Glenn, The fading of lunar echos is primarily due to two causes. The first cause is Faraday rotation of the signal arriving at your linearly polarized receive antenna as the waves transit the ionosphere. I do not know if the uplink is circularly polarized but if not, there would also be rotation of the uplink polarization. This rotation depends on the amount of ionized gas and the frequency used. For a given ionization level, the rotation becomes greater as the wavelength gets longer. This effect can be measured at microwave frequencies and is a concern when designing satellite communications links. The second cause is the rough surface of the moon providing multiple reflection points. Some times the reflections add in phase and sometimes they cancel. The moon's attitude oscillates slightly, a phenomenon called "libration". Libration causes the angles involved to all reflection points to shift slightly with time.
The ERP of the transmitted beam was 3.6 megawatts maximum. You can read more about this experiment at: <http://www.sciencedaily.com/releases/2008/01/080108113605.htm> Joe Buch FL --- Glenn Hauser <[EMAIL PROTECTED]> wrote: > ** INTERNATIONAL VACUUM I wonder if the wide variation in echo strength was > solely a funxion of terrestrial ionospheric factors, or were the signals > focused tightly on the Lunar surface so that different parts of it reflected > differently. What is the Lunar albedo, anyway at 7 MHz? What was the ERP of > these transmissions? Did it vary during the hour? > ____________________________________________________________________________________ Never miss a thing. Make Yahoo your home page. http://www.yahoo.com/r/hs _______________________________________________ Swprograms mailing list [email protected] http://montreal.kotalampi.com/mailman/listinfo/swprograms To unsubscribe: Send an E-mail to [EMAIL PROTECTED], or visit the URL shown above.
