ELCT564
Spring 2013
Chapter 4: Microwave Network
Analysis
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Equivalent Voltages and Currents
Voltage is proportional to the transverse electric field
Current is proportional to the transverse magnetic field
The product of equivalent voltage and current is the power flow
The ratio of the voltage to the current should be equal to the characteristic
impedance of the line
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Impedance Matrices
Reciprocal Networks
Lossless Networks
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Example
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The Scattering Matrix
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The Scattering Matrix
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The Scattering Matrix
Reciprocal Networks
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Lossless Networks
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Example: The Scattering Matrix
A two port network is known to have the following scattering matrix:
Determine if the network is reciprocal, and lossless. If port two is terminated
with a matched load, what is the return loss seen at port 1? If port two is
terminated with a short circuit, what is the return loss seen at port 1?
-0.452
6.9dB
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Reference Plane
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The Transmission (ABCD) Matrix
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The ABCD Parameters Examples
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ABCD Parameters Relation to Impedance Matrix
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ABCD Parameters Relation
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Signal Flow Graph
Nodes: Each port, I, of a microwave
network has two nodes, ai and bi. Node
ai is identified with a wave entering port I,
while node bi is identified with a wave
reflected from port i. The voltage at a
node is equal to the sum of all signals
entering that node.
Branches: A branch is a directed path
between two nodes, representing signal
flow from one node to another. Every
branch has an associated S parameter
or reflection coefficient.
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Signal Flow Graph Representations
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Signal Flow Graph Rules
Series rule
Parallel rule
Self-loop rule
Splitting rule
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Signal Flow Graph Example
Use signal flow graphs to derive expressions for Гin and Гout for the two-port
network shown in the above Figure.
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Signal Flow Graph Example
Use signal flow graphs to derive expressions for Гin and Гout for the two-port
network shown in the above Figure.
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TRL Network Analyzer Calibration
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Microstrip Discontinuities
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