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relative permittivity and relative permeability of water - RF Cafe Forums

Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views. It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if you would like to post something on RF Cafe's Facebook page, please do.

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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 
 
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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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