Implementation of an FM Transmitter Circuit for FM Radio Signal Communication

This paper presents the design and implementation
of a three-stage FM transmitter for short-range audio broadcasting within the 88-108 MHz FM band. The system consists of
three primary stages: pre-amplification, carrier generation, and
power amplification. Initially, the weak audio signal is amplified
by Q1, a NPN transistor, to a level suitable for modulation. In
the next stage, Q2, configured as a Colpitts oscillator, generates
a stable high-frequency carrier signal. This carrier is modulated
by the audio signal in the FM stage, where the frequency of
the carrier is varied in proportion to the amplitude of the audio
input, encoding the audio information.The modulated signal is
then amplified by Q3 in the power amplification stage, ensuring
sufficient strength for short-range transmission. The amplified
FM signal is passed to the antenna, which broadcasts the signal
for reception by FM radios. The system was validated using
MATLAB simulations, which modeled the frequency response,
power spectral density (PSD), and the effects of Additive White
Gaussian Noise (AWGN) and multipath interference on the signal.
The Proteus simulation environment was used to further verify
the circuit’s performance in real-world conditions. The results
demonstrate that the transmitter is capable of handling signal
interference, maintaining frequency stability, and delivering a
robust FM signal for broadcasting.This work provides a novel
approach to FM transmission, integrating theoretical analysis,
simulation models, and practical validation. It addresses common
challenges in wireless communication, such as signal clarity, frequency drift, and interference, making it a valuable contribution
to the field of short-range FM broadcasting and educational
applications