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Re: lower frequency downlinks cont.



Ok,
 I was under the impression the antennas on the birds were omnidirectional. 
I was speaking of them being full sized at higher frequencies in comparison 
to some "compromise" antenna on the satellite for HF.
I only meant to refer to gain antennas in reference to ground station use.
Like I said, I'm still new to all this and learning so if my assumptions 
were mistaken, I apoligize.
73,
Michael , W4HIJ

----- Original Message ----- 
From: "John B. Stephensen" <kd6ozh@comcast.net>
To: "Michael A. Tondee" <mat_62@netcommander.com>; <amsat-bb@amsat.org>
Sent: Tuesday, January 31, 2006 8:18 PM
Subject: Re: [amsat-bb] lower frequency downlinks cont.


> The optimal antennas for a HEO would just illuminate the earth with 1 dB
> variation at apogee -- about 14 dB of gain at 35,000 km. However, you 
> either
> have to reduce the gain to allow for squint or be able to point the 
> antenna.
>
> 73,
>
> John
> KD6OZH
>
> ----- Original Message -----
> From: "Michael A. Tondee" <mat_62@netcommander.com>
> To: <amsat-bb@amsat.org>
> Sent: Tuesday, January 31, 2006 23:33 UTC
> Subject: Re: [amsat-bb] lower frequency downlinks cont.
>
>
>> Once again this is an opinion from the perpesctive of a "newbie" but I'n
> not
>> really understanding the concept of HF downlinks on an HEO. Seems
> backwards
>> to me and that  we should be going the other direction. The higher the
>> frequency, the smaller the antenna can be physically which makes it much
>> easier to build high gain beam and dish antennas which will be easier to
>> rotate and have less wind resistance, at least from the ground station.
> The
>> satellite itself can also have superior antennas because they can be 
>> close
>> to full size, if not full sized and be much more efficient. Just my
> opinion.
>> 73,
>> Michael W4HIJ
>> AMSAT #36017
----
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