The BIG and SMALL ANTENNA topic part 2


#169

so you buy antennas in a DUTCH shop ?


(Remko) #170

I prefer this one:

as the others have to much metal that can corrode.


(Radius) #171

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 :smiley:
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


(Tony Smith) #172

have a look here Antenna_gain in dBi or dBd?


(Ud Lo Ra) #173

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


#174

That’s me and I get very good results with this antenna.
https://ttnmapper.org/colour-radar/?gateway=84EB18FFFEE55226&type=radar


#175

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.

image1

image2

image3


#176

great find ! :sunglasses:


#178

For sale by banggood ADSB antenna


(Kylix) #179

The active version:


#180

doubt if that will work… its ‘active’ on 1090 Mhz
anyway… here’s a cheaper one if you want to try :wink:

ADS-B%20active%20receiving%20antenna%201090MHz


(LoRaTracker) #181

What is meant by ‘active’ ?


#182

@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.

20190326_ADSB_cutout

@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.


#183

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.

20190326_ttmapper


#184

antanalyzer


(LoRaTracker) #186

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.


#187

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.


(Jeff Uk) #188

Eerrrm…illegal in NL/EU?! (unless cable and losses >4-6db giving EIRP <16dbm (14dbm +2.15dbI ant)) :wink:


#189

I doubt my antenna has 2.15dBi gain. The antenna Q is not high enough for that. Gain is likely in the negative ranges. And I have some (semi rigid) coax and connector losses. I might be a bit over the 16dBm EIRP limit, but not much. To compensate I always use SF7 and only 19 bytes per message. :innocent:


(Pierrot10) #190

Good day,

I need to order a couple of Antenna and I have some doubt about the Antenna requierement, specialy about the gain.

I am used to with 2db antenna https://shop.imst.de/wireless-modules/accessories/19/sma-antenna-for-ic880a-spi-wsa01-im880b-and-lite-gateway but I guess, there is restriction about de dbi?

Can I use a more powerfull antenna of 3 or 5 dbi? I hert than 2db is a good range. By digikey, I can found several antena with positiv and negatif dbi. So I am confused about what to choose if wither is there a limitation about dbi.

In my cas, the nodes are in orchard at about 1km of the gateway. One can transmit but not the second. Excepted of the small apple tree, there is no a lot of obstacle, but I would like to make sure that the node can transmit in a distance of 3-6km, (or more) .

Then I was thinking to buy some antenna more powerfull. As for exemple:
https://www.digikey.ch/product-detail/fr/linx-technologies-inc/ANT-868-CW-RCS/ANT-868-CW-RCS-ND/1942299
That a good idea?

Cheers