I’m currently looking at the LimeSDR Mini 2.0 and the LimeRFE to broadcast FM radio using a LPFM radio license, with a maximum transmit radius of the LPFM license of 3.5 miles. I was wondering, what SMA antenna for the LimeRFE would work to be able to transmit at the given range of 3.5 miles?
A simple ground plane designed for the frequency of interest would work well.
With a 100 watts you would get 3.5 miles in just about any conditions and to any point in the line of sight.