Terahertz Antenna Research Articles

Plasmonic antennas based on rectangular graphene nanoribbons with controlled polarization of terahertz and infrared radiation

Background. To develop new terahertz wireless communication systems with high throughput and transmission speeds, such as 6G and above, effective control of the polarization direction of emitted terahertz waves is necessary, but most methods are technologically complex and expensive. The implementation of terahertz antennas and devices based on 2D materials such as graphene solves the problem associated with developing effective control. Aim. Study of the possibility of controlling the polarization of terahertz and IR radiation of plasmonic antennas based on rectangular graphene nanoribbons by changing the chemical potential (application of an external electric field). Methods. This important scientific problem related to the design of terahertz antennas can largely be solved by simulation using the electrodynamic simulation program CST MWS 2023. Results. Plasmon terahertz antennas based on rectangular graphene nanoribbons were chosen as the object of analysis and the possibility of emitting waves of two orthogonal polarizations was shown. Methods have been identified for controlling the polarization of terahertz and IR radiation from such antennas, based on the selection of operating frequencies corresponding to the resonances of the modes of surface plasmon-polaritons, and the application of metallization to the dielectric substrate. Conclusion. The ability to control the polarization of terahertz and IR radiation makes it possible to create both new elements of plasmonic antenna arrays and new communication technologies, including future 6G networks.

CPW fed optically transparent ultrawideband fractal MIMO terahertz antenna with meshed ground plane

Abstract An optically transparent UWB antenna element and its two-element pattern diversity MIMO configurations are presented in this paper. Three iterations of the quarter elliptical coplanar waveguide ground plane, rectangular microstrip feedline, and octagonal annular rings make up the antenna element. By metal meshing the ground planes and loading the radiator with several octagonal slots, the optical transparency is improved. It has a maximal achieved gain of 6.78 dBi and operates with steady radiation characteristics over the frequency spectrum of 4.52–28.64 THz (145.48%). The dimensions of the antenna element are 18 × 20.5 μm2. A metallic stub is positioned between two identical antenna components that are positioned orthogonally to one another to create a two-element pattern diversity MIMO antenna arrangement. The MIMO antenna is 20.5 × 42.5 μm2 in total. Its impedance bandwidth is 23.72 THz for port 2 and 22.68 THz for port 1. Using a rectangular stub results in an intraport isolation of >19 dB. Between the two ports, the planes in the radiation patterns have switched places. The diversity performance characteristics, which are considerably below the permissible limitations, are as follows: ECC > 0.01, CCL < 0.3 b/s/Hz, DG ∼ 10, TARC < 0 dB, MEG ∼ −3 dB, and 1≤VSWR_MIMO≤2. Compared to previously published structures, the suggested antenna structures have the advantages of smaller dimensions, a larger bandwidth, and improved optical transparency.

Generation and tuning of notched bands in wideband THz antennas using graphene/metal strips

Abstract A technique is implemented for obtaining tunable band notch/filtering features in terahertz (THz) monopole wideband antennas. A parasitic metal strip is engraved in the antenna radiator, which creates the band notch characteristics in the wideband response. The tunability of the created notched band can be obtained by engraving a non-resonant U-shaped graphene strip in the radiator. The change in the material properties of the graphene strip alters the nature of field confinement in the antenna structure, enabling tunability in the filtering frequency band. Moreover, multiple notch bands can be obtained by carefully selecting the material of the parasitic element U-shaped graphene strip. Thus, the antenna response can be configured for dual- and triple- band filtering operation by varying the materials used for the strips to obtain band notch operation and a U-shaped graphene sheet.

Rapid terahertz beam profiling and antenna characterization with phase-shifting holography

In this paper we investigate the application of phase-shifting digital holography for the real-time characterization of electromagnetic sources in the THz frequency range. We use an off-the-shelf terahertz detector array composed of 64×64\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$64 \ imes 64$$\\end{document} power-sensitive pixels, over an area of 96mm×96mm\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$96\\,\\hbox {mm} \ imes 96\\,\\hbox {mm}$$\\end{document}, to record intensity interferograms cast between the coherent radiation emitted from a reference source and an unknown antenna under test. This approach parallelizes the acquisition process with respect to conventional near-field point scanning methods, reducing the measurement time by orders of magnitude. In our system, the measurement time is limited only by the refresh rate of the detector array and the speed of a delay line stage that is used to phase-shift the reference wave. As a proof-of-principle demonstration, we map the 2D near-field distribution and estimate the far-field radiation pattern emitted by a plano-convex PTFE spherical lens antenna illuminated by a diagonal horn at 290 GHz frequency with ∼1Hz\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sim \\,1\\,\\hbox {Hz}$$\\end{document} refresh rate.

THz band drone communications with practical antennas: Performance under realistic mobility and misalignment scenarios

For 6G non-terrestrial communications, drones will offer uninterrupted connectivity for surveillance, sensing, and localization. They will also serve as drone base stations to support terrestrial base stations, providing large bandwidth, high-rate, and ultra-reliable low latency services. In this paper, for the first time in the literature, we depict the true performance of Terahertz (THz) band communications among drones by applying various channel selection and power allocation schemes with practical THz antennas within (0.75–4.4) THz under realistic mobility and misalignment scenarios. Through numerical simulations, we unveil the capacity of drone links under different channel selection and power allocation schemes within 10s to 100s of Gbps at distances (1–100) m, when drones are in motion and subject to (mis)alignment due to mobility and even under beam misalignment fading. However, when exposed to real drone mobility traces, the performance of all channel selection schemes drops significantly, sometimes by up to six orders of magnitude, due to the occasional reverse orientations of antennas. In addition to the capacity analysis, we report available frequency bands (transmission windows) considering all schemes and mobility patterns. We also identify a band that is commonly available under all considered mobility and misalignment settings, and we evaluate its performance in terms of spectral and energy efficiencies, which can be useful in designing THz transceivers for drone communications. Our findings emphasize the essence of active beam control solutions to achieve the desired capacity potential of THz drone communications, while also highlighting the challenges of utilizing the THz band for drone communications.

The smart enhancement of near field sensing range for terahertz antenna in 6G wireless communication systems

The smart enhancement of near field sensing range for terahertz antenna in 6G wireless communication systems

A defected ground structure based ultra-compact wider bandwidth terahertz multiple-input multiple-output antenna for emerging communication systems

This work presents a quad-port Multiple Input Multiple Output (MIMO) wideband antenna that operates in the terahertz (THz) frequency range is designed and analyzed. To improve MIMO performance, a defective ground structure (DGS) is used. A rectangular metallic patch was altered by adding parasitic elements to the radiator with the lowered ground plane on a polyamide substrate in order to achieve the wideband THz operating frequency. The THz antenna was turned into a MIMO antenna by replicating horizontally and vertically with a spacing of 0.05 λ and 0.002 λ, respectively (λ calculated at 1.7 THz). The designed THz MIMO antenna, comprising 40 μm × 46 μm × 2 μm, operates across the 1.7–10.4 THz frequency region. The THz MIMO antenna provides isolation of more than 20 dB in the frequency range of 2.8–10.4 THz and more than 10 dB for the frequency of 1.7–2.7 THz. Isolation augmentation is accomplished by establishing different local current channels using the antenna's DGS. The MIMO diversity properties of the proposed THz MIMO antenna are analyzed and found to be ECC<0.004, DG ~ 10 dB, TARC < −10 dB, MEG < −3 dB, and CCL<0.23 bps/Hz over the antenna's operating frequency.

GA optimized novel design and analysis of graphene-based antennas for THz spectroscopic security applications

The proposed research paper introduces a novel design of THz graphene-based antennas capable of countering terrorism by detecting explosive materials and drugs. The research work is subdivided into three distinct sections; the initial research entails conducting a comparative analysis of conventional and genetic algorithm-based optimised designs of terahertz antennas utilising graphene material. Subsequently, three supplementary designs are evaluated in comparison to the optimum design: one integrating a copper ground with a graphene patch, another integrating a copper patch with a graphene ground, and a third incorporating both a copper patch and ground. All four optimised designs, each resonating at a frequency of 5.6 THz, are used to detect explosive compounds like Trinitrotoluene (TNT). The optimised graphene-based antenna outshines the rest of the designs in terms of radiation efficiency, with a value of 90.03 %. It also exhibits superior performance regarding S11 parameters, with a value of −53.38 dB, and VSWR, with a value of 1.004, at the resonant frequency. The optimised antenna demonstrates superior performance concerning gain (dB) and directivity (dBi), measuring 6.56 dB and 7.02 dBi, respectively. During the final phase of the proposed research, a graphene antenna was modified to function as a tri-band antenna by incorporating a 180° mirrored f-shaped slot within the antenna’s patch. The tri-band antenna functions at resonant frequencies of 3.37 THz, 4 THz, and 5.2 THz. These frequencies detect explosives and narcotics, notably l-histidine, ammonium nitrate (NH4NO3), and PETN in PE. These resonant frequencies hold the potential to be utilised in future applications of 6G technology worldwide.

Lateral photoconductivity of InAs/GaAs quantum dots for 1.5 μm-wavelength excitation photoconductive terahertz antenna devices

We report lateral photoconductive properties of multilayer-stacked undoped InAs/GaAs quantum dots (QDs) for the application of photoconductive terahertz (THz) antenna devices that operate in a 1.5 μm-telecom-wavelength band. The excitation power-dependent photocurrent showed a high value without saturation under high excitation power for the excitation wavelength of 1460 nm. From the reflection pump-probe signal, a fast photocarrier lifetime was derived. These results, together with the low dark current characteristic, support the applicability of the multilayer-stacked undoped InAs/GaAs QDs to photoconductive THz antennas operating in a 1.5 μm-wavelength band.

Broadband complementary ring-resonator based terahertz antenna for 6G application

Broadband complementary ring-resonator based terahertz antenna for 6G application

3D Terahertz Antenna Measurement: A comparison between solid-state electronics and photomixing approaches

3D Terahertz Antenna Measurement: A comparison between solid-state electronics and photomixing approaches

Design and review of terahertz antennas

Design and review of terahertz antennas

A novel tree-slotted metamaterial terahertz antenna to diagnose breast cancer cells

A novel tree-slotted metamaterial terahertz antenna to diagnose breast cancer cells

Innovations and Progress in Terahertz Antenna: A Literature Review

Innovations and Progress in Terahertz Antenna: A Literature Review

A simulation study of dual band THz soft antenna for biomedical applications

The demand for multiband and high-gain THz antennas is escalating due to advancements in terahertz (THz) applications, particularly in biomedical conditions. An innovative fork microstrip antenna design has been introduced, operating at THz frequencies, providing multi-band capability, soft characteristics, and high-gain results. The recommended antenna utilizes a series-fed configuration with dual patch elements constructed on a polyethylene substrate, with a thickness of 0.0224 mm, a loss tangent of 0.001, and a permittivity of 2.25. The proposed antenna, with dimensions of 1 × 0.6 × 0.0224 mm³ in its maximum configuration and operating at 0.530 THz and 0.590 THz, exhibits a 10 dB return loss bandwidth of 13 GHz and 15 GHz, respectively. Notably, the realized antenna gain is simulated at 9.01 dBi and 9.53 dBi for their respective frequencies. To assess the antenna's flexibility, simulations are conducted with the antenna configured in bent positions, considering radii of 7 mm, 6 mm, and 5 mm. Furthermore, the study includes an examination of the specific absorption rate (SAR) to validate the suitability of this pliable antenna. The outcomes underscore the potential of the recommended antenna for flexible biomedical THz applications such as the detection of skin tumours and medical imaging.

A four-port self-multiplexing tunable graphene based dielectric resonator antenna with defective ground structure for high isolation and MIMO capabilities

Objectives and designA novel self-multiplexing terahertz antenna with four tunable ports is proposed in this work. The configuration comprises four rectangular dielectric resonators (DRs) affixed to a substrate, which are excited through L-shaped microstrip-fed slots positioned beneath them. To guarantee efficient isolation among the tunable antenna components, periodic unit cells are introduced into the ground plane, forming a defective ground structure (DGS). Each L-shaped slot element is equipped with a graphene strip to regulate the tunability of each DR element. Results and applicationsThis antenna can operate in various modes with resonant frequencies at 4.01, 4.23, 4.37, and 4.57 THz. It holds potential for future terahertz wireless applications that require the utilization of adjacent channels with distinct communication frequencies. Furthermore, a four-port antenna design is implemented, offering tunable MIMO capabilities with self-quadruplexing ability. The MIMO parameters, specifically the envelope correlation coefficient (ECC) and diversity gain (DG), have been assessed and found to fall within acceptable limits across the operating frequency bands. Additionally, an equivalent circuit model (ECM) is analysed to shed light on the antenna's working principle and verify the obtained results.

Influences of excitation signals on terahertz antenna radiation characteristics

This work focuses on the influences of excitation signals on the radiation characteristics (directivity, bandwidth, and gain) of electronics-based antennas by utilizing the CST Studio Suite software. Today, terahertz (THz) waves have attracted intense attention due to their significant advantages: high penetration, low quantum energy, high-frequency bandwidth, spectral fingerprints, and transients, etc. As a type of THz radiation source and a core element of communication systems, THz antennas have essential application value. However, there are challenges for THz antenna technology, such as low radiation efficiency, high fabrication difficulty, high cost, and complex tests. Previous studies have achieved expected radiation performance for electronics-based THz antennas, mainly by changing the materials and the structure. As passive devices, antennas require excitation signals to operate, which may affect the radiation characteristics. This work takes the THz dipole antenna as the primary example to study the influences, while patch and horn THz antennas are built as auxiliary examples. The research results demonstrate that different excitation signals have significant influences on the antenna’s radiation characteristics (bandwidth and gain). This work can thus help to achieve the desired antenna radiation goals to improve the controllability and practicality of antennas, making antennas suitable for various application scenarios and requirements.

Graphene–metal hybrid based reconfigurable wideband terahertz antenna with improved far-field characteristics

Graphene–metal hybrid based reconfigurable wideband terahertz antenna with improved far-field characteristics

Terahertz Antenna Impedance Matched to a Graphene Photodetector

Terahertz Antenna Impedance Matched to a Graphene Photodetector

Design and Modeling of a Terahertz Transceiver for Intra- and Inter-Chip Communications in Wireless Network-on-Chip Architectures.

This paper addresses the increasing demand for computing power and the challenges associated with adding more core units to a computer processor. It explores the utilization of System-on-Chip (SoC) technology, which integrates Terahertz (THz) wave communication capabilities for intra- and inter-chip communication, using the concept of Wireless Network-on-Chips (WNoCs). Various types of network topologies are discussed, along with the disadvantages of wired networks. We explore the idea of applying wireless connections among cores and across the chip. Additionally, we describe the WNoC architecture, the flip-chip package, and the THz antenna. Electromagnetic fields are analyzed using a full-wave simulation software, Ansys High Frequency Structure Simulator (HFSS). The simulation is conducted with dipole and zigzag antennas communicating within the chip at resonant frequencies of 446 GHz and 462.5 GHz, with transmission coefficients of around -28 dB and -33 to -41 dB, respectively. Transmission coefficient characterization, path loss analysis, a study of electric field distribution, and a basic link budget for transmission are provided. Furthermore, the feasibility of calculated transmission power is validated in cases of high insertion loss, ensuring that the achieved energy expenditure is less than 1 pJ/bit. Finally, employing a similar setup, we study intra-chip communication using the same antennas. Simulation results indicate that the zigzag antenna exhibits a higher electric field magnitude compared with the dipole antenna across the simulated chip structure. We conclude that transmission occurs through reflection from the ground plane of a printed circuit board (PCB), as evidenced by the electric field distribution.