Simulational Approach to Realize a Triplexer Based on Bandpass Filters Using Wideband Resonators

Kosei TANII  Koji WADA  

IEICE TRANSACTIONS on Electronics   Vol.E99-C   No.7   pp.751-760
Publication Date: 2016/07/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E99.C.751
Type of Manuscript: Special Section PAPER (Special Section on Recent Advances in Simulation Techniques and Their Applications for Electronics)
triplexer,  bandpass filter,  wideband resonator,  electromagnetic simulation,  

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A triplexer is presented by using bandpass filters (BPFs) which consist of two-stage of wideband resonator and additional open-circuited stubs. The resonator is firstly proposed by using a coupled-line and an inductive element loaded transmission line. This resonator produces the wide passband by a dual-mode resonance, high attenuation level at stopbands, and the steepness at the edge of the passband due to the attenuation poles. In order to understand the behavior of the resonator, the conditions for resonances and attenuation poles are especially solved and their current densities are analyzed by an electromagnetic simulation. Secondly, three types of wideband BPFs are constituted and finally a wideband triplexer is composed by using these BPFs. The basic characteristics of the proposed BPFs and the matching methodology enable to realize the triplexer whose desired passbands are around 3.1-5.1 GHz, 5.85-7.85 GHz, and 8.6-10.6 GHz with high isolation performance at the other passbands. The proposed triplexer is predominance in the flexible bandwidth or wide operating frequency range. All the BPFs and the triplexer are implemented on a planar printed circuit board assuming the use of the microstrip line structure.