Considering the low power used in LoRa applications the dipole design without balun seems to be a good and simple to build antenna.
diy swr tool
I suggest a competition to establish the worst performing ‘868Mhz antenna’
To start the ball rolling today I tested an ‘868Mhz 5dbi antenna’ I got off eBay, the RF output was -18dB down on a 1/4wave vertical with radials.
I suspect this ‘868Mhz 5dbi antenna’ was actually a WiFi antenna.
I carried out some tests on the very simple dipole for 868Mhz that I posted earlier, the results are posted here;
A simple clamp on ferrite choke seems to eliminate most of the issues caused by using co-ax cable to connect up the antenna.
A larger cap performs better?
Just to add to the discussion.
I’ve come across some nice vids and links regarding the use of RTL-SDR and/or AirSpy to perform antenna analysis for those of use who don’t have access to Vector analysers and VSWR meters that cover ISM bands.
Looks like a low cost way to check DIY/Chinese antennas and perform some fine tuning.
Is that a mini circuits coupler…?
If so which model and how do you find it performs…?
I’m going to ask my question here as it seems fitting… Obvious eBay rip-off aside, on a few “respected” websites (that’s e.g. Conrad, Reichelt, Voelkner in Germany), I found 4 dB omnidirectional antennas advertised at a fraction of the price of the 0 db antennas also available from these vendors. Is this always a “it depends” and “you have to try it out”, or are there general rules of thumb which specs to expect in a certain price range?
I’m especially curious as this Conrad-brand 4 db antenna comes with plenty of cable and a SMA connector, while for the Aurel GP868 I’m thinking about I’d need extension cabling and adapters, likely adding to further signal loss.
The conrad comes with 5m RG174 attached - not good That will cost you around >4-4.5db of loss - offsetting the 4dbi gain (if that is reliable). for anything more that a couple of meters avoid RG158, RG174 & their ilk as losses too high - look to ultra low loss cables instead.
I have both and I agree with Jeff-UK… I prefer the Aurel GP 868, is build for outdoor use and comes with a reasonable cable (I use it indoors with supplied cable) overall quality is good.
The only disadvantage is, on the supplied cable , the BNC connector on the GW side, the side that goes into the GP is not visible but is an 'F connector :
So to connect this GP to your gateway you’ll need a adapter plug BNC-SMA
Yep, that would be my setup, too. Unfortunately, I may have to get an extension as the 2.5m cable is quite short… …and flat/ribbon cable for the window if I should move the antenna outside.
if that cable is to short then maybe this vid comes in handy
I must warn you for the cheap chinese 10 mtr cables… the loss is very high
Ouch. It looks even more fiddly than SMD soldering, and that ain’t exactly my specialty.
About the Aurel 868 GP Baseantenna.
At last meeting, called “Stammtisch”, a buddy has his Aurel there by. I shoot some photos:
Needs a Pigtail from F-Connector <-> (RP)SMA with a lowloss-cable
About this theme.
We need standards!
s a list of good baseantennas.
For stationary SenseNodes good antenna`s.
And for mobile nodes good little antenna`s.
They should be verified and in a good quality!
Need a list
s in own threads with links where we can buy it.
it’s not a bad idea… the same thing was discussed before with nodes and gateways , creating lists and keeping them up to date is a job… so… be my guest, start that antenna list, find those shops and prices, test those antenna’s
For baseantennas we need a type that can recieve the signal in any position. Not only in one, most vertical.
Mobile nodes are sending in many positions. Vertical, horizontal, diagonal and so on.
What is the best antenna for this?