I’m experimenting with LoRa gear, and am getting range well below what seems to be possible. I’m located in Canada, so I’m using the 915MHz band. My hardware is below:
Antenna Adapter (5cm IPEX version): https://www.aliexpress.com/item/5PC-PCI-U-FL-to-SMA-Female-Connector-Antenna-WiFi-1-13-Pigtail-Cable-IPX-to/32955443108.html
I’m not running any kind of network yet, just sending data directly over LoRa sans-LoRaWAN (using https://github.com/sandeepmistry/arduino-LoRa).
I’m using a spreading factor of 12, a bandwidth of 500khz (with the 500khz optimization registers changed as mentioned in the SX12xx errata sheet), a frequency of 920.0 MHz a coding rate of 4/7, an 8 symbol preamble, and a set tx power of 20 dBm (my understanding is that the module contains an amplifier to raise the transmit power to 30 dBm, is that correct?). With this I’m getting a range of only 350 to 650 meters in a suburban environment, with the transmitting antenna on my house (mounted vertically on the end of a 1 meter wooden stick stuck out my upstairs window) and the receiving antenna in my hand, held up in the air. I should note that this 650 meter range is line-of-sight, straight down a road. Of course, this worsens if I leave the LoS (as expected). Any further than this, and I get garbled packets, or nothing at all.
While I know that some of the advertised ranges for LoRa gear are often not possible in the real world, a few hundred meters seems much worse than what other people seem to be managing, especially considering how high my SF is, and the fact that in Canada we’re allowed much higher transmit powers (1 watt conducted, 4 watts EIRP) than in many other regions.
What am I doing wrong, or what piece of hardware is the limit here? Am I misunderstanding how to set TX power? Is my antenna setup wrong? Or is this just the range I should expect?
Thanks in advance!