Ictrns. Co., Inc.: 2 C3we Irstruments , Ltd.: 1, 2 "i ttmore-'^reimuth Corp.: 2 Diversified rictrns.: 5 "^ranetz Enqra. Labs.: 1, 2, 5 Cvra Technology Inc.: 4 3ytronics Co.: 1, 2, 3 !-H Resch. Labs., Inc.: 1 E lectro-?3ci f ic , Inc.: 4 E laar Coro . ; 4 Exact Elctrns., Inc.: 4 '^'sderal Sci. Corp.: 1 Feedback, Inc.: 1, 2, 4 Fermont 3iv. : 4 '"erranti Ltd. : 7

MANUFACTURERS

Forney Inds., Inc.: 4 Frequency Enqrq. Labs.: 1 General Elec. : 2 General riec. Co., Flctrn. Comos.

Sis . D«ot . : 2 General Equip, i Mfq.: 5 General Radio Co.: 7 Georator Corp .

Could, Inc. : 1 Guide Inds., Inc.: 7 Hewlett-Packard: 2. 4, 6 HI—';, 'Windsor Locks, Connecticut:

Ind'l. Test Equip.: 2, 3, 4 Ithaco , Inc . : 1 , 2 Fa to Fnqrq. Co. : 4 Fatoliqht Corp . : 4 Kratos: 2 Xrohn-Hite: 2 Loqi tek , Inc . : 5 Loral Flctrn. Sys.: 1 Lorch-Adret Coro.: 3, 4, 7 Maury Microwave Coro.: 6, 7 Mequro Cenpa 3okki .'.K.: 2 Micro Instr. , Co. : 1 Microlao/F'<R: f- . 7 Microwave Labs. America: S Multi-Amo Coro.: 1 Sarda Microwave Coro.: " North Atlantic Inds.: 1, 2, 4 Mu-Oevices: 1, 3, 5 Cmeqa Labs., Inc.: 6, 7 OMNI ?oectra: ONAN 31 V. : 4 Ooad Elec. Co., Inc.: 5 PRO Elctrns . , Inc. : 2 Premier Micrcwave: ~

Princeton i\Dplied Resch. Corp.: 2, Quan-Tech . : 1 , 2 Rantec Div . : 1 , 3 RF Systems , Inc. : 6 RLC Elctrns., Inc.: 7 Rohde i Schwarz Sis.: 2, 7 Scientific-Atlanta, Inc.: 1, 2 Scientific Columbus: 2 Servo Corn. A.merica: ], 4 Siemens Corp . 2 Signal Analysis Inds, Ccro: 1 Sinqer I ns trumenta ticn . Lcs Angeles Oner.; 1, 2, : Special Microwave C«"iccs C::er.: - Soectral Ovnam.ics Ccrr. ?.ir Cieqc: 1, 2 Struthers rictrns. Ccro.: ' Sunshine 5ci. Instrs., T.-c.: 1 Svstron-Oonner Oatarulse Iiv.: 4, Teledyne 'net : 4 Theta Ir.str. Coro.: 1, 2, 1, 4 Trio Labs , Inc. : 2 rPW/Clobe Motors: 4 L'niversal Ad-Yu Clctrr.s.: 1, 2, 3, Varo , Inc . : 4 Vernitron Corp.;

^'ibration Instrs., C-.: 1, 2-5 Video =esch. Corp.: 2 Wavelme, Inc.: , Wavetec: 2, 4 '.-.'emschei Engrg. Co.: " Westinghouse Elec. Corp.: 2, 4 Weston Instruments, Inc.: 1, 2

'''i 1 tron Co . : 2 Yewtec Corporation: 2 7onic Tech. Labs,: 2, 5
ATTENUATION

MEASUREMENT INSTRUMENTATION

1-Attenuators

2-Calibrators

3 - Comparators

4- Insertion Loss

Meas. Systems

5-Meters

?CC Products : 1 Aerolite Flectronics Coro.: 1 AIL Civision, rutlex-ilamner Ire: 1, 2, 5 Aircon Inc. : 1 Airtron: 1 Alford: 1, 3, 4 Al len-3radley : 1 Alien Avionics: 1 Altec: 1 ATerican, Aerospace Controls: 1 .American riectrn. Labs, Inc.: 1 Anerican Microwave Inds, Inc.: 1 Amofienol Division: 1 A.O.r.P. Paris, Trance: 1 Anzac Elctrns . : 1 Acolied Sesearch, Inc.: 1 Arenbero Ultrasonics I.ab., Inc.: 1 Arra, Inc.: 1, 2 Arteeh Corp. : 1 AIL Instrs. , Inc. : 1 Automation Dev.: 1 Automation Oynanica: 4 Ava Elctrns . : 1 Aviel Electronics Inc. : 1 3arth rictrns. Inc.: 1 Sell P/A Products Coro.: 1 Bird Elctrn. : 1 Slonder-Tonaue Labs., Inc.: 1> 4 Carter "ifg. , Corn.: 1 Centralab Tentralab Electrns.: Electr 1 CES Elctrns. : 1 Cir-C-Tel.: 1 Clarostat Mfg., Co, Inc.: 1 Coax Devices Inc. : 1 Comdel Inc. : 1 ConiDuter Labs.: 1 Daico Inds, Inc. : 1 Damon Corp . : I Delta-Senco Ltd. : 1 Dittmore-rreinuth Corp.: 1 Edison Elctrns. , Div.: 1, 5 E-H Research Labs., Inc.: 1 Elcom Sys . : 1 Elctrn. "laviaation Inds., Inc.: 1 Electronautics : 1 Electro Imoulse Inc. : 1 E t M Labs. : 1 FVC Technolo<7y Inc.: 1 Emerson i Curamq, Inc.: 4 Enqelmann Microwave.: 1 EairCiild Sound Equip.: 1

MANUFACTURERS

Fifth Dimension: 1 ntS Comms., Inc.: 1 GAT Corp.: 1 (General Microvave Corp.: J, 3, 4, 5 General Radio Co.: 1, 4 General Resistance, Inc.: 1 Gothan Audio Corp.: 1 Guide Inds., Inc.: 1 Guideline Instrs,, Inc.: 2 Hewlett-Packard: 1, 3, 4, 5 Honeywell: 1 Hope Elctrns.: 1 Hughes Aircraft Co.: 1 It.'iaco, Inc. : 1 Jerrold Elctrns., Corp.: 1, 4 Jewell Electrical Instrs.: 1, 5 Kay Eleratrics: 1 Xllovac Corp. : 1 Lab Eiectro-Acoustique: 1 Lecroy Pasch, Sys., Corp.: 1 Litton Inds . : 1 Larch-Adret Corp.: 1 Larch Elctrns., Corp.: 1 Marconi Instrs.: 1 Maury Microwave Corp.: 1, 2, 3, 4, 5 MCS Corp. : 1 Megura Denpa Sokki K.K.: 1 Merrimac Reach, t Dev., Inc.: 1 Metric Sys. : 1 Microlab/FXS: 1, 5 Micrometals: 1 Microtech: 1 Micro-Tel Corp.: 2 Microwave Aasocs., Inc.: 1 Microwave Developtnent Labs., Inc.: 1 Microwave Filter Co., Inc.: 1 Microwave Labs., America: 1 Mini-Circuits Lab.: 1 Mu-Del Elctrns.: 1 Narda Microwave rorp.: 1, 2, 3, 4, 5 Nurad, Inc.: 1 Ohmite Mfg. , Co. : 1 Olektron Corp.: 1, 4 Omega Labs . : 1 Omni Spectra: 1 OPT Industries; 1 Pabst Engrg., Ecpt., Co. Inc.: 1 PRO Elctrns., Inc.: 1, 2, 5 Premier Microwave: 1 Pyrof ila Coro. : 1 Q.V.S. Inc.: 5 Radiation Int'l., Inc.: 1Radio Resch., Cc. : 1 Faf ec Elctrns . : 1 Rantec Div. : 1 Raytheon Co. : 1 Re-el Circuits, Inc.: 1 Reeve Elctrns., Inc.: 1 Relcom: 1 RF Interonics: 1 RLC Elctrns. , Inc. : 1 Rohde i Schwarz Sis.: 1, 4, 3 Scientific-Atlanta, Ire.: 1, 2 Sealectro Corp.: 1 Sennherser Elctrn., Corp.: 1 Shallco. , Inc. : 1 Sie.Tiens Corp. : 1, 5 Sinclair Radio Labs.: 1 Singer Instrumentation: 1, 2, 4 Solar Elctrns., Co.: 4 Somerset Radiation Lab. : 1 Special Microwave Devices Cper . : 1 Stoddard Electro Sys.: 1 Struthers Elctrns., Corp.: 1, 3 Stromberg Carlson Corp.: 1 Systron-Donner Kruse Elctrns.: 1, 4 Systron-Donner Microwave Div. : 1 Takeda Riken Ind. , Co. , Ltd. : 3 Tech Labs . , Inc. : I Technical Research i "ifg. Co. : 1 Teledyne .Microwave: 1 Telonic Inds., Inc.: 1 Tennelec. , Inc. : 1 Texscan Corp. : 1 Thompson-CSF Electron Tubes: 1 Transco Prods., Inc.: 1 TRG Products: 1 Trompeter Elctrns. : 1 Van an Assocs. : 1 Varian Assocs. Electron Tube

t Device Group: 1 Vari-L Co. , Inc. : 3, 4, 5 Vega Products : 1 Vishay Resistor Prod., Div.: 1 Wandel & Goltermann: 1, 4 Waters Mfg., Inc.: 1 Watkins Johnson Co, : 1 Waveline Inc.: 1 Wavetek Ihdiana. , Inc.: 1 Weinschel Engrg., Co.: 1, 2, 3, 4, 5 Welwyn Elec, Ltd.: 1 Welwyn Int'l., Inc.: 1 Wiltron Co. : 1, 4 'finegard Co. : 1

33
NOISE

MEASUREMENT INSTRUMENTATION

1-Analyzers 3-Standards

2-Meters 4-Sources

AIL 3iv. Cutler-Hammer, Inc.: I, 3, 4 A. P. Circuit Coro. : 1 3 s IC Instrs. , Inc. : 1, 4 Searmo Inaoaccion: 1. 5eede Electrical Instr. Co., Inc.: 2 BowTTiar/ALI , Inc. : 1 Chesterfield Prods. Inc.: 1 Collins Sadio Comoany: 1 Dawe Instruments, Ltd.: 1 OuMont Electron Tubes: 4 3utrex Inds., Inc.: 4 Edison Elctrns. Div. : 2, 4 Elcorn Sys . : 4

^ Electro-Ootioal Inds., Inc.: 1 Eloenco, Inc. : 1 r-oiisn Elactric Valve Co., Ltd.: 4 rair:hild "lactro-'letr ics : 1, 4 ""ederal 3ci . Corn.: 1 "reed Transformer Co. : 2 "requency Enqrq. Labs.: 1 "eneral Microwave Corp.: 1, 4

MANUFACTURERS

General Radio Co.: 1, 2 GTE Svlvania Inc.: 4 Heath Co. : 2 Hewlett-Packard: 1, 2, 4 Honeywell: l IRD Mechanalysis , Inc.: 1 Int'l. Elctrns.: 4 Int'l. "licrowave: 2, 4 Kay Elemetrics: 1. 4 Lab Electro-Acoustique: 1,2 London Co., Cleveland Ohio: 2 •!arconi Instrs., Enqlewood, S.J.: 2 Maury "Microwave Coro.: 3 Metropolitan Supply Corp. : 4 Micro Instr. Co. : 2 lilletron , Inc. : 1 Melson Soss Slctrns.: 1 Northeast Elctrns. Corp.: 2 Polarad Elctrn. Instrs.: 1 Princeton Applied Resch. Corp.: 1

Cuan-Tech. : 1 , 2 , 3 , 4 Rockland Sys. Core.: 1 Ronde • Schwarz Sis.: 1, 2 Siemens Corp.: 1, 2, 4 Signal Analysis Inds. Corn.: 1 Siqnalite, Neptune, N.J.: 4 Singer Instrumentation: 1 Solatron Enterprises: 4 Soltac Corp. : 2 Soectral Dynamics Corp.: 1 Sperry Elctrn. Tube: 4 Sprengnether , W. r. Instr. Co.: 2. 4 Thompson-CSF Electron Tubes : 4 Thor Elctrns. Corp.: ! Tracor, Inc. : 1 Varian Assocs . : 4 Vibration Instrs. Co.: 1, 2 Wandei i Goltermann: 2 Warnecki Electron Tribes, I.ic: 4 wavelme. Inc. : 4

EM FIELDS

MEASUREMENT INSTRUMENTATION

1-Measuring Equipment 3-Antenna Analyzers

2-Meters 4-Analyzers

MANUFACTURERS

.V-:erican Elctrn. Labs., Inc.: 1, Aralv-tical 'teas.. Inc.: 1 3eir, f. W., Inc.: 2 ?londer-Tonaue Labs., Inc.: 2 Carco Electronics: 4 Cclii.-.s Padio Co.: 1 Delta-Benco Ltd.: 2 Oiitrr.are-rreinuth Corp.: 2 ?rareti Enora. Labs.: 4 Ficon Sys . : 2 Flectro-Mechanics Co.: 1, 2 Fairchild "lectro-'tetrics : 1, 2

'"-TF Svlvana Inc. Elactrn.

Svs . C-c. : 4 Hewlett-Packard.: 1 Hiram Jcnes : 1 i?onewell: 1, 2 KuGhes Aircraft Co.: 4 r.-.cal Service Corp.: 1

Instrs. for Ind., Inc.: 1, 2 Jerrold Elctrns. Corp.: 2 Kahl Scientific Instr. Corp.: 2 Labgear , Ltd . : 2 LDJ Electronics: 2 Leader Instruments Corp. : 2 Loral Electrn. Sys.: 4 Maanaflux Corp.: 2 Micro-Tel. Corp.: 1 '•tobil Elctrns., Inc.: 7 Monroe Elctrns., Inc.: 2 Narda Microwave Corp.: 2 Nelson Ross Elctrns.: 1, 4 Ohio Semitronics: 1 0. S. Walker Co. : 2 Oxford Instr. Corp.: 2 Polarad Elctrn. Instrs.: 1, 2, 4 Raf ec Elctrns . : 1 Reeve Elctrns., Inc.: 2

Pohde i Schwarz Sis.: 1, Scientific-Atlanta Inc.; Shurite "teters: 2 Siemens Corp.; 1, 2 Singer Instrumentaticn,

Angeles Cper . : 1 , 2 Singer Instrumentation,

Al to Oper . : 2 , 4 Solar Elctrns. Co.: 1, ; Sorague Elec. Co.: 1 Stoddat't Electro Sys.: ] Vari L Co .

, Inc . : 4 Varian Assocs . : 2 Velonex: 1 Matkins Johnson Co.: 1, Wemschel Engrg. Co.: 4 Wilkinson rictrns.: 2 Wiltron Co. : 4

MATERIAL PROPERTIES

MEASUREMENT INSTRUMENTATION

1-Analyzers 2-Meters

Advanced Patent Technology, Inc.: 1 A. P. Circuit Corp.: 1 B i K Instrs . , Inc. : 1 3ell, F. w.. Inc.: 1, 2 Chesaoeake Instr. Corp.: 1 Ccnouter Test Corp.: 1 r'.ectro-Mecftanics Co.: 1 Tederal Sci. Corp.: 1 "eneral Radio Co.: 1 KallTark Standards, Inc.: 1 Hioh Voltaae Enqra. Coro.: 1 Ind' 1 . Control Co . : 1 Irwm Labs., Inc.: 1

MANUFACTURERS

ISC Magnetics Div.: 2 Kinetic Tech., Inc.: 1 Lab Electro-Acoustique ; 1 LDJ Electronics: 1, 2 Maqnaflux Corp.: 1 Magnetic Analysis Corp.: 1 Nelson Ross Elctrns.: 1 NuSonics, Inc.: 1 Oeco Corn . : 1 Ohio Semitronics: 1 0. ?. Walker Co. : 1 , 2 Polarad Electrn. Instrs.: 1

Quan-Tech : 1 RFL Inds., Instr. 3iv. : 1 Shur-Lok Coro. : 1 Spectr'im Instrs., Inc.; 1 Stoddart Electro Sys.: 1 Sunshine Sci . Instrs., Inc.: 2 Systron-Donner .Alpha Sci- entific Sub . : 1 Svstrcn-Oonner Coro.: I Tecnsonics : 1 Thomas i Skinner, Inc.: 1, 2 Varian Assocs . 1

34
APPENDIX C - LABORATORIES AND CAPABILITIES*

Private Laboratories

0 Service To Parent Organization Only

r Ud iiuraLiwri ocrviuca nvaiiauic >>

N Calibration Services Available On A

No Fee Basis

t a Krt i^a v*T flc Lauu ret r i 7-in Lip ><

0 RAYTHEON COMPANY 01778 0 RCA 01801 0

•»MT fDnUAUP i's^nrTiTP^ T MP U 1 OUJ 0 *RiiVTHPnM rriMPANY U I O 1 u 0

IINTV uiviv • OFur 1uuricu^ nUFl I RP'^F^lRrW r\cocnr\v,/n FHlINn ruuiiu U 1 O^f F *AVCO CORP. 01887 F RAYTHEON COM 02062 F 02107 0 *rHARl F"^ '^TARK DRAPFR 1 ARORATOR 0

ITEK CORP. 021 7"? 0 *SANDERS ASSOCIATES, INC. 03060 F EATH IRON WORKS CORP. 04530 0 *FRATT A UHTTNFY ATRrRAFT Dfil Oft 0 *GFNFRAI OYNIAMTC^ rORPflRATTflN 0

*PFRKTN Fl MFR fORP UOO 1 u 0 CAPITAL MAGNETIC PRODUCTS 06906 0 RFL INDUSTRIES, INC. 07005 0 *TTT__a\/TnMTr<; nrui^inM U/ U 1 H 0

*i nr/uccn ri crTDnwir'; rn tmp u/ UO 1 F

unMCvtJci 1 Twr nUiNtlVicLL ilNL. u/uyu F "-WESTON INSTRUMENTS, INC. 07114 0 SINGER COMPANY 07424 0

0 noi no Uo 1 U? F

ora U03H-U 0 UOO/ o 0 ELECTRICAL TESTING LABORATORIE 10021 F ELECTRICAL INSTRUMENT SERVICE, 01550 F SPERRY GYROSCOPE 11020 0 GRUMMAN AEROSPACE CORP. 11714 F GENERAL ELECTRIC COMPANY 13201 F NIAGARA MOHAWK POWER CORP. 13202 0 SPERRY RAND CORP. 13501 0 EASTMAN KODAK COMPANY 14650 0 EASTMAN KODAK COMPANY 14650 0 '^ESTINGHOUSE ELECTRIC COMPANY 15235 0 AMP INC. 17105 0 GAGE LAB "corporation 19006 F CLIFTON PRECISION 19018 0

Private Laboratories

0 Service To Parent Organization Only

F Calibration Services Available On A Fee Basis

N Calibration Services Available On A No Fee Basis

Laboratories Zip

GENERAL ELECTRIC 19101 AMERICAN INSTRUMENT SERVICE, I 19123 HONEYWELL INC. 19406

AMERICAN ELECTRONIC LABS., INC 19446

COMSAT LABORATORIES 20734

FAIRCHILD SPACE + ELECTRONICS 20767

APPLIED PHYSICS LAB 20810

AUTOMATION INDUSTRIES, INC. 20910

WESTINGHOUSE ELECTRIC CORPORAT 21203

KOPPERS CO., INC. 21203

>

0

F

F

F0

F00

F0

MARTIN MARIETTA CORP. 21220 0 E-SYSTEMS 22046 F HONEYWELL INC. 22151 F NEWPORT NEWS SHIPBUILDING 23607 F MARTINSBURG ELECTRONICS 25401 F

LOCKHEED AIRCRAFT CORP. 30063 0 SPERRY RAND CORP. 32601 F HONEYWELL INC. 32803 F MARTIN MARIETTA AEROSPACE 32S05 0 HARRIS CORPORATION 32901 F RCA INTERNATIONAL SERVICE CORP 32925 0 FLORIDA STANDARDS LAB 33405 F HONEYWELL INC. 33733 0 BATTELLE MEMORIAL INSTITUTE 43201 0 ROCKWELL INTERNATIONAL 43216 0

HONEYWELL INC. • 44135 F NORTH ELECTRIC CO. 44833 0 HONEYWELL INC. 45324 F AVCC CORP. 47374 F HONEYWELL INC. 48024 F SSCO STANDARDS LABORATORY 48237 F ROCKWELL INTL. COLLINS RADIO G 52406 F SPERRY UNIVAC, DEFENSE SYSTEMS 55165 0 MEDTRONIC, INC. 55432 0 MOTOROLA, INC. 60172 0 IIT RESEARCH INSTITUTE 60616 F f^ESTERN ELECTRIC COMPANY 50623 0 HONEYWELL INC. 50634 F MCDONNELL DOUGLAS CORP. 63166 F BEECH AIRCRAFT CORPORATION 67201 0

+Source: NCSL Directory of Standards

Laboratories, 1976

35
Private Laboratories Private Laboratories

0 Service To Parent Organization Only

F Calibration Services Available On A Fee Basis —

N Calibration Services Available On A

No Fee Basis

Laboratories Zip

fO <c *BEECH AIRCRAFT CORP. 67201 0 *BOEING COMPANY 67210 F ROCKWELL INTERNATIONAL - TULSA 74151 F *TUCKER ELECTRONICS COMPANY 75040 F COLLINS RADIO COMPANY 75080 c

r

GENERAL ELECTRIC COMPANY 75220 F LOCKHEED ELECTRONICS CO., INC. 77058 0 *TRACOR INC. 78721 0 *RHODES-GROOS LABORATORIES 78724 F *MASON + HANSILAS MASON CO. 79177 0

"HUlNttWbLL INC. oUd 1 7 F ntWLt 1 1 HALNAKU UU . oObJ/ F AEROJET NUCLEAR COMPANY 83401 0 SPERRY RAND CORP. 84116 0 THICKOL CORP. 84302 u

HONEYWELL INC. 85017 F *SANDIA LABS 8711 5 F LOCKHEED ELtCTRONICS CO. INC. 88001 0 EG+G INC. 89101 F HONEYWELL INC. 90040 r

HUGHES AIRCRAFT COMPANY 90230 0 NORTHROP CORP. 90250 0 GENERAL ELECTRIC INSTRUMENTION 90301 F MCDONNELL DOUGLAS CORPORATION 90846 0 CALIFORNIA INSTITUTE OF TECHNO 91103 0 BELL + HOWELL ELECT. + INSTR. 91109 0 TELEDYNE SYSTEMS CO. 91324 F LITTON GUIDANCE + CONTROL SYST 91364 0 CERTIFIED SERVICES 91406 F LOCKHEED-CALIFORNIA COMPANY 91520 r AEROJET ELECTROSYSTEMS COMPANY 91702 0 GENERAL DYNAMICS /POMONA OIVISI 91766 F TELEDYNE RYAN AERONAUTICAL 92112 0 GENERAL DYNAMICS CORPORATION 92138 F GENERAL DYNAMICS CORPORATION 92138 F CELESCO INDUSTRIES, INC. 92625 0 BECKMAN INSTRUMENTS, INC. 92634 F MCDONNELL DOUGLAS ASTRONAUTICS 92647 F AERONUTRONIC-FORD CORPORATION 92663 0 ROCKWELL INTERNATIONAL 92803 F OALMO VICTOR COMPANY 94002 F FAIRCHILO CAMERA AND INSTRUMEN 94042 0 HEWLETT PAC:<ARD CO. 94043 F AjMpex corporation 94063 0 LOCKHEED MISSILES AND SPACE CO 94088 F

0 Service To Parent Organization Only

F Calibration Services Available On A

Fee Basis

N Calibration Services Available On A

No Fee Basis

Laboratories Zip ^

'/JESTINGHOUSE ELECTRIC CORPORAT 94088 0 VARIAN 94303 F HEWLETT PACKARD CO. 94304 F HEWLETT PACKARD CO. 94304 F SYSTRON-OONNER 94518 0

HONEYWELL INC. 94545 F HEWLETT PACKARD CO. 95050 F HONEYWELL INC. 95110 F HEWLEH PACKARD CO. 95401 F TELETEK ENTERPRISES, INC. 95570 F

TEKTRONIX, INC. 97077 0 HONEYWELL INC. 98109 F BOEING COMPANY 98124 0

Government Laboratories

DEPARTMENT OF NATIONAL DEFENCE 0 NAVAL UNDERWATER SYSTEMS CENTE 02840 0 PORTSMOUTH NAVAL SHIPYARD 03801 0 U.S. ARMY ELECTRONICS COMMAND 07703 F NAVY EASTERN STDS LAB 20374 F

DEPARTMENT OF DEFENSE 20755 0 HARRY DIAMOND LABS, AMXDC-EDG- 20783 0 NAVAL AIR REWORK FACILITY 370 23511 F NORFOLK NAVAL SHIPYARD 23709 0 L.S. MARINE CORPS 31704 0

TYPE II STANDARDS LABORATORY 32508 F NASA/IN-MSD-4 32899 0 U.S. ARMY METRO + CALIB CENTER 35809 0 NASA 35812 N TENNESSEE VALLEY AUTHORITY 37^01 0

AEROSPACE GUIDANCE + METROLOGY 43055 0 NASA JOHNSON SPACE CENTER 77058 0 NAVAL AIR REWORK FACILITY 94501 F U.S. BONNEVILLE POWER ADMIN. 98650 0

36
U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

jri e c 1

1. PUBLICATION OR REPORT NO.

NBSIR 75-936

2. Gov't Accession

No.

3. Recipient's Accession No.

4. TITLE AND SUBTITLE

The National Electromagnetic Measurement System

5. Publication Date June 1977

6. Performing Organization Code

276.00

7. AUTHOR(S)

Robert A. Kamper

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/ Work Unit No. 2760905

11. Contract/ Grant No.

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

Same as Xtem 9

13. Type of Report & Period

Covered

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less (actual sutiunary oi most si^ificant information. If document includes a significant

bibliography or literature survey, mention it here.)

This 'report reviews the scientific, commercial, civil, and

military activities that use electromagnetic measurements, and the

measurement techniques and standards, and the institutions

developing and using them, that have evolved to satisfy their

needs. Through the early influence of the Department of Defense,

this part of the National Measurement System is well coordinated,

with NBS established as the central reference point. The

measurement needs of lasers are included in the discussion.

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons)

Electromagnetic quantities; laser; microwave; National Measurement

System; radio measurements.

18. AVAILABILITY Unlimited

1 For Official Distribution. Do Not Release to NTIS

i Order From Sup. of Doc, U.S. Government Printing Office

Washington, D.C. 20402. SD Cat. No. CH

' X Order From National Technical Information Service (NTIS)

Springfield, Virginia 22151

19. SECURITY CLASS

(THIS REPORT)

UNCLASSIFIED

21. NO. OF PAGES

40

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

22. Price

$4.00

USCOMM-OC 29042-P74