Standing Wave Ratio and Frequency Dependence in Transmission Lines

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The standing wave ratio (VSWR) in a transmission line is influenced by the load impedance and the characteristic impedance, but it also varies with frequency due to the frequency-dependent nature of load impedance. While the VSWR is primarily determined by the reflection coefficient, changes in load impedance across different frequencies will affect the ratio. The input impedance at the load (z = 0) is equivalent to the load impedance, and under certain conditions, the tan(Bl) terms may cancel out. Therefore, the relationship between VSWR and frequency is significant, as load impedance can change with frequency. Understanding this relationship is crucial for effective transmission line design and analysis.
seang
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If I have a section of transmission line, with a characteristic impedance Z0, how does the standing wave ratio in that section change as a function of the frequency of operation?

Doesn't the stading wave ratio just depend on the characteristic impedance of the line, and the load impedance?
 
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Yes, the VSWR ratio depends only on the magnitude of the reflection coefficient, which is a function of the load impedance and characteristic impedance. However, in general, the load impedance will be a function of frequency, so the VSWR will be as well.
 
Finding the Input Impedance at z = 0 (the load) is equal to the load impedance, maybe? If so, don't the tan(Bl) all cancel anyway since l = 0?
 
seang said:
Finding the Input Impedance at z = 0 (the load) is equal to the load impedance, maybe? If so, don't the tan(Bl) all cancel anyway since l = 0?

Which would make sense wouldn't it?
 
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