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Fw: Dish questions for 2.4GHz and 24GHz




Don,  If the RMS surface tolerance of your DH Satellite dish is very small
compared to the operating wavelength - and since it is made of aluminum - it
should be - you shouldn't lose too much gain using it at 24 GHz with an
appropriate 24GHz feed.  At 24GHz, corresponding to a wavelength of 1.25cm
or .492 inches, you will have the following loss in gain performance:

   RMS surface tolerance        Gain Reduction
 .005 inches  or .127 mm          .071 dB
 .01 inches    or  .254 mm        .283 dB
 .02 inches    or  .508 mm        1.133 dB
 .03 inches    or  .762 mm        2.549 dB
 .04 inches    or  1.016 mm      4.531dB
 .05 inches    or  1.27 mm        7.1dB

Thus, to be on the safe side- if you are interested in using the dish for
24GHz, contact DH Satellite and ask them to tell you what is the RMS surface
tolerance of the dish you are purchasing. If they tell you that they don't
know- find yourself another dish manufacturer who knows and who can
guarantee what they manufacture - for as you can see above- with a
.05 inch rms surface tolerance - you will give up 7.1 dB gain at 24 GHz.  On
the other hand , this same .05 inch rms surface tolerance at 2.4 GHz yields
a gain reduction of  only .071 dB

All the Best,
Jim, N6MV

----- Original Message -----
From: "Don Woodward" <dbwoodw@abraxis.com>
To: "amsat-bb" <amsat-bb@AMSAT.Org>
Sent: Thursday, September 20, 2001 7:03 PM
Subject: [amsat-bb] Dish questions for 2.4GHz and 24GHz


> Would the dish below from DH Satellite be suitable for 2.4GHz now and then
> be adaptable to 24GHz later provided substitution of two correct feed
mounts
> and feeds?
>
> Don Woodward
> KD4APP
> AMSAT 33535
> kd4app@amsat.org
> sales@sunsunsun.net
> www.sunsunsun.net
>
>
> ----- Original Message -----
> From: Michael Doll
> To: dbwoodw@abraxis.com
> Sent: Thursday, September 20, 2001 11:56 AM
> Subject: Antenna
>
>
> Attn: Mr. Woodward
>
>     Thanks for your email.  We manufacture a 48" (1.2m) antenna.  This has
a
> focal length of 22" and an f/d ratio of .45.  This is a one piece antenna
> and is made from solid aluminum.  When shipping one at a time this is an
> expensive piece.  If we can deliver it with our truck to your area you
would
> save both on the freight and the packaging.
>     The 1.2m antenna with mount sells for $142.00 this includes the
painted
> antenna, complete polar mount with feed collar and struts and stainless
> steel hardware.   Crating will be approx. $30.00 and it will have to go
> truck freight.  Contact me with any questions.
>
> Michael Doll
>
> ----
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