Novel H-Shape Element for the Sandwich Photonic Bandgap Structure

Yunbo PANG  Baoxin GAO  Zhenghe FENG  

IEICE TRANSACTIONS on Electronics   Vol.E86-C   No.8   pp.1704-1708
Publication Date: 2003/08/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Microwave and Millimeter Wave Technology)
photonic bandgap,  microstrip,  finite difference time domain method,  

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A novel periodic element for the sandwich photonic bandgap (PBG) structure named as H-shape element is presented in this paper. Sandwich PBG structure is a kind of PBG structure whose periodic lattice is buried in the midmost of the substrate. There's no requirement to drill or suspend the substrate. The new H-shape element is made of a central block connected with a long and narrow block on either side, and possesses a quite deep forbidden gap, whose width and depth can be tuned by varying the dimension of the central block. Theoretical results, as confirmed experimentally, indicate that the maximum insertion loss in the stopband is up to 80 dB. This sandwich microstrip structure can be constructed using conventional printed-circuit-board fabrication processes and integrated with other microwave components in a multilayered circuit. An improved notch filter with chirped central blocks is presented. The length of the filter is reduced by 16.7%, and the fractional bandwidth is increased by 8.1% compared with that of a conventional sandwich microstrip notch filter on the same substrate. The experimental results agree well with the finite difference time domain (FDTD) simulations.