Beam Synthesis Research Articles

Deep learning-based general beam synthesis for atmospheric propagation

Optimizing the transmit light beams unlocks the full potential of free-space optical systems. However, designing application-specific light beams remains a challenge, especially for those traversing random media. In this study, we address this gap by proposing a deep learning-based method to generate optimal beams for propagation through atmospheric turbulence. The key mechanism is approximating the receiver statistics through batch-wise computation during the training of a convolutional neural network (CNN). On that basis, statistical performance metrics including average received power, scintillation index, and mean signal-to-noise ratio (SNR) are considered for optimization. Pseudo-modes of the beam are synthesized by weighted superposition of Hermite-Gaussian eigenmodes, enabling the creation of arbitrary complex amplitude profiles, i.e., general beams. An end-to-end implementation framework is designed to facilitate self-supervised learning and eliminate the need for pre-calculated datasets. Effectiveness of the synthesized beam is validated by wave optics simulation and experiments. In particular, comparison with Gaussian Schell-model beams demonstrates that the synthesized beam can achieve lower scintillation and greater intensity at the same time, leading to markedly enhanced receiver SNR. This advantage persists in a wider range of link configurations, extending the application range of stochastic beams.

Enhanced Microwave Beam Synthesis for Phased Array Antennas in High Power Applications

Enhanced Microwave Beam Synthesis for Phased Array Antennas in High Power Applications

Design of a Compact Log Periodic Dipole Array Antenna for Broadband and High-Power Beam Synthesis Using Superposition

This paper investigates various array beam shapes for high-power electronic warfare applications using an actual broadband array antenna. For use in a limited mounting space, a compact printed log periodic dipole array (LPDA) operating over a wide bandwidth is designed. The LPDA is then extended to an 8 × 1 array, with active element patterns (AEPs) obtained through simulation and measurement. Beam synthesis is performed by the superposition of several array patterns, which involves adjusting the weight of each AEP. To derive a synthesized array beam shape that is similar to the guided mask, the Taylor window weighting method is applied to each array pattern. Finally, beam synthesis for the flat-top beam, cosecant-squared beam, and iso-flux beam is performed using Taylor window-weighted AEPs, and the results are compared with those of beam shapes using ideal isotropic patterns. The results demonstrate that various beam shapes can be achieved for high-power electronic warfare applications using the AEPs of an actual array antenna.

Accelerating optical phased array calibration with improved SPGD algorithm

As a new type of beam pointing control technology, optical phased array has broad application prospects in the fields of laser radar and beam synthesis. However, the phase error in practical application brings great difficulties to beam detection and deflection, which must be calibrated. In this paper, a SPGD algorithm combined with Adam algorithm (ASPGD) is proposed and compared with the traditional optimization algorithm. The results show that the improved SPGD algorithm can double the convergence speed and increase the cosine similarity value by about 10%.

A Shaped Reflector Antenna Design Approach for Contoured Beam Synthesis With Surface Curvature Constraints

A Shaped Reflector Antenna Design Approach for Contoured Beam Synthesis With Surface Curvature Constraints

Analytical Study of 2D Beam Synthesis in Configurable Multi-Port Periodic Radiators

Analytical Study of 2D Beam Synthesis in Configurable Multi-Port Periodic Radiators

Regenerative effects of immobilized hyaluronidase and subtilisin enzymes on experimental models of chemical and mechanical corneal trauma

Purpose: to study the regenerative potential of immobilized hyaluronidase and subtilisin enzymes preparations in experimental models of chemical and mechanical corneal trauma.Material and methods. The study involved 28 mongrel rabbits weighing 3.5 to 4 kg, divided into 4 groups for separate studies of repair models according to different types of injury (chemical vs. mechanical), and different drugs and the methods of administration thereof. Hyaluronidase (PEG-hyaluronidase) and subtilisin (PEG-subtilisin) pegylated by electron beam synthesis technology were used. The condition of the cornea was assessed 24 hours after the injury had been inflicted, whereupon the eyes were enucleated and histologically examined.Results. The chemical trauma groups treated by PEG-hyaluronidase revealed a decrease in the wound area by an average of 36.6 mm2, while those given a subconjunctival injection showed a 36.08 mm2 decrease. If PEG-subtilisin was applied, the area of the corneal defect revealed an average increase of 11.63 mm2 (with a case of perforation registered). In subconjunctival injection of PEG-subtilisin, the wound area decreased by 27.42 mm2. In the mechanical trauma groups, a similar pattern was observed: with the instillation of PEG-subtilisin, the wound area averaged 53.63 mm2 and 1 case of perforation was registered, whilst with subconjunctival administration, the wound area decreased to 28.76 mm2. With PEG-hyaluronidase instillations, a significant wound area decrease of 36 mm2 was noted, and with subconjunctival administration, the wound area decreased by 70.3%. A higher corneal transparency in the optical zone and a weaker inflammatory reaction with the use of PEG hyaluronidase were revealed by histological testing.Conclusion. A positive effect of PEG-hyaluronidase, specifically concerning the enhancement of regenerative processes in the wound in chemical and mechanical wounds could be seen. PEG-subtilisin showed no positive effects, which may be associated with high fibrinolytic activity.

Synthesis of flat‐top beampatterns based on simple polynomial transforms of Gaussian excitations

AbstractIn the design of antenna arrays which require fast and robust flat‐top beam synthesis, computationally efficient methods are preferred. This feature is usually met by analytical techniques or simple optimisation procedures. On the other hand, in the flat‐top beam synthesis, a common requirement is the ability to control beamwidth or sidelobe level. However, this can result in a high dynamic range ratio (DRR) of array's excitation coefficients. In this paper, a straightforward method for the design of symmetrical flat‐top arrays with controllable sidelobe level or DRR is proposed. The method is based on quadratic and cubic transforms of Gaussian excitations. In addition, the method utilises zero coefficients whose positions are used to control the DRR, including the ability to achieve its minimum. Compared to other flat‐top arrays with analytically shaped beams, the proposed arrays have lower DRRs for the same sidelobe level.

Superflux of an organic adlayer towards its local reactive immobilization

On-surface mass transport is the key process determining the kinetics and dynamics of on-surface reactions, including the formation of nanostructures, catalysis, or surface cleaning. Volatile organic compounds (VOC) localized on a majority of surfaces dramatically change their properties and act as reactants in many surface reactions. However, the fundamental question “How far and how fast can the molecules travel on the surface to react?” remains open. Here we show that isoprene, the natural VOC, can travel ~1 μm s−1, i.e., centimeters per day, quickly filling low-concentration areas if they become locally depleted. We show that VOC have high surface adhesion on ceramic surfaces and simultaneously high mobility providing a steady flow of resource material for focused electron beam synthesis, which is applicable also on rough or porous surfaces. Our work established the mass transport of reactants on solid surfaces and explored a route for nanofabrication using the natural VOC layer.

Full-Vectorial Light Propagation Simulation of Optimized Beams in Scattering Media

Volumetric scattering prevents imaging modalities in biomedical optics from imaging deep inside tissue. The optimization of the incident wavefront has the potential to improve these imaging modalities. To investigate the optimization and light propagation of such beams inside scattering media rigorously, full-vectorial simulations based on solutions of Maxwell’s equations are necessary. In this publication, we present a versatile two-step beam synthesis method to efficiently simulate the scanning and phase optimization of a focused beam inside a static scattering medium. We present four different approaches to the phase optimization of the energy density and the absolute value of the Poynting vector. We find that these quantities have two regions with different, almost exponential decays over depth for a non-optimized beam. Optimization by conjugating the phase of the projected electric field in various directions at the focus shows an improvement below a certain penetration depth. Seeking global solutions to the optimization problems reveals an even better enhancement in the energy density and the absolute value of the Poynting vector in the focus. For Poynting vector optimization, the differences between the presented optimization approaches are more significant than for the energy density. With the presented method, it is possible to efficiently simulate different imaging methods improved by wavefront shaping to investigate their possible penetration depths.

ARU-GAN: U-shaped GAN based on Attention and Residual connection for super-resolution reconstruction

Plane-wave ultrasound imaging technology offers high-speed imaging but lacks image quality. To improve the image spatial resolution, beam synthesis methods are used, which often compromise the temporal resolution. Herein, we propose ARU-GAN, a super-resolution reconstruction model based on residual connectivity and attention mechanisms, to address this issue. ARU-GAN comprises a Full-scale Skip-connection U-shaped Generator (FSUG) with an attention mechanism and a Residual Attention Patch Discriminator (RAPD). The former captures global and local features of the image by using full-scale skip-connections and attention mechanisms. The latter focuses on changes in the image at different scales to enhance its discriminative ability at the patch level. ARU-GAN was trained using a combined loss function on the Plane-Wave Imaging Challenge in Medical Ultrasound (PICMUS) 2016 dataset, which includes three types of targets: point targets, cyst targets, and in-vivo targets. Compared to Coherent Plane-Wave Compounding (CPWC), ARU-GAN achieved a reduction in Full Width at Half Maximum (FWHM) by 5.78%–20.30% on point targets, improved Contrast (CR) by 7.59–11.29 percentage points, and Contrast to Noise Ratio (CNR) by 30.58%–45.22% on cyst targets. On in-vivo target, ARU-GAN improved the Peak Signal-to-Noise Ratio (PSNR) by 11.94%, the Complex-Wavelet Structural Similarity Index Measurement (CW-SSIM) by 17.11%, and the Normalized Cross Correlation (NCC) by at least 2.17% compared to existing deep learning methods. In conclusion, ARU-GAN is a promising model for the super-resolution reconstruction of plane-wave medical ultrasound images. It provides a novel solution for improving image quality, which is essential for clinical practice.

Time-Efficient Multiplex Orbital Angular Momentum Beam Synthesis With Arbitrary-Shaped Array Using Multipole Moment Expansion

Despite the significant interest in pattern synthesis over the decades, the beam synthesis of orbital angular momentum (OAM) has received relatively little attention. In this paper, we present a time-efficient method for OAM beam synthesis based on multipole moment expansion. The approach introduces the multipole moment term as a transforming level, which separates the excitation coefficients and radiation pattern. We evaluate the performance of our proposed method through several examples and demonstrate its high capability to synthesize multiplex OAM beams with arbitrary-shaped arrays, ensuring reasonable accuracy. The theoretical analysis shows a significant improvement in computational efficiency and a great reduction in computational complexity compared to conventional synthesis methods. Finally, we design, fabricate, and measure a double-ring concentric circular patch antenna array using our proposed method, and the measured results confirm the validity of our approach. The work provides a valuable contribution to the field of OAM beam synthesis and offers a promising avenue for future research.

Power Pattern Synthesis With Peripherally Excited Phased Arrays

Peripherally excited phased arrays have been demonstrated as an effective way to realize some aspects of phased array performance with a simple design and reduced cost. This work develops a method to realize shaped beams with peripherally excited arrays by controlling the relative magnitude and phase of the antenna’s peripheral sources. Through a simple model of fields in a parallel-plate waveguide, a linear system of equations can be defined and solved to find the peripheral source excitations that best approximate a desired field pattern. This model is used to solve for a uniform broadside beam, and yields a higher aperture illumination efficiency than a broadside beam obtained from an equal-amplitude excitation. A cosecant beam is also synthesized, showing good agreement with the goal beam pattern. The linear system of equations can be easily integrated into other beam synthesis techniques for increased design flexibility. A particle swarm optimization is used to solve for controlled side lobe-levels, flat-top and multi-beam patterns. Beams realized with full-wave simulation show good agreement with the ideal and predicted beams.

Room Temperature Ion Beam Synthesis of Ultra-Fine Molybdenum Carbide Nanoparticles: Toward a Scalable Fabrication Route for Earth-Abundant Electrodes.

Molybdenum carbides are promising low-cost electrocatalysts for electrolyzers, fuel cells, and batteries. However, synthesis of ultrafine, phase-pure carbide nanoparticles (diameter<5nm) with large surface areas remains challenging due to uncontrollable agglomeration that occurs during traditional high temperature syntheses. This work presents a scalable, physical approach to synthesize molybdenum carbide nanoparticles at room temperature by ion implantation. By tuning the implantation conditions, various molybdenum carbide phases, stoichiometries, and nanoparticle sizes can be accessed. For instance, molybdenum ion implantation into glassy carbon at 30keV energy and to a fluence of 9×1016 atcm-2 yields a surface η-Mo3C2 with a particle diameter of (10±1)nm. Molybdenum implantation into glassy carbon at 60keV to a fluence of 6×1016 atcm-2 yields a buried layer of ultrafine γ'-MoC/η-MoC nanoparticles. Carbon ion implantation at 20keV into a molybdenum thin film produces a 40nm thick layer primarily composed of β-Mo2C. The formation of nanoparticles in each molybdenum carbide phase is explained based on the Mo-C phase diagram and Monte-Carlo simulations of ion-solid interactions invoking the thermal spike model. The approaches presented are widely applicable for synthesis of other transition metal carbide nanoparticles as well.

Green Joint Communications and Sensing Employing Analog Multi-Beam Antenna Arrays

Joint communications and sensing (JCAS) is potentially a hallmark technology for the sixth generation mobile network (6G). Most existing JCAS designs are based on digital arrays, analog arrays with tunable phase shifters, or hybrid arrays, which are effective but are generally complicated to design and power inefficient. This article introduces the energyefficient and easy-to-design multi-beam antenna arrays (MBAAs) for JCAS. Using pre-designed and fixed analog devices, such as lens or Butler matrix, MBAA can simultaneously steer multiple beams yet with negligible power consumption compared with other techniques. Moreover, MBAAs enable flexible beam synthesis, accurate angle-of-arrival estimation, and easy handling/ utilization of the beam squint effect. All these features have not been well captured by the JACS community yet. To promote the awareness of them, we intuitively illustrate them and also exploit them for constructing a multi-beam JCAS framework. Finally, the challenges and opportunities are discussed to foster the development of green JCAS systems.

Multiple Scattering Model for Beam Synthesis With Reconfigurable Intelligent Surfaces

This article presents a method of synthetic beamforming for reconfigurable intelligent surfaces (RIS). The method uses a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</i> -matrix based multiple scattering model to compute the scattering from the RIS. We assume that the elements of the RIS are infinite circular cylinders. This allows us to make the model two-dimensional. Furthermore, we assume that the RIS elements satisfy the impedance boundary condition (IBC), the complex parameter of which adjusts the phase shift of the scattered field. We synthesize the beam both analytically and numerically. Both approaches rely on an approximation that assumes RIS elements that are small compared to the wavelength. We demonstrate the efficacy of the beam synthesis by applying it in a test case that features a linear array of RIS elements.

Spherical Fourier-Transform-Based Real-TimeNear-Field Shaping and Focusing in Beyond-5G Networks

For ultra-reliable high-data-rate communication, the beyond fifth generation (B5G) and the sixth generation (6G) wireless networks will heavily rely on beamforming, with mobile users often located in the radiative near-field of large antenna systems. Therefore, a novel approach to shape both the amplitude and phase of the electric near-field of any general antenna array topology is presented. Leveraging on the active element patterns generated by each antenna port, the beam synthesis capabilities of the array are exploited through Fourier analysis and spherical mode expansions. As a proof-of-concept, two different arrays are synthesized from the same active antenna element. These arrays are used to obtain 2D near-field patterns with sharp edges and a 30 dB difference between the fields' magnitudes inside and outside the target regions. Various validation and application examples demonstrate the full control of the radiation in every direction, yielding optimal performance for the users in the focal zones, while significantly improving the management of the power density outside of them. Moreover, the advocated algorithm is very efficient, allowing for a fast, real-time modification and shaping of the array's radiative near-field.

Wing Conformal Load-Bearing Endfire Phased Array Antenna Skin Technology

In this article, a phased array antenna skin is proposed for conformally assembling scenarios and wide scanning applications. Planar inverted F antenna (PIFA) is used as a radiation element of the proposed array due to its low profile and omnidirectional radiation pattern. The PIFA element is conformally assembled in a wing of an aircraft and is designed and fabricated with the technology of composite material, which makes the PIFA element load bearing. The endfire beam synthesis is also investigated, and the proposed array supports wide-angle beam scanning in both forward and backward regions. An array of 240 PIFA elements are designed, simulated, fabricated, and experimentally tested. The fabricated sample is able to bear an overload of 1 g in the mechanical test, and all the electronic experiment results agree well with the simulation data.

A study on the material properties of novel PEGDA/gelatin hybrid hydrogels polymerized by electron beam irradiation.

Gelatin-based hydrogels are highly desirable biomaterials for use in wound dressing, drug delivery, and extracellular matrix components due to their biocompatibility and biodegradability. However, insufficient and uncontrollable mechanical properties and degradation are the major obstacles to their application in medical materials. Herein, we present a simple but efficient strategy for a novel hydrogel by incorporating the synthetic hydrogel monomer polyethylene glycol diacrylate (PEGDA, offering high mechanical stability) into a biological hydrogel compound (gelatin) to provide stable mechanical properties and biocompatibility at the resulting hybrid hydrogel. In the present work, PEGDA/gelatin hybrid hydrogels were prepared by electron irradiation as a reagent-free crosslinking technology and without using chemical crosslinkers, which carry the risk of releasing toxic byproducts into the material. The viscoelasticity, swelling behavior, thermal stability, and molecular structure of synthesized hybrid hydrogels of different compound ratios and irradiation doses were investigated. Compared with the pure gelatin hydrogel, 21/9wt./wt. % PEGDA/gelatin hydrogels at 6kGy exhibited approximately up to 1078% higher storage modulus than a pure gelatin hydrogel, and furthermore, it turned out that the mechanical stability increased with increasing irradiation dose. The chemical structure of the hybrid hydrogels was analyzed by Fourier-transform infrared (FTIR) spectroscopy, and it was confirmed that both compounds, PEGDA and gelatin, were equally present. Scanning electron microscopy images of the samples showed fracture patterns that confirmed the findings of viscoelasticity increasing with gelatin concentration. Infrared microspectroscopy images showed that gelatin and PEGDA polymer fractions were homogeneously mixed and a uniform hybrid material was obtained after electron beam synthesis. In short, this study demonstrates that both the presence of PEGDA improved the material properties of PEGDA/gelatin hybrid hydrogels and the resulting properties are fine-tuned by varying the irradiation dose and PEGDA/gelatin concentration.

Экспериментальное изучение аллергизирующего действия препарата на основе гиалуронидазы, пегилированной по технологии электронно-лучевого синтеза

Introduction. Hyaluronidase is an enzyme preparation widely used in medicine, including ophthalmology. Hyaluronidase, having a protein structure, carries a potential danger in the form of undesirable allergic reactions. To avoid allergenic effects, protein structures are modified by combining with a polymer carrier, for example, by polyethylene glycol (PEG). Aim. To study the possible allergenic potential of hyaluronidase, PEGylated using the technology of electron beam synthesis, with various routes of administration. Materials and methods. The object of the study is PEGylated hyaluronidase (PEG-Hyal). Experimental animals are hybrid mice and guinea pigs. Seven types of experiments were carried out: anaphylactogenic activity; conjunctival challenge test; cutaneous applications; delayed-type hypersensitivity (DTH); active cutaneous anaphylaxis; indirect mast cell degranulation; inflammatory response to concanavalin A (ConA). Results. When studying anaphylactogenic activity, an anaphylactic reaction was not observed in guinea pigs. The conjunctival challenge test also revealed no signs of hypersensitivity to the drug. In the study of sensitization, no development of local allergic reactions was observed. In experiments to the study DTH in mice, there were no significant differences for the DTH index in the experimental and control groups. The assessment of active skin anaphylaxis has been showed that the diameter of the stained spot did not significantly differ in both experimental groups from the control one. In indirect mast cell degranulation experiments, it was found that there was no statistically significant change in the mast cell degranulation index. Evaluation of the allergenic potential of PEG-Hyal in the inflammatory response to ConA showed that there is no statistically significant difference between the experimental and control groups. Conclusion. Based on the results of the experiments, it can be concluded that PEG-Hyal does not have an allergenic potential in various routes of administration, which significantly expands the possibilities of its clinical use.