@TonySmith, thanks I will take your points into consideration.
Hi guys,
I wish to build gateway in Czech Republic, I will use unused RP1 (SW from this repo https://github.com/ttn-zh/ic880a-gateway/wiki).
And which antenna should I buy?
this
or this
or another one?
Regarding on limitations, max transmit power is 25mW + 0.1% “on air time” in Czech, right?
Site 3, label h, h1 or h2 probably.
Antennas are high gain, is possible to limit from software power (and probably “on air time”)? I have found that on new ttn router is it possible (but no information on limiting on air time), but this repo has some kind of older (generic) router? Is another supported pack of software for RPi1?
In Czech is very bad (mostly no) coverage, I wish to get most coverage what could it be.
Thanks Radius
so you buy antennas in a DUTCH shop ?
I prefer this one:
as the others have to much metal that can corrode.
Hi,
yes, I will buy everything in dutch eschop, because in czech we are living 100 years before apes. I have found one eshop that have ic880a and price is same, like in dutch with shipping + ideetron has antennas, I don’t find good in czech republic + they have cables and connectors (this we will have here probably too).
We have this: vswr 2.5 
http://eshop.comprint.cz/d.DL1536.html
I prefer SDBF0.5-868 too, but there are no reviews and I don’t know how to limit transmit power.
GP901C has bad frequency range: 870-960 MHz, when I look to my nodes, they are transmitting on range 867.1 - 868.5MHz. But one user from czech group says, that he has two antennas in Prag and they are good. He buys them from ideetron too.
Radius
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Not too far from you there is a vendor from which someone here on the forum bought this antenna: https://www.ebay.it/itm/Antenna-collinear-868-Mhz-869-mhz-LORAWAN-LORA-great-gain-SDR-USB-smart-grid/303076435196
That’s me and I get very good results with this antenna.
https://ttnmapper.org/colour-radar/?gateway=84EB18FFFEE55226&type=radar
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Last saturday at a national radio fleemarket I bought a set of two ADSB antennas. The goal was to study them and design my own scaled version for 868 MHz. Turns out it only really needs some change to the tuned ‘sleeve’. The only thing you need is some copper tape, a knife and a solding iron.
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great find ! 
The active version:
doubt if that will work… its ‘active’ on 1090 Mhz
anyway… here’s a cheaper one if you want to try 
What is meant by ‘active’ ?
@bvdbrule, this antenna has got some cutouts. The antenna I used does not have these and resonates at about 1070MHz, the sleeve needs to be a bit shorter to get to 1090MHz. That’s probably the reason why they made these cuts.
@kylix, the active version probably also has a filter implemented. Good for ADSB, but not for LoRaWAN.
@LoRaTracker. Active means “with preamplifier”, probably with power via the coax.
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By the way, my tuned ADSB antenne works quite nicely from behind my rear view mirror. Better than the untuned dipole I used before. That dipole turned out to be to short and needed to be extended about 2cm on each end.
Here an impression of my route to work. I use 20dBm@SF7.
Be interesting to see how much the “preamplifier” improves reception. With LoRa operating well under nosie level it needs a good quality LNA to improve things.
I do experiment with an added Minicircuits PSA-5043+ and a 868MHz bandfilter. For now I’ve only seen higher RSSI levels, the C/N-values are about the same. I do use a short good quality coax, people with longer cables would probably benefit more. Down side is that I can not transmit downlink messages anymore, or else I will blow up my preamplifier.
Without a proper implementation to get statistics from the gateway I can not give any conclusive statistics yet. And it would also be nice if BEACE103 would come online again.
Eerrrm…illegal in NL/EU?! (unless cable and losses >4-6db giving EIRP <16dbm (14dbm +2.15dbI ant)) 
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