This research paper focuses on designing and analysing a tri-band antenna for RF energy harvesting within the sub-6 GHz spectrum, specifically targeting 2.1 GHz (3G), 2.3 GHz (4G), and 3.5 GHz (5G). The antenna structure incorporates three dipole elements that resonate at distinct frequencies while maintaining a compact footprint. Characteristic Mode Analysis (CMA) is applied to refine the antenna design, improving its radiation efficiency and ensuring enhanced broadside performance. The antenna's performance is evaluated through simulated and measured S₁₁ parameters and radiation patterns. A tri-band bandpass filter is integrated into the system to enhance impedance matching across the 2.1 GHz, 2.3 GHz, and 3.5 GHz bands, ensuring efficient signal transfer at each operational frequency. Additionally, an RF-to-DC rectification circuit is designed using a Schottky diode alongside a low-pass filter and load resistor, enabling effective conversion of ambient RF signals into usable DC power for energy harvesting applications. The results obtained from this study validate the tri-band antenna’s capability to efficiently harvest RF energy within the 3G, 4G, and 5G frequency ranges. By leveraging Characteristic Mode Analysis (CMA), the proposed design optimizes radiation efficiency, while the rectifier circuit exhibits stable RF-to-DC conversion across different power levels.