Improved performance of photonic band-gap microstripline structures with the use of Chebyshev distributions

Conventional uniform circular-patterned photonic band gaps (PBGs) have constraints in the broadband passband and stopband performance because of the high ripple heights in S parameters. This Letter suggests a novel configuration with nonuniform dimensions of circular-patterned PBG to improve both pass- and stopband bandwidths and the ripples. The dimensions of the circles are varied proportionally to the relative Chebyshev amplitudes of a 10-element PBG array, and the dispersion characteristics are analyzed. It is seen that the Chebyshev distribution of the circular-patterned PBG line produces excellent performance by suppressing ripples and yielding better selectivity at cut-offs.