In this work, a subharmonic frequency mixer for millimeter wave applications has been designed. The mixing and multiplication phenomena are simultaneously achieved via a nonlinear component consisting in a microstrip line gap covered by a graphene film coating. The circuit structure is made up of various filters, which have been optimized to ensure high port-to-port isolation. The nonlinear behavior of the subharmonic frequency mixer has been experimentally evaluated within the 39-40.5 GHz RF frequency band. The frequency downconversion is achieved by mixing the RF signal with the second harmonic component of a 17.9 GHz LO signal. Conversion losses are minimized by generating a return path for IF, through the use of a quarter wavelength open-ended stub.
In this work, the nonlinear electromagnetic response of a few-layer graphene sheet is experimentally analyzed. The few-layer graphene sheet is obtained through mechanical exfoliation from highly ordered pyrolytic graphite and embedded in a rectangular waveguide structure which is used to guide the exciting and the output signals. The nonlinear electromagnetic response of the graphene sheet is exploited to implement a frequency multiplier in which the output signal, in the 330-500 GHz frequency band, will be obtained as a high-order harmonic component of the input signal, in the 26-40 GHz frequency band. Due to the particular selection of the input and output frequency ranges, the behavior of several harmonic components, from order 9 to 17, can be characterized. The analysis will be focused on the frequency response of the graphene sheet, the influence of the input power on the output signal and the differences between the even-and odd-order harmonic components. Finally, it will be shown that the developed assembly can be used as THz signal source based on high-order frequency multiplication.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.