
284 Microwave Engineering
s
b
a
V
V
a
a
22
2
2
0
2
2
0
1
1
= =
=
=
reflected-at-port
towards-port
(8.7b)
s
b
a
V
V
a
a
21
2
1
0
2
1
0
2
2
= =
=
=
outof-port
towards-port
(8.7c)
s
b
a
V
V
a
a
12
1
2
0
1
2
0
1
1
= =
=
=
outof-port
towards-port
(8.7d)
In view of Equation 8.7 and Figure 8.3, different s-parameters can now be
dened as follows:
• s
11
is the input reection coefcient measured when (output) port 2
is terminated by a matched load (Z
L
= Z
0
, Z
0
sets a
2
= 0) and ratio of
reected wave and incident wave is measured at port 1.
Incident
(b)
Source
DUT
Reflected
Load
Z
0
Load
Z
0
s
21
s
11
s
11
=
=
s
22
s
12
s
12
= =
=
s
22
=
Reflected
Load Z
0
is fully absorptive and all power is absorbed by the load; thus, a
2
= 0
Load Z
0
is fully ...