[amsat-bb] vertical antenna

[Bob Liddy (K8BL)]

 Bob W7LRD,

Keep in mind that SATs tumble during their flight in space todifferent attitudes. When the SAT antenna is vertical with respectto your vertical antenna, the signal level will be at its best. But, whenit is horizontal with respect to your vertical, it will be at its worst by20 dB or more. That will be a very deep fade.
So, as the SAT tumbles, you would experience fading from 0 to 20 dBeven if the SAT was completely facing you in the same plane. As it turns away from you, it could even be wore. That's why gain antennasare helpful to make up for some of those drawbacks. 
In the link below is a chart showing the polarization losses when theantennas are in the same plane. I found it interesting that the loss isonly 3 dB when the angle is off by 45. It really gets severe in the next45 degrees (20 dB!!).
GL/73,    Bob K8BL
http://www.tscm.com/polariza.pdf


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I wrote a blogpost about vertical antennas (in german - maybe google translate can help you). But there are some radiation patterns in the article from different antennas. They can help you for understanding in which situation it works also with satellite.
https://www.michi-dani.ch/2020/10/21/es-geht-auch-mit-rundstrahlenden-antennen/

73s Michael
hb9wdf

----Ursprüngliche Nachricht----
Von : amsat-bb at amsat.org
Datum : 26/11/2020 - 23:28 (MN)
An : amsat-bb at amsat.org
Betreff : [amsat-bb] vertical antenna

anyone using a vertical antenna for the FM satellites?  Which one & how does it work?
73 Bob W7LRD
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_______________________________________________
Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available
to all interested persons worldwide without requiring membership. Opinions expressed
are solely those of the author, and do not reflect the official views of AMSAT-NA.
Not an AMSAT-NA member? Join now to support the amateur satellite program!
Subscription settings: https://www.amsat.org/mailman/listinfo/amsat-bb