Miniaturized quad-channel microstrip diplexer with low insertion loss and wide stopband for multi-service wireless communication systems

摘要

In this paper, a compact four-channel diplexer is designed using a microstrip structure to separate input signals at 2.07/3.94GHz and 2.37/4.49GHz and load them on two output ports. The presented diplexer is designed utilizing a novel structure, which can be applied in modern multi-band wireless communication systems and IEEE 802.16 WiMAX that covers 3.17-4.2GHz. This diplexer is consisting of coupled lines, a spiral cell and U-shape structures that are integrated to obtain a high performance. To create four passbands at two output ports, the proposed structure is miniaturized so that it occupies only a 0.0252 circuit size where (g) is the guided wavelength calculated at 2.07GHz. Moreover, the low insertion losses are obtained at all channels. Another achievement of this work is obtaining a wide stopband. After the last passband, harmonics are attenuated up to 8GHz, which is suitable for ultra wideband applications. The introduced diplexer is fabricated to confirm the design process where the measured results are in a good agreement with the simulations.