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relative permittivity and relative permeability of water - RF Cafe Forums

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 Post subject: relative permittivity and relative permeability of water
Posted: Mon Jan 05, 2009 5:49 am 
 
Lieutenant

Joined: Thu Dec 18, 2008 10:56 pm
Posts: 4
Location: shah alam,selangor
Do anybody knows the relative permeability and relative permittivity for water?


 
   
 
 Post subject:
Posted: Wed Jan 07, 2009 12:10 pm 
 
General
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Joined: Fri Feb 17, 2006 12:07 pm
Posts: 268
Location: London UK
Hi ella_lyza
Try this url.
http://www.lsbu.ac.uk/water/microwave.html
The complex permittivity data given is good if the water is pure, but if mixed with other complex molecules, the value drops rapidly according to the relative mixture %.
Water is paramagnetic, but probably has a very low value ie close to 1.0

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 Post subject:
Posted: Wed Jan 07, 2009 12:21 pm 
 
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Joined: Fri Feb 17, 2006 12:07 pm
Posts: 268
Location: London UK
Further data:
at X band these figures are very reliable, coming from Institute of Physics, where the data was claimed to be accurate to within 0.2%. I quote:
It is found that epsilon '=62.256(37), epsilon "=31.570(47) at f=9.346 GHz, T=293K; and epsilon '=64.156(38), epsilon "=28.623(43) at f=9.370 GHz, T=298K.

My comment:
Note that over a small frequency range (9.34 to 9.37GHz) the value changes by about 4%, which I find rather surprising.

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 Post subject:
Posted: Wed Jan 07, 2009 12:28 pm 
 
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Joined: Fri Feb 17, 2006 12:07 pm
Posts: 268
Location: London UK
Even further data, applicable to water at 20* C and at F=2.45GHz can be found at
http://www.bsyse.wsu.edu/tang/Previousw ... ang100.pdf
This shows epsilon' as 78 and epsilon" as 6.8

Google is a great tool for this sort of question.

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