Langxing: Thank you very much. I think defected ground plane is used much on EBG structures. You can simulate such structures efficiently and accurately on IE3D using finte ground plane modeling. You just need to use differential ports (+ and - for extension ports) and the v-localized and h-localized ports. Our latest IE3D FASTA can speed up simulation and reduce the RAM significantly for large DGP structures. Please give it a try. I am Jian from Zeland.