Hello, I am using the rfm95 shield for my high altitude balloon project and I am currently designing a ground plane antenna to transmit data to the ground station. Will this (circled in red) part of the shield affect the length of my antenna?
Also, I have another question: Using this LoRa shield, is bandwidth 125khz and power output 100mw enough for this project, or do I need a lower bandwidth to achieve a greater distance?
Thank you for your help.
I suspect the circles spot is directly connected to the coax connector right next to it. You will HAVE TO use the coax connector to connect to your ground plane antenna and NOT have a wire connected to the spot you circled.
It might, slightly, but not a lot, assuming you remove the red wire and use the SMA socket of course.
If you want a 1/4 wave with radials to transmit maximum power you might get a dBm or two more if you tune the length of the 1/4 wave vertical bit for maximum radiated signal. This is actually quite easy, you have the TX sending packets that are received say 100m away with a LoRa receiver that displays RSSI. Start with an overlong TX antenna and trim a bit off each time and recored the received RSSI.
A distance of 832km has been achieved high altitude balloon to ground with LoRa. That was at 868Mhz, 125khz bandwidth, spreading factor 12, power output 14dBm. Would you need more range ?
Take care with power output levels and air time of packets, there may well be restrictions in yourpart of the World.
Guide to adding a ground plane antenna to a payload box;
Thank you for your help! I appreciate it.
Obviously line of sight is important. I don't know how that 832 km was achieved exactly - one side was indeed a high altitude balloon - but nonetheless the other end must be at sufficient elevation with clear lines of sight to where-ever that balloon is going.
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