Orthogonal Field Research Articles

High gain and circularly polarised metasurface suspended twin port Al2O3 based antenna for mm-wave 5 G communication system

Abstract This article discusses design and analysis of two-port alumina ceramic based aerial in mm-wave spectrum. Aperture coupling stimulate ceramic and produce dual fundamental orthogonal field i.e. HEM 11 δ x and HEM 11 δ y mode. Important features of structured aerial are: (i) designed antenna produces the circular wave within 32.65–33.25 GHz; (ii) double negative unit cell based metasurface suspension enhances the antenna’s broadsided gain to 9.0 dBi; and (iii) orthogonal arrangement of aerial ports improve the separation to over 25 dB. Experimental outcomes confirm the working spectrum of design aerial in between 32.21–33.55 GHz. Directional pattern and decent assessment of diversity parameters prepares the planned aerial appropriate for 5 G communication in mm-wave regime (n260/n511 frequency bands).

Compact UWB Slot Antenna With Dual‐Circular Polarization and Improvement of CP Performance

ABSTRACTThis study presents an ultrawideband (UWB) slot antenna with a dual‐circular (left‐ and right‐hand) circular polarization. The presented circularly polarized (CP) antenna involves 45° oriented patches cooperating with I‐ and L‐shaped stubs fed by a directional coupler. Using a directional coupler produces orthogonal electric fields to generate CP operation, and as a result of the cooperation between patches and stubs, antenna CP performance is improved. The fabricated antenna, including two microstrip ports, occupies an area of 50 × 50 × 1.016 mm3. By stimulating each antenna port independently, it is possible to obtain right‐hand circular polarization (RHCP) and left‐hand circular polarization (LHCP). The experiments show that the antenna being presented has an operating frequency of 116.14% (2.87–10.82 GHz) and an axial ratio bandwidth of 33.97% (7.11–10.02 GHz). Furthermore, a stable radiation pattern was also measured for the antenna, which had a maximum gain of 2.77 dBic in the operating frequency band.

Study on concentration distribution and detonation characteristics of typical multiphase fuel in orthogonal flow field

The fuel concentration distribution and detonation characteristics are important for performance evaluation. In order to meet the needs of airdrop, launcher and missile, the transient flow and detonation process of multiphase fuel in orthogonal flow field are analyzed by experiments and numerical simulations. The dynamic detonation model of ethyl ether (EE), propylene oxide (PO) and tetrahydro dicyclopentadiene (JP-10) is built. The flow process, concentration distribution, overpressure, temperature and detonation wave structure of the three fuels are obtained. The results show that the falling velocity has obvious influence on the detonation process of fuel droplets. The falling velocity of 0.5 Ma makes the fuel concentration distribution more uniform and the energy output is better. The peak overpressure of EE, PO and JP-10 is 2.88 MPa, 3.21 MPa and 2.96 MPa respectively. The peak temperature is 2885 K, 3230 K and 2955 K respectively. The burn out rate increases by 8.5%, 8.1% and 13.7% respectively. JP-10 has higher sensitivity to falling velocity, and there are obvious secondary peaks of overpressure in low-speed state. PO has higher stability for falling velocity, and the scaled length of high temperature/pressure after detonation wave is 0.145 m·kg-1/3.

Path Planning for Mobile Robots Based on the Improved DAPF-QRRT* Strategy

The rapidly exploring random tree star (RRT*) algorithm is widely used to solve path planning problems. However, the RRT* algorithm and its variants fall short of achieving a balanced consideration of path quality and safety. To address this issue, an improved discretized artificial potential field-QRRT* (IDAPF-QRRT*) path planning strategy is introduced. Initially, the APF method is integrated into the Quick-RRT* (Q-RRT*) algorithm, utilizing the attraction of goal points and the repulsion of obstacles to optimize the tree expansion process, swiftly achieving superior initial solutions. Subsequently, a triangle inequality-based path reconnection mechanism is introduced to create and reconnect path points, optimize the path length, and accelerate the generation of sub-optimal paths. Finally, by refining the traditional APF method, a repulsive orthogonal vector field is obtained, achieving the orthogonalization between repulsive and attractive vector fields. This places key path points within the optimized vector field and adjusts their positions, thereby enhancing path safety. Compared to the Q-RRT* algorithm, the DPF-QRRT* algorithm achieves a 37.66% reduction in the time taken to achieve 1.05 times the optimal solution, and the IDAPF-QRRT* strategy nearly doubles generated path safety.

Electro-optical properties of rectangle-shaped crater quantum rings under orthogonal electric and magnetic fields

The electronic and optical properties of an electron in realistic rectangle-shaped crater quantum rings under orthogonal electric and magnetic fields have been theoretically studied. The Schrödinger wave equation was solved using the finite element method within the effective mass approximation. A Stark effect with anomalous oscillatory behavior was observed for electric field strengths less than 10 kV/cm. The threading magnetic field leads to the formation of damped oscillations in the absorption coefficient peaks, which are closely related both to the Aharonov-Bohm oscillations and to a shift of the absorption peaks towards blue or red, depending on the dimensions and morphology of the central crater. Our model is sufficiently flexible such that several results appear as particular cases of the quantum ring with a rectangular central crater.

A perspective on guided electrophoretic transport of particles in liquid crystals

Nonlinear electrophoresis in complex fluids like nematic liquid crystals provides new pathways toward achieving precisely controlled motion and assembly of microscopic objects. The nematic host introduces a paradigm shift in the mechanism of electrophoretic transport by generating unbalanced electro-osmotic flows around the colloidal particle due to symmetry breaking of the medium caused by the induced topological defects. Rationally designed particles, which induce various types of defects and asymmetries, provide new opportunities in this regard. In this Perspective article, we discuss how the asymmetry in the shape and interfacial properties help in piloting the particles using an AC electric field. Finally, we propose some feasible strategies to achieve navigational control using magnetic and photo-responsive particles, guided by orthogonal electric, magnetic fields, and light, respectively.

Measurement of microwave polarization using two polarization orthogonal local microwave electric fields in a Rydberg atom-based mixer.

We propose and demonstrate what we believe to be a novel method for measuring the polarization direction of a microwave electric field in a single measurement using a Rydberg atom-based mixer with two orthogonally polarized local microwave electric fields. This approach eliminates the need for physical rotation of the local field, allowing the polarization angle of the signal field to be determined directly by measuring the ratio of the two beat signals. Furthermore, introducing a weak static magnetic field enables the utilization of the Zeeman effect and exploitation of polarization asymmetry. This distinction allows for determining the polarization direction of the microwave field is θ or 180° - θ within the 0 to 180-degree range. The capability to measure microwave polarization in real-time across this range is very valuable for applications in microwave sensing and information transmission.

Carrier Mobility Enhancement in Ultrathin-Body InGaAs-on-Insulator n-Channel Metal-Oxide-Semiconductor Field-Effect Transistors Based on Dual-Gate Modulation

As a promising candidate for More Moore technology, InGaAs-based n-channel metal-oxide-semiconductor field-effect transistors (nMOSFETs) have attracted growing research interest, especially with InGaAs-on-insulator (InGaAs-OI) configurations aimed at alleviating the short channel effects. Correspondingly, the fabrication of an ultrathin InGaAs body becomes necessary for the full depletion of the channel, while the deteriorated semiconductor–insulator interface-related scattering could severely limit carrier mobility. This work focuses on the exploration of carrier mobility enhancement strategies for 8 nm body-based InGaAs-OI nMOSFETs. With the introduction of a bottom gate bias on the substrate side, the conduction band structure in the channel was modified, relocating the carrier wave function from the InGaAs/Al2O3 interface into the body. Resultantly, the channel mobility with an inversion layer carrier concentration of 1 × 1013 cm−2 was increased by 62%, which benefits InGaAs-OI device application in monolithic 3D integration. The influence of the dual-gate bias from front gate and bottom gate on gate stability was also investigated, where it has been unveiled that the introduction of the positive bottom gate bias is also beneficial for gate stability with an alleviated orthogonal electric field.

Superelliptic quantum rings under orthogonally applied electric and magnetic fields: Electronic and thermal properties

A systematic study was undertaken to analyze the electronic and thermal properties of a single electron within a superelliptic quantum ring under orthogonal magnetic and electric fields. The corresponding Schrödinger equation for this system was numerically solved using the finite element method within the effective mass approximation. The influence of geometric effects associated with the morphology of the inner and outer contours of the superellipse, as well as the impact of external fields on electronic and thermal properties, were analyzed. The flexibility of the superellipse shape parameters considered in this study allows the consideration of different types of rings and the derivation of several electronic properties previously published in the literature as particular cases of our model. It was observed that thermal properties are highly sensitive to external fields and the geometrical potential linked to the topological variations experienced by the superellipse during the growth of the quantum rings.

Toward 3D magnetic force microscopy: Simultaneous torsional cantilever excitation to access a second, orthogonal stray field component

Magnetic force microscopy (MFM) is long established as a powerful tool for probing the local stray fields of magnetic nanostructures across a range of temperatures and applied stimuli. A major drawback of the technique, however, is that the detection of stray fields emanating from a sample’s surface rely on a uniaxial vertical cantilever oscillation, and thus are only sensitive to vertically oriented stray field components. The last two decades have shown an ever-increasing literature fascination for exotic topological windings where particular attention to in-plane magnetic moment rotation is highly valuable when identifying and understanding such systems. Here, we present a method of detecting in-plane magnetic stray field components, by utilizing a split-electrode excitation piezo that allows the simultaneous excitation of a cantilever at its fundamental flexural and torsional modes. This allows for the joint acquisition of traditional vertical mode images and a lateral MFM where the tip–cantilever system is only sensitive to stray fields acting perpendicular to the torsional axis of the cantilever.

Global well-posedness of strong solutions to the two-dimensional inhomogeneous biaxial nematic liquid crystal flow with vacuum

This paper considers the inhomogeneous biaxial nematic liquid crystal flow in a smooth bounded domain Ω⊂R2, where the velocity u and the orthogonal unit vector fields (m,n) admit the Dirichlet and Neumann boundary condition, respectively. By applying piecewise estimate and continuity method, we get the global existence of strong solutions, provided that the basic energy is suitably small. Our result may be regarded as an extension and improvement of Gong-Lin (2022) and Li-Liu-Zhong (2017) to the Neumann boundary condition, where the initial vacuum is allowed. Some new techniques are developed in order to deal with integral estimates caused by the boundary condition, and more complicated model.

Magnetic-Nanorod-Mediated Nanowarming with Uniform and Rate-Regulated Heating.

Rewarming cryopreserved samples requires fast heating to avoid devitrification, a challenge previously attempted by magnetic nanoparticle-mediated hyperthermia. Here, we introduce Fe3O4@SiO2 nanorods as the heating elements to manipulate the heating profile to ensure safe rewarming and address the issue of uneven heating due to inhomogeneous particle distribution. The magnetic anisotropy of the nanorods allows their prealignment in the cryoprotective agent (CPA) during cooling and promotes subsequent rapid rewarming in an alternating magnetic field with the same orientation to prevent devitrification. More importantly, applying an orthogonal static magnetic field at a later stage could decelerate heating, effectively mitigating local overheating and reducing CPA toxicity. Furthermore, this orientational configuration offers more substantial heating deceleration in areas of initially higher heating rates, therefore reducing temperature variations across the sample. The efficacy of this method in regulating heating rate and improving rewarming uniformity has been validated using both gel and porcine artery models.

Electrodynamic model of ball lightning

The paper considers a hypothesis of the structure of ball lightning core as an ensemble of dynamic electric capacitors. The dynamic capacitor is an object consisting of spatially separated charges – electrons and protons. Electrons, due to the action of mutually orthogonal electric and magnetic fields, move in a circle, oscillating in the radial direction. The magnetic field is generated by the movement of protons around the electron ring. The number of protons exceeds the number of electrons, due to which the dynamic capacitor has a positive electric charge. The system of dynamic capacitors is located inside a spherical shell consisting of water molecules polarized in the electric field of the charge of the dynamic capacitor. The shell creates a force that prevents the expansion of dynamic capacitors. It is shown that 1900 dynamic capacitors with a radius of 0.5 cm with a total kinetic energy of 6.36 MJ can fit in ball lightning with an internal shell radius of 6.2 cm. In this case, the energy density in the core of ball lightning can be about 6.4·109 J/m3. This is comparable with the result of measurements of energy density of natural ball lightning.

Entropy generation in a chemically reactive magnetohydrodynamic unsteady micropolar nanofluid flow with activation energy over an inclined stretching sheet: A Buongiorno model approach

The goal of this research is to inspect the heat and mass transfer trends and entropy generation in a time-reliant stagnation point stream of a micropolar fluid across an inclined stretched surface. For this objective, a chemically reactive, electrically conducting fluid exposed to an orthogonal magnetic field is studied. The flow governing equations are modelled using Buongiorno model and are reformed to a system of higher order ordinary differential equations by administering appropriate similarity transformations. This system is quantitatively examined by employing the fourth-order Runge-Kutta scheme with shooting approach. The effects of thermal radiation, magnetic field, uniform heat source/sink, Brownian motion, thermophoresis, activation energy, and binary chemical reaction are studied on velocity, microrotation, temperature, and concentration profiles. It is observed that magnetic field and Brownian motion elevate the flow temperature. Increased activation energy spikes the fluid concentration while increase in binary chemical reaction reduces the particle concentration. Later, impact of various parameters on skin friction coefficient and heat and mass transfer rates are tabularised. Increasing values of thermophoretic diffusion parameter, Brownian diffusion parameter, and chemical reaction parameter improve the rate of mass transfer. Unsteadiness parameter triggers the skin friction coefficient 53.2% when the parameter value was increased from 0.7 to 1.0. Viscous dissipation and thermal radiation increase the rate of entropy generation. A comparison of skin friction coefficient with previous studies demonstrates a strong agreement.

Enhanced optical pumping using mutually orthogonal magnetic fields for quantum sensing

The atomic population trapped in irrelevant atomic states is a limiting factor for sensors based on laser-atom interaction. Using a bi-chromatic light field along with a specific combination of magnetic fields, we show a significant increase in the amplitude (i.e., more than seven times) of a two-photon coherent population trapping (CPT) resonance, which can be effectively used for atomic magnetometry. This increase in amplitude can be explained through enhanced optical pumping via the transfer of population to the relevant Zeeman states. Our experimental observations are consistent with the theoretical calculations carried out for a realistic three-level atomic system using density matrix formalism. We further discuss the optimum condition for enhanced optical pumping by adjusting the ground-state decoherence rate. Enhanced optical pumping through the manipulation of the magnetic field is quite important and is of great interest in the field of quantum technology.

Anisotropy and Cross Fields

AbstractWe consider a cross field, possibly with singular points of valence 3 or 5, in which all streamlines are finite, and either end on the boundary or form cycles. We show that we can always assign lengths to the two cross field directions to produce an anisotropic orthogonal frame field. There is a one‐dimensional family of such length functions, and we optimize within this family so that the two lengths are everywhere as similar as possible. This gives a numerical bound on the minimal anisotropy of any quad mesh exactly following the input cross field. We also show how to remove some limit cycles.

Miniaturized, Broadband, Circular Polarized Horn Antenna With Groove Gap Waveguide Technology

AbstractIn this study, a wideband circularly polarized (CP) H‐plane horn antenna based on Gap Waveguide (GW) technology in K‐band is presented. The proposed antenna consists of two unconnected metal planes. To produce broadband CP radiation, two main methods are utilized. First, two antipodal tapered plates (ATPs) are added in front of the horn. The ATPs are carefully designed for dissimilar polarization orientations. By this technique, the orthogonal electric fields can be prepared. Then, by embedding three metal square pins near the center of the aperture in both inner plates, the impedance bandwidth (BW) and BW of CP radiation of the proposed horn is entirely improved. Its BW for target |S11| < −10 dB is 18–28 GHz. Also, the peak gain fluctuates between 11.5 and 13 dB. This antenna can provide a 3 dB polarization axial‐ratio BW of about 28.5% (20–26 GHz). Total radiation efficiency is higher than 94%. To verify the design, the proposed structure is manufactured and tested. The proposed horn antenna result has an appropriate agreement between measurement and simulation. Its miniaturized dimensions, easy and cheap fabrication, and broadband CP capability make it a proper volunteer for broadband communication systems.

Spatiotemporal characteristics of magneto-acousto-electric fields generated by Bessel beams

The magneto-acousto-electric (MAE) effect shows great significance in neural modulation, whereas the high-precision stimulation cannot be realized by the unidirectional electric distribution perpendicular to the orthogonal acoustic and magnetic fields. A new MAE model is established based on helical wave fronts of Bessel beams in a coaxial magnetic field. Numerical and experimental studies are conducted for quasi-Bessel beams constructed by the saw-tooth phase modulation for a sectorial planar transducer array in a coaxial toroidal magnet. The MAE field induced by the Bessel beam of lth order is determined by those of (l-1)th and (l + 1)th orders. The rotary MAE field with a constant peak-intensity center can only be constructed by the Bessel beam of 1st order, which is effective for neural stimulation. Assisted by therapeutic effects of center-captured drug particles by acoustic-vortex tweezers, the center-converging MAE field may advance a new collaborative stimulation strategy with improved accuracy and reduced acoustic energy.

Circularly Polarized Vivaldi Antennas Integrated with Septum-like Polarizer.

In this paper, two orthogonally placed Vivaldi antennas with a septum-like polarizer to generate circular polarized (CP) waves are presented. Septum polarizers have garnered attention due to their simple structure and high quality of CP waves. While a typical septum polarizer has been applied to various types of waveguides, its applicability to the substrate integrated Vivaldi antenna is demonstrated here for the first time. A pulse train-shaped polarizer is used, which is placed on one of the two Vivaldi antennas. The contours of the polarizer are optimized using a genetic algorithm to provide an equal amplitude and 90° phase difference between the two orthogonal electric fields. In contrast to typical feed networks with a 90° phase shifter, any unwanted loss caused by an electronic circuit can be greatly mitigated. The antenna prototype was fabricated, and its radiation pattern and impedance matching were measured and compared to the simulated results.

Velocity inversion of a relativistic electron incident by a vortex beam in a magnetic field

A method is proposed to invert the velocity of a relativistic electron incident by a vector Bessel vortex beam in a magnetic field by analyzing the spectra of the backward scattered echoes. The scattering power and spectra are investigated based on the vector plane wave angular spectrum theory and the Thomson scattering theory. The results indicate that the high velocity of an electron causes the distribution of the scattered power on the xoy plane to shift in the direction of the velocity. Additionally, the spectra of the scattered echoes display periodic bimodality due to the cyclotron motion of the electrons. The velocity of a relativistic electron parallel to the applied magnetic field can be obtained from the spectrum of the scattered echoes and the parameters of the vortex beam. The conclusions suggest that both the magnitude and the direction of the velocity of a relativistic electron can be determined using a set of orthogonal magnetic fields. This work is significant for studying the scattering of vortex beams by plasmas and developing diagnostic techniques of plasmas.