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18 pages, 5585 KiB

Open AccessArticle

Analysis of Mouse Blood Serum in the Dynamics of U87 Glioblastoma by Terahertz Spectroscopy and Machine Learning

by Denis Vrazhnov, Anastasia Knyazkova, Maria Konnikova, Oleg Shevelev, Ivan Razumov, Evgeny Zavjalov, Yury Kistenev, Alexander Shkurinov and Olga Cherkasova

Appl. Sci. 2022, 12(20), 10533; https://doi.org/10.3390/app122010533 - 19 Oct 2022

Cited by 5 | Viewed by 1763

Abstract

In this research, an experimental U87 glioblastoma small animal model was studied. The association between glioblastoma stages and the spectral patterns of mouse blood serum measured in the terahertz range was analyzed by terahertz time-domain spectroscopy (THz-TDS) and machine learning. The THz spectra [...] Read more.

In this research, an experimental U87 glioblastoma small animal model was studied. The association between glioblastoma stages and the spectral patterns of mouse blood serum measured in the terahertz range was analyzed by terahertz time-domain spectroscopy (THz-TDS) and machine learning. The THz spectra preprocessing included (i) smoothing using the Savitsky–Golay filter, (ii) outlier removing using isolation forest (IF), and (iii) Z-score normalization. The sequential informative feature-selection approach was developed using a combination of principal component analysis (PCA) and a support vector machine (SVM) model. The predictive data model was created using SVM with a linear kernel. This model was tested using k-fold cross-validation. Achieved prediction accuracy, sensitivity, specificity were over 90%. Also, a relation was established between tumor size and the THz spectral profile of blood serum samples. Thereby, the possibility of detecting glioma stages using blood serum spectral patterns in the terahertz range was demonstrated. Full article

(This article belongs to the Special Issue Applications of Millimeter-Wave and Terahertz Technologies)

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16 pages, 59343 KiB

Open AccessArticle

Atmospheric Propagation Studies and Development of New Instrumentation for Astronomy, Radar, and Telecommunication Applications in the Subterahertz Frequency Range

by Yurii Balega, Gregory Bubnov, Mikhail Glyavin, Aleksandra Gunbina, Dmitry Danilevsky, Grigory Denisov, Andrey Khudchenko, Ilya Lesnov, Andrey Marukhno, Kirill Mineev, Sergey Samsonov, Gennady Shanin and Vyacheslav Vdovin

Appl. Sci. 2022, 12(11), 5670; https://doi.org/10.3390/app12115670 - 2 Jun 2022

Cited by 6 | Viewed by 1955

Abstract

Current progress in the development of new subterahertz instruments discussed in this paper, including antennas, high-power gyrotrons, and low-noise receivers, provides a wide range of possible applications. Atmospheric absorption has now become a major limitation in the application of such high-performance subTHz systems, [...] Read more.

Current progress in the development of new subterahertz instruments discussed in this paper, including antennas, high-power gyrotrons, and low-noise receivers, provides a wide range of possible applications. Atmospheric absorption has now become a major limitation in the application of such high-performance subTHz systems, and the choice of the optimal location of antennas for astronomical, radar, and communication systems is important. The latest results of studying the microwave astroclimate in northern Eurasia are presented. Based on these studies, new perspectives and corrected plans for installing new antennas at the Suffa Plateau and in the Caucasus are formulated, and possible applications of new instruments such as radars for locating space debris and communication hubs for deep space communications, which are based on extremely-high-power gyrotrons and low-noise superconducting receivers, are discussed. Full article

(This article belongs to the Special Issue Applications of Millimeter-Wave and Terahertz Technologies)

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13 pages, 3641 KiB

Open AccessArticle

A THz Passive Image Generation Method Based on Generative Adversarial Networks

by Guan Yang, Chao Li, Xiaojun Liu and Guangyou Fang

Appl. Sci. 2022, 12(4), 1976; https://doi.org/10.3390/app12041976 - 14 Feb 2022

Cited by 3 | Viewed by 1491

Abstract

A terahertz (THz) passive imager with automatic target detection is an effective solution in the field of security inspection. The high-quality training datasets always play a key role in the high-precision target detection applications. However, due to the difficulty of passive image data [...] Read more.

A terahertz (THz) passive imager with automatic target detection is an effective solution in the field of security inspection. The high-quality training datasets always play a key role in the high-precision target detection applications. However, due to the difficulty of passive image data acquisition and the lack of public dataset resources, the high-quality training datasets are often insufficient. The generative adversarial network (GAN) is an effective method for data augmentation. To enrich the dataset with the generated images, it is necessary to ensure that the generated images have high quality, good diversity, and correct category information. In this paper, a GAN-based generation model is proposed to generate terahertz passive images. By applying different residual connection structures in the generator and discriminator, the models have strong feature extracting ability. Additionally, the Wasserstein loss function with gradient penalty is used to maintain training stability. The self-developed 0.2 THz band passive imager is used to carry out imaging experiments, and the imaging results are collected as a dataset to verify the proposed method. Finally, a quality evaluation method suitable for THz passive image generation task is proposed, and classification tests are performed on the generated images. The results show that the proposed method can provide high-quality images as supplementary. Full article

(This article belongs to the Special Issue Applications of Millimeter-Wave and Terahertz Technologies)

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8 pages, 937 KiB

Open AccessArticle

Investigation of THz Absorptive Signatures in Opioids

by Weidong Zhang, Alexei Bykhovski and Elliott R. Brown

Appl. Sci. 2022, 12(1), 61; https://doi.org/10.3390/app12010061 - 22 Dec 2021

Cited by 2 | Viewed by 2294

Abstract

We investigate the possibility of sensing opioid drugs, such as fentanyl, by their THz electromagnetic signatures. The methods include both computer modeling and experiments. Molecular dynamics simulations predict that fentanyl should display THz resonances, with several of them occurring below 1.0 THz; the [...] Read more.

We investigate the possibility of sensing opioid drugs, such as fentanyl, by their THz electromagnetic signatures. The methods include both computer modeling and experiments. Molecular dynamics simulations predict that fentanyl should display THz resonances, with several of them occurring below 1.0 THz; the lowest one is at around 0.337 THz (337 GHz). Spectroscopy measurements were conducted on oxycodone, which was used as a surrogate for fentanyl. They display vibrational absorption resonances between ∼1.4 and 1.6 THz. Full article

(This article belongs to the Special Issue Applications of Millimeter-Wave and Terahertz Technologies)

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17 pages, 10129 KiB

Open AccessArticle

Multiscale Compact Modelling of UTC-Photodiodes Enabling Monolithic Terahertz Communication Systems Design

by Djeber Guendouz, Chhandak Mukherjee, Marina Deng, Magali De Matos, Christophe Caillaud, Hervé Bertin, Antoine Bobin, Nicolas Vaissière, Karim Mekhazni, Franck Mallecot, Akshay M. Arabhavi, Rimjhim Chaudhary, Olivier Ostinelli, Colombo Bolognesi, Patrick Mounaix and Cristell Maneux

Appl. Sci. 2021, 11(23), 11088; https://doi.org/10.3390/app112311088 - 23 Nov 2021

Cited by 2 | Viewed by 2764

Abstract

Due to the continuous increase in data traffic, it is becoming imperative to develop communication systems capable of meeting the throughput requirements. Monolithic Opto-Electronic Integrated Circuits (OEICs) are ideal candidates to meet these demands. With that in mind, we propose a compact and [...] Read more.

Due to the continuous increase in data traffic, it is becoming imperative to develop communication systems capable of meeting the throughput requirements. Monolithic Opto-Electronic Integrated Circuits (OEICs) are ideal candidates to meet these demands. With that in mind, we propose a compact and computationally efficient model for Uni-Traveling Carrier Photodiodes (UTC-PDs) which are a key component of OEICs because of their high bandwidth and RF output power. The developed compact model is compatible with existing SPICE design software, enabling the design of beyond 5G and terahertz (THz) communication circuits and systems. By introducing detailed physical equations describing, in particular, the dark current, the intrinsic series resistance, and the junction capacitance, the model accurately captures the physical characteristics of the UTC-PD. The model parameter extraction follows a scalable extraction methodology derived from that of the bipolar and CMOS technologies. A detailed description of the de-embedding process is presented. Excellent agreement between the compact model and measurements has been achieved, showing model versatility across various technologies and scalability over several geometries. Full article

(This article belongs to the Special Issue Applications of Millimeter-Wave and Terahertz Technologies)

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19 pages, 4171 KiB

Open AccessArticle

A High-Frequency Vibration Error Compensation Method for Terahertz SAR Imaging Based on Short-Time Fourier Transform

by Yinwei Li, Qi Wu, Jiawei Jiang, Xia Ding, Qibin Zheng and Yiming Zhu

Appl. Sci. 2021, 11(22), 10862; https://doi.org/10.3390/app112210862 - 17 Nov 2021

Cited by 1 | Viewed by 1708

Abstract

High-frequency vibration error of a moving radar platform easily introduces a non-negligible phase of periodic modulation in radar echoes and greatly degrades terahertz synthetic aperture radar (THz-SAR) image quality. For solving the problem of THz-SAR image-quality degradation, the paper proposes a multi-component high-frequency [...] Read more.

High-frequency vibration error of a moving radar platform easily introduces a non-negligible phase of periodic modulation in radar echoes and greatly degrades terahertz synthetic aperture radar (THz-SAR) image quality. For solving the problem of THz-SAR image-quality degradation, the paper proposes a multi-component high-frequency vibration error estimation and compensation approach based on the short-time Fourier transform (STFT). To improve the robustness of the method against noise effects, STFT is used to extract the instantaneous frequency (IF) of a high-frequency vibration error signal, and the vibration parameters are coarsely obtained by the least square (LS) method. To reduce the influence of the STFT window widths, a method based on the maximum likelihood function (MLF) is developed for determining the optimal window width by a one-dimensional search of the window widths. In the case of high noise, many IF estimation values seriously deviate from the true ones. To avoid the singular values of IF estimation in the LS regression, the random sample consensus (RANSAC) is introduced to improve estimation accuracy. Then, performing the STFT with the optimal window width, the accurate vibration parameters are estimated by LS regression, where the singular values of IF estimation are excluded. Finally, the vibration error is reconstructed to compensate for the non-negligible phase of the platform-induced periodic modulation. The simulation results prove that the error compensation method can meet THz-SAR imaging requirements, even at a low signal-to-noise ratio (SNR). Full article

(This article belongs to the Special Issue Applications of Millimeter-Wave and Terahertz Technologies)

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9 pages, 8944 KiB

Open AccessArticle

Flexible Ultra-Wide Electro-Optic Frequency Combs for a High-Capacity Tunable 5G+ Millimeter-Wave Frequency Synthesizer

by Li Liu, Yangguang Liu, Xiao-Zhi Gao and Xiaomin Zhang

Appl. Sci. 2021, 11(22), 10742; https://doi.org/10.3390/app112210742 - 14 Nov 2021

Cited by 1 | Viewed by 1967

Abstract

This paper presents a new scheme of a cost-effective tunable millimeter-wave (MMW) frequency synthesizer based on an ultra-wideband electro-optic frequency comb. The architecture for the quasi-tunable millimeter-wave frequency synthesizer mainly consists of a compact ultra-wide flat electro-optic frequency comb and a multi-tone frequency [...] Read more.

This paper presents a new scheme of a cost-effective tunable millimeter-wave (MMW) frequency synthesizer based on an ultra-wideband electro-optic frequency comb. The architecture for the quasi-tunable millimeter-wave frequency synthesizer mainly consists of a compact ultra-wide flat electro-optic frequency comb and a multi-tone frequency generator, which only includes a quantum dot mode-locked laser, a LiNbO

_{3}

dual-driving Mach–Zehnder modulator (DD-MZM) and Uni-traveling-carrier photodiode (UTC-PD). MMW signals generated with a quasi-tunable frequency are experimentally demonstrated. The difference in power is obtained for the different frequencies. The linewidth of the quasi-tunable frequency signals is less than 273 Hz. In addition, the single side band (SSB) phase noise of the 25, 37.5, 50 and 75 GHz is measured as −115, −106, −102 and −95 dBc/Hz at an offset of 1 kHz, respectively. The proposed frequency synthesizer has ultra-low phase noise, quasi-tunable frequency and simple structure. The research results of the frequency synthesizer are applied for 5G+ transmission with radio wave working at K-band and V-band. The flexible, compact and robust MMW frequency synthesizer is suitable for the future of ultra-high capacity 5G+ communication. Full article

(This article belongs to the Special Issue Applications of Millimeter-Wave and Terahertz Technologies)

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12 pages, 5082 KiB

Open AccessArticle

Optical Injection Locking for Generation of Tunable Low-Noise Millimeter Wave and THz Signals

by Gleb Nazarikov, Simon Rommel, Weiming Yao and Idelfonso Tafur Monroy

Appl. Sci. 2021, 11(21), 10185; https://doi.org/10.3390/app112110185 - 30 Oct 2021

Cited by 5 | Viewed by 2219

Abstract

This article presents the experimental demonstration of synchronization of two integrated semiconductor distributed Bragg reflector lasers, fabricated with a generic multiproject wafer platform, by means of injection locking. Substantial linewidth reduction and frequency stabilization of the lasers were shown during locking of the [...] Read more.

This article presents the experimental demonstration of synchronization of two integrated semiconductor distributed Bragg reflector lasers, fabricated with a generic multiproject wafer platform, by means of injection locking. Substantial linewidth reduction and frequency stabilization of the lasers were shown during locking of the lasers to an optical frequency comb. Phase noise was measured for different injected powers and different laser cavities. For a generation of millimeter-wave signals up to 80 GHz, two lasers were simultaneously locked to the comb. Fine-tuning was performed by tuning the repetition rate of the comb and coarse-tuning was carried out by switching to another comb line. A suppression ratio of 37 dB was achieved for unwanted comb lines. The achieved signal purity, phase noise, and suppression of unwanted components demonstrate the viability of injection locking for the generation of high-quality signals at sub-THz and THz frequencies and with substantial tunability. Full article

(This article belongs to the Special Issue Applications of Millimeter-Wave and Terahertz Technologies)

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14 pages, 3956 KiB

Open AccessArticle

Performance Enhancement of Inexpensive Glow Discharge Detector Operating in Up-Conversion Mode in Millimeter Wave Detection for Focal Plane Arrays

by Arun Ramachandra Kurup, Daniel Rozban, Lidor Kahana, Amir Abramovich, Yitzhak Yitzhaky and Natan Kopeika

Appl. Sci. 2021, 11(20), 9564; https://doi.org/10.3390/app11209564 - 14 Oct 2021

Viewed by 1690

Abstract

Performance enhancement of a very inexpensive millimeter-wave (MMW)/terahertz (THz) sensor for MMW/THz imaging systems is experimentally demonstrated in this study. The MMW sensor is composed of a glow discharge detector (GDD) and a light-to-frequency (LTF) converter combination. The experimental results given in this [...] Read more.

Performance enhancement of a very inexpensive millimeter-wave (MMW)/terahertz (THz) sensor for MMW/THz imaging systems is experimentally demonstrated in this study. The MMW sensor is composed of a glow discharge detector (GDD) and a light-to-frequency (LTF) converter combination. The experimental results given in this study show an improvement in the performance parameters of the detector element, such as the minimum detectable signal, as well as the signal to noise ratio (SNR) and the noise equivalent power (NEP), when a NIR long-pass filter was inserted between the GDD and the LTF combination. A detailed derivation of the NEP of this unique sensor is presented in this work. Based on this derivation and the experimental measurements, the NEP value was calculated. Full article

(This article belongs to the Special Issue Applications of Millimeter-Wave and Terahertz Technologies)

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7 pages, 1938 KiB

Open AccessArticle

High Linearity DC-38 GHz CMOS SPDT Switch

by Jin-Fa Chang and Yo-Sheng Lin

Appl. Sci. 2021, 11(20), 9402; https://doi.org/10.3390/app11209402 - 11 Oct 2021

Cited by 3 | Viewed by 2511

Abstract

In this paper, we demonstrate a low-loss and high-linearity DC-38 GHz CMOS SPDT switch for 5G multi-band communications in 0.18 μm CMOS. Traveling-wave matching (CLCL network) is used for the output-port (ports 2 and 3) matching and isolation enhancement, while π-matching (CLC matching) [...] Read more.

In this paper, we demonstrate a low-loss and high-linearity DC-38 GHz CMOS SPDT switch for 5G multi-band communications in 0.18 μm CMOS. Traveling-wave matching (CLCL network) is used for the output-port (ports 2 and 3) matching and isolation enhancement, while π-matching (CLC matching) is adopted for the input-port (port 1) matching. Positive/negative gate-bias is adopted for linearity enhancement because larger P_in (i.e., AC signal with larger negative V_in) is required to conduct the off-state series switch transistor. Negative-body bias is used for insertion-loss reduction because the off-state series switch transistor is closer to an open state. The SPDT switch achieves insertion loss of 0.4–1.4 dB, 3.6–4.3 dB, and 4.5–5.9 dB, respectively, for DC-6 GHz, 21–29 GHz, and 31–38 GHz. Moreover, the SPDT switch achieves isolation of 37.5–59.4 dB, 25.7–28.7 dB, and 24.3–25.2 dB, respectively, for DC-6 GHz, 21–29 GHz, and 31–38 GHz. At 28 GHz, the SPDT switch achieves remarkable input 1-dB compression point (IP_1dB) of 25.6 dBm, close to the simulated one (28 dBm). To the authors’ knowledge, this is one of the best IP_1dB results ever reported for millimeter-wave (mm-wave) SPDT switches. Full article

(This article belongs to the Special Issue Applications of Millimeter-Wave and Terahertz Technologies)

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17 pages, 5177 KiB

Open AccessArticle

Concealed Object Detection and Recognition System Based on Millimeter Wave FMCW Radar

by Jie Liu, Kai Zhang, Zhenlin Sun, Qiang Wu, Wei He and Hao Wang

Appl. Sci. 2021, 11(19), 8926; https://doi.org/10.3390/app11198926 - 24 Sep 2021

Cited by 11 | Viewed by 3259

Abstract

At present, millimeter wave radar imaging technology has become a recognized human security solution in the field. The millimeter wave radar imaging system can be used to detect a concealed object; multiple-input multiple-output radar antennas and synthetic aperture radar techniques are used to [...] Read more.

At present, millimeter wave radar imaging technology has become a recognized human security solution in the field. The millimeter wave radar imaging system can be used to detect a concealed object; multiple-input multiple-output radar antennas and synthetic aperture radar techniques are used to obtain the raw data. The analytical Fourier transform algorithm is used for image reconstruction. When imaging a target at 90 mm from radar, which belongs to the near field imaging scene, the image resolution can reach 1.90 mm in X-direction and 1.73 mm in Y-direction. Since the error caused by the distance between radar and target will lead to noise, the original reconstruction image is processed by gamma transform, which eliminates image noise, then the image is enhanced by linearly stretched transform to improve visual recognition, which lays a good foundation for supervised learning. In order to flexibly deploy the machine learning algorithm in various application scenarios, ShuffleNetV2, MobileNetV3 and GhostNet representative of lightweight convolutional neural networks with redefined convolution, branch structure and optimized network layer structure are used to distinguish multi-category SAR images. Through the fusion of squeeze-and-excitation and the selective kernel attention mechanism, more precise features are extracted for classification, the proposed GhostNet_SEResNet56 can realize the best classification accuracy of SAR images within limited resources, which prediction accuracy is 98.18% and the number of parameters is 0.45 M. Full article

(This article belongs to the Special Issue Applications of Millimeter-Wave and Terahertz Technologies)

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12 pages, 4323 KiB

Open AccessArticle

Terahertz Sensing for R/S Chiral Ibuprofen via All-Dielectric Metasurface with Higher-Order Resonance

by Weinan Shi, Fei Fan, Ziyang Zhang, Tianrui Zhang, Shanshan Li, Xianghui Wang and Shengjiang Chang

Appl. Sci. 2021, 11(19), 8892; https://doi.org/10.3390/app11198892 - 24 Sep 2021

Cited by 10 | Viewed by 1991

Abstract

A terahertz (THz) all-dielectric metasurface with crescent cylinder arrays for chiral drug sensing has been demonstrated. Through the multipole expansion method, we theoretically found that breaking the symmetry of the metasurface can excite higher-order resonance modes and provide stronger anisotropy as well as [...] Read more.

A terahertz (THz) all-dielectric metasurface with crescent cylinder arrays for chiral drug sensing has been demonstrated. Through the multipole expansion method, we theoretically found that breaking the symmetry of the metasurface can excite higher-order resonance modes and provide stronger anisotropy as well as enhanced sensitivity for the surroundings, which gives a better sensing performance than lower-order resonance. Based on the frequency shift and transmittance at higher-order resonance, we carried out the sensing experiments on (R)-(−)-ibuprofen and (S)-(+)-ibuprofen solution on the surface of this metasurface sensor. We were able to monitor the concentrations of ibuprofen solutions, and the maximum sensitivity reached 60.42 GHz/mg. Furthermore, we successfully distinguished different chiral molecules such as (R)-(−)-ibuprofen and (S)-(+)-ibuprofen in the 5 μL trace amount of samples. The maximum differentiation was 18.75 GHz/mg. Our analysis confirms the applicability of this crescent all-dielectric metasurface to enhanced sensing and detection of chiral molecules, which provides new paths for the identification of biomolecules in a trace amount. Full article

(This article belongs to the Special Issue Applications of Millimeter-Wave and Terahertz Technologies)

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10 pages, 2330 KiB

Open AccessArticle

Tunable Temperature Characteristic of Terahertz Bragg Fiber Filled with Liquid Water

by Cuijuan Guo, Mengya Su, Jia Shi, Linlin Tian, Wei Xu, Hongli Chen, Hua Bai, Zhitao Xiao, Degang Xu and Jianquan Yao

Appl. Sci. 2021, 11(18), 8306; https://doi.org/10.3390/app11188306 - 7 Sep 2021

Cited by 2 | Viewed by 1940

Abstract

Hollow-core terahertz (THz) fibers have attracted a lot of research interest due to the low loss and easy inner modification with functional materials. Liquid water has unique properties in the THz region and has been widely investigated in THz emission, sensing, and devices. [...] Read more.

Hollow-core terahertz (THz) fibers have attracted a lot of research interest due to the low loss and easy inner modification with functional materials. Liquid water has unique properties in the THz region and has been widely investigated in THz emission, sensing, and devices. In this paper, a hollow-core THz Bragg fiber with a water defect layer is proposed. The finite element method is used to verify and analyze the tunable temperature characteristic of the water-filled THz fiber. The numerical analysis results show that the confinement loss and the low-frequency side of the dip near 0.5 THz can be controlled by the temperature of the liquid water. The temperature sensitivity of the THz fiber is obtained at 0.09614 dB·m⁻¹/K at 0.45 THz with a high core power fraction up to 98%. The proposed THz fiber has potential applications in THz interaction with liquid and THz tunable devices. Full article

(This article belongs to the Special Issue Applications of Millimeter-Wave and Terahertz Technologies)

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12 pages, 4988 KiB

Open AccessArticle

A New and Simple Design Method for End-Fire Dipole Antenna Array and Three Two-Element 24 GHz Planar End-Fire Dipole Antenna Arrays

by Yanfei Mao, Shiju E and Chungeng Zhu

Appl. Sci. 2021, 11(16), 7720; https://doi.org/10.3390/app11167720 - 23 Aug 2021

Cited by 2 | Viewed by 3719

Abstract

For an RF system, a high-gain antenna helps to improve the equivalent isotropic radiated power (EIRP) of the transmitter and an end-fire antenna array helps to improve the directivity (D) and half power beam width (HP) of the antenna. This work presents a [...] Read more.

For an RF system, a high-gain antenna helps to improve the equivalent isotropic radiated power (EIRP) of the transmitter and an end-fire antenna array helps to improve the directivity (D) and half power beam width (HP) of the antenna. This work presents a new and simple design method for end-fire antenna array design. The method states that when antenna elements are λ/2 apart, a simple end-fire antenna array could be designed and constructed easily without matching networks between antenna elements. Utilizing Rogers 4350 PCB technology, three 24 GHz high-gain, compact planar two-element end-fire dipole antenna arrays are designed to verify this new design method. The achieved results are three two-element end-fire antennas with gains of 8.8, 9.9 and 9.1 dBi. These antenna arrays are characterized by high gain and simplicity in design. They are also very compact in size, with an area of about 1.9 × 1.7 cm². The benefit of this work is that a new and simple design for end-fire antenna design is suggested, and three two-element end-fire dipole antenna arrays in planar technology which adopt the design method are presented. A utility model patent was granted for this end-fire dipole array antenna topology, ZL 202022106332.1. Full article

(This article belongs to the Special Issue Applications of Millimeter-Wave and Terahertz Technologies)

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7 pages, 398 KiB

Open AccessArticle

Improvement of the Electro-Optical Process in GaAs for Terahertz Single Pulse Detection by Using a Fiber-Coupling System

by Adnan Haj Yahya, Nezah Balal, Avi Klein, Jacob Gerasimov and Aharon Friedman

Appl. Sci. 2021, 11(15), 6859; https://doi.org/10.3390/app11156859 - 26 Jul 2021

Cited by 1 | Viewed by 1826

Abstract

The electro-optical process is a popular method for terahertz radiation detection. Detectors based on the electro-optical process have large bandwidth, and the signal-to-noise ratio (SNR) is relatively high. Further, this detector can be applied to detect high-power signals without using radiation attenuation. This [...] Read more.

The electro-optical process is a popular method for terahertz radiation detection. Detectors based on the electro-optical process have large bandwidth, and the signal-to-noise ratio (SNR) is relatively high. Further, this detector can be applied to detect high-power signals without using radiation attenuation. This paper presents a method to improve the electro-optic process to THz radiation detection based on GaAs crystals by coupling the optical output signal into fiber. Results demonstrated an improvement in the signal-to-noise ratio that means an increase in the dynamic range of the electro-optical detector. Full article

(This article belongs to the Special Issue Applications of Millimeter-Wave and Terahertz Technologies)

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14 pages, 9190 KiB

Open AccessArticle

Non-Ionizing Millimeter Waves Non-Thermal Radiation of Saccharomyces cerevisiae—Insights and Interactions

by Ayan Barbora, Shailendra Rajput, Konstantin Komoshvili, Jacob Levitan, Asher Yahalom and Stella Liberman-Aronov

Appl. Sci. 2021, 11(14), 6635; https://doi.org/10.3390/app11146635 - 20 Jul 2021

Cited by 5 | Viewed by 3029

Abstract

Non-ionizing millimeter-waves (MMW) interact with cells in a variety of ways. Here the inhibited cell division effect was investigated using 85–105 GHz MMW irradiation within the International Commission on Non-Ionizing Radiation Protection (ICNIRP) non-thermal 20 mW/cm² safety standards. Irradiation using a power [...] Read more.

Non-ionizing millimeter-waves (MMW) interact with cells in a variety of ways. Here the inhibited cell division effect was investigated using 85–105 GHz MMW irradiation within the International Commission on Non-Ionizing Radiation Protection (ICNIRP) non-thermal 20 mW/cm² safety standards. Irradiation using a power density of about 1.0 mW/cm² SAR over 5–6 h on 50 cells/μL samples of Saccharomyces cerevisiae model organism resulted in 62% growth rate reduction compared to the control (sham). The effect was specific for 85–105 GHz range and was energy- and cell density-dependent. Irradiation of wild type and Δrad52 (DNA damage repair gene) deleted cells presented no differences of colony growth profiles indicating non-thermal MMW treatment does not cause permanent genetic alterations. Dose versus response relations studied using a standard horn antenna (~1.0 mW/cm²) and compared to that of a compact waveguide (17.17 mW/cm²) for increased power delivery resulted in complete termination of cell division via non-thermal processes supported by temperature rise measurements. We have shown that non-thermal MMW radiation has potential for future use in treatment of yeast related diseases and other targeted biomedical outcomes. Full article

(This article belongs to the Special Issue Applications of Millimeter-Wave and Terahertz Technologies)

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7 pages, 373 KiB

Open AccessArticle

Comparison between Up-Conversion Detection in Glow-Discharge Detectors and the Schottky Diode for MMW/THz High-Power Single Pulse

by Adnan Haj Yahya, Avi Klein, Nezah Balal, Dmitri Borodin and Aharon Friedman

Appl. Sci. 2021, 11(9), 4172; https://doi.org/10.3390/app11094172 - 3 May 2021

Cited by 5 | Viewed by 1867

Abstract

Generally, glow-discharge detectors (GDD), acting on miniature neon indicator lamps, and Schottky diode detectors serve as efficient, fast, and room-temperature millimeter wave (MMW)/THz detectors. Previous studies on GDD implemented a repetition of terahertz sources, and low-power radiation, and showed good results in terms [...] Read more.

Generally, glow-discharge detectors (GDD), acting on miniature neon indicator lamps, and Schottky diode detectors serve as efficient, fast, and room-temperature millimeter wave (MMW)/THz detectors. Previous studies on GDD implemented a repetition of terahertz sources, and low-power radiation, and showed good results in terms of detection, responsivity, and noise-equivalent power. This paper presents a comparison between a detector based on a GDD lamp and a Schottky diode detector for the detection of a high-power single pulse. With this comparison, we touch upon two GDD detection methods, the visual light emitting from the GDD and the electrical current of the GDD detector. Results showed better response time and better sensitivity for the GDD detection method compared to with the Schottky diode. Full article

(This article belongs to the Special Issue Applications of Millimeter-Wave and Terahertz Technologies)

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Review

Jump to: Research

35 pages, 4047 KiB

Open AccessReview

A Review on LiFi Network Research: Open Issues, Applications and Future Directions

by Rozin Badeel, Shamala K. Subramaniam, Zurina Mohd Hanapi and Abdullah Muhammed

Appl. Sci. 2021, 11(23), 11118; https://doi.org/10.3390/app112311118 - 23 Nov 2021

Cited by 21 | Viewed by 11785

Abstract

This paper extensively reviews and analyses Light Fidelity (LiFi), a new technology that uses light to transmit data as a high-speed wireless connection system from a wide spectrum of domains. An in-depth analysis and classifications of pertinent research areas for LiFi networks are [...] Read more.

This paper extensively reviews and analyses Light Fidelity (LiFi), a new technology that uses light to transmit data as a high-speed wireless connection system from a wide spectrum of domains. An in-depth analysis and classifications of pertinent research areas for LiFi networks are presented in this paper. The various aspects constituting this paper include a detailed literature review, proposed classifications, and statistics, which further is deliberated to encompass applications, system architecture, system components, advantages, and disadvantages. LiFi and other technologies are compared, multi-user access techniques used in LiFi networks are investigated and open issues are addressed in detail. The paper is concluded with a comprehensive taxonomy of literature comparison that has served as the basis of the proposed open issues and research trends. Full article

(This article belongs to the Special Issue Applications of Millimeter-Wave and Terahertz Technologies)

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