[time-nuts] Difference in antennas

[Forrest Christian (List Account)]

Like many things, price does not necessarily reflect a better antenna,
however there are differences between antennas.

One difference is in the quality of the filters in the antenna itself.
 This matters more when one is mounting an antenna at a communications site
than say at a home timing lab.  If you're at a site with a lot of RF noise,
if the antenna can pre-filter this out this will help the GPS receiver
dramatically.   I just pulled the spec sheet for one that I'm familiar with
and the filter in this one drops signals outside the GPS band by 65dB at
the band edges.

Another difference is the robustness of the higher end units, including
surviving nearby lightning strikes, operating at a wider voltage range, etc.

I'm not enough of a time-nut (yet) to be able to tell you if there is some
subtle difference between the antennas which would matter once you get to
some level of precision I don't have to deal with yet.

I've personally had good luck with the PCTEL/maxrad timing
reference antennas (GPS-TMG series).  I usually have been able to pick them
up off of ebay for not a lot of money.   These also seem to be often
re-sold with a lucent or symmetricom label or some other company's label on
them, mainly because they seem to be a supplier to all of these providers.
 I don't seem to recall ever having one of this type fail.    That can't be
said of other ones I've bought from random no-name suppliers.


On Thu, Nov 21, 2019 at 12:00 AM Taka Kamiya via time-nuts <
time-nuts at lists.febo.com> wrote:

> I have been looking antennas.  Prices seem to range less than 30 dollars
> to more than 500 dollars.  Some are 20db gain and some are 40 db gain.
> Some are specified as marine use only.  Some are specified as timing use.
> Some doesn't say anything at all.  Power supplies are different.
> Other than obvious, antenna is an antenna, isn't it?  It captures L1
> signal, amplify it and send it down the coax.  What makes one more costly
> than others?  What makes one timing antenna and one navigation antenna?  It
> doesn't make sense to me.
>
> I did some simple experiment with 26db, 40db, and magnetic stick on type.
> I didn't really see significant difference.  Signal level itself even
> wasn't all that different.  I have nearly a clear sky view 360 degrees
> above 30 degrees above horizon.  In some directions, clear view to
> horizon.  My feed is Timewave type.  So It may not be the best but nearly
> ideal.
>
> Can someone shed light on this topic?  (of course, I know some antenna has
> integrated receiver.  I am not talking about those)
>
> ---------------------------------------
> (Mr.) Taka Kamiya
> KB4EMF / ex JF2DKG
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-- 
- Forrest