Design of Compact and High-Isolation Quadruplexer With Novel Matching Network

A novel matching network to design quadruplexer is proposed in this paper. The matching network is comprised of two parts and each part consists of a short-circuited transmission line, an open-circuited transmission line, and a series transmission line. The matching network is analyzed to obtain the design curves, which lead to various design parameters. Using this matching network, the quadruplexer can be easily realized by the connection of different bandpass filters without further tuning. Systematic design procedure for quadruplexer is fully presented in this paper. To illustrate the concept, a quadruplexer is designed, fabricated, and measured. Simulated and measured results are found to be in good agreement with each other.