Related Experiment Video
Updated: Aug 3, 2025
11:42
Fabrication of Gate-tunable Graphene Devices for Scanning Tunneling Microscopy Studies with Coulomb Impurities
Published on: July 24, 2015
15.6K
Reconfigurable Single-Layer Graphene Radio Frequency Antenna Device Capable of Changing Resonant Frequency
Hyeon Jun Hwang1, So-Young Kim1, Sang Kyung Lee2
1Center for Semiconductor Technology Convergence, Department of Electrical Engineering, Pohang University of Science and Technology, Cheongam-ro 77, Nam-gu, Pohang 37673, Gyeongbuk, Republic of Korea.
Nanomaterials (Basel, Switzerland)
|April 13, 2023
Summary
Researchers developed a reconfigurable graphene antenna. By adjusting the Fermi level with an electric field, they achieved a 6% resonant frequency shift, simplifying device design for tunable radio frequency applications.
Area of Science:
- Electrical Engineering
- Materials Science
- Condensed Matter Physics
Background:
- Traditional antennas often lack tunability, limiting their application in dynamic communication systems.
- Graphene's unique electronic properties offer potential for novel reconfigurable electronic devices.
Purpose of the Study:
- To investigate a reconfigurable passive device capable of manipulating resonant frequency.
- To explore the use of graphene's quantum capacitance for frequency tuning without complex equipment.
Main Methods:
- Experimentally investigated a passive graphene device.
- Modified the Fermi level of large-area graphene using an external electric field.
- Controlled quantum capacitance to alter resonant frequency.
Main Results:
- Achieved a 6% shift in resonant frequency by increasing capacitance change to 60%.
- Demonstrated reconfigurable characteristics using only gate bias changes.
- Observed that graphene antenna signal characteristics are inferior to conventional metal antennas.
Conclusions:
- A simplified, reconfigurable passive device using graphene and gate bias is feasible.
- This approach offers a pathway to tunable antennas with reduced structural complexity.
- Further research may improve signal characteristics for practical applications.
Related Concept Videos
01:24Characteristics of Series Resonant Circuit
290
Series resonance occurs in a circuit containing inductive (L), capacitive (C), and resistive (R) elements connected sequentially. At the resonance frequency, the inductive and capacitive reactances are equal in magnitude but opposite in sign, effectively canceling each other. This causes the circuit's impedance is minimal, primarily determined by the resistance R. The resonant frequency of an RLC circuit is defined as:
290
01:23Parallel Resonance
242
The parallel RLC circuit is an arrangement where the resistor (R), inductor (L), and capacitor (C) are all connected to the same nodes and, as a result, share the same voltage across them. The parallel RLC circuit is analyzed in terms of admittance (Y), which reflects the ease with which current can flow. The admittance is given by:
242
01:17Series Resonance
222
The RLC circuit impedance is defined as the ratio of the supply voltage to the circuit current. Resonance in such a circuit occurs when the imaginary part of this impedance equals zero. This specific condition means that the inductive reactance is exactly equal to the capacitive reactance. The frequency at which this happens is known as the resonant frequency. Mathematically, the resonant frequency is inversely proportional to the square root of the product of the inductance (L) and capacitance...
222
01:26Resonance in an AC Circuit
2.1K
The property of an inductor makes it resist any change in the current passing through it, while the property of a capacitor is to build up the charge across its terminals. Hence, if an inductor and capacitor are connected in series, they have opposite effects on the relative phase between current and voltage. The current through the circuit undergoes forced oscillation at the frequency of the source. The resistance term in an R-L-C circuit acts as a damping term because power is dissipated...
2.1K
01:17Design Example: Underdamped Parallel RLC Circuit
349
Consider designing an oscillator circuit, a crucial component in various electronic devices and systems. The objective is to create an oscillator circuit with specific characteristics: a damped natural frequency of 4 kHz and a damping factor of 4 radians per second. To accomplish this, a parallel RLC circuit is employed, known for its ability to sustain oscillations at a resonant frequency. In this case, the damping factor is pivotal in achieving the desired performance.
Starting with a fixed...
Starting with a fixed...
349
01:24Frequency Response of BJT
925
The frequency response of a Bipolar Junction Transistor (BJT) in a common-emitter configuration is critical to its functionality, especially in applications involving amplification of alternating current (AC) signals. This response can be analyzed through low-frequency and high-frequency equivalent circuits, considering various internal parameters and external conditions.
Low-Frequency Response: At low frequencies, the behavior of the BJT is determined by its DC bias point, which is set by the...
Low-Frequency Response: At low frequencies, the behavior of the BJT is determined by its DC bias point, which is set by the...
925