On Tue, 29 Jan 2019 21:29:20 +0100 Achim Gratz <[email protected]> wrote:
> Typically if they already have a ground plane mounted it's between > 6cm…10cm in diameter (or side length if quadratic). Over that size you > shouldn't see much effect anymore on the antenna sensitivity pattern, There is quite a big difference in radiation patterns depending on the size of the ground plane. The back lobes but also the low-elevation sidelobes change quite dramatically when going from 10cm to 20cm to 1m. And even with the 1m antenna, having a sharp edge vs a serrated or curved edge makes again quite a bit of difference for back lobes. On Wed, 30 Jan 2019 20:41:26 +0100 Achim Gratz <[email protected]> wrote: > Use a resonant ground plane with four or eight tuned radials instead, > that also has the advantage of way lower wind load… Tuned elements with high Q are definitely not what you want with a GNSS antenna used for precision applications, as they cause large changes in group delay. Keep in mind that the GNSS signal has +/-6kHz of Doppler frequency. Also, having a non-planar ground plane will cause the phase centre to shift depending on the azimuth where the satellite is seen. Again something you do not want with precision applications. Attila Kinali -- Science is made up of so many things that appear obvious after they are explained. -- Pardot Kynes _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
