Wideband evaluation of two types of slow-wave microstrip lines

The design, characterization and comparison of two widely used approaches in realizing slow-wave effect on microstrip transmission lines, that is stub loaded and defected ground structure loaded microstrip lines are presented in a wide bandwidth (10-67 GHz) for the first time. Transparent substrate and dielectric material are chosen to ease the alignment of electrode and ground plane. Thin dielectric layer are applied to make the comparison prominent. The results indicate that defected ground structure loaded microstrip line has better RF performance in terms of compactness and insertion loss than stub loaded method within the whole band especially in thin film applications.