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Scattering parameter interpretation

 
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shahid78



Joined: 29 Jul 2006
Posts: 169
Helped: 17
Post12 May 2008 18:39   Scattering parameter interpretation
i am a bit confused on interpreting the scattering parameter results shown by network analyzer

for example the S11 shown by network analyzer for any antenna is in dB.

now if i want to calculate the abosulte values which formula should i use

S11(dB)=20 log ( S11)

or

S11(dB)=10 log (S11)


any help will be highly appreciated

regards
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radiohead



Joined: 13 May 2004
Posts: 317
Helped: 20
Location: Heart of Europe
Post12 May 2008 22:03   Re: Scattering parameter interpretation
S-paramters are theoretically calculated as voltage ratios. So you would use 20log instead of 10log.
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supersage



Joined: 03 Feb 2007
Posts: 31
Post13 May 2008 5:13   Scattering parameter interpretation
In general, if you want to transfer to dB values from voltage, current, and field intensity quantities, you could use 20log; however, use 10log for power, radiation intensity, gain, and directivity quantities
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