Defect modes in microstrip lines on electromagnetic band-gap substrates of finite extent

Suppression of surface waves propagating in a grounded dielectric substrate slab can be achieved by using electromagnetic band-gap (EBG) substrates. In this paper, a 2D-planar EBG substrate is investigated experimentally and simulated by a simple method based on the chain-matrix conversion. Good agreement between the measured and simulated results is observed. We also show that other defect modes can appear in the band gap, and explain their existence by the finite size of the EBG structure under investigation.