The designed photonic bandgap (PBG) structure consists essentially of periodic perforations on a ground plane to provide effective and flexible control of electromagnetic waves along a specific direction. By controlling the position of the microstrip line, the designed PBG structures exhibit stop-band character. The optimal position of the 50/spl Omega/ microstrip line to bring about perturbation of electromagnetic waves is determined. The simulated results with a 2.5D full wave electromagnetic analysis are in good agreement with experimental data.