Phase properties of chebysheb distributed electromagnetic Bandgap Structures (EBGSs) for phased arrays

Non-uniform EBGS improves the lowpass filter properties in terms of ripples in the passband, wider stopband, sharp cut-off and minimum return loss (RL). The phase properties of the non-uniform EBGS is an unaddressed issue in the open microwave literature. In this paper we have investigated an ideal microstrip transmission and EBGS assisted microstrip transmission lines. The non-uniformity of the amplitudes of EBG elements are calculated on the basis of the Chebyshev distribution. The S-parameter performances of uniform and non-uniform circular patterned EBGSs have been reported. Finally the phase properties of an ideal microstrip transmission line and lines having perturbation in the ground plane with uniform and non-uniform circular EBGSs are reported. It can be seen that non-uniform EBGS not only improves the S-parameter performance but also provides more transmission phase. Therefore non-uniform EBGSs have the superiority over the uniform EBGS in realizing phased arrays with more beam squinting capabilities.