Hi For a variety of reasons, a puck antenna is a bad choice for a lab timing receiver. Because the ground plane (and other issues like feed line) are a variable, getting a good pattern is a matter of luck. Multipath ( = low angle) rejection is rarely going to work well with them. They also are not really good at standing up to years and years of exposure outdoors.
Since “real” antennas are a sub $20 sort of thing at L1 and sub $70 at L1/L2 … why bother with the minor leagues? Get something that does the job properly and use that. No matter what you do, (survey or timing) multipath is what gets you. Rejecting it is what you design the antenna for. Stuff that is properly polarized, you keep. Stuff that is not properly polarized you strongly reject. Very low angle stuff (especially below zero degrees) you strongly reject. Your typical ground plane acts as a knife edge at low angles to “help” below zero degree stuff …. not good. Indeed some light weight antennas take off into spurious oscillation land under this or that condition. When they do nothing works well. The answer there is to get another antenna. We’re talking the price of a case of beer …. Bob > On Apr 30, 2019, at 6:52 PM, Taka Kamiya <[email protected]> wrote: > > Yes, I saw your particular mention of survey antennas. My concern was that > multi-path will affect any setup. > > I've seen pros and cons of placing a cookie sheets and pizza pans under > antennas to enhance "efficiency". I'm not exactly buying into this idea but > I thought your discussions were similar. > > I have two identical antennas and one is already installed in a manner I > described. I suppose I could purchase a pole and mount it all by itself in > middle of my yard. Comparison will be very interesting. > > Thanks for your reply. > > --------------------------------------- > (Mr.) Taka Kamiya > I'm stuck in a wormhole.... Hello, worms! > > > On Tuesday, April 30, 2019, 6:28:11 PM EDT, Bob kb8tq <[email protected]> wrote: > > > Hi > > The pictures shown earlier are of a “survey antenna”. In the post I was > careful to refer to a “survey antenna” > as the point of the post. Ideally you want to be meters away from any metal. > > Bob > > > On Apr 30, 2019, at 5:42 PM, Taka Kamiya via time-nuts > > <[email protected] <mailto:[email protected]>> wrote: > > > > I can see that on survey situation but will it affect timing installations? > > Will you give me an idea how far those bullet type antenna needs to be? My > > antenna sits on a very short pole (2 feet?) and its base is mounted to > > frame of my screened in porch. Roof and structure is aluminum, which is > > very much like ground plane and reflective. > > > > --------------------------------------- > > (Mr.) Taka Kamiya > > I'm stuck in a wormhole.... Hello, worms! > > > > On Tuesday, April 30, 2019, 5:01:05 PM EDT, Bob kb8tq <[email protected] > > <mailto:[email protected]>> wrote: > > > > Hi > > > > You very much do *not* want to put a ground plane on one of the modern > > survey > > antennas.(Chinese or US or Canadian or …) The better ones are very > > explicit > > about this. They are optimized to sit on a pole in free air. Anything else > > and the > > pattern is degraded. ( = multipath gets worse) > > > > Bob > > > >> On Apr 30, 2019, at 2:23 PM, David J Taylor via time-nuts > >> <[email protected] <mailto:[email protected]>> wrote: > >> > >> Hi David, > >> > >> No, no ground plane. Don’t really have a lot of room for that in the > >> window. Out of curiosity, how large of an impact have you found with a > >> ground plane? > >> > >> Btw, I love the pan! > >> > >> Denny > >> ============================ > >> > >> Yes, Denny, choosing the baking tray (IIRC) was fun - I wanted as large a > >> flat area as I could reasonably get, but it has to be magnetic. I don't > >> recall what I took into the shop to test with! > >> > >> Unfortunately I didn't make any specific measurements with and without the > >> ground plane, but I did see a noticeable increase in SNR. Even a small > >> e.g. tobacco tin may help. > >> > >> Cheers, > >> David > >> -- > >> SatSignal Software - Quality software for you > >> Web: http://www.satsignal.eu <http://www.satsignal.eu/> > >> Email: [email protected] <mailto:[email protected]> > >> Twitter: @gm8arv > >> > >> _______________________________________________ > >> time-nuts mailing list -- [email protected] > >> <mailto:[email protected]> > >> To unsubscribe, go to > >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > >> <http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com> > >> and follow the instructions there. > > > > > > > _______________________________________________ > > time-nuts mailing list -- [email protected] > > <mailto:[email protected]> > > To unsubscribe, go to > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > <http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com> > > and follow the instructions there. > > > > _______________________________________________ > > time-nuts mailing list -- [email protected] > > <mailto:[email protected]> > > To unsubscribe, go to > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > <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.
