The application of photonic bandgap structures (PBG's) as substrates i
n microstrip circuits has been investigated. The effects of substrate
thickness, microstrip transmission line location, and length of the PE
G structure were studied using a finite-difference time-domain (FDTD)
simulation and experimental measurement. A low-pass filter with a very
wide high-frequency rejection bandwidth was constructed from a serial
connection of many different PEG structures.