Investigating the effects of graphene-based superstrate on characteristic of microwave filters

Abstract

This paper presents a study based on changes in the cut-off frequency and sharpness of different types of filter by loading with glass and graphene–glass superstrate. Design and fabrication of four basic types of microwave filter – low-pass, high-pass, band pass, and band stop filter are presented and S-parameters are measured with superstrate. The impact of superstrate on the filter characteristics such as cut-off frequency, bandwidth, and sharpness are analyzed experimentally by comparing these characteristics for without superstrate and with superstrate. The superstrate loading resulted in the decrease of cut-off frequency for low-pass and high-pass filter, whereas the bandwidth is decreased for band pass filter and band stop filter with larger shift in high cut-off frequency. Such effects have been confirmed by the simulation of low-pass filter and band pass filter on placing a glass. It is estimated from the filter responses that graphene–glass has conducting as well as dielectric nature compared to glass in the frequency range of study. It has been shown that the cut-off frequency and bandwidth can be tuned by dielectric kind of superstrate without varying the physical dimension of filter.