48dBi is way way too big 18 I might go for
Look at aperture. Say it's six square wavelengths(40x60 cm). A dipole is about 1/8th square wave lengths..so the gain is 48 times that of a dipole. Say about 17dB +2dB or 19 dBi On Oct 8, 2010, at 3:05 PM, Magnus Danielson <[email protected]> wrote: > On 10/08/2010 08:22 PM, jimlux wrote: >> Brooke Clarke wrote: >>> Hi Jim: >>> >>> I've got a spare Ku band satellite dish and would like to use it for GPS. >>> In an ideal application the GPS antenna would be mounted in the normal >>> manner and above it would be a sub-reflector aimed at the Ku dish. >>> That way the antenna might pickup sats near the horizon directly and >>> from a narrow part of the sky by means of the dish. >>> The dish might be aimed at a WAAS GPS sat. >>> I've heard that you can just use the TV dish with a normal GPS >>> antenna, and it gas gain even though the polarization is reversed. >>> >>> >> >> Give it a shot. The other thing is that if you have your GPS antenna >> facing straight up, at the focus of the dish, you're looking at the side >> of the gps antenna, where the polarization might be less circular. >> >> But one thing to think about here... a standard Ku dish isn't very big.. >> >> At GPS frequencies, you're looking at 20 cm wavelength. The dish is >> perhaps 2, maybe 3 wavelengths across. That's not a huge amount of gain. >> >> You might do just as well with a flat cookie sheet. > > Well, a 1 m dish gives you 48 dB gain at L1 if I calculate correctly. The > normal antenna is at 6 db of antenna gain? > > Even if less than perfect, not too big size is needed to get meaningful > antenna gain. > > Cheers, > Magnus > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
