
304 Microwave Engineering
Here, s
11
= s
22
= 0 represents that there is no reection across the input and
output ports. In general, s
12
= s
21
= attenuation constant (
α
).
8.6.8 Gyrator
A gyrator given in Figure 8.14 is a 2-port non-reciprocal device. In the for-
ward direction, it introduces 180° phase shift while in the backward direc-
tion, the phase shift introduced is 0°. Its scattering matrix can be written as
S
s
s
=
0
0
12
21
(8.78)
As expected, there are only two transmission coefcients −s
12
and s
21
,
which are 180° out of phase. For an ideal case, s
12
= 0 and s
21
=
π
radians.
8.6.9 Isolator
An isolator (Figure 8.15) is a 2-port non-reciprocal ...