In this work, a novel planar four-port microstrip triplexer is designed and analyzed to operate at 1.9GHz, 2.5GHz, and 3.35GHz for wireless communication applications. The proposed structure consists of a compact patch and spiral cells. The main advantage of this triplexer is its very compact size, with a cross size of only 15mm × 15mm (0.017λ2g). Sharp frequency response at the edges of all passbands, low insertion losses (0.25dB, 0.4dB and 0.11dB), and high return losses (45dB, 54dB and 40dB) in all channels are the other advantages of the designed triplexer. Additionally, the triplexer has reasonable isolations (S23, S24, S34), better than 20dB. To verify the design method, both EM simulation and measurement results are obtained. The comparison shows that the measured and simulated results are in good agreement, which proves the feasibility of this work
