[time-nuts] Anyone have experience with this antenna?
kb8tq at n1k.org
Tue Feb 6 08:54:23 EST 2018
One gotcha (if the data sheets are correct) is going to be the supply voltage.
We normally stay away from 12V antennas because TBolt’s put out 5V. In the
case of a survey antenna, 12V is what most of the gear puts out. I don’t know
of any L1 / L2 gear that puts out 5 rather than 12V ….
> On Feb 6, 2018, at 6:48 AM, Attila Kinali <attila at kinali.ch> wrote:
> On Mon, 5 Feb 2018 21:33:59 -0600
> John Green <wpxs472 at gmail.com> wrote:
>> Listed on eBay as a L1/L2 antenna with decent specs. They seem to indicate
>> it is as good as a choke ring antenna. I suspect it is just a patch in a
>> fancy package.
> It actually is. The fourth picture in the ebay listing shows that it's
> a dual, stacked patch antenna with a 4 point (0°, 90°, 180°, 270°)
> excitation using fiberglass as substrate. I am not sure I would trust
> the +/-2mm phase center error, but it's probably quite decent.
> But advertising it as "high precision" or even "chocke ring antenna
> functionality without out the size or weight" is an outright lie.
> For one, they are too cheap to use nylon screws instead of
> metal screws in the antenna, which will lead to distortions in the
> radiation pattern. For another the fiberglass/epoxy substrate is going
> to change its dielectric constant with humidity, which will inevitably
> lead to changes in its resonance and radiation pattern. Third, the
> choke ring is to minimize influence of reflections close to or below
> the antenna horizon. This antenna does not have anything that comes even
> close to provide this feature.
> Judging from the meager information on the ebay lsting, it's most likely
> a Shenzen Beitan 7151 or a 7201 ("data"sheets attached).
> BTW: You can get the 7151 for 75USD and free sheeping on aliexpress.
>> That is what the Leica and Trimble survey grade antennas I
>> have contain anyway. I bought one but haven't had the chance to do any
>> testing. I couldn't figure out how to get to the insides to take a peek
>> without damaging it. My antenna testing abilities are pretty feeble.
>> Mostly, I will just compare it to the Leica and Trimble to see how many
>> satellites it sees and look at position wander of the uBlox. Is there any
>> simple way to judge the quality of a GPS antenna?
> If you have a known-good reference antenna and two receivers that can
> record the carrier phase data of the two antennas, then it's relatively
> easy to compare them (although there is quite a bit of math involved
> and you probably eed to write the software yourself, as i am not aware
> of any publicly, for hobbyists available software package).
> Attila Kinali
>  http://www.sz-beitian.com/ProductsDetail?product_id=53
>  http://www.sz-beitian.com/ProductsDetail?product_id=52
> It is upon moral qualities that a society is ultimately founded. All
> the prosperity and technological sophistication in the world is of no
> use without that foundation.
> -- Miss Matheson, The Diamond Age, Neil Stephenson
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
More information about the time-nuts