UNIVERSITY OF UTAH
ELECTRICAL AND COMPUTER ENGINEERING DEPARTMENT
ECE 5320/6322 Problems 10-12 Fall 2014
10. The S-matrix of a three-port circuit is given as follows:
0.4 0.25j 0.5
S 0.25 j 0.2 0.6 j
0.5 0.6 j 0.2
a. Is it a reciprocal circuit? Give reasons.
b. Is it a lossless circuit? Give reasons.
c. Draw the signal flow graph of the circuit.
d. Calculate the reflection coefficient at port 1 if ports 2 and 3 are connected to loads that
are mismatched each with a reflection coefficient of 0.4.
e. Calculate the insertion loss between ports 1 and 2 for the above circuit with mismatched
loads connected as in part d.
f. Calculate the power delivered to the load at port 3 as a fraction of the power input to
port 1.
11. Following Example 11.1 on p. 539 of the text, calculate the power gains of a microwave
amplifier using a transistor (e.g., Fujitsu FHX04FA/LG) with S-parameters at 10 GHz as
follows:
11
S0.653160;
12
S0.14
21
S3.220;
22
S 0.552 126
a. Calculate the power gain of the amplifier using Eq. 11.8 for L0
.
b. Using Eq. 11.12, the available power gain input and output circuits are approximately
conjugate-matched, i.e.
s11 L22
~S and ~S
