[time-nuts] gps timing antennas
Bruce Griffiths
bruce.griffiths at xtra.co.nz
Wed Feb 13 11:30:42 UTC 2008
Poul-Henning Kamp wrote:
> In message <ad9f78230802130122l3ca4df5cka68d24704f574230 at mail.gmail.com>, "Matt
> Ettus" writes:
>
>> Is there really anything in particular which is different about the
>> antenna requirements of timing receivers as compared to ordinary
>> high-quality receivers? The timing antennas seem to be in pointy
>> radomes, so that tells me they are probably quad-helixes rather than
>> patch antennas. How is that advantageous for timing in particular?
>>
>
> All the ones I've seen are patches.
>
> I would suspect that the higher domes is a concession to weather:
> when mounted on a building or tower, a steeper angle of the surface
> will collect less snow and dirt.
>
>
The old Datum and the current Micropulse timing antennas intended for
cell sites, use a quad helix antenna plus several 1575.42MHz ceramic
bandpass filters.
The data sheets claim that the pointy ends also deter birds from
perching on the antenna.
Novatel have a pinwheel antenna for precision applications as well as
the traditional (expensive) choke ring antennas.
These have the advantage of a reduced response to low angle multipath
signals.
Bruce
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