EBG-based transmission lines with slow-wave characteristics and application to miniaturization of microwave components

© 2016, Springer-Verlag Berlin Heidelberg. In this paper, artificial transmission lines implemented by means of electromagnetic band gaps and consisting of a host line periodically loaded with reactive elements (either shunt capacitances or series inductances) are presented. The considered implementations are restricted to microstrip lines either loaded with patch capacitors or with inductive slots (etched in the ground plane). It is demonstrated that these structures are useful for device miniaturization due to the slow-wave effect associated with the presence of the reactive elements. A prototype device example consisting of a microstrip power divider implemented by means of a 35.35 Ω slow-wave impedance inverter with inductive slots is reported. It is shown that, by virtue of the slow-wave effect, the length of the inverter is reduced by a factor of two. The performance of the resulting power divider is comparable to the one based on an ordinary inverter. The possibility to suppress spurious (harmonic) bands by means of the Bragg effect is also discussed.