Dynamically Tunable Phase Shifter with Commercial Graphene Nanoplatelets

Abstract

In microwave frequency band the conductivity of graphene can be varied to design a number of tunable components. A tunable phase shifter based on commercial graphene nanoplatelets is introduced. The proposed configuration consists of a microstrip line with two stubs connected with a taper. On each side of the stubs there is a gap, short circuited through a via, where the commercial graphene nanoplatelets are drop casted. By applying a DC bias voltage that alters the graphene resistance the phase of the transmitted signal through the microstrip line can be varied. In order to maximize the phase shift of the transmitted signal and minimize the insertion loss, the length of the taper and the stubs are optimized by the help of circuit model and full-wave simulations. A prototype working at 4GHz is fabricated and measured. A phase variation of 33 degrees is acquired with an amplitude variation of less than 0.4 dB.

Morphological Characterization and Lumped Element Model of Graphene and Biochar Thick Films

“…The graphene nanoplatelets (see Figure 6a) shows that they are flaky and two dimensional. Seen with a higher magnification (see Figure 6b), They exhibit transparency, which shows that they are thin and hence composed of a few graphene layers [31]. The FESEM analysis of biochar used as filler in the films is shown in Figure 7.…”

Extended Single-Sideband Light Intensity Modulation Formats

“…The development of such phase shifters is a long-standing and not an easy problem in microwave electronics. Discussion of possible approaches appeared in the literature only recently and has aroused great interest [4][5][6][7][8].…”

“…Due to dispersion, each spectral component of an electromagnetic wave (2) acquires phase incursion at the exit from an optical fiber with length L. So, for a component with frequency it makes where is the frequency propagation constant of carrier wave , coefficient is equal to the reciprocal of the group velocity of the signal and coefficient was determined through dispersion coefficient D of the fiber as [9]. As a result, at the exit from the fiber, we have an electromagnetic wave in form (6) where (7) is the parameter of transporting the optical signal along the fiber.…”

Amplitude-Phase Variation in a Graphene-Based Microstrip Line

“…Several attempts have been made to exploit the variable conductivity for designing tunable microwave components. Attenuators, phase shifters and antennas based on graphene have been proposed in a number of works [6][7][8][9][10][11]. In all of the cases, either the amplitude or the phase was varied, exploiting the tunable conductive behavior of graphene.…”

“…In all of the cases, either the amplitude or the phase was varied, exploiting the tunable conductive behavior of graphene. In the final version of the phase shifter in [ 11 ], the number of stubs were increased in order to maximize the phase variation in a graphene-loaded microstrip line. However, it has been noted that the variation of both the amplitude and phase is important to the microwave community for many applications.…”