A Compact MTM-EBG-Enabled Common-Mode Filter Without A Defected Ground

A bandgap structure for common-mode suppression in conductor-backed coplanar stripline is presented, which achieves wideband performance in a fully-printed and single-layer topology. The bandgap structure is designed utilizing multiconductor transmission-line metamaterial techniques, does not require defects in the conductor backing, and may be directly embedded into the transmission line traces. Common-mode signals are rejected while differential-mode signals are passed with greater than 10 dB return loss over 2.3-4.2 GHz.