[amsat-bb] Effects of ionosphere in sat comms

Paulo Pinto pspinto at yahoo.com
Thu Feb 22 03:26:14 PST 2007


I've been active in VHF/UHF LEO satellites for a couple of years now, after having spend many years around HF DX'ing. I always enjoyed sat operation since my first sat qso back in 1993 on RS-12 Mode K. One of my favorite subjects is propagation phenomena and I pay special attention to the VHF/UHF freqs. I pick as an example VO-52 satellite. The day before yesterday, on a 52 degree pass, I got very good downlink signals with my narrow and limited antenna setup: a fixed 9 elem TONNA at abt 30 deg. El. and 10 deg. Az. Yesterday, the same pass conditions gave me very poor reception. I understand that lack of satellite axis stabilization can be a high factor for this behavior, as the antennas may be turned around. But my question is: How severe earth's magnetic field and ionization of the atmosphere can affect Satellite Communications? If we must apply same theory as for ground communication, as logic suggests, what kind of refraction or dispersion may be associated with this epoch ?

If don't know if this is a dummy question, but I would like to hear from those of you interested in this matters.

73 CT1ETE, Paulo

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