Isotropic Radiation Research Articles

A compact 6‐shaped high isolation MIMO antenna for 28 GHz 5G applications

SummaryThis study presents the design, fabrication, and measurement of a novel MIMO antenna for 28 GHz 5G applications. The design includes two compact antennas with dimensions of 12.8 × 12.8 × 1.6 mm3, placed side by side in a symmetrical arrangement. The antenna being considered operates within the 28 GHz frequency range and has excellent characteristics in terms of reflection coefficient, isolation, and impedance matching. The measurements conducted encompassed both single and MIMO setups and focused on important parameters such the reflection coefficient, transmission coefficient, gain, and efficiency. The MIMO antenna exhibited a reflection coefficient of −62.52 dB at a frequency of 27.93 GHz, while the transmission coefficient was found to be −37.23 dB. The antenna attained a gain of 6.02 dB relative to an isotropic radiator (dBi) and exhibited a maximum efficiency of 90.73%, encompassing a bandwidth of 4.45 MHz (MHz). The simulated envelope correlation coefficient (ECC) was found to be less than 0.003, indicating a very low error rate. Additionally, the antenna attained a diversity gain of 9.998 dB. The suggested MIMO antenna is very suitable for 5G applications operating at 28 GHz.

Isotropic High‐Frequency Radiation in Near‐Fault Seismic Data

AbstractWe compare Fourier Amplitude Spectra of Fault Normal (FN) and Fault Parallel (FP) seismograms at near‐fault sites for seven strike‐slip earthquakes with moment magnitudes Mw ≥ 6. For all events we find large FN/FP ratios at low frequencies consistent with near‐fault S‐wave radiation patterns for strike‐slip earthquakes. However, the difference diminishes with increasing frequency and FN/FP is about 1 above a transition frequency. The results may reflect small tensile/isotropic components in the earthquake rupture zones that homogenize the high‐frequency radiation in different directions at near‐fault sites. The FN/FP ratios at low frequencies and transition frequencies above which FN ∼ FP vary among the analyzed earthquakes and have no clear correlation with the magnitudes. The lack of correlation may signify a characteristic scale (e.g., process zone size, duration of source time function) controlling the isotropic radiation, and/or wave propagation and other effects that mask the source effects.

Magneto-optical Particles in Isotropic Spinning Fields Mimic Magnetic Monopoles.

In contrast with the typical electric currents accelerated under the influence of a Coulombic force, there are only a few condensed matter examples of particles experiencing a force proportional to a constant, external magnetic field. In this Letter, we present a new alternative, based on an isotropic radiation spinning field and the magneto-optical effect, in which a particle is propelled by a magnetic field just like a magnetic monopole will do. This is a purely nonreciprocal effect as the reciprocal equivalent (a chiral dipole), despite presenting a dichroic response, does not experience any force when illuminated by the spinning field. The "magnetic charge" induced by impinging radiation on the magneto-optical dipole is found to depend linearly on the helicity of the field. In addition, this artificial monopole experiences a dichroic permanent optical torque and does not interact with an external electric field.

Microstrip antenna system for communication capabilities applications

In this comparative study, seven different microstrip antenna shapes, including rectangular, elliptical, triangular, inset fed, H-notch, and E-notch, were observed and analyzed, focusing on their suitability for global positioning system (GPS) application in microsatellites. To enable meaningful comparison, the study utilized the optimal resonant frequency in GPS applications, which is 1.57542 GHz. All the antenna designs have been generated using MATLAB’s Antenna Toolbox and are 100% efficient under ideal conditions with zero polarization loss, which is assumed in the link budget analysis. The results show that each antenna shape has been found to offer distinct advantages and limitations. Along with this, the circular and elliptical patch antenna presented a well-balanced performance, which is suitable for GPS applications. However, the elliptical shape falls behind the circular shape, which was determined to be the most optimal choice for GPS application, providing excellent isotropic antenna gain, return loss, voltage standing wave ratio (VSWR), and strong link budget analysis results.

Nature of spontaneous signal and detection of radiation emitted from hydrogen Rydberg matter

In this article, we report on laser-induced radiation and spontaneous radiation emitted from a chamber containing hydrogen Rydberg matter. The emitted isotropic radiation penetrates a 3-mm-thick steel wall and several meters of air. The radiation can be detected using a simple photoelectric multiplier (PM) detector with aluminum foil covering the front end of the PM tube. The experimental setup, how to initiate the radiation, and radiation detector construction are discussed in this article. In addition, the detector stability and time development of detector response when the chamber is activated by gas loading and laser excitation are reported. Gamma-ray sensitivity, x-ray sensitivity, and pulse shape are further examined to characterize the emitted radiation. The results presented herein have been recorded for the past 4 years. The extensive and extended research shown in this work verifies that when hydrogen enters an iron oxide Rydberg state catalyst containing potassium, the catalyst will eventually emit penetrating radiation that behaves as x rays. The radiation can easily be detected using several detector methods. The spontaneous signal shows all indications of being x-ray radiation in character. The findings of this study regarding hydrogen’s behavior in materials have not been previously reported and require additional investigation by other research teams.

Breaking the cosmological principle into pieces: a prelude to the intrinsically homogeneous and isotropic spacetimes

In this manuscript, we show that there are three fundamental building blocks supporting the cosmological principle. The first of them states that there is a special frame in the Universe where the spatial geometry is intrinsically homogeneous and isotropic. The second demands the existence of a fiducial observer to whom the Hubble parameter is isotropic. The last piece states that matter and radiation behave as a perfect fluid. We show that these three hypotheses give us the Friedmann–Lemaître–Robertson–Walker (FLRW) spacetimes, the central pillar of the standard model of cosmology. We keep with the first of them and start to investigate the so-called intrinsically homogeneous and isotropic spacetimes. They emerge after the decoupling of the CMB with the geometric frame of reference. Furthermore, a ‘ΛCDM-like’ effective theory arises naturally in those backgrounds, together with some new density parameters relating to the local inhomogeneities, the internal energy density, and the local and global magnitudes of the Hubble anisotropy. All those properties make this class of inhomogeneous models, which roughly speaking, keeps ‘1/3’ of the cosmological principle, worth investigating in applications to cosmology, for it can accommodate the same ingredients of the standard model, as a geometric frame and a free-falling isotropic cosmic background radiation, and reduce to the latter when some observable parameters vanish.

Isotropic antenna based on Rydberg atoms.

Governed by the hairy ball theorem, classical antennas with isotropic responses to linearly polarized radio waves are unrealizable. Also, their calibrations face a causal dilemma. Therefore, radio wave measurements based on classical antennas are challenging to achieve high accuracy. This work shows that the antenna based on Rydberg atoms can theoretically achieve an ideal isotropic response to linearly polarized radio waves; that is, it has zero isotropic deviation. Although this conclusion is straightforward, it is not theoretically clear when complex atomic energy levels are taken into account. Experimental results of isotropic deviation within 5 dB and 0.3 dB possible with optimization in microwave and terahertz wave measurements support the theory and is at least 15 dB improvement than the classical omnidirectional antenna. Combined with the SI traceable and ultrawideband property, the ideal isotropic response will make radio wave measurement based on atomic antenna much more accurate and reliable than the traditional method. This isotropic atomic antenna is an excellent example of what a tailored quantum sensor can realize, but a classical sensor cannot. It has crucial applications in fields such as radio wave electrometry.

Research on Quasi-isotropic Radiation of Small Circular Arc Antenna

The radiation characteristics of circular arc antennas are studied by applying the method of moments (MoM) to solve the electric field integral equation (EFIE). Based on the triangular current distribution of small circular arc antennas, the analytical expression of radiation fields of circular arc antennas is derived. It is found that the circular arc antenna is equivalent to a superposition of an electric dipole and a magnetic dipole, resulting in near isotropic radiation pattern. Finally, both MoM and CST simulations show that the small arc antenna can realize the near isotropic radiation pattern.

Advancements in nanoscale coherent emitters: The development of substrate-free surface plasmon nanolasers

The surface plasmon effect can be used to confine electromagnetic fields to a small footprint measuring tens of nanometers. The resultant resonant cavities function as optimal coherent light sources with subwavelength scale configurations. The plasmonic laser sources based on nanoshell structures, in particular, have demonstrated the potential for use in the detection of subcellular mesoscopic molecular structures. However, this structure has a high plasmon dephasing rate, which can increase the threshold of the device, making it difficult to achieve electrically excited structures, thereby rendering them unsuitable as an active component for integration into optoelectronic circuits. A different approach to confining electromagnetic fields involves using a propagating surface plasmon laser structured on a planar layered semiconductor–insulator–metal. This design enables the surface plasmon to propagate along the direction of the nanowire and offers the potential to achieve electrically driven structures by injecting current into the semiconductor nanowire. Consequently, this structure is more effective in guiding energy into integrated optoelectronic circuits compared to the isotropic radiation of nanoshell structures. However, this design also necessitates a supporting substrate, resulting in the actual device volume exceeding the nanoscale and, in some cases, even larger than the size of a cell. This limitation hinders the application of integrated optoelectronic circuits at the micro/nanoscale for bio-applications. To address these challenges, we developed a substrate-free surface plasmon polariton laser. We demonstrated that allowing direct contact between the film and the air significantly reduced the laser threshold. Furthermore, the device maintained its operational capability across different surfaces.

α-enhanced astrochemistry: the carbon cycle in extreme galactic conditions

ABSTRACT Astrochemistry has been widely developed as a power tool to probe the physical properties of the interstellar medium (ISM) in various conditions of the Milky Way (MW) Galaxy, and in near and distant galaxies. Most current studies conventionally apply linear scaling to all elemental abundances based on the gas-phase metallicity. However, these elements, including carbon and oxygen, are enriched differentially by stellar nucleosynthesis and the overall galactic chemical evolution, evident from α-enhancement in multiple galactic observations such as starbursts, high-redshift star-forming galaxies, and low-metallicity dwarfs. We perform astrochemical modelling to simulate the impact of an α-enhanced ISM gas cloud on the abundances of the three phases of carbon (C+, C, CO) dubbed as ‘the carbon cycle’. The ISM environmental parameters considered include two cosmic-ray ionization rates (ζCR = 10−17 and $10^{-15}\, {\rm s}^{-1}$), two isotropic FUV radiation field strengths (χ/χ0 = 1 and 102), and (sub-)linear dust-to-gas relations against metallicity, mimicking the ISM conditions of different galaxy types. In galaxies with [C/O] < 0, CO, C, and C+, all decrease in both abundances and emission, though with differential biases. The low-J CO emission is found to be the most stable tracer for the molecular gas, while C and C+ trace H2 gas only under limited conditions, in line with recent discoveries of [C i]-dark galaxies. We call for caution when using [C ii] $158\, \mu$m and [C i](1–0) as alternative H2-gas tracers for both diffuse and dense gas with non-zero [C/O] ratios.

Angle-of-Arrival Estimation With Practical Phone Antenna Configurations

With the advances of the Internet of Things and mobile connectivity, location-based services are becoming increasingly popular and continue to enhance our experience. Multiple antennas have been pivotal in providing reliable wireless communications and high-resolution localization. If the antennas of the array are isotropic, then the simplified array manifold determined by the array geometry can be used to estimate the angle-of-arrival (AOA). However, in the real world, mobile handsets tend to have very limited space, where the practical antennas are equipped on the same ground plane, and the array geometry hardly obeys the rule of half-wavelength spacing. Therefore, a practical antenna couples signals from other antennas, causing a mutual coupling effect. Complex array manifolds are produced on an antenna even if the received signal is propagated through a single path channel. In addition, the irregular radiation pattern of each antenna further impairs the AOA estimation capability. Given the above effects, the simplified array manifold determined by the array geometry can no longer provide precise localization. In this paper, we propose a generic array manifold model for both isotropic and practical antennas. We also present an efficient algorithm to enable AOA estimation on practical antennas on the basis of the proposed model and implement it on a 5G phone at a mid-band spectrum with a 100MHz channel bandwidth. Results reveal the promising performance of the proposed model, with the AOA estimation errors lower than 10∘ in over 90% of the scenarios.

Frequency–Redshift Relation of the Cosmic Microwave Background

We point out that a modified temperature–redshift relation (T-z relation) of the cosmic microwave background (CMB) cannot be deduced by any observational method that appeals to an a priori thermalisation to the CMB temperature T of the excited states in a probe environment of independently determined redshift z. For example, this applies to quasar-light absorption by a damped Lyman-alpha system due to atomic as well as ionic fine-splitting transitions or molecular rotational bands. Similarly, the thermal Sunyaev-Zel’dovich (thSZ) effect cannot be used to extract the CMB’s T-z relation. This is because the relative line strengths between ground and excited states in the former and the CMB spectral distortion in the latter case both depend, apart from environment-specific normalisations, solely on the dimensionless spectral variable x=hνkBT. Since the literature on extractions of the CMB’s T-z relation always assumes (i) ν(z)=(1+z)ν(z=0), where ν(z=0) is the observed frequency in the heliocentric rest frame, the finding (ii) T(z)=(1+z)T(z=0) just confirms the expected blackbody nature of the interacting CMB at z>0. In contrast to the emission of isolated, directed radiation, whose frequency–redshift relation (ν-z relation) is subject to (i), a non-conventional ν-z relation ν(z)=f(z)ν(z=0) of pure, isotropic blackbody radiation, subject to adiabatically slow cosmic expansion, necessarily has to follow that of the T-z relation T(z)=f(z)T(z=0) and vice versa. In general, the function f(z) is determined by the energy conservation of the CMB fluid in a Friedmann–Lemaitre–Robertson–Walker universe. If the pure CMB is subject to an SU(2) rather than a U(1) gauge principle, then f(z)=1/41/3(1+z) for z≫1, and f(z) is non-linear for z∼1.

Application of displacement damage dose approach to low-energy proton irradiated GaInP/GaAs/Ge solar cells

In this paper, a displacement damage simulation model for proton-irradiated GaInP/GaAs/Ge triple junction (TJ) solar cells is constructed in Geant4, and the problem of the displacement damage dose curve deviation for low-energy protons is analyzed. The modeling results show that energy loss effects and local displacement damage are important factors for the deviation of the displacement damage dose curve. The non-ionizing energy loss (NIEL) values of GaAs sub-cells calculated by Geant4 can effectively improve the deviation of the curve caused by energy loss effects. The NIEL should be constrained by the structure and size of the device rather than just the proton energy and material type. In addition, the isotropic radiation field numerical method proposed in this paper allows the displacement damage simulation model constructed in Geant4 to be expediently applied to the radiation environment in space.

Measurements of multijet event isotropies using optimal transport with the ATLAS detector

A measurement of novel event shapes quantifying the isotropy of collider events is performed in 140 fb−1 of proton-proton collisions with s\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\sqrt{s} $$\\end{document} = 13 TeV centre-of-mass energy recorded with the ATLAS detector at CERN’s Large Hadron Collider. These event shapes are defined as the Wasserstein distance between collider events and isotropic reference geometries. This distance is evaluated by solving optimal transport problems, using the ‘Energy-Mover’s Distance’. Isotropic references with cylindrical and circular symmetries are studied, to probe the symmetries of interest at hadron colliders. The novel event-shape observables defined in this way are infrared- and collinear-safe, have improved dynamic range and have greater sensitivity to isotropic radiation patterns than other event shapes. The measured event-shape variables are corrected for detector effects, and presented in inclusive bins of jet multiplicity and the scalar sum of the two leading jets’ transverse momenta. The measured distributions are provided as inputs to future Monte Carlo tuning campaigns and other studies probing fundamental properties of QCD and the production of hadronic final states up to the TeV-scale.

A Data-Driven Variance Reduction Technique for Efficiently Modelling Astronaut Radiation Doses in Spacecraft in High-Energy Isotropic Radiation Fields.

The ionizing radiation exposure to crew on current and future space missions can significantly increase their health risks for cancers, degenerative diseases, and other acute and late effects. A common approach for estimating risk to crew is by completing stochastic (e.g., Monte Carlo) or deterministic particle transport simulations. Within the simulated environment, a small fraction of the particle histories tracked will interact with the astronaut or detector, particularly for larger spacecraft such as the International Space Station, Tiangong Space Station or Lunar Gateway. These simulations can be computationally intensive as they require a very large number of particle histories to achieve a low statistical uncertainty. Variance reduction techniques are applied to simulations to reduce the computational time of the simulation while maintaining the same (or less) statistical uncertainty. The variance reduction technique developed herein involves applying a directional source bias to an isotropic radiation field, such as galactic cosmic rays, to reduce the quantity of particles that have a low probability of interacting with the astronaut or detector. A custom application has been developed utilizing the Geant4 Toolkit that computes the trajectories and energies of particles in three dimensions in the International Space Station using the Monte Carlo method. The results demonstrate the impact of our variance reduction technique on effective dose equivalence depending on: primary and secondary particle type (proton, neutron, photon, heavy ion, etc.), geometric volumes and spacecraft materials. Our variance reduction technique can be tuned by the user to optimize the simulation time depending on their objectives and enables rapid testing of different shield configurations and materials. This variance reduction technique is implemented easily using several input parameters for boundary conditions. Recommended values are presented for rapid implementation in simulations.

Position‐only planar hexagonal array antenna pattern nulling with simultaneous side lobe reduction at multiple azimuth planes

SummaryThis article presents a study on the placement of multiple nulls as well as minimization of side lobe level in the radiation pattern using a planar hexagonal antenna array structure in two different vertical planes. The desired null depth is achieved to suppress the interference signal by the position‐only control of the uniformly excited isotropic antennas in the array structure. The immediate solution to the mentioned computational problem is reached by various meta‐heuristic optimization algorithms such as teaching learning‐based optimization (TLBO), symbiotic organism search (SOS), and moth fly optimization (MFO) within a considerably reduced processing time with a control over the design constrains. Various examples for diversified scenarios are demonstrated to place multiple deep nulls in the radiation pattern without compromising the pattern constraints and all other radiation pattern characteristics. This experiment sought to illustrate and quantify the unique benefits and limitations of proposed technique using three considered meta‐heuristic optimization algorithm.

Modeling and Simulation of a Micro-Strip Patch Antenna in Pentagonal Fractal Geometry

The antenna is an important element in the field of communication for transmitting and receivinginformation in the form of electromagnetic waves, it is also used in several fields such as detection systems, satellites and surveillance aircraft, communications networks and GPS automobiles and satellite communications through the system. The design of the antennas using the A-HFSS software "Ansoft- High Frequency Structure Simulator" is essentially based on the variation of the shape of the antenna and its conductive material, the nature and the thickness of the substrate in order to have a structure that resonates in the desired frequencies for applications precise.The goal of this work is to study and design a micro strip patch antenna in fractal geometry, regarding thecharacteristics such as the reflection coefficients, the gain and the radiation implemented in the environment HFSS software. The patch antenna is characterized by its small size, low cost, easy manufacturing and network connectivity. Despite its space-saving appearance, it retains the electromagnetic properties that ensure the device connectivity. We have compared the patch antenna in pentagonal and fractal pentagonal geometry in 1D to 3D pentagonal antenna array on the resonance frequency fed by a micro-strip line in order to have the best characteristics of these antennas; the bandwidth and the directivity of this antenna, using the electromagnetic simulation tool in the frequency domain CST MICROWAVE STUDIO.The information’s will reach: -The resonance frequency is higher for a normal patch antenna compared to that of a fractal patch antenna.- There is a presence of interferences due to the correctly destination.- The gain radiation pattern is a dipole (isotropic antenna) in the fractal antenna.– The bandwidth is wider for a fractal patch antenna compared to that of a normal patch antenna.

A Proposed Analytical Inter-Cell Interference Model for Mobile Cellular Systems with Isotropic Antenna

4G and beyond cellular systems intend to use a frequency reuse factor of one with three sectors per BS site. This configuration leads to an increase in inter-cell interference (ICI). Thus, ICI modeling is very necessary to design and analyze any cellular system. The impact of ICI is modeled analytically in this paper. The effect of six interfering BS sites surrounding the serving BS is examined. The ICI is first mathematically modeled as a function of BS-UE distance for several environments based on pathloss exponent and then validated using an explicit simulation model. Secondly, the results obtained from the proposed model and the explicit simulation model are compared. The comparisons showed good agreement between the results of the proposed model and the simulation model. The mathematical model is convenient to the standardized ITU-R model and has the flexibility to apply any antenna patterns that is compatible with these international models. Furthermore, this model enables ICI estimation by deploying the serving BS cell only without the need to deploy the surrounding nine interfering cell. This has positive impact on reducing the time required for system level simulation.

Synthesis of Reconfigurable Multiple Shaped Beams of a Concentric Circular Ring Array Antenna Using Evolutionary Algorithms

The approach described in this paper uses evolutionary algorithms to create multiple-beam patterns for a concentric circular ring array (CCRA) of isotropic antennas using a common set of array excitation amplitudes. The flat top, cosec2, and pencil beam patterns are examples of multiple-beam patterns. All of these designs have an upward angle of θ = 0◦. All the patterns are further created in three azimuth planes (φ = 0◦, 5◦, and 10◦). To create the necessary patterns, non-uniform excitations are used in combination with evenly spaced isotropic components. For the flat top and cosecant-squared patterns, the best combination of common components, amplitude and various phases is applied, whereas the pencil beam pattern is produced using the common amplitude only. Differential evolutionary algorithm (DE), genetic algorithm (GA), and firefly algorithm (FA) are used to generate the best 4-bit discrete magnitudes and 5-bit discrete phases. These discrete excitations aid in lowering the feed network design complexity and the dynamic range ratio (DRR). A variety of randomly selected azimuth planes are used to verify the excitations as well. With small modifications in the desired parameters, the patterns are formed using the same excitation. The results proved both the efficacy of the suggested strategy and the dominance of DE over GA as well as FA.

A Miniaturized Arc Shaped Near Isotropic Self-Complementary Antenna for Spectrum Sensing Applications

This paper presents the design of an arc-shaped near-isotropic self-complementary antenna for spectrum sensing application. An arc-shaped dipole with horizontal and vertical arms is used to achieve a near isotropic radiation pattern. The radiation pattern improved by adjusting the horizontal and vertical arm lengths. Simulated and experimental results show that the proposed antenna has an impedance bandwidth of 146% (2.4-18.4 GHz) for VSWR ≤ 2 with a good radiation pattern. In order to quantify the antenna performance, antenna gain variation, bandwidth, efficiency, and size have been compared with previously reported designs. It is shown that the proposed arc-shaped antenna can achieve nearly isotropic radiation patterns with a maximum radiation efficiency of 92%. The isotropic performance of the antenna has been characterized by observing the radiation pattern and solid angle. The FR4 substrate is used as a dielectric with relative permittivity 4.4 and loss tangent of 0.02. (εr = 4.4, h = 1.6 mm) The simulated and measured results are in good comparison, and the proposed design is a suitable candidate for spectrum sensing.