[amsat-bb] Re: Mode S advice

Michael Heim kd0ar at sbcglobal.net
Mon Oct 6 04:53:05 PDT 2008

Actually, I just looked at the new operating schedule that was just posted.  This turns out to be fantastic for me.  I have a couple weeks to get things set up, and several days of testing before its switched to V/s while its in L/s.   During the testing mode, while its in L/s (I cant transmit mode L yet), I just might put both antennas and converters up and switch between them and make comparisons using several passes, lets say I'm able to catch all of the available passes for 2 days, I can use one unit one day, record my results, use the other antenna the next day, record the results and compare.  By the time I can get on and operate, I should have made my choice.  Might even try out the DSS dish with the little helix feed on it as Art also suggested.  When I do test with that, one of the biggest things I'll be watching for is beamwidth.

I am going to venture a guess however that the helix will win out.  It sort of makes sense, especially if one does not know the linear polarity the satellite is running, and what sense the signal is coming in to a fixed point while its moving.

One thing of note... I am using a linear antenna for V/u, vhf with horizontal elements, vertical 70 cm elements, and I'm quite happy with the arrangement.  Therefore, I'll try the linear antenna on 2401 vertical

 Michael Heim

----- Original Message ----
From: Luc Leblanc <lucleblanc6 at videotron.ca>
To: amsat-bb at amsat.org
Sent: Sunday, October 5, 2008 11:16:36 PM
Subject: [amsat-bb] Re: Mode S advice

On 5 Oct 2008 at 18:27, Michael Heim wrote:

I noticed, while listening in using either antenna, a noticeable amount of deep fades on the bird.  I'm not sure if it was caused by 
reflections nearby, or uplink fades on 1269 mhz. 

Hi Michael

If your fades are on the S band downlink it is you downlink antenna who probably gives you the fades. I tested a standard BBQ grill screen 
meshed and i also got theses huges fades. When i switched to a linear 42 stacked elements (A WIFI antenna)  theses fades disappear 
completely. as AO-51 S band antenna is linear i guess a linear antenna is the best choice?


Luc Leblanc VE2DWE
Skype VE2DWE

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