A Novel Schiffman Phase Shifter with a Defected Microstrip Structure

Abstract

In a standard Schiffman phase shifter a coupled section and a uniform transmission line are used to give a differential phase shift. In order to achieve a larger bandwidth it is necessary to use tight coupled sections which are difficult to be realized. Further more, a 90° Schiffman phase shifter can hardly be realized with a low permittivity substrate. In this letter a novel Schiffman phase shifter is proposed with a defected microstrip structure. The S-parameters of the proposed structure show that the novel Schiffman phase shifter can achieve a phase shift with a low permittivity substrate and can obtain a 30% bandwidth with a phase error +/− 3 deg.