Millimeter-wave Radiation Research Articles

Passive Millimeter-Wave Radiation Calculation of Chaff Cloud Based on a Hybrid Method

Passive Millimeter-Wave Radiation Calculation of Chaff Cloud Based on a Hybrid Method

Exploring Skin Interactions with 5G Millimeter-Wave through Fluorescence Lifetime Imaging Microscopy

The ongoing expansion of fifth-generation (5G) and future sixth-generation (6G) mobile communications is expected to result in widespread human exposure to millimeter-wave (mmWave) radiation globally. Given the short penetration depth of mmWaves and their high absorption by the skin, it is imperative to investigate the potential effects of 5G radiation not only in terms of temperature increase but also at the cellular level. To understand the biological mechanisms of mmWave effects, accurate methods for assessing mmWave absorption in the skin are crucial. In this study, we use fluorescence lifetime imaging microscopy (FLIM) to explore these effects. Employing a mmWave exposure system operating at 26 gigahertz (GHz), porcine skin is irradiated for varying durations (5, 10, 20, and 30 min). We investigate changes in tissue temperature and the autofluorescence of flavin adenine dinucleotide (FAD). Our findings suggest that operating our mmWave exposure systems at the configured power level of 26 GHz is unlikely to cause damage to FADs, even after a 30 min exposure duration.

Unveiling the Impact: Human Exposure to Non-Ionizing Radiation in the Millimeter-Wave Band of Sixth-Generation Wireless Networks

The investigation into potential hazards linked with millimeter-wave (mmWave) radiation is crucial, given the widespread adoption of body-centric wireless sensor nodes operating within this frequency band. This is particularly pertinent in light of its envisaged use for the upcoming 5G/6G networks and beyond. As 6G is anticipated to leverage a broad spectrum, including both sub-6 GHz and mmWave bands (30–300 GHz), concerns arise regarding increased human exposure to non-ionizing radiation (NIR). This work highlights the advantages of deploying 6G in the mmWave band, focusing on evaluating human body exposure to NIR interactions. Additionally, this research aims to address mmWave NIR exposure by introducing a Distributed Base Station (DBS) network. Utilizing low-power remote antennas to extend network coverage, the DBS architecture seeks to effectively minimize NIR’s impact without compromising overall network performance. The findings underscore the significant potential of the DBS approach in mitigating NIR-related concerns associated with mmWave utilization in 6G networks.

Quasiparticle Poisoning of Superconducting Qubits from Resonant Absorption of Pair-Breaking Photons.

The ideal superconductor provides a pristine environment for the delicate states of a quantum computer: because there is an energy gap to excitations, there are no spurious modes with which the qubits can interact, causing irreversible decay of the quantum state. As a practical matter, however, there exists a high density of excitations out of the superconducting ground state even at ultralow temperature; these are known as quasiparticles. Observed quasiparticle densities are of order 1 μm^{-3}, tens of orders of magnitude greater than the equilibrium density expected from theory. Nonequilibrium quasiparticles extract energy from the qubit mode and can induce dephasing. Here we show that a dominant mechanism for quasiparticle poisoning is direct absorption of high-energy photons at the qubit junction. We use a Josephson junction-based photon source to controllably dose qubit circuits with millimeter-wave radiation, and we use an interferometric quantum gate sequence to reconstruct the charge parity of the qubit. We find that the structure of the qubit itself acts as a resonant antenna for millimeter-wave radiation, providing an efficient path for photons to generate quasiparticles. A deep understanding of this physics will pave the way to realization of next-generation superconducting qubits that are robust against quasiparticle poisoning.

Optimization of the collective Thomson scattering diagnostic for the GDT open magnetic trap

The collective Thomson scattering of high-power millimeter-wave radiation on plasma density fluctuations (CTS) is widely used for diagnosing the velocity distribution function of energetic ions in fusion plasma. In this paper, we discuss a non-standard scheme of CTS measurements, which exploits strong refraction of probing and scattered microwave beams when reflecting from the cut-off layer in dense plasma. The scheme may be realized with the existing CTS diagnostic system at the Gas-Dynamic Trap (GDT) facility, a large open magnetic trap operating at Budker Institute (Novosibirsk, Russia). This requires a minor upgrade of the available hardware and essentially increases the range of plasma densities allowed for CTS measurements, as well as its sensitivity and spatial resolution. A detailed study of CTS efficiency for different geometries and plasma conditions at GDT is performed by means of an advanced numerical model that allows for an accurate description of non-Gaussian beam scattering in inhomogeneous plasma. To perform this task, we develop a quasi-optical theory of scattering, which itself may be of general interest.

Precision Spectroscopy of Rydberg States in Alkaline Earth Atoms for Millimeter-Wave Radiation Measurement

Precision Spectroscopy of Rydberg States in Alkaline Earth Atoms for Millimeter-Wave Radiation Measurement

RF Health Safety Limits and Recommendations [Health Matters

The rapid proliferation of cellular mobile telecommunication devices and systems is raising public health concerns about the biological effects and safety of RF radiation exposure. There is also concern about the efficacy of promulgated health safety limits, rules, and recommendations for the RF radiation used by these devices and systems. This article reviews and discusses the U.S. Federal Communications Commission (FCC) notices and rules, International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines, and International Committee on Electromagnetic Safety (ICES) standard for safety levels with respect to human exposure to electric, magnetic, and electromagnetic fields (EMFs). The recently revised RF exposure limits are adjusted only for heating with RF radiation. These limits are largely intended to restrict short-term heating by RF radiation that raises tissue temperatures. They are narrow in scope and are not applicable to long-term exposure at low levels. This review discusses the assumptions underlying the standards and the outdated exposure metrics employed, and concludes that the revised guidelines do not adequately protect children, workers, or the public from exposure to RF radiation or people with sensitivity to electromagnetic radiation from wireless devices and systems. Furthermore, the review discusses important animal data that the standards do not appear to take into account. Moreover, for millimeter-wave radiation from 5G mobile communications, there are no adequate human health effects studies in the published literature. The conclusions by scientific organizations, such as the International Agency for Research on Cancer (IARC), that diverge from these standards are also discussed. The review concludes that many of the recommended limits are debatable and require more scientific justification from the standpoint of safety and public health protection.

Membrane Proteomics to Understand Enhancement Effects of Millimeter-Wave Irradiation on Wheat Root under Flooding Stress.

Millimeter-wave irradiation of wheat seeds enhances the growth of roots under flooding stress, but its mechanism is not clearly understood. To understand the role of millimeter-wave irradiation on root-growth enhancement, membrane proteomics was performed. Membrane fractions purified from wheat roots were evaluated for purity. H+-ATPase and calnexin, which are protein markers for membrane-purification efficiency, were enriched in a membrane fraction. A principal-component analysis of the proteomic results indicated that the millimeter-wave irradiation of seeds affects membrane proteins in grown roots. Proteins identified using proteomic analysis were confirmed using immunoblot or polymerase chain reaction analyses. The abundance of cellulose synthetase, which is a plasma-membrane protein, decreased under flooding stress; however, it increased with millimeter-wave irradiation. On the other hand, the abundance of calnexin and V-ATPase, which are proteins in the endoplasmic reticulum and vacuolar, increased under flooding stress; however, it decreased with millimeter-wave irradiation. Furthermore, NADH dehydrogenase, which is found in mitochondria membranes, was upregulated due to flooding stress but downregulated following millimeter-wave irradiation even under flooding stress. The ATP content showed a similar trend toward change in NADH dehydrogenase expression. These results suggest that millimeter-wave irradiation improves the root growth of wheat via the transitions of proteins in the plasma membrane, endoplasmic reticulum, vacuolar, and mitochondria.

ICNIRP Guidelines’ Exposure Assessment Method for 5G Millimetre Wave Radiation May Trigger Adverse Effects

The current global roll-out of 5G infrastructure is designed to utilise millimetre wave frequencies (30-300 GHz range) at data transmission rates in the order of gigabits per second (Gbps). This frequency band will be transmitted using beamforming, a new introduction in near-field exposures. The International Commission on Non-Ionising Radiation Protection (ICNIRP) has recently updated their guidelines. We briefly examine whether the new approach of the ICNIRP is satisfactory to prevent heat damage and other adverse bio-effects once millimetre wave 5G is included, and we challenge the use of surface-only exposure assessment for local exposures greater than 6 GHz in part due to possible Brillouin precursor pulse formation. However, this is relevant whether or not Brillouin precursors occur from absorption of either 5G or future G transmissions. Many significant sources conclude there is insufficient research to assure safety even from the heat perspective. To date, there has been no published in vivo, in vitro or epidemiological research using exposures to 5G New Radio beam-formed signals.

Proteomic and Biochemical Approaches Elucidate the Role of Millimeter-Wave Irradiation in Wheat Growth under Flooding Stress.

Flooding impairs wheat growth and considerably affects yield productivity worldwide. On the other hand, irradiation with millimeter waves enhanced the growth of chickpea and soybean under flooding stress. In the current work, millimeter-wave irradiation notably enhanced wheat growth, even under flooding stress. To explore the protective mechanisms of millimeter-wave irradiation on wheat under flooding, quantitative proteomics was performed. According to functional categorization, proteins whose abundances were changed significantly with and without irradiation under flooding stress were correlated to glycolysis, reactive-oxygen species scavenging, cell organization, and hormonal metabolism. Immunoblot analysis confirmed that fructose-bisphosphate aldolase and β tubulin accumulated in root and leaf under flooding; however, even in such condition, their accumulations were recovered to the control level in irradiated wheat. The abundance of ascorbate peroxidase increased in leaf under flooding and recovered to the control level in irradiated wheat. Because the abundance of auxin-related proteins changed with millimeter-wave irradiation, auxin was applied to wheat under flooding, resulting in the application of auxin improving its growth, even in such condition. These results suggest that millimeter-wave irradiation on wheat seeds improves the recovery of plant growth from flooding via the regulation of glycolysis, reactive-oxygen species scavenging, and cell organization. Additionally, millimeter-wave irradiation could promote tolerance against flooding through the regulation of auxin contents in wheat.

Passive Millimeter-Wave Imaging for Burns Diagnostics under Dressing Materials.

This paper presents a feasibility study of using a passive millimeter-wave imaging (PMMWI) system to assess burn wounds and the potential for monitoring the healing process under dressing materials, without their painful removal. Experimental images obtained from ex vivo porcine skin samples indicate that a ThruVision passive imager operating over the band 232–268 GHz can be used for diagnosing burns and for potentially monitoring the healing under dressing materials. Experimental images show that single and multiple burns are observed throughout dressing materials. As the interaction of millimeter-wave (MMW) radiation with the human body is almost exclusively with the skin, the major outcomes of the research are that PMMWI is capable of discriminating burn-damaged skin from unburned skin, and these measurements can be made through bandages without the imager making any physical contact with the skin or the bandage. This highlights the opportunity that the healing of burn wounds can be assessed and monitored without the removal of dressing materials. The key innovation in this work is in detecting single and multiple burns under dressing materials in noncontact with the skin and without exposing the skin to any type of manmade radiation (i.e., passive sensing technology). These images represent the first demonstration of burns wound under dressing materials using a passive sensing imager.

Demonstration of a Ka-Band Oversized Coaxial Multi-Beam Relativistic Klystron Amplifier for High Power Millimeter-Wave Radiation

We proposed an oversized coaxial multi-beam relativistic klystron amplifier (OCMB-RKA) with a new input coupler of lesser complexity giving enhanced input microwave power absorption rate for generating high power millimeter-wave radiation in Ka-band. The high-frequency structure of the OCMB-RKA was designed, fabricated, and cold-tested for results that agreed well with the simulated results. Furthermore, using the 3D particle-in-cell (PIC) code, the beam-wave interaction of the OCMB-RKA was simulated, considering two different materials (stainless steel and copper) making the interaction structure. When a 500 kV, 3 kA electron beam, and a focusing magnetic flux intensity of 1 T were adopted in the PIC simulation, a five-cavity OCMB-RKA yielded the output power of 610 MW at 30.525 GHz with the electronic efficiency of 40.7% and the saturated gain of 55.3 dB. Experimentally, the OCMB-RKA demonstrated its capability of generating high power Ka-band radiation typically of 390 MW power with the pulse width of 27 ns.

Theoretical foundations for the evanescent mode oscillator (EMO) as a high-efficiency source of millimeter-wave and terahertz radiations

Evanescent mode oscillators (EMO) are investigated as high-efficiency sources of millimeter-waves and low-frequency parts of terahertz radiation. EMO can be considered a high-efficiency version of the extended interaction oscillator (EIO) using the evanescent resonance mode (ERM) of a slow-wave structure. It has been shown quantitatively that the efficiency of the EMO is superior to that of the conventional EIO having the same periodic unit cell. The condition to have an evanescent resonant mode in a chain is derived in this article. EMO threshold excitation condition is expressed in terms of the beam and RF mode parameters. A Typical EMO is systematically modeled, and its performance is checked with a particle-in-cell simulation software package. The excitation of the ERM modes is illustrated, with the results being close to the prediction of the non-linear model used in the paper.

Adaptogenic effect of low-intensity millimeter-wave electromagnetic radiation on Glycine Max L. under osmotic stress

This study is devoted to identification of the adaptogenic effect of low-intensity electromagnetic radiation (EMR) of the millimeter (MM) range (wavelength – 7.1 mm, radiation frequency – 42.3 GHz, radiation power flux density – 0.1 mW/cm2) on seed germination and growth processes of Glycine max L., cultivar Apollo under osmotic stress. The stimulating effect of millimeter-wave electromagnetic radiation on seed germination, morphometric parameters (height of the aerial part, length of the main root, accumulation of wet and dry matter mass) in plants of Glycine max L., cultivar Apollo has been revealed. Thus, it has been shown that pre-sowing irradiation with this physical factor increases the salt tolerance of Glycine max L., cv. Apollo. Germination energy and laboratory germination increase on average by 8–12% at simulated chloride salinity in the experimental variants, compared to the control ones. The positive effect of low-intensity EMR of the MM range on the morphometric parameters of Glycine max L. was established, while the shoot height significantly increased by 14%, the length of the main root – by 18%, the weight of the wet matter – by 5–13% in the experimental plants compared to control conditions of chloride salinization.

Influence of low-intensity electromagnetic radiation of the millimeter range on the antioxidant system of juvenile Glycine max L. plants under osmotic stress

This study is devoted to identifying the adaptogenic effect of low-intensity electromagnetic radiation (EMR) of the millimeter (MM) range (wavelength – 7.1 mm, radiation frequency – 42.3 GHz, radiation power flux density – 0.1 mW/cm2) on the antioxidant system indicators of juvenile plants Glycine max L., cv. Apollo under osmotic stress caused by salinity. The stimulating effect of millimeter-wave electromagnetic radiation on the content of proline and carotenoids in Glycine max L. plants was revealed. The results obtained on the quantitative content of carotenoids showed that their content increased both in the normal conditions and under osmotic stress by an average of 1.2–1.8 times. An increased content of free proline in leaves was found in comparison with soybean roots under optimal conditions and under salinity.

Proteomic and Biological Analyses Reveal the Effect on Growth under Flooding Stress of Chickpea Irradiated with Millimeter Waves.

Chickpea cultivated on marginal lands in arid and semiarid tropics is one of the food legumes, and its growth is reduced by flooding stress. Millimeter-wave irradiation has influences on organisms, and it improves the growth of plants such as soybean. To reveal the dynamic effects of millimeter-wave irradiation on chickpea under flooding, gel- and label-free proteomic analysis was conducted. Millimeter-wave irradiation improved chickpea growth and its tolerance to flooding stress. According to functional categorization, oppositely changed proteins were correlated with photosynthesis, fermentation, and protein degradation. Immunoblot analysis confirmed that RuBisCO activase and large subunits decreased in leaves under flooding; however, they are recovered in irradiated chickpea even if it was in this condition. The activity and accumulation of alcohol dehydrogenase increased in roots under flooding; however, this followed the same pattern. Cell death was significantly increased and decreased by flooding on unirradiated and irradiated chickpeas, respectively. These findings suggest that irradiation with millimeter waves on chickpea seeds improves the recovery of plant growth through regulation of photosynthesis in leaves and fermentation in roots. Furthermore, millimeter-wave irradiation might promote chickpea tolerance under flooding via the regulation of cell death.

An investigation of the dynamic beam-steering capability of a liquid-crystal-enabled leaky-wave antenna designed for 5G applications

In this Letter, an investigation is performed on the utilization of nematic liquid crystal (NLC) cells in the design of leaky-wave antennas (LWAs) for millimeter-wave (mm-wave) radiation in order to dynamically control its beam scanning capability at a single frequency. A NLC compound is sandwiched between two single-sided copper-plated substrates allowing a traveling wave to be guided through a substrate-integrated waveguide. The tuning capabilities of the structure, based on the use of K15 or GT7-29001 as the middle layer, were evaluated for different biasing conditions demonstrating the associated dynamic scanning of the main beam. A quasi-periodic LWA was designed to operate in the 5G mm-wave band, thus supporting a fast-wave propagation with tunable phase constant and dynamic beam steering at a single frequency. The simulated results clearly illustrate a dynamic beam scanning range of 45° through the use of an external bias voltage ranging between 0 and 40 V. These results are quite promising creating a fertile ground for the utilization of NLCs in the design and fabrication of LWAs for 5G wireless communication networks.

A Carbon Nanotube-Based Hundred Watt-Level Ka-Band Backward Wave Oscillator

Carbon nanotube (CNT) cold-cathodes hold much promise in a variety of millimeter-wave and terahertz vacuum electronic radiation devices due to their inherent near instantaneous temporal turn-on and near-ideal ideal field electron emission performance. Here we report on the development of a CNT cold-cathode Ka -band backward-wave oscillator (BWO). Using a novel beam compression stage, theoretical studies, simulation results, and empirical findings collectively demonstrate that this device affords an unprecedentedly high output power of 230 W at a technologically important operating frequency of 33.65 GHz. The developed magnetic injection electron gun achieves a high emission current of 265.5 mA (emission current density of 188.3 mA/cm2) and a high focused beam current density of 18.5 A/cm2, which our studies suggest, is essential to the BWOs high output power.

Investigation on a 220 GHz Quasi-Optical Antenna for Wireless Power Transmission

This paper investigates a 220 GHz quasi-optical antenna for millimeter-wave wireless power transmission. The quasi-optical antenna consists of an offset dual reflector, and fed by a Gaussian beam that is based on the output characteristics of a high-power millimeter-wave radiation source-gyrotron. The design parameter is carried on by a numerical code based on geometric optics and vector diffraction theory. To realize long-distance wireless energy transmission, the divergence angle of the output beam must be reduced. Electromagnetic simulation results show that the divergence angle of the output beam of the 5.6 mm Gaussian feed source has been significantly reduced by the designed quasi-optical antenna. The far-field divergence angle of the quasi-optical antenna in the E plane and H plane is 1.0596° and 1.0639°, respectively. The Gaussian scalar purity in the farthest observation field (x = 1000 m) is 99.86%. Thus, the quasi-optical antenna can transmit a Gaussian beam over long-distance and could be used for millimeter-wave wireless power transmission.

ДЕТЕКТОРЫ МИЛЛИМЕТРОВОГО И ТЕРАГЕРЦОВОГО ИЗЛУЧЕНИЯ

The aim of this work is an analytical review of terahertz and millimeter-wave radiation receivers. Classification of terahertz radiation receivers and their comparative characteristics are made. Various aspects of the application of terahertz radiation, as well as the main types and types of receivers of this radiation, are considered in this paper. Photon and thermal receivers, terahertz receivers based on Go-lay cells, and terahertz-to-infrared convectors are analyzed. As a result, a method for increasing the sensitivity of electromagnetic radiation receivers based on the application of the photon jet effect is proposed.