Can I know how your circuit works and its schematic diagram?
I never built an FM radio. I buy good ones and poor ones. The FM radio from The Dollar Store is very poor. My clock radio and Sony Walkman radios are not bad but not good. The good ones are excellent.
Are you asking about how my FM transmitter circuit works? Then you need to learn about electronics.
Somebody posted a defective FM transmitter circuit that they found on the internet. I looked at its schematic and explained why it did not work but they did not believe me so I fixed its 4 problems, one at a time:
1) Its mic preamp transistor was poorly biased so it was saturated and did not work when there was a new 9V battery and the transistor was cutoff and also did not work when the battery voltage ran down a little. So I biased it correctly and added a voltage regulator.
2) The radio frequency changed as the battery voltage ran down. So I powered the FM oscillator from the voltage regulator that I added.
3) The radio also frequency changed when something moved towards or away from the antenna. So I added an RF amplifier transistor to isolate the FM oscillator from the antenna.
4) The sounds were muffled with no high audio frequencies when heard on any FM radio. So I added pre-emphasis (treble frequencies boost) like all FM radio stations have that matches the de-emphasis (treble frequencies and hiss reduction) like all FM radios have.
I called my project "FM tx mod4" and here it is: