III II HIIIIllffll llllilllllM

NBSIR 73-307 (01

A DUAL CHANNEL, DOUBLE HETERODYNED PHASE SHIFT

MEASUREMENT SYSTEM 110 MHz TO 18 GHz

Keith C. Roe

Electromagnetics Division

Institute for Basic Standards

National Bureau of Standards

Boulder, Colorado 80302

July 1973

Prepared for

ARMY/NAVY/AIR FORCE

Calibration Coordination Group

CCG 71-47

NBSIR 73-307

A DUAL CHANNEL, DOUBLE HETERODYNED PHASE SHIFT

MEASUREMENT SYSTEM 110 MHz TO 18 GHz

Keith C. Roe

Electromagnetics Division

Institute for Basic Standards

National Bureau of Standards

Boulder, Colorado 80302

July 1973

Prepared for

ARMY/NAVY/AIR FORCE

Calibration Coordination Group

CCG 71-47

U.S. DEPARTMENT OF COMMERCE, Frederick B. Dent, Secretary

NATIONAL BUREAU OF STANDARDS, Richard W. Roberts, Director

CONTENTS

Page

1. Background 1

1.1 Goals 2

1.2 Selection of Measurement Method 3

2. Measurement System Description 4

2.1 Introduction 4

2.2 Overall System 4

2.2.1 First Heterodyne Stage 6

2.2.2 20.178 MHz Signals 6

2.2.3 Second Heterodyne Stage 7 2.2.4 Wave Shaping at 100 kHz 7 2.2.5 Time- Interval Measurements 7

2.2.6 Computation 8

2.2.7 Display 9

3. Operating Procedure 9

3.1 Introduction 9

3.2 System Set-Up 10

3.2.1 Cable Connections for the PSMS 10

3.2.2 Switch Position for Measurement System 12

3.2.3 Power Level Setting 13

3.2.4 Computer Program for Phase Measurement 14

3.2.5 Zero Crossing Adjustment 15

3.3 Measurement Procedure 16

iii
CONTENTS (continued)

Page

4. Errors 18

4.1 Introduction 18

4.2 Theoretical Error Analysis 19

4.2.1 Frequency Instability of the HP 5360

Reference Oscillator (e^) 20

4.2.2 Time - Interval Measurement Uncertainty

(e

2

) 20

4.2.3 Cross Channel Leakage 21

4.2.4 Environmental Effects 22

4.2.5 Amplitude Errors 2 3

4.2.6 Instability of Preset Trigger Level in

the Time - Interval Plug-In 24

4.2.7 Error Summation in the PSMS 25

5. Experimental Evaluation 25

5.1 Introduction 25

5.2 Measurements at 10.23 GHz 27

5.2.1 Phase Shifts Produced by a Rotary Vane

Phase Shifter 27

5.2.2 Phase Shifts Produced by a Sliding

Short Circuit in a Precision Waveguide

Section 30

5.3 Measurements at 17.0 GHz 32

6. Conclusions 34

7. Recommendations 34

iv
CONTENTS (continued)

Page

Appendix A. Auxiliary Equipment 36

Appendix B. Circuit Schematics of Non -Commercial

Equipment 42

Appendix C. Modifications of Commercial Equipment 47

Appendix D. Parts Lists 49

Appendix E. Sample Data Sheet for Phase Shift

Measurements 55

8. References 57

v
LIST OF FIGURES

Page

Figure 1. Block diagram of the Phase Shift Measurement

System • 5 Figure 2. Simplified block diagram of a test set-up

in WR-90 waveguide using a rotary vane phase

shifter 27

Figure 3. Results of measurements of phase shift produced by a rotary vane phase shifter at

10 .2 30 GHz 28

Figure 4. Simplified block diagram of a sliding short

circuit test system using WR-90 waveguide 30

Figure 5. Results of phase shift measurements at 10.23

GHz. Phase shifts produced by a sliding

short circuit technique 31

Figure 6. Results of phase shift measurements at

17.0 GHz 33

Figure 7. Block diagram at an auxiliary system used in

conjunction with the PSMS for phase shift

measurements 37

Figure 8. Circuit schematic of Mixer Amplifier 43

Figure 9. Circuit schematic of 20.178 MHz Buffer

Amplifier 44

Figure 10. Circuit schematic of Squaring Circuits 45

Figure 11. Circuit schematic of 100 kHz Distribution

Amplifier 46

LIST OF TABLES

Table 1. Major Components of the PSMS 49

Table 2. Parts Information for Mixer Amplifier Circuit 50

Table 3. Parts Information for 20.178 MHz Amplifiers- 51

Table 4. Parts Information for Squaring Circuits 52

Table 5. Parts List for 100 kHz Distribution Amplifier 53

vi
A DUAL CHANNEL, TIME - INTERVAL

,

PHASE SHIFT MEASUREMENT SYSTEM

This report presents a system description,

error analysis and operating procedure for a dual

channel phase shift measurement system operable

in the frequency range 110 MHz to 18 GHz.

Basic principles of operation include double

stage heterodyning from RF and microwave frequencies

to 100 kHz, time- interval and period measurements,

and automatic conversion to phase in degrees through

use of a digital computer.

Key words: Computer; counter; heterodyne; period;

phase shift; time - interval

.

vii

DATE: April, 1973

OBJECTIVES: Establish or improve the phase measurement capability of calibration laboratories through the development

of an appropriate phase measuring system and related

standards operating from 110 MHz to 18 GHz.

IMPORTANT NOTICE: Certain commercial equipment is identified

in this report. This identification does not imply

endorsement by the National Bureau of Standards nor does

it imply that the equipment identified is necessarily the

best available for the purpose.

1. Background

Microwave phase shift measurements, in general, use

rotary vane phase shifters as transfer standards. Calibration

of the transfer standards is performed at a few specific frequencies (usually three or less) using sliding short circuit

in precision waveguide section techniques [l]. 1 Uncertainties

for the calibration of rotary vane phase shifters are usually

within the range 0.1 to 1.0°. In turn the calibration

of other phase shift devices by comparison with the rotary

vane transfer standard has uncertainties which may be in the

range 0.2 to 2.0°.

figures in brackets indicate literature references at the

end of this report.
The disadvantages in using sliding short circuit techniques to calibrate the rotary vane phase shifters are:

1. Systematic uncertainties better than 0.05° are

difficult if not impossible to achieve.

2. Data reduction is complicated and time consuming.

3. Systems are expensive and must be duplicated for

each waveguide size.

Recent efforts at the National Bureau of Standards have

been directed toward producing an improved phase shift measurement system to be used in calibrating rotary vane phase

shifters or low loss lengths of waveguide transmission line

used as phase shift transfer standards.

1.1 Goals

The proposed characteristics of an improved phase shift

measurement (PSMS) include the following:

1. Frequency range: 10 MHz - 40 GHz*

2. Phase shift range: 0 - 360°

3. Uncertainty of phase displacement measurements: 0.01°

4. Measurement resolution: 0.001°

5. Readout: direct reading

*The frequency range goal (1) was reduced through mutual agreement between the sponsor and NBS to 110 MHz - 18 GHz which

meets immediate needs of the sponsor and conforms with equipment capabilities used in the system.

2
1.2 Selection of Measurement Method

Three different phase shift measurement techniques were

investigated to determine which one would most nearly satisfy

the goals. These three techniques involved: 1) A pulseoperated electronic phase shifter, 2) A resolver phase shifter,

and 3) A time interval counter.

The pulse operated phase shifter was designed to retard

the phase of a synchronous clock by a specified amount over a particular period of time. One of these instruments has been

built with a phase shift accuracy of 5 nanoseconds at 100 kHz

(0.18°), which was insufficient for the requirements of this

pro j ect

.

The resolver phase shifter operated at 30 MHz and had

deviations in repeatability ranging from 0 to 27°. This technique was not pursued further.

The resolution of the t ime - interval counter was measured

using a high stability 100 kHz source and found to be 100 picoseconds which in terms of phase at 100 kHz is equivalent to

0.0072°. (See Section 4.2.1b). In addition, the system could

be broadband and direct reading in phase from 0° to 360°;

therefore, the time - interval method of phase shift measurements

was chosen as the basis of the PSMS.

3
2. Measurement System Description

2 . 1 Int roduct ion

The basic operational principles of the PSMS are heterodyning and time - int erval measurement. No theory for these

techniques will be pre sented, s ince these subjects are covered

in numerous texts and papers involved in RF and microwave

theory

This description follows a step-by-step explanation of

the various signal processing stages from RF input to output

phase display. Refer to Figure 1 for a block diagram of the

PSMS.

2.2 Overall System

The PSMS has two channels, called test and reference, which

accept two coherent RF signals and double heterodynes both

signals to two 100 kHz sine waves. These are shaped to square

waves from which two quantities are measured by a counter:

1. the period of one complete cycle and 2. the time interval

occurring between the zero crossing points of the waveforms

of the two 100 kHz square waves. These data are then used to

compute (using a digital computer) the phase displacement in

degrees between the two 100 kHz signals.

4
6

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2.2.1 First Heterodyne Stage

The technique used in the first heterodyne stage of each

channel is referred to as harmonic mixing [2]. At this stage

any two input RF signals in the 0.11 to 18 GHz range are converted to two 20.278 MHz IF signals. High frequency harmonics

of the self-tuning local oscillator are applied to the first

mixers to obtain 20.278 MHz IF difference frequency signals.

(See Figure 1 .

)

The self-tuning local oscillator contains a pulse generator, a voltage tuned oscillator (VTO) and a frequency and

phase control system. Signals from the VTO are applied to the

pulse generator to obtain harmonics in the 0.12 - 18 GHz range

which are mixed with the RF input signals. A harmonic 20.278

MHz above the RF input signal is used to phase lock the VTO

to the RF input signal. The phase lock loop supplies tuning

control voltages to the VTO to perform the following functions:

1. Initially sweeps the VTO to search for the RF input

frequency

.

2. Phase locks the reference channel first IF to a 20.278 MHz crystal oscillator reference. [2, Section

3 , page 95] .

2.2.2 20.178 MHz Signals

A 100 kHz signal derived from the time base oscillator

in the counter is mixed (see Appendix B for circuit) with a

6
20.278 MHz signal from the crystal oscillator reference for

the first heterodyne stage. The difference IF frequency,

20.178 MHz, is selected using a very narrow band crystal filter (3 dB bandwidth = 5 kHz) and is split into two channels

(test and reference), where each signal is then buffer amplified (Appendix B) and fed to the second heterodyne stage in

the test and reference channel.

2.2.3 Second Heterodyne Stage

The two 20.278 MHz signals from the first heterodyne

stage are mixed with the two 20.178 MHz signals to obtain two

100 kHz difference frequency signals.

2.2.4 Wave Shaping at 100 kHz

The 100 kHz difference IF signals from the second heterodyne stage are each amplified and filtered in very narrow band

crystal filters (3 dB bandwidth = 5 kHz) and sent to squaring

circuits (Appendix B) used to obtain square waves having

voltage steps which are coincident with the zero crossing of

the input sine waves. The rise time of the 100 kHz square

waves is less than 10 nanoseconds and rises from -0.5 volts

to 4.5 volts.

2.2.5 Time - Interval Measurements

The 100 kHz square waves go to the t ime - interval counter,

where two quantities are measured:

7
1. The period of the reference channel square wave.

2. The time interval between the positive going steps

of the reference channel and test channel 100 kHz

square waves.

2.2.6 Computation

A digital computer connected to the counter and located

in the same chassis utilizes these measured values of period

and time interval to compute the phase difference between two

100 kHz square wave signals. The relationship is:

<j> = 360 y C 1 ) where

cj) = relative phase difference (degrees)

t = time interval (seconds)

T = period of one cycle at 100 kHz (seconds)

The digital computer is programmed through a keyboard.

Random differences in the measurement of time interval and

period occurring from one measurement to the next can be

reduced by programming the computer to average the results of

a number (N) of measurements. The possible selections for N

are 1, 10, 100, 1000, and 10,000. The variation in readings

is reduced by 1//N [3] if the difference in readings is caused

by randomne ss

S
2.2.7 Display

The computed phase difference is displayed on the front

panel of the counter in digital form. Eleven digits may be

observed; however, only six digits (three to the right of the

decimal) have any significance. The duration of the display

depends on the number N selected for the measurement and may

vary from a few tenths of a second (N = 1) to 50 seconds

(N = 10,000)

.

3. Operating Procedure

3.1 Introduction

The instructions cover setup and use of the PSMS. The

order of the instructions is chronological in the sequence

which is normally followed, starting with assembly of the system from the major component pieces through control settings

to use of the system in a measurement procedure.

The setup procedure refers to certain specific equipment

in the PSMS by the model numbers assigned to these items by

their manufacturer.* Referral by model number rather than descriptive terms is done to reduce ambiguity in following these

instructions. Model numbers are printed on the front panels

*Important Notice: Certain commercial equipment is identified

in this report. This identification does not imply endorsement by the National Bureau of Standards, nor does it imply

that the equipment identified is necessarily the best available for the purpose.

9
of each major component; therefore, no difficulty is anticipated in identifying each major component by its model number

3 . 2 System Setup

3.2.1 Cable Connections for the PSMS

Most of the cables referred to are semi-rigid coaxial

cables especially constructed for inter-system connections.

These cables have been shaped to fit when the relative rack

position of the major components is from top to bottom --

(1) 5360A, (2) 8410A, (3) mixer amplifier chassis.

The following cables should be connected before AC power

is turned on.

a. Connect the 8411A to the 8410A, using the cable attached

to the 8411A.

b. Connect the reference output on 8410A plug-in to input A

of the 5365A module in the 5360A counter, using the semi

rigid coaxial cable with BNC connectors supplied.

c. Connect the reference output on 8410A plug-in to the T^

input of the 5379A time - interval plug-in, using the semi

rigid coaxial cable with BNC connectors supplied to fit.

d. Connect the test output on the 8410A plug-in to the T2

input on the 5379A plug-in, using the semi-rigid coaxial

cable supplied to fit.

10
Connect the 100 kHz clock output on the rear panel of the

5360A counter to the 100 kHz input on the rear panel of

8410A plug- in, us ing the semi-rigid coaxial cable with

BNC connectors supplied to fit.

Connect the 100 kHz output on the rear panel of the 8410A

plug-in to the 100 kHz input on the rear panel of the

mixer amplifier chassis, using the semi-rigid coaxial cable

with SMA connectors supplied to fit.

Connect the 100 kHz arming output on the rear panel of

the 8410A plug-in to the Ext. Meas . Time input on the

rear panel of the 5360A counter, using the semi-rigid

coaxial cable with BNC connectors supplied to fit.

Connect the cable from the 5375A keyboard to the connector which fits on the rear panel of the 5360A counter.

Connect the 20.278 MHz output on the rear panel of the

8410A to the 20.278 MHz input on the rear panel of the

mixer-amplifier chassis, using the semi-rigid coaxial cable

with SMA connectors supplied to fit.

Connect the 20.178 MHz outputs on the rear panel of the

mixer-amplifier chassis to the 20.178 MHz inputs on the

rear panel of the 8410A, using the two semi-rigid coaxial

cables with miniature Sealectro connectors on one end and

SMA connectors on the other end which are supplied to fit.

11
3.2.2 Switch Position for Measurement System

Switch positions and controls on the front panel of the

5360A and the plug-ins 5365A and 5379A are:

a. Push button switch to EXT

b. Measurement time to 1 ms with multiplier to 1

c5365A function to period

d. 5365A input to middle position

e . 5365A sensitivity to XI

f5365A level controls to preset

g- 5379A time interval T-^ slope to t

h. 5379A time interval slope to r

i . 5379A T

1

to XI

j

• 53 7 9A T

2 to XI

k. 5379A arming to auto

1

5379A sep-com to sep

Switch positions and controls on the front panel of the

8410A are:

a. Amplitude test channel gain to 69 dB

b. Amplitude vernier control full clockwise

c. Frequency range control set to the frequency of

operat ion

Set the trig-norm switch on the rear panel of the 5360A

to norm.

12
3.2.3 Power Level Setting

Check to see if the AC power cord to the 8410A plug-in

unit is connected and turn on AC power to the 5360A, 8410A

and mixer - ampl ifier chassis.

The following sequence is suggested for adjusting the RF

signal levels at the inputs to the phase measurement system:

a. Adjust the power levels of the RF signals in both the

test channel and the reference channel to minimum.

b. Connect the phase shift measurement system to the external

system through the APC-7 (7 mm) connectors. The external

reference channel should be connected to the reference

input of the 8411A.

c. Bring the power level of the reference channel RF up

until the indication on the front panel of the 8410A is

at the left edge of the operate region. Then increase

the power level by 3 dB. The indicator should be near

the left center of the operate region.

d. Reverse the input connections so that the test channel RF

signal is entering the reference channel part of the

8411A.

e. Adjust the test channel RF signal so that the indicator

on the front panel of the 8410A is at the right edge of

the operate region.

f. Reverse the connections again so that the test channel RF

enters the test channel of the 8411A and the reference

channel RF enters the reference channel of the 8411A.

13
3.2.4 Computer Program for Phase Measurement

The following program is entered on the 5375A keyboard

so that the phase will be displayed in degrees [4]:

a

.

Set sub -norm-man to norm

b . Select N (Set to 1, 10, 100,

c

.

Pre ss : Manual

d

.

Load

:

360

e . Pre s s : C exchange X (C ;x ) ->

rr

.

Press : Learn

g- Pre ss : Clear XYZ

h

.

Pre ss : a exchange with X

i . Pre s s : X for prog

j

• Pre s s : Module A

i

,

K . Pre s s : b exchange with X

1

.

Pre s s : Plug- in

m. Pre ss : b-*x->-y

n

.

Pre s s : t (divide)

o . Pre s s : c->x+y

P • Pre ss : a ^ mu 1 1 1 p i y J

q. Pre ss : a-*x->-y

r

.

Press : + (add)

s . Pre ss : a exchange with X

t

.

Pre s s : Repeat

u

.

Pre ss : a->x->-y

V. Pre ss : N+x+y

14
w. Press

x. Press

y. Press

z. Press

Display X

Run

Start

3.2.5 Zero Crossing Adjustment

a. Connect an oscilloscope to the Ref output on front panel

of the 8410A plug-in.

b. Reduce the power level of the RF input to the reference

channel by 26 dB . (This should cause the 8411A and 8410A

to lose lock.)

c. Adjust the ref channel pot on rear of 8410A plug-in unit

until the output of the ref channel squaring circuits observed on scope is between its upper and lower state.

(Output appears noisy.)

d. Return reference channel power to normal operating range.

e. Connect scope to test channel output on front of 8410A

plug- in

f. Reduce RF power level to test channel approximately 40 dB.

g. Adjust test channel pot on rear of plug-in until output

appears between its upper and lower states.

h. Return power level of RF input to test channel to normal

operating position.

i. Return connections to counter from Blank-Plug - In

15
3.3 Measurement Procedure

The system should now be operating and reading phase in

degrees. The measurement of phase shift is ready to begin.

With the device under test at its initial starting value

record the phase reading observed on the counter. Take several

readings to make sure that the system is not drifting. (With

normal operation and proper warm-up -- four hours -- the variation from reading to reading should be random and have a standard deviation of about 0.007°.) Next change the phase in

the test channel to the desired nominal value of phase shift

and observe the phase readings on the counter. Take several

readings to see that the readings are repeating. (In most

cases, the first reading of phase after a phase shift has

occurred will be in error because part of the measurement

occurred while the phase was being shifted. Time should be

allowed for a full measurement after the phase has been

shifted .

)

The largest potential error observed in making phase

shift measurements is referred to in this report as quadrature

error. (Quadrature refers to the measurement technique used

to reduce the error.) This error was unanticipated in designing this system and its source is not definitely known at this

time. However, the effect of this quadrature error can be reduced (± 0.25° reduced to ± 0.06°) by the following measurement procedure:

16
1. Make the first measurement of phase shift by recording the phase readings before and after a phase

shift has been produced. Record the difference

between the phase readings.

2. Insert a 90° phase shift in the reference channel

RF signal.

3. Repeat the phase shift measurement as in (l )

4. The phase shift value to be recorded as the measured

value is the average of the measurements in (1) and

(3).

For added confidence in the measurement of phase shift

the measurements should be repeated with the reference channel

RF phase shifted by 180° and 270° from its initial value of

phase in (1) . A comparison of the average of phase shift

measurements taken for reference channel RF phase settings of

(0° and 90°), (90° and 180°), (180° and 270°), (0° and 270°)

or (0°, 90°, 180° and 270°) will give the user a good approximation of the random and systematic changes occurring in the

measurement

If more than one phase shift is to be measured, as in

calibrating a rotary vane phase shifter, the phase shifts may

be measured successively without changing the reference channel RF phase until the complete string of phase shifts has

been recorded. Then the reference channel phase can be changed

by 90° and the phase shift readings recorded again.

17
A suggested procedure for measurement of successive phase

shifts -- for example, calibrating a rotary vane phase shifter

at increments of 20° through a total range of 720° -- is to

record the initial value of phase before and after each incremental value of phase shift. This reduces the effect of

drift which may occur in the measurement system and in the

external system. If the initial value of phase is not recorded

between successive phase shifts, the effect of drift is cumulative .

Errors in the measurement of phase shift result from two

main sources

1. Errors from the PSMS.

2. Errors from the auxiliary equipment. (The auxiliary

equipment includes the RF source, signal splitting

components and the phase shift device under test.

Appendix A includes a more complete description of

a typical auxiliary system and the treatment of

errors associated with that system.)

This error analysis considers all predictable sources of

random error in the PSMS. The quadrature error previously mentioned is not included in the theoretical analysis, since

4. Errors

4.1 Introduction

18
it is systematic and its source has not yet been determined;

thus no theoretical limits can be assigned. However, the

experimental evaluations (Section 5) indicate the extent of

reduction of quadrature error from the quadrature averaging

measurement procedure.

Specifically, the errors in the PSMS result from:

1. Frequency instability of the HP 5360 reference

oscillator (e, )

2. Time - interval measurement uncertainty (e^).

3. Cross -channel leakage (e^)

4. Environmental effects (e^)

5. Errors caused by amplitude variations of the input

signal U 5 ).

6. Error caused by trigger instability (e^)

These errors will be discussed individually.

From (1) Section 2.2.6 the equation for the conversion

of t ime - interval and period measurement to phase in degrees is

4.2 Theoretical Error Analysis

<J> = 360 (^) (degrees) CD

s ince

(hertz) . Then

$

= 360 t f (degrees)

(2)

19
The derivatives of (1) and (2) will be used in the discussions of and &2

4.2.1 Frequency Instability of the HP 5360

Reference Oscillator (e^)

The derivative of equation (2) with respect to the frequency (f) gives

dcf) = (360 t) df,

letting

z

1 = | Acj) | = 360 t | Af | . (3)

The reference oscillator frequency is 5 MHz, and its

stability is given as less than 5 parts in 10^ per twentyfour hours [3, p. 2]. A divide-by-5 and a divide-by-10 network

in the 5360A provides the required 100 kHz reference signal.

The stability after frequency division is no worse than 2.5

7 parts in 10 . Inspection of (3) shows that the error (e-^)

increases with t and is maximum for t = T = 10 seconds.

Substituting in (3) we get

- 7 £

^ = 9 x 10 degrees

This error is not significant with respect to other

errors to be discussed.

4.2.2 Time Interval Measurement Uncertainty (e^)

This error can be determined from the partial derivative

of (1) with respect to the time interval (t) and the period (T)

20
d , = M dt + H dT

» ± 360 360t » rp Acj) = At - —~— AT.

T T

The maximum error c~ occurs for t = T and At = AT which

gives :

e

2 = >T |.

The result of an experiment to determine AT using a high

stability 100 kHz source (short term stability equal to

2 x 10 °) is AT = 100 x 10 seconds, i.e., repetitive

readings of period measurements differed by no more than

100 x 10 seconds

- 12 Using AT = 100 x 10 seconds the value for (e

2

) is

e

2 = 0 . 0072 °

4.2.3 Cross Channel Leakage

A signal that reaches the test channel from the reference

channel input is a cros s - channel leakage signal. A leakage

signal of any magnitude may introduce a measurement uncertainty. In general, leakage signals are treated as random error

sources because it is an extremely difficult task to completely

characterize them in terms of their magnitude and phase.

The maximum error generated by a leakage signal can be

estimated from [5, Section 8, p. 12]:

, 3max

= 104.6 A- degrees, (4)

21
where | is the magnitude of the leakage signal and | E^

|

is the magnitude of the test signal and | EjJ

<< | E^ | . Measurements of cross - channel leakage in the 8411A and

8410A indicated a maximum leakage of -74 dB occurring in the

frequency range 11 - 16 GHz. The resulting phase error from

(4) is

e 7 = 0 .020°

3max

4.2.4 Environmental Effects

Even though the environment within many calibration laboratories is closely controlled, inhomogeneous temperature

variations can still easily occur. It would be an extremely

difficult task to attempt a theoretical determination of the

magnitude of the error introduced by changes in the environment. The experimental approach is the most practical way of

evaluating this random error (e^)

The error resulting from environmental changes is observed

as drift during a measurement. To minimize drift, sufficient

warm-up time -- four hours -- must be allowed. Stabilities within

0.015° have been attained for periods of two hours after warmup, however, most phase shift measurements can be accomplished

in thirty minutes or less. Furthermore, the drift time per

measurement can be reduced to approximately two minutes by

rechecking the zero reference point prior to each calibration

22
point. Using this technique the estimated limit of error (e^

from environmental changes is less than 0.005°.

c

4

= 0.005°.

4.2.5 Amplitude Errors

The measured time interval is the time displacement between the reference and test channel signals. If the amplitude of the test channel signal remains constant as the micro

wave device under test is adjusted, the start trigger level o

the squaring circuits can be set at any arbitrary value. But

the amplitude of the test channel signal may vary a finite

amount during a measurement; thus the zero crossing point is

used to minimize counter degradation caused by amplitude

variations in the microwave test signal. Further, the greatest trigger resolution is obtained at the zero crossing point

Triggering the squaring circuit at the zero crossing of

the 100 kHz sine waye can be accomplished only within a certain tolerance. Triggering no longer occurs if the amplitude

of the test signal is reduced to -30 dB below the normal

operating level. At -30 dB however, it was possible to adjust the level control so that the displayed phase was within

2.0° of that displayed at 0 dB . Thus the error caused by

amplitude changes in the test channel can be determined as:

2.0| AL I j £c = ?k degrees,

23
where AL is the change in the insertion loss of the microwave

device under test.

Typically, a rotary vane phase shifter produces an insertion loss change of less than 0.1 dB for any setting on the

dial. For a rotary vane phase shifter calibration, the error

become s

where AE is the instability of the trigger level; T is the

period of the input signal and R is the rise rate of the input signal; and the factor (4) is due to the start/stop trigger

points in measuring both time interval and period. It has

o been experimentally determined that R = 4 x 10 volts/sec.

The manufacturer specifies that the trigger level in the time

interval plug-in can be adjusted within 0.005 volts [7, Section 5 - 3] .

Thus, the error becomes

£ 5max

= 0 .007 °.

4.2.6 Instability of the Preset Trigger Level

in the Time - Interval Plug-In

This error (e A

) can be determined as

z, = 0 .002 °. o

2 4
4.2.7 Error Summation in the PSMS

The total maximum theoretical error is determined by

simple addition of the magnitudes of the individual theoret

ical errors

a. Frequency instability of the reference oscillator

= not sufficient

b. Time - interval measurement uncertainty:

c. Cross -channel leakage

d. Environmental effects

e. Amplitude changes:

f. Trigger instability

e

2 = 0.007°

c

3 = 0 .020

e

4

= 0.005°

c

5 = 0.007°

e

6 = 0.002°

Total error: e total

= 0.041°

5. Experimental Evaluation

5 . 1 Int roduct ion

Systematic uncertainties in measurements using the PSMS

are due to residual quadrature errors. The magnitude of

these errors cannot be predicted theoretically; however,

25
experimental measurements can be performed to determine the

limits of systematic error. In addition random error limits

can be experimentally verified.

Systematic errors can affect the measurement results of

the PSMS in two ways: 1. as bias errors producing an offset

of measured values from the true value and 2. errors contribut

to the spread between measured values. Normally differences

between measured values of the same phase shift are caused by

random errors. However, because of the measurement procedure,

successive measured values of the same phase shift are not

from the same population; hence, differences in the measured

values cannot be considered random.

To determine the limits of systematic error and verify

the random error limits given in (4) three separate groups of

phase shift measurements were performed. For each group of

measurements the initial phase setting was zero degrees; the

increments were 20 degrees (two groups) and 24 degrees; and

the final phase setting was nominally 360 degrees.

The measurement procedure described in section 3.3 was

used in all the measurements , and the results were determined

from averages of quadrature related sets. The results for

each group of measurements are shown in the form of correction curves; where the difference between measured values and

dial reading (or calculated value) is plotted along the ordi26
nate, and the dial reading or calculated value of phase shift

is plotted along the abscissa.

The measurements were made at 10.23 GHz and at 17.0 GHz.

5.2 Measurements at 10.23 GHz

5.2.1 Phase Shifts Produced by a Rotary Vane Phase Shifter

A system was set up, using WR-90 waveguide with two chan

nels (test and reference) having a microwave signal in each

channel derived from a reflex klystron - - frequency locked at

10.23 GHz to a crystal controlled reference oscillator. See

figure 2 .

Microwave

Source

Test

iShif ter

Signal

Splitter

Shifter

•4* PS MS

Figure 2. Simplified block diagram of a test set-up in

WR-90 waveguide using a rotary vane phase shifter

The phase shifter used in the test channel is a WR-90

rotary vane phase shifter with a precision dial such that

phase position (on the dial) can be reset within ± 0.02 degrees. The phase shifter in the reference channel was used to

obtain 90-degree phase shifts for quadrature averaging.

27
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coo

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COO

00

CvJ o

CvJ oo

CvJ o

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CC

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oo oo

ooo G

aJ>

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>-<

03

>>

J=> Xl

CDUO

PhPmH

in

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to

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28
Results from this group of measurements are shown in

figure 3. The major deviations of the correction curves from

the zero degree difference line are characteristic for a rotary vane phase shifter. Phase shifts from rotary vane

phase shifters will differ from the dial readings, depending

upon the orientation of the vane in the waveguide, the gearing

eccentricity and the mismatch [6] at the insertion point.

These deviations from zero will typically vary by as much as

0 . 5 degrees

Systematic errors cannot be evaluated from these results

since the phase shifts are not well known; but since they

are repeatable, the difference (spread) between curves is of

interest in verifying the random error limits given in

section 4. The random errors producing spread between the

curve s are

1. Errors from resettability of the rotary vane phase

shifter (includes an initial and a final phase

setting) = ± 0.030 degrees

2. Environmental effects on the waveguide system

(temperature) = ± 0.005 degrees

3. Frequency and power instability of the microwave

source = ± 0.005 degrees

4. Random error from the PSMS = ± 0.041 degrees

The maximum expected variation in phase shift measurements determined by the square root of the sum of the squares

29
of the contributing random errors is ± 0.051 degrees. The

maximum observed phase shift measurement error is ± 0.045 degrees, which is within the theoretical limit; and the conclusion is that the PSMS random error limit = + D . 041 degrees

is valid

The following group of measurements provides some information about systematic errors.

5.2.2 Phase Shifts Produced by a Sliding Short Circuit

in a Precision Waveguide Section

The waveguide system described in Section 5.2.1 was modified so that the test channel phase shifter was a sliding

short circuit in a precision waveguide section. (See Figure 4.)

Microwave

Source

Test

Tuner

i

j Aj Signal

Splitter

Tuner

Position

Indicator

Figure 4. Simplified block diagram of a sliding short

phase shift test system using WR-90 waveguide.

The phase shifts resulting from movement of the sliding

short circuit are calculable with uncertainties of ± 0.0(

(The uncertainties were calculated using equations given

30
z: CD

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UJ

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GE

<C <C <C <c

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UJ

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31
[1] resulting from non-perfect tuning of Y and S,^ , waveguide dimensional variations, motional resettabili ty of the

short circuit, cross channel leakage, frequency instability,

and environmental temperature effects.)

The results from quadrature averaged measurements are

shown in Figure 5, where the difference between the measured

value and the calculated value of phase shift is plotted

against the total phase shift.

The differences between the measured and calculated values

of phase shift are well within the total uncertainties assigned

to the calculated values; however, no technique has been

developed to separate the uncertainties of the PSMS from

those of the sliding short circuit system used to produce

the phase shifts. Therefore, the limit of systematic uncertainty of the PSMS is taken as the worst case difference between the measured and calculated phase shifts. From the data

the worst case difference is 0.064°, and the systematic uncertainty Usys temat ic ) is given as:

e «. «_

• = ± 0 . 064 °

sys temat ic

5.3 Measurements at 17.0 GHz

These measurements were performed to verify that the

error limits (systematic and random) observed at 10.23 GHz

are also valid at 17.0 GHz.

For these measurements a system was set up using WR-62

waveguide with a rotary vane phase shifter as a transfer

32
w

Ehco

COW

CO<

w

CD

CD CD^

'

'

l l UJ

| j

j 1 1

[

CO

1 1 1 UJ LO

UO

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(_/") O

in Q

Q_

UJ

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ry UJ

UJ 1 1 LI J

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U_ 1

u_ U_ O o 0 0

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CD

<c <c < <:

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03 m

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to

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vO

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(S33y33Q; 33N3cJ3JJia 3SVHd

33
standard. Phase shifts produced using the transfer standard

were measured with the PSMS and the NBS sub-carrier phase

shift measurement system. (SC/MS) Results of measurements

from both systems are shown in figure 6.

An analysis of the data from the two different systems

gives a mean difference of 0.031 degrees between the PSMS

measurements and the SC/MS measurements with a two sided 95

percent confidence interval between 0.049 degrees and 0.012

degrees. These 95% confidence intervals are well within the

systematic uncertainty limits of 0.08 degree and (3S) random

uncertainty limits of 0.129 degree established for the SC/MS.

No definite conclusions concerning systematic and random

error limits for the PSMS can be drawn. However, these results

(figure 7) are definitely similar to the results obtained at

10.23 GHz (figure 4), and the errors are no worse at 17.0 GHz

than at 10.23 GHz.

6. Conclusions

Phase shift measurements using the PSMS can be within

the systematic uncertainty limits of 0.064 degrees and a random uncertainty of 0.041 degrees if the quadrature

averaging procedure is used.

7. Recommendations

Accurate phase shift measurements require consideration

for the following:

34
1. Auxiliary system--see Appendix A for a description

of requirements and a discussion of the errors

from the auxiliary system.

2. Operating procedure - -Without quadrature averaging

errors as large as 0.25 degrees will occur.

3. Frequency range--The manufacturer's specification

for operation of the 8411A is 110 MHz to 18 GHz.

This specification has not been verified; however,

no difficulty has been encountered in operation at

frequencies selected at random within this range.

In addition, successful operation at 18 GHz was

achieved during developmental stages. None of the

circuits developed at NBS (see Appendix B) or modifications of commercial equipment (see Appendix C)

will affect the frequency range specification given

by the manufacturer.

4. Power range--The safe levels of RF and microwave

power input are given in section 3.2.3, and operation

within this range is recommended. In addition,

variations of power level during the measurement will

affect the uncertainty of the results. This error,

listed in section 4.2.5, will be increased if the

phase shift measurements are accompanied by power

level changes greater than 0.1 dB

35
Appendix A. Auxiliary Equipment

1. Function

Shown in figure 7 is a block diagram of a system used

successfully at NBS as an auxiliary system to the phase shift

measurement system. The functions of the auxiliary system are:

1. Generate an RF signal which is stable in power and

frequency

2. Split the RF signal into two channels (test and

reference) with cross channel leakage less than 80

dB below the signal level in either channel.

3. Provide the insertion point in the test channel for

the phase shift device under test.

4. Have phase shift capability in the reference channel of at least 90 degrees.

2 . Requirement s

2.1 RF Source

The RF source should be frequency controlled so that fre-

- 7 quency variations will be less than 1 x 10 in a thirtyminute period. In addition, fluctuations in power level should

be less than 0.1 dB in a thi rty -minute period.

2.2 Signal Splitter and Isolators

The RF signal should be split approximately equally into

two channels in such a way that the leakage from either channel

to the other is less than -80 dB. With uniconductor waveguide

36
1)

4-" •Ho

•H

4-* u3

•r-» ou

•HT3

<D36

<D •M

(f)

t/) <D

fH (I) 03 fn •H

rH V) •H o3 X <D 3 6

o3

+-> Mh

03

H

•P

1) S (A

03 03

fHW)

o3 •H om ^U CO O

i—

00 «03H

37
magic tees or hybrid tees will work, and in coaxial systems

power splitters with 30 dB isolation between channels will

work. In coaxial or waveguide systems additional isolation

should be used so that the leakage is reduced.

2 . 3 Tuners

The device under test in the test channel should have

minimum mismatch at its input and output ports. The effect

of mismatch on phase measurements is covered in Section 3 of

this Appendix.

2.4 Reference Channel Phase Shifters

The measurement procedure given in Section 3 requires a

90° phase shift in the reference channel RF signal.

3. Errors in Auxiliary System

The following errors contribute significantly to the

total error related to a specific measurement.

1. Frequency instability of the microwave signal

source

A simple analysis shows this error to be dependent upon

the frequency instability of the microwave oscillator and the

differential length between the reference and test channels

from oscillator to the 8411 input. This error can be minimiz

in two ways. First, the frequency stability of the microwave

oscillator can be minimized; and second, the differential

length (ideally thought of as the differential electrical

38
length) of the reference and test channels should be minimized.

A sample result given on p. 8-13, [5], is repeated here.

Assume the differential physical length of a waveguide system

operating at 10 GHz to be 10 ft. and the microwave frequency instability to be 10 kHz. The maximum error caused by

these two uncertainties becomes 0.036 degrees. Frequency

dependence of the components would increase this error. The

best way to evaluate this error in a given laboratory setup

is to change the microwave frequency in known, finite amounts,

and measure the corresponding phase shifts. From a plot of

these data and a knowledge of the frequency instability of

the microwave oscillator, the maximum error for the specific

equipment arrangement can be determined quite accurately.

2. Mismatch of the Device Under Test.

This error is a function of reflections from the device

under test and the system containing the insertion point terminals. In the analysis [6] the coefficients and represent the reflection coefficients of the generator and load,

respectively, as seen at the insertion point terminals.

The VSWR at the input to the HP 8411A is specified by the

manufacturer as less than 1.5 up to 8 GHz and less than 2.0

at higher frequencies. The effect of such a mismatch shows

up in the error calculation in the coefficient T^. Suppose,

for example, that the device under test is a rotary vane phase

39
shifter (VSWR = 1.3), and it is connected with a waveguide to

coaxial adapter to the input of the HP 8411 . The maximum

phase error caused by mismatch is 11.0 degrees. This error

can be reduced with tuners and/or isolators at the insertion

point terminals. For example, the rotary vane phase shifter

(VSWR = 1.3) connected to a tuned insertion point where

r rr = r T = 0 . 0005 will have a maximum phase error of 0.02 de

grees [6 , p . 620] . More typically the same rotary vane phase shifter with

insertion point mismatch r = T T = 0.015 would have a maximum

g L

phase error of 0.4 degrees.

3. Cross Channel Leakage

This error has been discussed in [5, p. 8-11]. RF leakage must be measured in each microwave system used. In

general an error of 0.012 degrees corresponds to a cross -channel leakage signal of -80 dB.

4. Environmental Effects

This error has also been discussed in [5, p. 8-11]. When

operating in a controlled laboratory environment the phase

error from this source is small unless the differential path

length between the reference and test channels is large (20

wavelengths) . For small differential path lengths (less than

five wavelengths) and temperature variations less than 0.1°C

during the measurement period the phase error is 0.007 degrees.

40
For a 1 foot differential path length at 10 GHz and

mismatch at the insertion point of r = T T = 0.015, typical

errors from the auxiliary system are:

1. Frequency instabilities of RF source z^ = 0.004

2. Mismatch at insertion point e m

= 0.40

3. Environmental effects on components z^ - 0.007

The total maximum possible r error is z = 0.41°

max

The treatment of errors from an auxiliary system will be

different for each system used. The example above is given

to show that errors from sources other than the PSMS must be

considered in phase shift measurements.

41
Appendix B. Circuit Schematics of Non- Commercial Equipment

This appendix contains circuit schematics for non-commercial equipment developed at NBS to perform particular functions

in the PSMS which are described in Section 2 of the report.

These circuits and their functions are:

1. Mixer-amplifier - -Produces a 20.178 MHz signal from

mixing 20.278 MHz with 100 kHz.

2. Squaring circuit - -Produce s a 100 kHz square wave

from a 100 kHz sine wave. The rise time is less

than 10 nanoseconds and can be triggered at the

zero crossing point of the input sine wave.

3. Buffer ampl if ier - -Provides between 30 and 40 dB

amplification of the low level 20.178 MHz signal

from the power splitter. See figure 1.

4. 100 kHz ampli f ier - -This circuit provides a 100 kHz

sine wave from a distorted 100 kHz signal from the

counter oscillator of the 5360A.

42
o

cm a, o o

i— r-~ ai csj VW

4- o a.

c_> o

o

o o

LlJ

X O

Hi'

m

i— s:

CL. CO

i—i C\J o

O J

C_J> o

o

I— =n

=3— O

o

•73 O

0)

• H

m

• i—

r—

e<

CD

X,

ooH

M

e

0)u

o

•r-f u

00

CDU

00

•H

43
r3 v; o en

44

n ^ h-

—

=t o a. cr: tohuj

N

=C I— ' CSJ ^ ZD o a. o i 3- o i— i— : •"3 O =D I

<-> o .

Q_ LU

O UJ Z O K a h i—< o <=c u_ ^

CD •H<o

•H

+->

•HQOomou

•H

+-> £

0)u3u• H

a>

fHUJ

•H

46
Appendix C. Modifications of Commercial Equipment

1. Modifications

1.1 General

The components of the PSMS include certain commercially

available equipment. Some parts of the 8410A have been modified to improve performance and/or to make the equipment compatible with system design.

The modifications include component changes in circuits

shown in Reference 2 schematic diagram 08410-90016 and are

referred to in terms A6 through A16, which are identifiable

in the reference.

The modifications are:

1. Circuit board A6 -- The output from collector of Q3 is

sent through a 2 K ohm resistor in series with a 1 pf

capacitor to a coaxial Rg 174 cable to the RF output jack

on the rear panel of the 8410A chassis.

2. Circuit board A12 -- The 20.178 MHz signal to this circuit board arrives via an Rg 174 coaxial cable from the

rear panel of the 8410A. Also, the base of Q7 has been

fixed biased through a 20 K ohm resistor between test

point 5 and the base and a 2 K ohm resistor to ground.

The AGC signal has been disconnected.

3. Circuit board All -- Capacitor C4 (470 pf) has been

changed to .059 yf.

47
4. Circuit board A16 -- Capacitor C8 (8200 pf) has been

changed to 0.067 uf.

5. Circuit board A13 -- This board has been removed, since a

20 MHz signal is not required.

6. Circuit board A14 -- The 20.178 MHz signal to this circuit board is input through an Rg 17coaxial cable from

the rear panel of the 8410A.

48
Appendix D. Parts Lists

The PSMS includes commercial and non -commercial equipment. The parts list for the commercial equipment is included

in references 2, 3, and 7. This appendix includes a listing

of all major components and a minor component list for the

non -commercial equipment. The minor component list refers to

the circuit schematics in Appendix B.

Table 1. Major Components of the PSMS

Description Manufacturer

Computing Counter Model 5360A

option H-14

Plug-In Time Interval Model 5379A

Harmonic Frequency Converter Model

8411A, option H-10

Network Analyzer Model 8410A

option HO - 7 Blank Plug-In Model 8410-K13

Keyboard Model 5375A

Filter 100 kHz, 3 dB Bandwidth

± 3 kHz

Filter 20.178 MHz, 3 dB Bandwidth

± 5 kHz

Power Supply Model LZS-11

Cabinet Rack Series 2000, Model

E-2024

Hewlett -Packard

Hewlett -Packard

Hewlett -Packard

Hewlett -Packard

Hewlett-Packard

Hewlett -Packard

McCoy Electronics

McCoy Electronics

Lambda Electronics

Bud Radio Inc.

Signal Splitter, Model PdM-20-55 Merrimac Industries Inc

49
Table 2. Parts Information for Mixer Amplifier Circuit

Part No. Descript ion

A101 Integrated Circuit Amplifier CA3028

A102 Integrated Circuit Amplifier CA3028

M101 Mixer

J101 Coaxial Connector Female SMA

J102 Coaxial Connector Female SMA

J103 Coaxial Connector Female SMA

C101 Capacitor Dipped Mica .01 yf 100 Volts

C102 Capacitor Tantalum Electrolytic 4.7 yf 35 Volts

C103 Capacitor Tantalum Electrolytic 4.7 yf 35 Volts

C104 Capacitor Dipped Mica .01 yf 100 Volts

C105 Capacitor Dipped Mica .01 yf 100 Volts

C106 Capacitor Dipped Mica .01 yf 100 Volts

C107 Capacitor Tantalum Electrolytic 4.7 yf 35 Volts

C108 Capacitor Tantalum Electrolytic 4.7 yf 35 Volts

C109 Capacitor Dipped Mica .01 yf 100 Volts

R101 Resistor 1 KQ, Carbon .25 Watt

R102 Resistor 270 Q, Carbon .25 Watt

R103 Resistor 2 KQ, Carbon .25 Watt

R104 Resistor 1 Kfi Carbon .25 Watt

R105 Resistor 2 70 Q, Carbon .25 Watt

R106 Resistor 2 Carbon .25 Watt

50
Table 3. Parts Information for 20.178 MHz Amplifiers

Part No. Description

A201 Integrated Circuit, Linear Amplifier, CA3028

A202 Integrated Circuit, Linear Amplifier, CA3028

C201 Capacitor, Fixed, Mica, .01 yf, 100 Volts

C202 Capacitor, Fixed, Tantalum Electrolytic, 1 yf,

35 Volts

C203 Capacitor, Fixed, Tantalum Electrolytic, 1 yf,

35 Volts

C204 Capacitor, Fixed, Mica, 0.001 yf, 100 Volts

C205 Capacitor, Fixed, Mica, 0.001 yf, 100 Volts

C206 Capacitor, Fixed, Tantalum Electrolytic, 4.7 yf

25 Volts

C207 Capacitor, Fixed, Tantalum Electrolytic, 1 yf,

35 Volts

C208 Capacitor, Fixed, Mica, .01 yf, 100 Volts

J201 Coaxial Connector, Bulkhead, Female, SMA

J202 Coaxial Connector, Bulkhead, Female, SMA

J203 Jack, 5 Pin Connector, Female

R201 Resistor, Variable 0-5 K, h Watt, 1 turn

R202 Resistor, Fixed, Carbon, IK ± 10%, h watt

R203 Resistor, Fixed, Carbon, 270 ± 10%, h watt

R204 Resistor, Fixed, Carbon, 2K ± 101, %watt

R205 Resistor, Fixed, Carbon, IK ± 10%, h watt

R206 Resistor, Fixed, Carbon, 2K ± 10%, h watt

L201 Inductor, Fixed, 10 yh ± 20%, 150 ma

51
Table 4. Parts Information for Squaring Circuits

Part No. Description

A3 01 Integrated Circuit Differential Voltage Comparator

SN72510P

C301 Capacitor Mica 1 yf 100 Volts

C302 Capaci tor Mica . 01 yf 100 Volts

C304 Capacitor Mica . 01 yf 100 Volts

C305 Capacitor Mica . 01 yf 100 Volts

C306 Capacitor Mica . 01 yf 100 Volts

C307 Capacitor Mica . 01 yf 100 Volts

J301 Coaxial Connector Bulkhead Female SMA

J302 Coaxial Connector Bulkhead Female SMA

R301 Resistor Carbon 1 YSl t 10%

R302 Resistor Variable Wirewound 0-10K 15 Turn h watt

R304 Res is tor Carbon 10K ± 10% h watt

R305 Resistor Carbon 10K ± 10% h watt

R306 Resistor Carb on 100 ± 10% 1/8 watt

R307 Resistor Carbon 100 Q ± 10% 1/8 watt

R308 Resistor Carbon 430 Q ± 10% 1 watt

R309 Resistor Carbon 750 a ± 10% 1 watt

R310 Resistor Carbon IK ± 10% \ watt

52
Table 5. Parts List for 100 kHz Distribution Amplifier

Part No. Description

A401 Integrated Circuit Linear Amplifier CA3028

C401 Capacitor, Fixed, Plastic Molded, .015 yf, 100 Volts

C402 Capacitor, Fixed, Plastic Molded, .1 yf, 100 Volts

C403 Capacitor, Fixed, Plastic Molded, .022 yf, 100 Volts

C404 Capacitor, Fixed, Tantalum Electrolytic, 1 yf,

35 Volt

C405 Capacitor, Fixed High-K Monolytic, 1 yf, 25 Volts

C406 Capacitor, Fixed Dipped Mica, 220 pf, 500 Volts

C407 Capacitor, Fixed, High-K Monolytic, 1 yf, 25 Volts

C408 Capacitor, Fixed Dipped Mica, 470 pf, 500 Volts

J401 Coaxial Connector, Bulkhead, Female, SMA

J402 Coaxial Connector, Bulkhead, Female, SMA

J403 Coaxial Connector, Bulkhead, Female, SMA

J404 5 pin miniature Socket, Female, Amphenol 126-218

L401 Variable Inductor, Delevan Series 4000, 15-44 yh

L-P401 Filter, Fixed, Low Pass, Cutoff 150 kHz, Kappa

1A 154L

Q401 Transistor, Medium Power, 2N3866

R401 Variable Resistor, 0-5Kfi, 0.5 watt

R402 Resistor, Fixed, 1K£J, h watt, Carbon

R403 Resistor, Fixed, 2Kft, %watt, Carbon

R404 Resistor, Fixed 330 £2 , h watt, Carbon

R405 Resistor, Fixed, 62KC2, h watt, Carbon

53
Part No. Description

R406 Resistor, Fixed, 16K9, , h watt, Carbon.

R407 Resistor, Fixed, 6.2Kfi, h watt, Carbon

R408 Resistor, Fixed, lKft, h watt, Carbon

54
Appendix E. Sample Data Sheet for Phase Shift Measurements

A sample data sheet is included as an example for those

intending to make phase shift measurements using the PSMS.

The data sheet was setup to allow for recording at

least five measurements at each phase shift setting.

55
vD

CM 11

O

CM .

O

(M

O

ro

'ING

o

oo

1—1

H

H

CO o

r—1

:

!

PHASE

o

1—i

o

cm

r—

(

CHANNEL o

o1—1

1 II11

o

00

TEST o

vD

O

:

O

CM

!

: ;

i

j !

o

i .III'

Reference Phase

. M \ ?\\\\

m j M i M i

III ! O

1 o

! 1 1 i iil I

o

i ! 00

—1

! .1 .! i i i I i

o 1

• r- ; ill

i 1 j 1 ]

!- ! i 1 1 1 i
REFERENCES

G.E. Schafer, R.W. Beatty, Error Analysis of a Standard

Microwave Phase Shifter, Journal of Research of the

National Bureau of Standards - -C , Engineering and Instrumentation, Vol. 64C, No. 4, October -December 1960, pages

261-265

, Operating and Service Manual Network

Analyzer 8410A, Harmonic Frequency Converter 8411A, published March 1970, copyright Hewlett-Packard Co.

, Service Manual - -Comput ing Counter

5360A and Input Module 5365A, published July 1970, copyright Hewlett-Packard Co.

, Phase Measurement in Degrees or

Radians, Computing Counter Applications Library, Number

2, Hewlett-Packard Co.

R.W. Beatty, D.A. Ellerbruch, D.H. Russell, G.E. Schafer,

R.S. Turgell, J. P. Wakefield, and T.L. Zapf, "Lecture

Notes for the Phase Shift Measurements Seminar," June

1967, Unpublished NBS Report. 8-1 to 8-15.

G.E. Schafer, Mismatch Errors in Microwave Phase Shift

Measurements, IRE Transactions on Microwave Theory and

Techniques, November 1960, 617-622.

, Operating and Service Manual Time Interval Plug-In 5379A, copyright Hewlett-Packard Company,

March 1970.

57
FORM NBS-114A (1-71) U.S. dept. of comm. 1. PUBLICATION OR REPORT NO. 2. Gov't Accession

BIBLIOGRAPHIC DATA NBSIR 73-307

^

3. Recipient's Accession No.

4. TITLE AND SUBTITLE

A Dual Channel, Double Heterodyned Phase Shift

Measurement System 110 MHz to 18 GHz

5. Publication Date July 1973

6. Performing Organization Code

7. AUTHOR(S)

Keith C. Roe

8. Performing Organization

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS, Boulder Labs.

DEPARTMENT OF COMMERCE

Boulder, Colorado 80302

10. Project/Task/Work Unit No. 2724144

11. Contract/Grant No.

12. Sponsoring Organization Name and Address

Same as Item 9-

13. Type of Report & Period

Covered

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here.) This report presents a system description, error analysis^ and operating

procedure for a dual channel phase shift measurement system operable in the

frequency range 110 MHz to 18 GHz.

Basic principles of operation include double stage heterodyning from RF

and microwave frequencies to 100 kHz, time-interval and period measurements, and automatic conversion to phase in degrees through use of a

digital computer.

17. KEY WORDS (Alphabetical order, separated by semicolons)

Computer; counter; heterodyne; period; phase shift; time -interval.

18. AVAILABILITY STATEMENT

I

| UNLIMITED.

I~xl FOR OFFICIAL DISTRIBUTION. DO NOT RELEASE

TO NTIS.

19. SECURITY CLASS

(THIS REPORT)

UNCL ASSIFIED

21. NO. OF PAGES

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

22. Price

USCOMM-DC 66244-P71

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