To the OP, Dan, Just curious - do you use something like this: https://endruntechnologies.com/products/antennas-accessories/lightning-arrestor
Good luck with the new antenna. 73's, John AJ6BC On Sat, Sep 7, 2019 at 3:17 AM Björn <[email protected]> wrote: > https://www.ngs.noaa.gov/ANTCAL/# > > Look at say an old Ashtech ASH700936D_M which you can find calibrations > for both SCIS and “Snow” radomes and without radome for the same antenna. > > I have seen more recent radomes that are hemisphere-shaped. However these > are more prone to be favored bird view points. > > Radomes, like the Aeroantenna SPKE with a plastic “spike” to discourage > birds are less ideal for super high accuracy applications due to its non > uniform signal delay impact. > > See also clear acrylic domes OSOD/OSOS > > http://www.euref.eu/symposia/2015Leipzig/p-02-01-Ohlsson.pdf > > https://kb.unavco.org/kb/article/unavco-resources-radomes-520.html > > /Björn > > Sent from my iPhone > > > On 7 Sep 2019, at 02:54, Bob kb8tq <[email protected]> wrote: > > > > Hi > > > > Based on the papers I have seen, there is no “magic” shape that can be > ignored. > > Part of the issue is that the cover is going to be in the near field of > the antenna. > > As noted in another post, the impact is more complex than a simple > delay. ( consider > > that signals bounce off the cover material …. ). > > > > Also consider that if I’m going to 3D print the device, I have a limited > number of > > materials available. Teflon isn’t going to run through a 3D printer. > Unless you paint > > the gizmo it will not be water tight so humidity will get into the act > as well. > > > > ===== > > > > A “good” GPS antenna should have roughly the same phase center > regardless of > > the angle to the sat it’s receiving. Indeed GPS antennas in general get > this right. > > There is a modest variation with angle, but it’s not all that great. > Units of mm are not > > uncommon. It will be greater on a multi band design. The impact of your > cover also > > will be greater on a multi band device. All the various delay /. loss / > reflection parameters > > are frequency dependent….. > > > > Bob > > > >> On Sep 6, 2019, at 5:57 PM, Hal Murray <[email protected]> wrote: > >> > >> > >> [email protected] said: > >>> The gotcha with putting anything on top of a GPS antenna is that it > impacts > >>> the phase shift from the sat’s. How important that is gets quickly > into just > >>> how picky you happen to be. > >> > >> How picky do I have to be before that is significant? How geeky would > I have > >> to be to measure it? > >> > >> Would a hemispherical cover provide equal delays at all elevations? I > think > >> the solidly mounted USGS fault/volcano monitoring setups have a round > top. > >> https://www.usgs.gov/media/images/gps-tracks-ground-deformation > >> > >> Do any antenna manufacturers advertise uniform phase delay? > >> Do any software vendors advertise that their software works better with > >> specific antennas? > >> > >> > >> > >> -- > >> These are my opinions. I hate spam. > >> > >> > >> > >> > >> _______________________________________________ > >> 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. > _______________________________________________ > 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.
