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This article provides a comprehensive analysis of low-profile, frequency-reconfigurable graphene dipole antennas for THz applications. The antenna consists of two graphene patches to form the bow-tie dipole and the wideband artificial magnetic conductor (AMC). Frequency tuning has been introduced by changing the chemical potential of graphene. The AMC has been designed to operate from 2 to 3.4 THz with a ± 90° reflection phase bandwidth of 50.39%. Using AMC surface, the total profile of the antenna has been achieved up to 0.09λ0 (where λ0 is free space wavelength) at the 0° operating frequency of 2.5 THz. In another approach, a hybrid surface combination of AMC and PEC has been used instead of AMC surface to enhance the radiation performance by reducing unwanted current distribution. The input impedance of the proposed antennas is almost stable and well-matched to the impedance of the THz source. [ABSTRACT FROM AUTHOR]

This paper proposes a graphene patch antenna for dual-band operation while maintaining a low profile. The antenna consists of the metasurface-based 4 x 4 AMC configuration and the square graphene patch driven through the aperture coupling. The fundamental TM 10 mode of graphene patch excites the first resonance frequency, while the TM 10 and antiphase TM 20 modes of metasurface simultaneously excite the second wide frequency band. The first resonance frequency excited by the graphene patch can be reconfigured by varying the external DC bias voltage on the graphene patch. An equivalent circuit of antenna using lumped elements has also been proposed using a vector fitting algorithm. The proposed antenna with a profile height of 0. 12 λ 0 (where λ 0 is free space wavelength) at a center frequency of 1.14 THz achieves the gain from 7.06 dB to 10.4 dB in the first band and an average gain of 10 dB in the second band. [ABSTRACT FROM AUTHOR]

This paper proposes a frequency reconfigurable dielectric lens antenna (DLA) to compensate high attenuation due to atmospheric losses in the THz region. An aperture coupled graphene plasmonic nanoantenna has been designed and used to feed DLA. Frequency tuning has been introduced by varying the chemical potential of graphene. A lumped elements equivalent circuit for graphene-based feed antenna has also been proposed. The values of the lumped elements are obtained using the vector fitting algorithm. The proposed DLA has high gain, narrow beamwidth, broadside radiation pattern and stable input impedance. Directivity achieved through simulation is up to 7.3 dBi with radiation efficiency of 70 % and 21.2 dBi with radiation efficiency of 65 % for feed antenna and DLA respectively. The performance of DLA has also been studied as the function of feed element, relative permittivity of lens material, radius of lens and off-axis displacement tolerances. [ABSTRACT FROM AUTHOR]