Design of a Planar Four-Port Microstrip Triplexer using Stub-Loaded Coupled Line Resonator for Advanced Wireless Applications

In the realm of high-frequency devices, effective management of circuit interactions holds the utmost significance within intricate environments. In light of this, a planar four-port microstrip triplexer employing a stub-loaded coupled line res-onator structure has been meticulously designed and examined. The triplexer filter exhibits seven transmission poles, strategically incorporated to ensure optimal performance across all three passbands. Targeting operation frequencies of 2.55 GHz, 3.94 GHz, and 5.74 GHz, the proposed triplexer is fabricated on a compact Rogers Duroid 5880 substrate. With insertion losses of 0.36 dB at 2.55 GHz, 0.53 dB at 3.94 GHz, and 0.33 dB at 5.75 GHz, the triplexer demonstrates excellent alignment between measured and simulated results, thereby substantiating its efficacy in meeting the specified requirements.