Bandwidth Optimization in FM Transmitter Antenna Design: A Practical Engineering Framework for Wideband FM Signal Transmission

Efficient bandwidth utilization in FM radio transmitters is a critical factor for enhancing signal clarity, minimizing interference, and ensuring energy-efficient broadcasting. This study investigates bandwidth optimization in FM transmitter antenna design, focusing on how impedance matching, antenna geometry, and material properties influence overall system performance. A prototype half-wave dipole and a modified folded dipole were designed and simulated using CST Microwave Studio. The half-wave dipole exhibited an impedance bandwidth of 4.2 MHz (87.5–91.7 MHz) with a return loss of –18.6 dB and a radiation efficiency of 84.3%, while the folded dipole achieved a broader impedance bandwidth of 7.9 MHz (87.5–95.4 MHz), a return loss of –22.1 dB, and a radiation efficiency of 91.7%. Field tests confirmed that the optimized folded dipole extended the effective coverage range by 12.5% compared to the conventional dipole, while maintaining a signal-to-noise ratio (SNR) improvement of 8.2 dB at a distance of 10 km. The results demonstrate that careful antenna bandwidth optimization through structural modifications and impedance matching networks can significantly improve FM broadcast quality, spectral efficiency, and power utilization. This work provides a practical framework for developing cost-effective, high-performance FM antennas suitable for community and commercial broadcasting applications.