Hi, I need to build a sensor network (e.g. 3 ambient sensors communicating to a base station that is ~100 meters away for any of the 3 sensors, in a forested area – internet connectivity not available nor necessary).  These are the options I know about (my question follows this):
 
WiFi — max ~40 meters inside with obstructions, less depending on the building, ~70 meters outside line-of-sight (power consumption an issue; would use a soft-AP)
Bluetooth — max ~10 meters (duh … forget it)
ESP-NOW — ~10 meters inside with obstructions, more than 100 meters outside line-of-sight (low power consumption)
LoRa RFM95 — ? with obstructions; googling suggests up to 2000 meters outside line-of-sight (power??)
RFM689 — ? with obstructions; googling suggests up to 500 meters outside line-of-sight (power??)
 
I was very attracted to ESP-NOW based on that wonderful 250 meter distance photo in the eBook (Learning ESP32 using Adruino ID) until I tested it and couldn’t get communication over more than 10 meters line-of-sight through a screen door.  I tested it outside in an alley and got 100 meters line-of-sight max.  The antenna orientation is critical (duh, this is RF communication after all!).
 
So, ESP-NOW is out, and I’m now looking at LoRa with a simple antenna.  An issue is cost – ESP-NOW was very attractive since it was just the ESP32, but now with LoRa, there is an additional $10-20 depending on mounting. 
 
My question: Does anyone have experience with LoRa with an omni-directional antenna (i.e a vertical wire at the base station) over a 100 meter distance in a wooded area?  … I realize “wooded area” is a bit nebulous, but is it even worth doing a LoRa experiment?
 
People do make these dispersed sensor measurements in wooded areas, but without an amateur radio license and big car batteries how do they do it?
 
Thanks for any enlightenment.  — JoeM

Hi Joe.
 
We got very good results with ESP-NOW as mentioned in the eBook. You can get better results if you have boards that can have an external antenna.
 
As for LoRa, we have tested it in a wooded area. We built a very basic homemade prototype board with an RFM95 and a wire working as an antenna. At the time, we got a communication up to 250 meters with trees and other obstacles in between.

There are LoRa boards that already come with the LoRa RF module and external antenna. So, you don’t have to build a prototype board.
Each case and environment is different and many factors can interfere with the distance, including LoRa settings (https://github.com/sandeepmistry/arduino-LoRa/issues/90).
 
You have to experiment yourself several conditions and try to get the best results.
 
I’m sorry that I don’t have a clear answer to your question…
Regards,
Sara
 

Great help Sara, and that website is a very good resource.  I will proceed with the LoRa approach and will report back in a month when it’s in use.  Thank you.

Great! Then, let us know the results.
Regards,
Sara