B&K Precision 4034 - Manual - Manual (Page 12)

12
R1 R2 = Z1 Z2, and R1 Z1 = R2 (Z2-Z1)
or
and
For example: to match a 50
Ω system to a 125Ω system, Z1 equals 50Ω and Z2 equals 125Ω
Therefore:
Ω
and
Ω
Although the illustrated network provides minimum attenuation, for a purely resistive impedance-matching device,
the attenuation as seen from one end does not equal that seen from the other end. A signal (E1) applied from the
lower impedance source, encounters a voltage attenuation (A1) which is greater than 1 and less than 2, as follows:
A signal (E2) applied from the higher impedance source (Z2) encounters a greater voltage attenuation (A2), which is
greater than 1 and less than 2 (Z2/Z1):
In the example of matching 50
Ω to 125Ω,
and
R Z Z Z 1 2 2 1
= −
( )
R Z
Z
Z Z
2 1
2
2 1
=
−
R1 125 125 50 96 8
= − =
( ) .
R2 50
125
125 50
64 6
=
−
=
.
A
E
E
R
Z
1
1
2
1
2
1
= = +
A
E
E
R
R
R
Z
2
2
1
1
2
1
1
1
= = + +
A1
96 8
125
1 1 77
= + =
.
.
A2
96 8
64 6
96 8
50
1 4 43
= + + =
.
.
.
.