beautypg.com

Agilent Technologies Agilent 4396B User Manual

Page 92

background image

Measuring

Phase

Response

A

two

input

ratio

measurement

can

also

provide

information

about

the

phase

shift

of

a

network.

The

analyzer

can

translate

this

information

into

a

related

parameter

,

group

delay

.

With

the

same

connection,

instrument

settings

,

and

calibration

used

in

the

previous

example

(see

\Measurement

Setup

"

in

\Measuring

Transmission

Characteristics

of

a

Filter"),

make

the

following

changes:

1.

Press

4

Chan

1

5

4

Sw

eep

5

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

COUPLED

CH

on

OFF

to

NNNNNNNNNNNNNNNNNNNN

ON

off

to

couple

sweep

parameters

of

channel

2

to

channel

1.

2.

Press

4

Chan

2

5

4

F

ormat

5

NNNNNNNNNNNNNNNNN

PHASE

to

display

the

phase

response

on

channel

2.

If

the

trace

needs

to

be

rescaled,

press

4

Scale

Ref

5

and

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

AUTO

SCALE

.

Figure

5-5

shows

the

phase

response

of

the

bandpass

lter

.

Notice

the

linear

phase

shift

through

the

passband

and

the

rapid

uctuations

that

occur

outside

this

region.

The

random

phase

of

the

broadband

noise

oor

causes

the

spurious

out-of-band

response

.

This

format

displays

phase

over

the

range

of

0180

to

+180

degrees

.

As

phase

increases

beyond

these

values

,

a

sharp

360

degree

transition

occurs

in

the

display

as

the

trace

\wraps"

between

+180

and

0180

degrees

.

This

wrap

causes

the

characteristic

\sawtooth"

display

usually

seen

on

devices

with

linearly

increasing

(or

decreasing)

phase

responses

.

Figure

5-5.

Amplitude

and

Phase

Response

of

a

Dielectric

Filter

5-6

Network

Measurement

Examples