A novel-excited inter-digit diplexer for WLAN applications

A new diplexer for WLAN applications using a combination of multi-finger periodic structure and a novel Wilkinson power divider is proposed. The proposed design consists of a transmitting and receiving bandpass filters using the interdigital capacitor based on the theory of quasi-lumped element equivalency. The filters relied on the capacitance occurring across the narrow gaps between the conductors. Size miniaturization becomes feasible as the gaps are folded in order to use a small amount of area. The resulting design is investigated using the commercially available numerical solver, and subsequently prototyped. Findings indicate acceptable agreement between the measured and simulated results.