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elgiovo
Joined: 16 Mar 2009
Posts: 13
Helped: 2
Location: Italy
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 24 Aug 2009 10:42 Input impedance |
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I have to measure the input impedance variation (with frequency) of a RFID tag (a simple circuit) from the antenna's terminals (call them in1 and in2). How should I do this in ADS? I tried with a termination between the inputs and with a HB simulation, but I get weird results.
Thanks for help.
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elgiovo
Joined: 16 Mar 2009
Posts: 13
Helped: 2
Location: Italy
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26 Aug 2009 7:48 Input impedance |
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Nobody? Impossible.
Maybe the wrong section?
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GGAPBE96
Joined: 21 Oct 2007
Posts: 39
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26 Aug 2009 17:50 Re: Input impedance |
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Why don't you calculate "Zin = (1+S11)*Z0/(1-S11)"?
(Z0 represents the characteristic Impedance)
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elgiovo
Joined: 16 Mar 2009
Posts: 13
Helped: 2
Location: Italy
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27 Aug 2009 9:00 Input impedance |
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First of all, thanks for your answer.
For Z0 you mean 50 ohms? In my circuit, anyway, I don't make use of transmission lines, it is just made of lumped components.
And what about S11? It is a two-terminal network, so I believe one should use S12 or S21 instead.
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27 Aug 2009 9:00 Ads |
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GGAPBE96
Joined: 21 Oct 2007
Posts: 39
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27 Aug 2009 12:25 Re: Input impedance |
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Z0 is the characteristic impedance of feed line.
You can use the equation for any 2-port passive circuit because the reflection coefficients are directly linked the impedance.
If you want to know the detail of the circuit,you assume the equivalent circuit and optimize it.
In this case,Sij (i,j=1,2) is needed.
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