Transmission line phase shifters using defected ground structures

Explorations into the domain of electromagnetic bandgap (EBG) structures have become increasingly common in recent years. By etching these structures into a circuit ground plane, they have been applied within the planar microstrip medium for use as filters at microwave and millimetre-wave frequencies. They have been effective within system designs in the suppression of undesirable harmonics, as well as within antenna applications to achieve improved radiation characteristics through loss suppression. However, their slow-wave properties have not been exploited to a large extent with regard to their impact on realizing a phase variation. These structures can be used to realize more compact phase shifter designs, while adding virtually no additional losses to the system.