Re: [time-nuts] Anyone have experience with this antenna?

On Wed, Feb 07, 2018 at 03:07:24PM +, Poul-Henning Kamp wrote: > > In message <875e4bc6-32c3-4724-afcd-086553ae5...@n1k.org>, Bob kb8tq writes: > > >Water wise, one might note the large piles of snow sitting on my antennas at > >the moment. Yes, I > >could go knock it off, but

Re: [time-nuts] Anyone have experience with this antenna?

Hi They probably have a group of people on staff to go out and dry them off after it rains …. :) Indeed, there are a lot of pictures of heated enclosures for antennas. The debate over the dielectric properties of the coverings goes back a long way. There are notes in the standard databases

Re: [time-nuts] Anyone have experience with this antenna?

In message <875e4bc6-32c3-4724-afcd-086553ae5...@n1k.org>, Bob kb8tq writes: >Water wise, one might note the large piles of snow sitting on my antennas at >the moment. Yes, I >could go knock it off, but somehow it just keeps coming back. Weird how winter >works …. There >is no perfect

Re: [time-nuts] Anyone have experience with this antenna?

Hi It’s not the end stops that are the issue. It’s the wall of the pipe. If the dimensions in the sketch are roughly correct and you scale it to the dimensions of the eBay antenna, that is a big tall pipe. Indeed “nothing overhead” would mitigate part of the issue. That magic line runs

Re: [time-nuts] Anyone have experience with this antenna?

On 6 February 2018 at 03:33, John Green wrote: > https://www.ebay.com/itm/High-Precision-L1-L2-GNSS-GPS-GLONA > SS-BeiDou-RTK-CORS-survey-antenna/162718512935?ssPageNam > e=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649 > > Listed on eBay as a L1/L2 antenna with decent specs.

Re: [time-nuts] Anyone have experience with this antenna?

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Re: [time-nuts] Anyone have experience with this antenna?

That does represent a limiting case but it's a bit pessimistic. The longest path is for very shallow incident angles eg a 3 mm thick and 150 mm radius disk gives an angle of only about 1 degree. At 10 degrees, the path is about 20 mm; with a refractive index of 1.5, the path is only 10 mm longer.

Re: [time-nuts] Anyone have experience with this antenna?

Hi Since we are talking about an L1 / L2 antenna here, a reasonable assumption would be that the target is something better than an “average result”. If you construct a cover out of a piece of PVC pipe (as shown in the original drawing), your worst case path has a foot or so of PVC in it

Re: [time-nuts] Anyone have experience with this antenna?

I can see why the geodetic community would worry about antenna phase centre variation when a radome is installed but is it really an issue in timing applications? The few papers I've read suggest PCVs of less than 10 mm, or equivalently, 30 ps. This is at the level of precision available from

Re: [time-nuts] Anyone have experience with this antenna?

Hi Indeed a radome may distort the antenna pattern. In teh case of DIY projects the trick that most can apply is to take a piece of the radome material and put it into a microwave own. If it doesn't get hot it is OK for most DIY cases. Infinion have some nice GNSS MMICs e.g. BGA924N6

Re: [time-nuts] Anyone have experience with this antenna?

Hi The microwave trick is fine for working out if it is a lossy material. Unfortunately what gets you in this case is more than just loss. A coax cable has core material that will (usually) do quite well in a microwave. None the less, the delay through the coax is different than through air

Re: [time-nuts] Anyone have experience with this antenna?

In a previous job, I used plastics to "lens" antennas at 2.4 GHz, shaping the patterns for more desirable results. XFDTD is a great software package for this application but it is expensive. ___ time-nuts mailing list -- time-nuts@febo.com To

Re: [time-nuts] Anyone have experience with this antenna?

Hi There are “cell site” specific GPS antennas on the market. Panasonic has had one out for quite a while. I’m sure there are several others. One issue with doing any sort of “cover” for a precision antenna is distorting it’s pattern. Plastic (or whatever you use) will have different

Re: [time-nuts] Anyone have experience with this antenna?

On Tue, 6 Feb 2018 08:54:23 -0500 Bob kb8tq wrote: > 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

Re: [time-nuts] Anyone have experience with this antenna?

Hi 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 …. Bob >

Re: [time-nuts] Anyone have experience with this antenna?

There's a picture of the guts in the ebay description...it's a dual patch antenna! the patches seem to be trimmed to get a pattern. On 2018-02-05 20:33, John Green wrote:

Re: [time-nuts] Anyone have experience with this antenna?

oops, sorry for the misfire. > I couldn't figure out how to get to the insides to take a peek > without damaging it. For $99 I would take the risk to damage it... Or find someone with x-ray gear and have a peak inside. Or take it with you on your next plane flight and grab a photo of the TSA

Re: [time-nuts] Anyone have experience with this antenna?

> 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 >