[time-nuts] Rooftop antenna and splitter

[jimlux]

On 1/27/19 6:24 AM, Bill Slade wrote:
> Hi again,
> The very best GNSS antennas tend to be based on suspended patch antenna
> (air-dielectric) structures because they give the best
> bandwidth/radiation efficiency (and hence, noise temperature)
> performance.  The very best include choke-rings for multipath
> suppression (Dorne-Margolin & variants), but these are costly items.


In the choke ring world, the typical elements I've seen recently tend to 
be crossed drooping dipoles

There's also the ever popular helibowl (a helix wound on a plastic cup 
(red Solo beer cup is a bit too big) in a metal bowl - think the things 
under a burner in a stove) - non-critical, wideband, etc.

https://www.febo.com/pipermail/time-nuts/2012-May/067138.html
One reference says Spitzmesser apparently based it on the "helicone"
Carver, K, "The Helicone - A Circularly Polarized Antenna with Low Side 
lobe Level" Proc IEEE, vol AP-55, #4, Apr 67, p559.

Maybe, maybe not - I get the impression it's a "lets try this and see if 
it works" antenna.


So I'm going to guess it's not the bit "IEEE Proceedings", but the Trans 
on Ant and Prop.


Helibowls don't have horizon to horizon coverage.




> Miniature ceramic pucks can have pretty horrible radiation efficiency,
> which degrades noise performance, so be careful when buying Chinese
> cheapies.    I have actually seen commercial antennas where resistors
> were added (before LNA) to improve antenna return loss!
> 
> On 27.01.19 14:28, Bob kb8tq wrote:
>> Hi
>>
>> With things like the uBlox F9 now out on the market cheap …. I would go with
>> an antenna that will do L1 / L2 / L5 and work with everything that it up there.
>> You still are in the “under $100” range (delivered) for new product from China.
>> It’s a good bet that the guts of all of them are made there. It’s also a good bet
>> that they all are ceramic slab style designs.
>>
>> Bob
>>
>>> On Jan 26, 2019, at 11:10 PM, Denny Page via time-nuts <time-nuts at lists.febo.com> wrote:
>>>
>>> Hi all,
>>>
>>> I’m looking for recommendations on an antenna / splitter configuration. I currently have six GPS/GLONASS/Galileo timing devices, each with it’s own puck antenna in a window. I have an opportunity to move to a (single) roof top antenna, with a splitter to feed the individual devices, and I am looking for recommendations on which antenna and splitter people would recommend.
>>>
>>> So far, I am looking at the following antennas:
>>>
>>> PCTEL GNSS1-TMG-26N (https://www.pctel.com/antenna-product/global-gnss-timing-reference-antenna-gnss1-tmg-26n/)
>>>
>>> PCTEL GNSS1-TMG-40N (https://www.pctel.com/antenna-product/global-gnss-timing-antenna-gnss1-tmg-40n/)
>>>
>>> And the following splitters:
>>>
>>> GPS Networking ALDCBS1x8 (https://www.gpsnetworking.com/products/aldcbs1x8)
>>>
>>> GPS Source S18 (https://www.gpssource.com/collections/gps-splitter/products/s18-1x8-standard-gps-splitter)
>>>
>>> The run from the antenna to the splitter will be 30-35 feet, and from the splitter to the units will be 3-5 feet. I’m wondering about the need for the 40dB vs the 26dB. I haven’t looked at any passive splitters, but even with the 40dB I’m thinking won’t offer enough to support even a 1x6 splitter.
>>>
>>> I would appreciate any thoughts folk have to offer.
>>>
>>> Thanks,
>>> Denny
>>>
>>>
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>>
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