Hi Indeed, putting a ground plane on a GPS antenna that is not designed to use one will make it perform worse than it will with one. If the antenna is a modern one that is designed for mounting on a tripod or a pole, it’s a good bet it was designed to not have a ground plane backing it up.
A magnetic puck antenna that goes on a car - sure, it wants a ground plane. It’s also a pretty sort term answer for a outdoor antenna….. One thing that the newer receivers are going to want is a stable antenna mount as well as a stable phase center. Since you now have L1 / L2 data, you can properly process things to get (claimed) mm level accuracy on the location. That is *way* better than you will get out of a normal “survey in” sort of approach. It’s also free …. Off to figure out how to get the F9P data into RINEX …. Bob > On Jan 30, 2019, at 5:29 PM, Attila Kinali <[email protected]> wrote: > > 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. _______________________________________________ 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.
