That can even be on the same day, in the same batch of antennas.
Not 100% guaranteed but you should try. Look on aliexpress for the brandname ´allishop´ , they have a lot of RF things.
They have a antenna called 5dBi omni antenna, i measured a few of them and they were exact on 868MHz.
Also they give specifications about the gain, vswr, BW, impedance and radiation pattern, nobrand name antenna´s usually do not do that.
Allishop antenna´s are a little bit more expensive than nobrand name antenna´s.
If you order one, look for the brandname ´allishop´ in the advertisement, I think you have a good chance of getting a real one.
There are many sellers who have an antenna that looks exact like that one, same length and they always claim it is on 868MHz and has 5dBi gain, but often the seller doesn´t know anything about RF. So chances are great you get something what is not as advertised.
A few days ago I tested for someone this same (lookalike) antenna, it was (according to the gateway owner) sold together with the 868MHz TTN-gateway by Farnell. The N1201SA analyser told us the antenna was spot on 915MHz. So even Farnell may be fooled by the chinese and sell you the wrong antenna.
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That is exactly the antenna that I mentioned some posts above and earlier in this thread. With a link, photos of its internals and a drawing with measures: The â5dBiâ 868MHz 19.5cm SMA antenna from ALLISHOP.
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Indeed bluejedi, it is the same antenna. Your drawing shows it is a full dipole. So it should be advertised as 2.15 dBi and not as 5dBi antenna.
I did a quickscan on 12 dBi antennas on internet:
- Ideetron has a antenna of 12 dBi with a length of 63 cm:
https://webshop.ideetron.nl/SDBF0.5-868 - At Aliexpress I find 12 dBi antennas with a length of 1,2 meter:
https://www.alibaba.com/product-detail/Hot-Selling-Outdoor-Omni-12dbi-Fiberglass_60377751688.html - At Taoglas (yes chineese) the 12 dBi gain antenna is 2,24 meters:
http://www.taoglas.com/product/barracuda-omb-868-b10f21-868mhz-12dbi-omnidirectional-outdoor-antenna/
It is tempting to believe the first two but I think that the chance for a real 12 dBi antenna is with Taoglas.
How about this to make a cheap 868 Mhz antenna.
- Buy a cheap one off Ebay
- Snap the top off
- strip a bit of insulation off, solder a small piece of single strand wire
- Repeat the following until satisfied - Put top back on, measure with N1201SA and cut until happy (see pics for difference if top is on or off)
Pic 1 shows stock Antenna which resonates at 915Mhz, Pic 4 shows final result - not too shabby (Measurements all at 868 Mhz) 
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Pic 1 - shows stock antenna
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Pic 2 - showing how much extra wire to solder on to tip
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Pic 3 - With top off
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Pic 4 - Final result - with top on
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edit Did some tests with a Heltec.
I sent a regular message within the house (> 10 lambda) and checked the RSSI after alternating between a stock and an altered antenna - did the altered antenna make a difference?
Ignoring spurious results, it did seem that the modified antenna was better - but only by a few dB. The test certainly wasnât scientific so maybe Loratracker can give a better test?
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Combining recreational activities is always nice. I decided to put a battery-powered node on the mast of my small sailing boat. I basically modified the rak811-trackerboard firmware to drastically reduce the number of transmissions and to reduce the size of the payload. I added a small rubber duck antenna and wrapped the lot in a pvc tube which is fixed to the mast with a couple of tiewraps.
Then I started sailing, all around the lake. Which is for about 50% covered if I check TTN mapper. However when I checked Cayenne after 3 hours of sailing i only found some datapoint from the morning before when I tested the node after building it into the tube, and same datapoints from when I returned home. No coverage on the lake at all. I am now thinking of replacing the antenna for something better.I was wondering if anyone here has positive experiences using lora on a small boat. I would figure a big flat body of water would be positive for the range, but my RF knowledge is non existent. If anyone can recommend an antenna that doesnât mind getting the occasional beating and can be put in a mast that would be great.
Hi guys!
This week we´re installing this antenna in a 30mts tower:
With a IP-65 enclousure using RAK813 gateway:
Our goal is to cover several end devices (street lamp modules we´ve made) and this is our first field test!
The ideal coverage: 10km. The nodes are going to be 9mts above ground so I think that it will work
I will let you now how it goes! If you have any advice, it would be great!!
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Finally found a use for one of my empty containers ⌠
I added my newly constructed ground plane tuned for 915 Mhz to my gateway. Tremendous improvement in signal quality. Was easy to build but took a bit of tuning to get it just right. I used my NS1201 VNA.
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Could be a topic for on te work bench thread.
I have measured the antenna I found in a device for elderly care.
It was told to me to be om 868 MHz. bu the device seems tuned for the US market eg. 915 MHz.
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Nice. âAged 12 yearsâ 
I had the impression that this antenna type already provides itâs own âground planeâ
(because it is some variation of a di-pole).
What was the effect of adding the container? Is it all metal or only a metal top?
The container is made of compressed cardboard⌠so no real impact from the container itself. That being said, the top is metallic. Some sort of tin or aluminum âŚ
To get a good match I had to tune the antenna once mounted on the top of the canister. The additional ground formed by the metallic top changed its impedance. All that was required to compensate was to change the angle on the ground radials so that the impedance at 915 mhz was 50 ohms. There was a small hole in the back of the container and I ran the feed line out that and connected it to the VNA. You can see the radials are not quite 45 deg.
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Yesterday I replaced my 10 Dbi for a 3 Dbi (testing)
Doing that I found⌠rust 
observation 1 : because this antenne is 2/3 smaller itâs not sticking anylonger above the apartment rooftop⌠hence it seems that itâs very directional now, probably using the concrete iron as a reflector.
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Hi Rob, funny coincidence
Yesterday evening I was in Dordrecht. My gps_ttn_mapper node was seen by 2 gateways, one in Rotterdam and the other was yours
For a few hours I was at the local radio amateur club PI4DEC and a little later I visited a friend at âNoordendijkâ both resulted in a cluster of dots.
Used node is a hallard-pcb with pro-mini, rfm95 and a Neo6 GPS, SF7 and a 85mm wire antenna, placed on dashboard of my car.
b.t.w., I believe we have met a very long time ago at the studio of Wick and also in your KCS-office.
greetings Coos
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yep⌠guilty Coos 
at SF 7 itâs very good I think
Too late to update my post 433 (on how to change a 915 Mhz antenna to 868 Mhz)
So posting here.
I thought Iâd check the stock antenna provided with the TTN gateway - sure enough it was set for 915 Mhz.
Not only that it looks almost identical to the cheap Chinese one I bought from eby.
So I swapped with one of my doctored antenna (as seen in previous post) and sure enough the RSSI improved for the gateway !
Be careful though, the antenna is fragile and easily broken - I would buy another antenna and doctor that (and keep the supplied TTN antenna spare). Going to buy a few more of these cheap antenna of Eby now !
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Hi CurlyWurly,
I did what you did (10 posts up from here) with a cheap antenna. Mine was even worse than yours, it originally had a VSWR of 12 and an impedance of 150+j250 ohms on 868MHz. It was tuned for 975 to about 1200 MHz and would have probably performed well on the 1090MHz ADS-B airplane band
Not only enlarged the center conductor but I also enlarged the brass tube at the bottom by soldering a flap of thin copper foil around the tube, making it about 15mm longer. Because of the copper foil it was not easy to slide the plastic top back completely therefor I slided it back partially and did a piece of heat shrink tube around the base. So the result was about a 1cm longer antenna
After the modification it behaved very well on 868MHz. Putting it on my RAK831 gateway it got at least 5dB better RSSI signals compared to the short stock antenna that was delivered with the RAK.
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With my antenna, the intial VWSR was 2.72 - Youâve done well in getting it work from 12 !!
Any chance of uploading a pic and showing what you did - also showing the VWSR result?
Iâve just ordered some more cheap antenna to try.
Unfortunately I couldnât get the same ones again - It might be that I have to do what you are doing?
So, which one you advise would be the best read?