A Novel Dual-Band Zero-Phase True Crossover With Arbitrary Port Impedance

Abstract

A novel dual-band true crossover that can match with any impedance presented at its input and output ports is proposed in this letter. To break through the conventional 50- $\Omega $ reference port impedance constraint, a planar crossover with a zero-phase delay in the transmission is designed first at a single operating frequency. The proposed single-band zero-phase crossover consists of outer branch lines and inner crossed lines, and the design parameters for each line are obtained by applying the even-odd mode analysis method. Second, the dual-band function is implemented on the proposed zero-phase crossover by replacing each line with dual-band transmission line, which has two series sections and one shunt section. A prototype of dual-band zero-phase crossover operating at 2.15 and 4.1 GHz is designed, fabricated, and measured. The simulation and measurement results agree well with each other to prove the design concept.