[time-nuts] Survey grade antennas

[jimlux]

On 11/18/20 2:49 PM, Charles Steinmetz wrote:
> Stu wrote:
> 
>  >> The usual auction site has a few true survey grade antennas for a 
> very good
>  >> price. Search for Novatel GPS-703-GGG. These cover all three frequency
>  >> bands (L1, L2, L5), which is still unusual to find in surplus.
> 
> Bob wrote:
> 
>> ….. and now they all seem to have been sold
> 
> If you look at the auctions linked from that one, you will find dozens 
> of other listings for similar multi-band antennas -- some of them 
> considerably less expensive than the Novatel.
> 
> Note that the Novatel information admits that the antenna is not a choke 
> ring design, but instead claims that it provides "Choke ring antenna 
> functionality without the size and weight."  Also note that the Novatel 
> datasheet makes no reference to it being a survey-grade antenna.

There are a lot of clever designs out there intended for "top of pole in 
a survey" kind of use that are quite good at suppressing multipath. A 
lot of interesting dielectric lenses and arrangement of multiple 
radiators within the radome. Like that weird multispiral design, or the 
3D choke of spikes instead of the more traditional nested cake pans.

Survey in the "let's go out and stake the construction site" (so 
uncertainties of few mm + 1ppm of baseline length for differential) but 
not in the geodetic "let's measure the plate movement in my backyard 
with a post driven 50 feet into the bedrock" sense.