The modified Schiffman phase shifter

This paper presents the modified 90-degree Schiffman phase shifter (phaser). The new phaser is based on the reentrant structure with unequal dielectric constants of the interior and exterior microstrip substrates. The general TEM circuit model for the proposed phaser in terms of a series connection of the two-ports is presented and then used to determine its electrical parameters. As a result, the modified Schiffman phaser (SP) has a good performance over almost octave frequency range and compact multilayer architecture, showing promising potential for a variety of applications.