Jim:

- the price of the antenna you think of may be FOB where you are. I was
talking about FOB here.

- the antenna I saw did have a dipole array inside but the cover was far
too thick to be just a cover, so I think that it was a lens.

- two ~30dB gain Yagis were required in a downlink from OSCAR?? satellites
on 432MHz. I do not remember the details. The Yagis had umpteen elements
(24 or more) each. They were built by hand using Al tubing and Al profile
for the girder according to plans from a magazine or book. This was a
friend's project so I do not know all the details. I assume that they
could be used in the opposite direction by feeding them with the
sattelite's tx power downgraded by the antenna gain, which should put it
about at the 0.6W level for an OSCAR sattelite but I am not sure about
their transponder powers.

- the bandwidth required to pass digital data by a cellular phone (GSM)
channel is about three times the bandwidth of a SSB voice channel and
requires a better S/N ratio than SSB for correct operation. With adjacent
channel etc it is probably even wider. Thus the equivalent power/bandwidth
is much lower. We are talking earth to space since the space segment is
supposed to determine the cellphone position.

- there are no 10 mile cells anywhere that I know of. There has to be a
reason for this.

- afaik EPIRBs have two frequencies, one is 130MHz-ish and the other
450MHz-ish. I need to look them up to be sure. They also have very narrow
band transmissions and were specifically designed for uplinks in difficult
conditions.

Peter

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