Novel microstrip diplexer for ultra-wide-band (UWB) and wireless LAN (WLAN) bands

A new microstrip diplexer for ultra-wide-band (UWB) and wireless LAN (WLAN) bands is presented in this paper. The proposed structure integrates a multipole directional filter operating at WLAN band coupled to a UWB filter. The prototype is capable of processing the whole UWB region (from 3.1 to 10.6GHz) with the WLAN band notch in one channel, and the passband WLAN band in other channel with a good selectivity due to the presence of transmission zeros at both sides of the WLAN band. The proposed diplexer is simple to fabricate, as it is designed using planar microstrip technology, and presents compact dimensions, making use of a low number of elements. Moreover, it presents the capacity of processing a narrow band (WLAN with 8% bandwidth) with a wide band (UWB). Simulated and measured results are presented with good agreement and the diplexer presents a good performance up to 15GHz.