Miniaturization Design Of EBG And Its Equivalent Circuit Analysis

The left-handed material is a kind of material with negative dielectric constant and permeability,because of its singular electromagnetic characteristics,such as reversed Doppler Effect,reversed Snell refraction effect and reversed Cherenkov effect and so on,receviving widespread attention,it gradually becomes the focus of the international research.But the fabrication of left-handed materials is not easy,The commonly used method is to load periodical lumped L-C elements in the transmission line.According to the periodic structure of Caloz model,parasitic capacitance and inductance exist in left-handed materials,and the transmission line itself has the right hand capacitor and the right hand inductance,Therefore,Itoh et al proposed a composite left and right handed transmission line model for metamaterials.This research is based on the traditional mushroom EBG.Because it has the characteristics of the left-handed material,it can be analyzed by the composite left-right handed transmission line theory.As the size in X and Ydirections of the well shaped EBG is different.it presents different electromagnetic characteristics for the X and Y polarized waves.Combined with the composite right and left transmission line theory,the scattering characteristics of EBG periodical arranged in Y direction under X and Y polarized waves are analyzed.By parametric research,the change of the center frequency of the scattering parameter under X and Y polarized waves working in X band are analyzed from the principle of equivalent circuit.The miniaturized EBG cell structure has always been the research hotspots.This paper proposes a novel EBG structure that is analyzed by the principle of LC equivalent circuit and the composite left-right handed transmission line theory,its lumped parameter inductance and capacitance increases,and then the resonant frequency is reduced.Compared with the rectangular patch EBG,the double slotted EBG along X direction,the frequency of the zero reflected phase under X,Y polarization are reduced by 1.41 GHz,3.34GHz;1.81 GHz,2.52 GHz.When working at the same frequency point compared with the rectangular patch EBG,the unit's size can be reduced by 1.4 times.Considering the checkerboard array,the slot size of the proposed EBG cell structure is optimized to obtain the wider bandwidth in the effective band.And the optimized parameters are reduced by 1.4 times compared with the rectangular patch EBG,the double slotted EBG in X direction under the same working frequency band.Our computational anlysis shows that the proposed EBG has a center frequency of 9.2GHz and a bandwidth of 8.6GHz-10.2GHz,an effective bandwidth of 17.4%;The center frequency of the rectangular patch EBG is 9.3GHz,a bandwidth of 8.2GHz-10.7GHz,an effective bandwidth of 26.8%;the center frequency of the double slotted EBG in X direction is 9.9GHz,a bandwidth of9.1GHz-11.3GHz,an effective bandwidth is 22.2%.The effective bandwidth is reduced by 9.6% and 4.8% respectively.