How to pick the right antenna for LoRa?

Hi

I just boughtthis LoRa shield. As you can see, there is an SMA antenna connection (but no antenna included). I am rather new to wireless stuff, so what sort of antenna should I buy? I really have no clue where to start looking...

Buy any SMA antenna that is correct for the frequency you will be using.

bestanamnetnogonsin: Hi

I just boughtthis LoRa shield. As you can see, there is an SMA antenna connection (but no antenna included). I am rather new to wireless stuff, so what sort of antenna should I buy? I really have no clue where to start looking...

Google for antennas that match the frequency range of the unit you have. Quote from the web site" Frequency Band: 915 MHZ/868 MHZ/433 MHZ (Pre-configure in factory)".

Paul

So really any SMA antenna will do, as long as it says 434 Mhz on the label?

bestanamnetnogonsin: So really any SMA antenna will do, as long as it says 434 Mhz on the label?

SMA refers to the coax connector on the coax cable. Has NOTHING at all to do with the antenna, except to connect to it.

If your unit is set for 434, then any antenna said to be tuned for that frequency will work. The coax between the antenna and the open end must have a SMA connector to fit your board.

Paul

So how do I know what "shape" is best?

If you have a look on eBay you find 20 different types...

Is this one any good?

Or might one like this or like this one be even better?

I am looking for maximum range. Size isn't important

Try several and pick the best one. Hint: eBay is the last place I would look for high quality antennas:

|500x375 (Note: adjust antenna angle for best reception).

http://scanlime.org/2011/05/another-reason-to-beware-bargain-basement-bluetooth/

bestanamnetnogonsin:
I am looking for maximum range. Size isn’t important

Assuming the descriptions are correct, the antenna with the higher “dBi” should provide more range. Thus the 5 dBi antenna in your second link should provide the greatest range of these options. If your installation is a fixed two point network, you could probably do better with more directional antennas.

The antenna you use hs nothing to do with LoRa as such, its the frequency counts.

Can you give details of the application, location, distance and data rate needed, you might not need much in the way of antennas at all.

I am using it to communicate with a high altitude balloon, at an altitude of maybe 20 - 30 000 meters.

Would it really make a big difference whether I buy an expensive antenna or not? After all, an antenna is just a bit of wire at the end of the day, what could the chinese versions do wrong?

bestanamnetnogonsin: I am using it to communicate with a high altitude balloon, at an altitude of maybe 20 - 30 000 meters.

Would it really make a big difference whether I buy an expensive antenna or not? After all, an antenna is just a bit of wire at the end of the day, what could the chinese versions do wrong?

Finally you are giving the key to your project. Many days time have been wasted!

You need a Yagi antenna with a lot of gain and mounted on a tripod or other device so yo can point it at the balloon. If you can't see the balloon, then you are screwed.

Paul

Are you sure? Srnet doesn’t seem to do it like that.

http://www.loratracker.uk/?p=30#more-30

bestanamnetnogonsin: Are you sure? Srnet doesn't seem to do it like that.

http://www.loratracker.uk/?p=30#more-30

It's one thing to build something and another to publish results of it actually working to track a balloon.

Paul

Srnet doesn't seem to do it like that.

Stuart Robinson used a 1/4 wave whip with radial ground plane leads for the transmitter, which is about as good as you can do for a short, omnidirectional antenna. A center fed dipole would be fine, but twice as long.

A high gain, highly directional multi-element YAGI antenna for the receiver, pointed at the balloon, would be necessary for long distance reception. They are not difficult to make, but are not "just a bit of wire".

Paul_KD7HB: It's one thing to build something and another to publish results of it actually working to track a balloon.

Paul

Here we go;

http://www.southgatearc.org/news/2015/january/lora_low_cost_long_distance_telemetry.htm

And a much more detailed report is published here;

Semtech LoRa Transceivers – a KISS approach to Long Range Data Telemetry - January 2015

For the same LoRa modes the current max recorded distance is 440km. Thats with a circa 6dB gain co-linear omni at the receiving end, 1/4 wave wire at the TX end.

Use a simple 1/4 wave wire at the RX end as well and expect 'only' 220km.

Stuart Robinson

jremington: A high gain, highly directional multi-element YAGI antenna for the receiver, pointed at the balloon, would be necessary for long distance reception. They are not difficult to make, but are not "just a bit of wire".

A yagi is really not needed for LoRa.

Its worth pointing out that the 440km I mentioned above was at 10mW @ 1500bps with a 5dB omni on the RX end. You can drop the data rate to 100bps, which is still enough for tracking, and you will get 3 times the range (yes really !).

So a simple 1/4 wire on the RX end as well should give you > 500km range at the lower data rate.

The real limiting factor with LoRa is the curvature of the Earth ...................

srnet: Here we go;

http://www.southgatearc.org/news/2015/january/lora_low_cost_long_distance_telemetry.htm

For the same LoRa modes the current max recorded distance is 440km. Thats with a circa 5dB gain co-linear omni at the receiving end, 1/4 wave wire at the TX end.

Use a simple 1/4 wave wire at the RX end as well and expect 'only' 220km.

Stuart Robinson

Very good! Hopefully the OP will study your link. Since a vertical omni antenna has very little vertical pattern, they must have tilted the antenna for best reception/transmission.

Paul

Paul_KD7HB: Very good! Hopefully the OP will study your link. Since a vertical omni antenna has very little vertical pattern, they must have tilted the antenna for best reception/transmission.

Nope, 'they' and I have no need to fiddle with the antennas, the co-linears such as the Diamond X50 have their gain very close to the horizon, which for tracking high altitude balloons is exactly where you want it.

Close in where the balloon may be at a higher angle, there is so much spare link margin that you wont have a problem.

Ok I studied your link and its very interesting. However its all getting a bit technical for me, as I'm rather new to LoRa and Radio.

So Srnet, are you saying that a "normal" antenna on Rx and Tx (like the antennas I linked) would work?

bestanamnetnogonsin: Ok I studied your link and its very interesting. However its all getting a bit technical for me, as I'm rather new to LoRa and Radio.

So Srnet, are you saying that a "normal" antenna on Rx and Tx (like the antennas I linked) would work?

Yes they should.

From the antenna perspective, LoRa behaves the same as any other radio frequency system, so you just use the appropriate antenna for the frequency.

Where LoRa is different is that it is very much longer range than other telemetry systems, therefore it is not so important that antennas used are high gain or of high quality.

What is not possible is to predict in advance is just how good cheap antennas from eBay are, they may be OK, they may not.