This is the actual power radiated by the antenna system. High-gain antenna arrays (like multi-bay dipoles) focus the energy toward the horizon rather than wasting it upward. Core Stages of a High-Power FM Transmitter
To hit a 100 km range, you generally need a combination of the following factors: 100 km fm transmitter circuit diagram pdf
This is the section that turns a weak oscillation into a powerful signal. This is the actual power radiated by the antenna system
Without a low-pass filter, your transmitter will spew harmonics on 196 MHz, 294 MHz, etc. This interferes with aviation and emergency services. Build a 5th or 7th order Chebyshev filter. The inductors are 3-5 turns of 1mm enameled copper wire on a 6mm drill bit. 100 km fm transmitter circuit diagram pdf