Hybrid triplexer design using microstrip coupled line resonators for multiband WiMAX front end

In this paper, a hybrid triplexer design using microstrip coupled line resonators is proposed for the front end of multiband WiMAX system. The proposed triplexer consists of three different combinations of microstrip coupled line resonators, which are the open loop ring, parallel coupled line and folded coupled line. They were used as bandpass filters in the triplexer design to meet three different bandwidths in 2.3, 2.5, and 3.5 GHz bands. As a result, good agreements were achieved between simulation and measurement in terms of return and insertion losses, out of band attenuation, and bandwidth.