UNBALANCED METAMATERIALS APPLIED TO PHASE SHIFTER: DEDICATED DESIGN METHOD AND APPLICATION IN C-BAND

In order to design differential phase shifters (DPS) from metamaterial-based transmission lines, research had a long tradition of using balanced transmission lines which are a particular case of metamaterials, specifically characterized by a simplified equivalent circuit model. This paper presents an innovative way of designing DPS metamaterials by exploiting metamaterial properties more widely, using both balanced and unbalanced cases to obtain a broader set of solutions. These solutions are acquired through the dedicated method this paper expounds, and conceived with the help of a new use of metamaterials. For the sake of ensuring time efficiency and implementation easiness of this design method for industrial purpose, the full wave parametric optimization is reduced to its minimum by exploiting as much as possible in analytic parametric study. This method is illustrated by an application of 180 • DPS on C-Band (5-6 GHz). Three prototypes were fabricated, and the measurements show that the best case of DPS has less than 9 • of phase error over the targeted 20% bandwidth, with a return loss less than −14 dB and insertion losses lower than 1 dB.