Interdigital Based EBG: Compact and Polarization Stable for MBAN and Wi-Fi

Abstract

This paper introduces a new method to design interdigital based EBG structure of very compact size at low frequencies such as MBAN and Wi-Fi. The proposed design utilizes interdigital electrodes (IDE) to miniaturize the conventional mushroom EBG cell by increasing the inductance of the unit cell. The technique presented in this paper miniaturizes the EBG cell size by 55% w.r.t standard cell while demonstrating a band gap from 2.32 - 2.85 GHz. Furthermore, equivalent lumped model of the proposed EBG cell has been developed for a y-polarized EM wave that complies with the frequency of interest. The polarization stability of the EBG cell for any x- or y-polarized EM wave has been demonstrated by a unique method utilizing the transmission characteristic in this work. In addition band gap property of the EBG cell has been validated on an array prototype of 8x7 unit cells. Subsequently planar microstrip antenna incorporating the proposed EBG cells enhances the gain, efficiency and reduces side lobe level by 2 dB, 20%, and - 7 dB respectively w.r.t reference antenna. The prototypes shows good results in terms of return loss.