Integration of Antenna Array and Self-Switching Graphene Diode for Detection at 28 GHz

Zaccagnini

Palmara

et al. 2021

Self Cite

Carbon based materials exhibit interesting mechanical, thermal and electrical properties which make them excellent contenders for use as fillers in composites as film. Graphene has been vastly used among the carbon-based materials. More recently eco-friendly carbon-based materials like biochar have emerged. The deployment of carbon-based materials in films needs to be studied since films are more versatile and permit the exploitation of electrical properties of such materials over circuits and systems. Typical circuits and systems exploiting electrical properties of novel materials perform a number of applications including sensing, detection, tunable devices and energy harvesting. In this paper, films composed of 9:1 graphene or biochar are deployed on a microstrip line. The morphological properties of graphene and biochar and their respective films are studied with Raman spectra and Field Emission Scanning Electron Microscope (FESEM). The electrical properties (four-point probe measurements and scattering parameter measurements) of the films. Low frequency measurements are used as starting point for circuit models estimating the lumped impedance of the films. From the morphological characterization it is shown that biochar films appear as granulates carbonaceous materials whereas graphene films contains several flakes forming a network. From the low frequency measurements and microwave characterization it is seen that graphene films are more conductive as compared to biochar films. In many applications, it is useful to know the surface impedance of the film since it varies on interaction with any external stimulus (variation of pressure, humidity, gas, etc.)

Section: Discussionmentioning

confidence: 99%

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

Zaccagnini

Palmara

et al. 2021

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“…This is an important parameter in the determination of the resistance R = Rg AR. The value of the resistance, R can also be calculated from the ratio of the applied bias voltage and the current drawn by graphene [19]. In order to evaluate the impact of the aspect ratio on the transmission properties of the phase shifter, full-wave simulations are performed with different values of the aspect ratio ranging from 0.2 to 0.8 at a frequency of 4 GHz.…”

Section: Full-wave Simulationsmentioning

confidence: 99%

“…Graphene has remarkable electrical, mechanical and thermal properties. Due to the remarkable properties of graphene, it has found inwards into several applications including electrochemical sensors [8,9], biosensors [10,11], gas sensors [12][13][14], humidity and temperature monitoring [15][16][17], absorbing materials [18], passive [19][20][21] and active devices [22,23]. The electrical properties of graphene vary with frequency.…”

Section: Introductionmentioning

confidence: 99%

Dynamically Tunable Phase Shifter with Commercial Graphene Nanoplatelets

Savi

2020

Micromachines

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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.

“…The tunable conductivity of graphene is valid for multi-layered graphene [6]. Carbon materials including multi-layered graphene are deployed in a number of microwave applications including, antennas [7][8][9], phase shifters [10] and attenuators [6,[11][12][13]. For tuning applications, dropcasting multi-layered graphene is the most convenient since it is the least complicated and the most cost-effective [6].…”

mentioning

confidence: 99%

Commercial graphene nanoplatelets‐based tunable attenuator

Savi

2020

Electron. lett.

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A commercial graphene nanoplatelets-based tunable attenuator is proposed. The attenuator comprises of a couple of microstrip lines connected through a gap where the commercial graphene nanoplatelets are drop casted. The transmitted signal through the microstrip line can be varied by an applied DC bias voltage that alters the graphene resistance. The DC resistance of commercially acquired graphene is higher than lab-grown graphene and so is the resulting minimum attenuation of the transmitted signal. The proposed structure is designed to reduce both the minimum graphene resistance and the transmission. The resultant dynamic range of attenuation is more than twice as compared to other series attenuators designed with lab grown graphene nanoplatelets. The operating frequency of the attenuator is from 1 to 5 GHz with maximum dynamic range of attenuation almost 10 dB.