The Study Of Electromanetic Band-Gap Materials And It's Using In Microwave Filters

Although EBG(Elctromagnetic Band Gap) structures were brought forward in the field of optics, however it is difficult to fabricate PBG in the frequency band of lignt-wave, therefore EBG is expanded to a wide range of frequency by size zooming, even the bands of millimeter wave and microwave. While typical EBG structures are periodic hole arrays of subduple wave length. To bring down the size of EBG, we have no choice but to adopt the high dielectric coefficient materials, the medium loss will inevitably arise. Many attempts to reduce the physical size of EBG have been reported in the literature. One such method is to develop UC-EBG(Uniplanar Compact Electromagnetic Band Gap Structures, this structure can bring down the length of EBG cell to one third of wavelength.The main feature of the paper is to design a new type of UC-EBG cell, which can bring down the cell size to one sixth of wavelength. Another feature of this kind of UC-EBG cell is that it can be used alone.The EBG structures can be combined with general microwave filters to improve the performance of the filters. The work of the paper indicates that EBG can improve the attenuation slope of the stopband in the lowpass filters effectively and hold back the parasitic passband of the lowpass filters and bandpass filters.