I made a node sensor by using the RFM95 component. I added a Temp et humidity sensors.
On my node I have this type of antenna :
My Gateway is in my house and my sensors also.
The node sends the data to gateway without problem.
But when I put the sensor at a distance greater than 20 meters I don’t receive any data.
I plot the RSSI :
The group of points between -100 and -108 it’s when my node is at 6 meters.
The other group is when it’s at 15 meters.
Normally the distance coverage should be 1km and mine is totally ridiculous.
Do you have an idea why this distance is so low ?
Try the sensor ant directly connected to the RFM ant o/p, then try with just a straight wire ant (depending on your frequency it wll need be 8.2-8.6cm in length(eff) and see what results you get in each case…
No it shouldn’t. There is no normal distance, it all depends on the environment where the gateway and node are located. In modern housing/offices with UV coated windows and radiation (RF) shielding in walls you are lucky to get hundred meters.
However, in your case you’ve chosen one of the worst antennas possible. These antennas rely on the PCB and position on the PCB to provide a ground plane to be a proper dipole. Your antenna and PCB combination will not come anywhere near the 50 ohms antenna ‘match’ required by the RFM95. A 8,6cm wire would be a better solution. Adding a SMA connector with a decent (at least 10cm long) SMA connected antenna tuned for the right frequency would be even better.
For the gateway antenna, have you checked the antenna has a pin and the SMA connector a hole? You would not be the first to discover both antenna and SMA connector don’t have a pin (because of mismatching SMA/RP-SMA combinations)
Thanks for your help ! @kersing@Jeff-UK
When I connect directly on the RFM the antenna it has the same RSSI so it doesn’t change.
I try with a straight wire like this :
and I obtain better results (I can communicate from a distance of 40 meters now).
At 40 meters I have -120 RSSI, so it’s the limit.
@kersing I don’t understand what are you saying in your last paragraph. My gateway connection is like this :
Is it the right connection ?
I meant something else, but it looks like your antenna is connected to the wrong u.Fl connector on the ic880a. You need to connect it to the u.Fl connector near the one of the connectors with three pins, not the one with 20 pins (that one is for GPS pps).
Do so asap to prevent damage to the ic880a!
Short answer no…the LoRa receiver is the chipset (sx1301 baseband processor + the 2 X sx125x RF/IF frontends connected to the 2 x filters) at the top of your pic so you need to use the ufl near there…
Hopefully running the concentrator card without ant attached hasnt damaged the board, if you find it unreliabe in future it may be a foreshortened life due to the rf energy reflecting back into the LoRa front end…
