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Line with
Low Loss |
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Here is an example of a lower loss line (in terms of wavelengths).
The electrical parameters of the line are R=1 W/m, L=1e-6
H/m, G=1e-3 Siemens/m, and C=1e-10 F/m. The frequency of
excitation is 5 MHz. |
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Voltages for a Low Loss Line |
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Notes: |
- On this example we can see some nice standing wave patterns.
However, we cannot really define a VSWR for a lossy line since the
ratio of traveling and standing waves changes as a function of
position on the line.
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- This line has the exact same electrical properties as the "High
Loss" example, except the frequency is 5 MHz instead of 1 MHz.
Be careful: both lines are 4 wavelengths in total distance, so
the 5 MHz example is actually 5 times shorter than the 1 MHz example.
Their actual loss in terms of dB/m is very similar. In reality,
the 5 MHz example would have even more loss per meter than the 1 MHz
example because of increased resistive losses at higher frequencies
for realistic conductors.
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- At higher frequencies, the electrical current clings to the
surface of the conductor, thereby raising the resistance, R. Do
you remember what this is called from class?
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