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Technical Discussions
Simon Griffin
Simon Griffin
05:47 Jul-27-1999
Air/gas transmission

'Gases are generally rather attenuating in the MHz range', Does anybody
have any tables or graphs representing this. After extensive searching
I cannot quantify this statement.

Regards

Simon Griffin B.Eng IoM


 
 Reply 
 
Wieslaw Bicz
Wieslaw Bicz
06:37 Jul-27-1999
Re: Air/gas transmission
: 'Gases are generally rather attenuating in the MHz range', Does anybody
: have any tables or graphs representing this. After extensive searching
: I cannot quantify this statement.

: Regards

: Simon Griffin B.Eng IoM

You can find some tables and graphs in Landold Börnstein: Molecular Acoustics or in older books (written about 1930).
It is difficult to find such data in newer books. If you are interested, I can send you the copies of such tables.

But you must know - if you will test sound propagation in air, it will be difficult to make reliable measurements with frequencies higher then about 2 MHz under
normal atmospheric condistions (without higner pressure). We have made some experiments with such frequencies and the results are not easy to compare.

You will need to find a good method for such measurements.

Sincerely


 
 Reply 
 
Robert (Rocky) A. Day
Engineering
Milky Way Jewels, USA, Joined Nov 1998, 40

Robert (Rocky) A. Day

Engineering
Milky Way Jewels,
USA,
Joined Nov 1998
40
00:00 Jul-28-1999
Re: Air/gas transmission
Try to get Eric Ash's book 'Scanned Image Microscopy' and in is an article by Kumar Wickramasinghe and C. Petts on 'Gas Medium Acoustic Microscopy' with data as a function of pressure for several gases. Has some references that may also be useful. Their data goes to 40 MHz and 200 bars.

: 'Gases are generally rather attenuating in the MHz range', Does anybody
: have any tables or graphs representing this. After extensive searching
: I cannot quantify this statement.

: Regards

: Simon Griffin B.Eng IoM




 
 Reply 
 
Leon Vandervalk
R & D
DeFelsko Corporation, USA, Joined Oct 1999, 3

Leon Vandervalk

R & D
DeFelsko Corporation,
USA,
Joined Oct 1999
3
08:11 Sep-02-1999
Re: Air/gas transmission
You may want to contact the folks at VN Instruments.
http://www.vninstruments.com
These guys have built some very impressive air coupled ultrasonic instrumentation. I've seen some of the experimental data generated using their gear and recall seeing attenuation plots...


: : 'Gases are generally rather attenuating in the MHz range', Does anybody
: : have any tables or graphs representing this. After extensive searching
: : I cannot quantify this statement.

: : Regards

: : Simon Griffin B.Eng IoM

: You can find some tables and graphs in Landold Börnstein: Molecular Acoustics or in older books (written about 1930).
: It is difficult to find such data in newer books. If you are interested, I can send you the copies of such tables.

: But you must know - if you will test sound propagation in air, it will be difficult to make reliable measurements with frequencies higher then about 2 MHz under
: normal atmospheric condistions (without higner pressure). We have made some experimentswith such frequencies and the results are not easy to compare.

: You will need to find a good method for such measurements.

: Sincerely




 
 Reply 
 

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