Q-factor and efficiency of carbon nanotube antennas

Majeed, Farhat; Shahpari, Morteza; Thiel, David V.

doi:10.1109/iceaa.2016.7731526

Cited by 4 publications

(4 citation statements)

References 14 publications

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“…This indicates that for CN dipoles resonating in the frequency range 43‐53GHz, higher feed line impedance Z 0 = 40 kΩ is required for improved matching. Note that the resonances of L = 1 and 10 μm CN dipoles are not included in the figure, but linearity of their resonance modes and non‐linearity of effective wavelength scaling (λ / λ eff ) are reported in section 3.3 and onwards.…”

Section: Resultsmentioning

confidence: 99%

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Pole-zero analysis and wavelength scaling of carbon nanotube antennas

Majeed

Shahpari

Thiel

2017

Int J RF Microw Comput Aided Eng

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Carbon nanotube (CN) antennas have applications in the THz electromagnetic spectrum. Nanotubes have a highly dispersive and frequency dependent conductivity model. In this article, we compare the poles and zeros in the input impedance of CN antennas at different lengths. We used model-based parameter estimation to approximate the input impedance of the antenna with a rational function in the complex frequency domain. Despite dispersive conductivity of CN, the imaginary part of the poles and zeros are respectively the integer multiples and odd multiples of the imaginary part of the first pole and zero. However, the real part of poles is almost constant, while the pattern was not observed for the real part of zeros. We also show that CN dipoles operating between 43 and 53 GHz are well matched if the source impedance is much higher than 50 ohms, and even higher than 12.9 kX. The fundamental resonances (f 0 ) of CN dipoles plotted versus their inverse-half-length (1/L) are linearly related, but the intercept of the fitted straight line is non-zero unlike that for perfect electric conductor (PEC) dipoles. This leads to non-linear variation in wavelength scaling of CN dipoles. The resonant CN antennas are relatively much shorter than PEC dipoles. K E Y W O R D S carbon nanotube, model-based parameter estimation, wavelength scaling Int J RF Microw Comput Aided Eng. 2017;27:e21103.

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Section: Resultsmentioning

confidence: 99%

“…The 4GB RAM memory was sufficient for running these simulations. However, the computational time was almost 48 hours for efficiency calculations of a CN dipole with 41200 mesh elements for 22 discrete frequency points over the frequency range 15‐1000 GHz, and the RAM requirement for running the simulation was greater than 20GB …”

Section: Introductionmentioning

confidence: 99%

Pole-zero analysis and wavelength scaling of carbon nanotube antennas

Majeed

Shahpari

Thiel

2017

Int J RF Microw Comput Aided Eng

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“…It has been used in the synthesis of various active devices including field effect transistors and modulators operating at 10‐20 KHz . It has also found application in nano‐antennas for communication in THz band either as a 2D or 1D material . Graphene placed close to metallic nano‐antennas can be used to modify their resonant frequency, radiation efficiency and radiation pattern .…”

Section: Introductionmentioning

confidence: 99%

“…3 It has also found application in nanoantennas for communication in THz band either as a 2D 4 or 1D material. 5,6 Graphene placed close to metallic nanoantennas can be used to modify their resonant frequency, radiation efficiency and radiation pattern. 7 A noncontact characterization of graphene surface impedance at micro and millimeter waves was presented by placing the monolayer graphene sample on a substrate consisting of quartz and foam in the cross sections of rectangular waveguides WR 28 and WR 90, respectively.…”

Section: Introductionmentioning

confidence: 99%

Measurement of surface conductivity of graphene at W‐band

Majeed

Fickenscher

Shahpari

et al. 2019

Micro & Optical Tech Letters

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Graphene has excellent mechanical and conducting properties. Scattering parameter measurements were made in W‐band (75‐110 GHz) on 25 mm × 25 mm monolayer graphene film printed on polyethylene terephthalate (PET) substrate. From near field measurements using WR10 horn antennas the surface conductivity was de‐embedded after calibrating the s11 data against the reflection of a copper plate of same cross‐sectional dimensions as the DUT and calibrating the s21 data against horn‐to‐horn measurements. A monolayer graphene strip (20 mm × 2 mm) printed on PET substrate (25 mm × 25 mm) showed higher reflection when it was aligned with the E field of the incident radiation (as compared to H field alignment). The surface conductivity of graphene was de‐embedded from s11 measurements using standard transmission line theory and from s21 measurements using cascade matrix theory. The measured real part of the surface conductivity of graphene ranges between 0.7 and 1.8 mS/sq.

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