A Miniaturized Diplexer Using Planar Artificial Transmission Lines for GSM/DCS Applications

In this paper, a new planar miniaturized diplexer is proposed for GSM/DCS dual band cellular phone applications. The design is composed of four sections of a recently proposed planar artificial transmission line (ATL) which is used to replace the conventional series quarter-wavelength transformers and the shunt open-circuited stubs. The experimental results reveal that the proposed diplexer features low insertion loss, high isolation and compact size. At the center frequency of the GSM system, the occupied size of the proposed miniaturized diplexer is merely 24.4 mm times 17.6 mm, or equivalently 0.119 lambda_g times 0.086 lambda_g . The design methodology, simulated and experimental results are discussed throughout the paper.