relation entre z et s11
Hi:
I think resonance frequency of a cirucit is changing with the excitation and load. If you use a different feed line to feed a structure, the resonant frequency will change. How much will it change? It depends upon how different the the source or load you put on it. Basically, a structure will have an intrinsic resonance and it is independent of the source and load. However, when you connect a source and a load to it and try to observe the the resonance, you are basically changing its resonance condition and the resonant frequency will change. A simple example is the following:
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| |
L C
| |
R |
| |
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Without connecting any source, load or monitoring circuit to the 2 terminal, you can find its resonant frequency easily and it will not change. Howver, when you put some monitoring circuit between the 2 terminals, it will change the resonant frequency of the structure because the monitoring circuit because part of the resonant structure.
For microwave applications, you put a different TLN of different Zc, you are basically connecting different source and load to the circuit. Its resonant frequency will change depending upon the Zc of the TLN line.
Regards.