Radiation Performance Research Articles

A P/X Dual-Band Co-Aperture Array with Dual-Polarized Antenna Based on Forest Biomass Measurement Applications

In this paper, a co-aperture dual-polarized antenna array is proposed. The frequency band covers the P-band (0.4–0.7 GHz) and the X-band (9.3–9.9 GHz). The P-band array is designed in the form of an all-metal Vivaldi, while minimizing the impact of the P-band antenna array structure on the X-band electrical performance. The final profile design for the dual-band antenna structure is only 0.12 λ0 (λ0 corresponds to the wavelength of 0.4 GHz). The X-band design adopts the miniaturized waveguide slot structure, which can be well embedded in the P-band array structure. In order to verify the feasibility of the scheme, prototype processing and testing were carried out, and the test results are consistent with the simulation results. The active VSWRs of the overall design are less than 2.0. Additionally, the dual-band antenna array has favorable radiation performance in each frequency band. It can be used in forest biomass measurements and other interferometric applications.

From structure to luminescence investigation of B2O3-GeO2-BaO-ZnO glass doped with Dy3+

This study describes the preparation of Dy3+ doped B2O3-GeO2-BaO-ZnO (BGBZ) glass using a high temperature melting technique. By means of excitation and emission spectroscopy, it was determined that the glass sample with 25 mol% BaO content had the maximum luminous intensity. The internal structure of the glass was investigated using FT-IR spectroscopy, absorption spectrum testing, and J-O theoretical analysis in order to investigate the principle. The FT-IR spectrum revealed the coexistence of [BO3], [BO4], [GeO4], and [GeO6] coordination polyhedra. The Ω2 value reaching its maximum when the BaO content reached 25mol%, indicating the highest degree of asymmetry in the glass structure at that time. After analyzing the impact of BaO content on the glass structure, it was investigated how the concentration of Dy2O3 doping affected the glass's optical characteristics and radiation performance. By calculating the CIE of glass samples, it was found that the CCT value of glass sample 1.25Dy was 6735 K, suggesting that the produced glass may find use in the w-LED commercial industry. The 0.50Dy glass sample was calculated to have a high σse (8.47×10−22 cm2) from the emission spectral data, suggesting that the prepared glass sample may also be suitable for lasers.

Gain Enhancement and Ground Plane Immunity of Mechanically Driven Thin‐Film Bulk Acoustic Resonator Magnetoelectric Antenna Arrays

AbstractCompact, conformal antennas with ground plane immunity and high gain are crucial to IoT, 5G, and biomedical applications. Conventional electrical antennas suffer large size, detuned impedance, and degraded gain and radiation efficiency on a ground plane as they operate on electromagnetic resonance and use electric dipole for radiation. Utilizing electromechanical resonance, magnetoelectric(ME) coupling, and magnetic dipole radiation in magnetostrictive/piezoelectric heterostructures, ME antennas exhibit ultra‐compact sizes comparable to acoustic wavelength and enhanced radiation performance on a ground plane. This study first utilizes parallel and series antenna array topology to achieve a profound gain and radiation efficiency enhancement without degrading impedance mismatch and quality factor of ME resonators. Notably, by increasing the array element number, 10 dBi gain enhancement is achieved in 3 × 3 thin‐film bulk acoustic resonator (FBAR) ME antenna array, reaching a peak antenna gain of −17.3 dBi. Unlike conventional antenna arrays, ME antenna arrays enhance radiation efficiency without affecting directivity, owing to ultra‐compact dimensions much less than one‐quarter of electromagnetic wavelength. Their ground plane immunity and 3 dB gain enhancement on ground planes with different shapes are also demonstrated. The demonstrated ME antenna arrays are outstanding platform‐independent ultra‐compact high‐gain conformal antenna candidates for wireless communication, wireless power transfer, and portable electronic and biomedical devices.

A meta-plate with radial rainbow reflection effect for broadband suppression of vibration and sound radiation

The suppression of vibration and sound radiation of thin plates has always been a concern in engineering fields such as aerospace, transportation, etc. The rainbow effect refers to that the waves with different frequencies can be stopped in different positions, where the wave energy is also enhanced, as the result of the spatial slowing-down of wave velocities. This effect exhibits great potential in suppressing structural vibration and sound radiation, but corresponding studies have not been reported yet. In this paper, a meta-plate composed of ring-type unit-cells with gradient heights is proposed to generate the radial rainbow reflection effect. Upon analyzing the dispersion relationship of unit-cells and revealing the rainbow reflection mechanism, the broadband vibration and sound radiation performances of a square meta-plate with free boundaries are studied. Numerical and experimental results demonstrate that the proposed meta-plate can suppress the vibration and sound radiation in broadband only with the extreme-low structural inherent loss. The wavenumber spectra of vibration velocity and supersonic intensity at typical frequencies including local and global resonant ones are analyzed to reveal the suppression mechanism of sound radiation, which is the vibration redistribution and systematic vibration reduction resulting from the rainbow reflection effect. Our design enhances the stiffness of plate structures and requires no additional damping, providing a novel approach for structural vibration and sound radiation suppression.

Horn Antenna on Chip Operating at 180 GHz Using the SiGe CMOS Process

This article proposes a chip antenna on millimeter-Waves. This antenna combined with TSMC 180 nm SiGe CMOS technology has the advantage of being small in size and is suitable for wireless communications. The multilayer architecture Horn antenna implemented on M4–M6 can meet both process reliability specifications and radiation performance. The results of the simulation show that the maximum gain is −4.2 dBi. The return loss measurement results are almost consistent with the simulation results, and the bandwidth range is 177.4–183 GHz. This article first describes the antenna production process and measurement results, analyses the impact of the parameters on the antenna, and further compares it with other designs. The excellence of this article is that it proposes a design that solves the problem of large millimeter wave loss and successfully reduces the area. At the same time, this article can contribute to readers’ future optimization and continued research directions, and at the same time contribute simulation and measurement trends to let readers understand the stability of CMOS chip antenna simulation and measurement.

Influence of an Engineered Notch on the Electromagnetic Radiation Performance of NiTi Shape Memory Alloy.

This work explores the influence of a pre-engineered notch on the electromagnetic radiation (EMR) parameters in NiTi shape memory alloy (SMA) during tensile tests. The test data showed that the EMR signal fluctuated between oscillatory and exponential, signifying that the specimen's viscosity damping coefficient changes during strain hardening. The EMR parameters, maximum EMR amplitude, and average EMR energy release rate remained constant initially but rose sharply with the plastic zone radius with progressive loading. It was postulated that new Frank-Read sources permit dislocation multiplication and increase the number of edge dislocations participating in EMR emissions, leading to a rise in the value of EMR parameters. The study of the correlation between EMR emission parameters and the plastic zone radius before the crack tip is a vital crack growth monitoring tool. An analysis of the interrelationship of the EMR energy release rate at fracture with the elastic strain energy release rate would help develop an innovative approach to assess fracture toughness, a critical parameter for the design and safety of metals. The microstructural analysis of tensile fractures and the interrelation between deformation behaviours concerning the EMR parameters offers a novel and real-time approach to improve the extant understanding of the behaviour of metallic materials.

Construction of thermally resistant and flame-retardant multifunctional polyester composite fabrics

The development of thermally resistant textiles with fire safety using thermo-expandable hollow microsphere (TEHM) has garnered significant interest. In this study, TEHM and ammonium polyphosphate (APP) were bonded to polyester fabric surface by using polyurethane coating. The surface morphology, thermally resistant, flame-retardant performance and mechanism of the developed PET@TEHM/APP composite fabric were investigated. The PET@TEHM/APP composite fabric exhibited the reduced thermal conductivity of 0.07458 W/m·K from 0.13120 W/m·K of pristine PET fabric. The thermal conduction and radiation performance of the PET@TEHM/APP composite fabric decreased owing to the low thermal conductivity of the expanded TEHM. The PET@TEHM/APP composite fabric presented a damaged length of 13.5 cm without melt dripping, achieving the B1 classification. The peak heat release of the PET@TEHM/APP composite fabric decreased by 58.3 % versus pristine PET fabric according to cone calorimetry test. PET@TEHM/APP composite fabric also had an FRI of 1.001, showing ‘Good’ flame retardancy performance. TG-IR and char residue analyses suggested that the flame retardancy of PET@TEHM/APP composite fabric improved by the synergic flame-retardant action in both gas and condensed phases.

Development of a metasurface-based slot antenna for 5G MIMO applications with minimized cross-polarization and stable radiation patterns through mode manipulation

This paper presents an approach for designing metasurface antennas using the characteristic mode analysis method for 5G mm-wave multiple input–multiple output (MIMO) systems. The proposed metasurface antenna consists of a 3 × 3 array of modified patches with additional slits and stubs, which are fed by a coupling slot. This configuration reshapes surface currents and improves the radiation performance across a broad frequency range. The design offers significant advantages such as reduced antenna size, minimized influence of higher-order modes, and maintained low cross-polarization (XP) level. Experimental results demonstrate that the proposed metasurface-based slot antenna provides a bandwidth of 29.6% (23–31 GHz) with a return loss better than 10 dB. It achieves a peak gain of 9.43 dB and exhibits an XP level below − 26 dB and − 48 dB at φ=0∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\varphi = 0^{ \\circ }$$\\end{document} and φ=90∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\varphi = 90^{ \\circ }$$\\end{document} planes, respectively. The physical dimensions of the antenna are 0.9λ0 × 0.9λ0 × 0.08λ0, where λ0 is the free space wavelength at 27 GHz, resulting in an approximately 41% reduction compared to the conventional metasurface patch antenna. Moreover, the design proves to be well-suited for MIMO systems, enabling close placement of antenna elements without degrading their radiation patterns. The experimental results in 1 × 2 and 2 × 2 MIMO configurations represent that the isolation between antenna elements are better than 18 dB and 21 dB, respectively. The performance of the antennas remains stable in both configurations, effectively addressing concerns such as beam squint and eliminating the common issue of beam splitting observed in conventional metasurface MIMO antennas. Moreover, the envelope correlation coefficient value in both MIMO configurations is lower than 0.003. This significant advancement offers a promising solution for compact 5G mm-wave massive MIMO applications.

Effect of vertical vibration on transient heat transfer characteristics of flow boiling in small rectangular channels

In the thermal management of fuel cell vehicles, radiators are subjected to vibrations due to vehicle speed and road surface irregularities. However, there has been no comprehensive study of the impact of these vibrations on the heat transfer performance of radiators. Therefore, this paper employs R141b to conduct three-dimensional transient numerical simulations of flow boiling in small channels under vertical vibrations. The study reveals that the single-phase heat transfer coefficient exhibits periodic variations. At the same vibration frequency, the heat transfer frequency for the vertically oriented heating surface is twice that of the horizontally oriented surface, This is because the thermal boundary layer varies with the vibration velocity. Furthermore, as the frequency increases to 21 Hz, the time-averaged heat transfer coefficient can increase by up to 2.5 times. Following boiling onset, for horizontally oriented heating surfaces, an increase in frequency or amplitude enhances the transient heat transfer performance. Under the conditions of 28 Hz and 5 mm, the heat transfer coefficient can increase by 125.7%. However, for vertically oriented heating surfaces, when the frequency exceeds 14 Hz or the amplitude exceeds 8 mm, the heat transfer performance weakens after 7.143 s due to the promotion of bubble coalescence by the vibrations.

High gain D‐band hybrid integrated on‐chip antenna based on low‐cost printed circuit board packaging technology

AbstractA high gain D‐band hybrid integrated on‐chip antenna (OCA) based on a low‐cost printed circuit board (PCB) packaging technology is analyzed and designed in a standard 40‐nm CMOS process in this paper. The proposed OCA is a hybrid structure of a slotted patch OCA with off‐chip PCB ground and off‐chip dielectric resonator (DR). The proposed OCA exhibits a simulated gain of 3.5 dBi and 53% radiation efficiency at 150 GHz. The simulated impedance bandwidth is 20 GHz. The radiation performance and impedance bandwidth of the OCA are observably improved with the proposed techniques. The proposed OCA occupies 0.52 × 0.56 mm2, and addresses the highly desirable yet challenging overall design of future low‐cost integrated millimeter‐wave (mm‐Wave) and terahertz (THz) systems, which hit the mark on cost and compatibility.

Far-Field Estimation Method of Antennas Above Conductive Plane Using a Partially Spherical Near-Field

For evaluating the practical performance of land mobile communication antennas via near-field measurement, it is essential to measure the electromagnetic field, including the housing in which the antennas are mounted. When measuring a heavy housing, scattered waves from the supporting turntable for the antenna under test (AUT) disturb the electromagnetic field. A technique for eliminating the influence of scattered waves is required to evaluate the abnormal AUT radiation performance. This paper proposes a method for estimating the far-field when the antenna exists above an infinite conductive plane, using partially spherical near-field measurements that include the turntable. The proposed method estimates the far-field by combining the equivalent source reconstruction and the far-field estimation with the reflection coefficient method. In the proposed method, the equivalent source distribution surrounding an AUT is reconstructed from a partially spherical near-field to remove the effects of the turntable. Through numerical calculations and experiments, this paper shows that the proposed method can estimate the far-field pattern above an infinite conductive plane, with arbitrary electric constants from a partially spherical near-field. The far-field estimation error is less than -20 dB when the upper hemispherical near-field can be obtained.

Bandwidth‐enhanced horizontally polarized omnidirectional slot antenna based on single‐ridge trapezoidal waveguide

AbstractThis letter presents a Ku‐band horizontally polarized (HP) omnidirectional antenna based on single‐ridge trapezoidal waveguide (STW). Four groups of longitudinal slots are etched on a pair of back‐to‐back arranged STWs to achieve the HP omnidirectional radiation performance. The number and distribution of each radiation slot group are optimized to reduce the gain variation. An out‐of‐phase stripline power divider cascaded with two probe‐based vertical power dividers is used to excite all radiating slots in a series‐parallel hybrid structure, which helps to enhance the boresight radiation bandwidth. For demonstration, a prototype covering 14.5 to 15.5 GHz is designed, fabricated, and measured. Experimental results show that the good impedance matching (|S11|←14 dB) and the measured out‐of‐roundness for the omnidirectional radiation pattern are less than 4.4 dB within the desired frequency band. High gain and wideband omnidirectional radiation characteristics can provide a wide range of coverage and good signal transmission performance for outdoor wireless communication systems.

CFD Analysis of Automobile Radiator Performance: Investigation of Heat Input, Mass Flow Rate, and Coating Thickness Effects

This research paper delves into the realm of Computational Fluid Dynamics (CFD) analysis to optimize the thermal performance of automobile radiators through the application of coatings. The study focuses on the impact of three different coating sizes, namely 50 micrometres, 80 micrometres, and 100 micrometres, aiming to enhance heat transfer efficiency and overall radiator performance. To systematically investigate the influence of these coatings on thermal behaviour, the L9 Orthogonal array is employed as a robust experimental design. The experimental methodology involves simulating the radiator's heat dissipation capabilities using CFD techniques, considering the interaction of fluid dynamics and heat transfer within the coated radiator. The L9 Orthogonal array provides a systematic and efficient approach to conducting experiments, allowing for the exploration of various coating combinations and their effects on thermal performance. The research not only analyses the impact of different coating sizes on the overall heat transfer efficiency but also seeks to identify optimal combinations that yield superior results. Insights gained from this study contribute to the development of advanced thermal management strategies in automotive engineering, aiming to enhance the cooling efficiency of radiators while maintaining operational and material constraints. Key findings highlight the significant role that coating thickness plays in augmenting the heat dissipation capabilities of automobile radiators. The outcomes of this research bear implications for the automotive industry, guiding future design considerations for improved radiator performance in terms of heat transfer efficiency, energy consumption, and overall system sustainability.

Enhanced performance of microstrip antenna fabricated on a composite dielectric substrate coupled with multiple dielectric superstrates

In this study, we introduce a unique geometrical design of a rectangular patch antenna for sub-6 GHz 5G applications. The proposed antenna is designed at 5.2 GHz, and design criteria and performance characteristics have been investigated through numerical simulations and verified using measured data. A composite structure is suggested to overcome the restrictive parameters of conventional antennas. Two different materials, Rogers RT5880, and RT5870, are utilized, achieving a maximum gain of 6.210 dB, and a 90.2% radiation efficiency was attained. Four layers of superstrates are placed above the antenna to enhance the antenna's radiation performance further. The fabricated antenna is evaluated by measuring its radiation characteristics and return loss. The final antenna prototype offers a maximum bandwidth of about 896 MHz at a −10 dB reflection coefficient with a maximum gain of 9 dB. The proposed model achieved ultimate efficiency as high as 89% by employing four superstrates. The results showed good impedance matching (S11, VSWR), high efficiency, and appropriate radiation patterns. The outcomes from simulation and measurement are well aligned, making this antenna suitable for high-performance 5G applications.

Circularly polarized 2 × 2 fractal antenna array for space borne tracking applications

A corporate feed sequentially rotated 2 × 2 circularly polarized fractal antenna array is investigated in this work. Four number of compact circular fractal antenna elements are positioned symmetrically across the geometry. The antenna elements in the subarray are incorporated with 1st order Koch fractal cuts and rotated with respect to its neighbor and the phase change thus generated becomes offset with the phase change in the excitation in the corporate feed. A 2nd order Minkowski fractal curve is implemented on the ground plane to optimize the radiation performance of the array. The proposed fractal antenna array (FAA) is powered with a coaxial feed, with its pin connected to the asymmetric line configuration placed on the top surface. The dimensional confinement of the array is limited to 0.904λ0 × 0.876λ0 × 0.012λ0 (fr = 2.27 GHz) and the overall layout of the geometry is built on a FR4 substrate having a dielectric constant of 4.4. The circularly polarized radiation characteristics of the elements are developed as a result of fractal cuts along the vertical and horizontal sides. A maximum gain response of 5.4 dBic is observed in the impedance band ranging from 2 GHz to 2.5 GHz. The measured results of the proposed array are found to be in good agreement. In quantitative comparison with a few existing arrays with respect to its diverse performance the proposed CP FAA is found to be suitable for space-borne applications operating in the S-band.

A High-Performance Flexible Hydroacoustic Transducer Based on 1-3 PZT-5A/Silicone Rubber Composite.

In recent years, hydroacoustic transducers made of PZT/epoxy composites have been extensively employed in underwater detection, communication, and recognition for their high energy conversion efficiency. Despite the ease with which these transducers can be formed into complex shapes, their lack of mechanical flexibility limits their versatility across various sizes of underwater vehicles. This study introduces a novel flexible piezoelectric composite hydroacoustic transducer (FPCHT) based on a 1-3 PZT-5A/silicone rubber composite and an island-bridge flexible electrode, which can break the limitations of existing hydroacoustic transducers that do not have flexibility. The finite element method is used to optimize the structural parameters of high-performance 1-3 FPC. A large-sized (187 mm × 47 mm × 5.12 mm) FPC is fabricated using an improved cutting-filling method and packaged into the FPCHT. Compared with the planar rigid PZT/epoxy composite hydroacoustic transducer (RPCHT) of the same size, the TVR (186.5 db) of the FPCHT has increased by about 7 dB, indicating that it has better acoustic radiation performance and electroacoustic conversion efficiency. Furthermore, its electroacoustic performance exhibits excellent stability under different bending states. Therefore, the FPCHT with high electroacoustic performance is an ideal substitute for the existing RPCHT and promotes the development of hydroacoustic transducers towards flexibility and portability.

Investigation of the infrared radiation characteristics modulation mechanism of titanium dioxide composite yttria-stabilized zirconia ceramics

Yttria stabilized zirconia (YSZ) presents a promising option for infrared camouflage applications due to its lower emissivity within the 3–5 μm waveband. Nevertheless, its emissivity increases within the 8–14 μm waveband, which is attributed to lattice vibration-induced absorption characteristics, combined with an extended Christiansen wavelength (K-point). In this study, we regulate YSZ’s infrared radiation performance in the 8–14 μm band by combining a material with lower infrared emissivity in the 8–14 μm band and lower lattice resonance frequencies such as titanium dioxide (TiO2) based on lattice vibration theory and classical electromagnetic theory. The results showed that as the TiO2 content increases, the emissivity of the composite ceramic block remains relatively stable in the 3–5 μm band. Notably, With a TiO2 content of 80 %, the emissivity within the 8–14 μm band decreases from 0.55 to 0.48 and within the 5–8 μm band increases from 0.33 to 0.41, the K-point of ceramics shifted from 12.8 μm to 11.8 μm. It provides an effective approach for modulating the infrared emissivity and K-point of YSZ.

Augmenting the heat transfer performance of automobile radiators by combining surface modification and nanofluid techniques

Augmenting the heat transfer performance of automobile radiators by combining surface modification and nanofluid techniques

Mechanical Robustness Enhanced Flexible Antennas Using Ti3C2 MXene and Nanocellulose Composites for Noninvasive Glucose Sensing.

Electromagnetic sensors with flexible antennas as sensing elements have attracted increasing attention in noninvasive continuous glucose monitoring for diabetic patients. The significant radiation performance loss of flexible antennas during mechanical deformation impairs the reliability of glucose monitoring. Here, we present flexible ultrawideband monopole antennas composed of Ti3C2 MXene and cellulose nanofibril (CNF) composite films for continuous glucose monitoring. The flexible MXene/CNF antenna with 20% CNF content can obtain a gain of up to 3.33 dBi and a radiation efficiency of up to 65.40% at a frequency range from 2.3 to 6.0 GHz. Compared with the pure MXene antenna, this antenna offers a comparable radiation performance and a lower performance loss in mechanical bending deformation. Moreover, the MXene/CNF antenna shows a stable response to fetal bovine serum/glucose, with a correlation of >0.9 at the reference glucose levels, and responds sensitively to the variations in blood glucose levels during human trials. The proposed strategy enhancing the mechanical robustness of MXene-based flexible antennas makes metallic two-dimensional nanomaterials more promising in wearable electromagnetic sensors.

Performance analysis of acoustically actuated magnetoelectric antennas via equivalent circuit method

Acoustically actuated magnetoelectric (ME) antennas based on resonant magnetoelectric coupling within ferromagnetic/piezoelectric ME laminated composites have recently been considered as a promising solution for antenna miniaturization. However, its radiation performance has been theoretically overestimated, since the negative effects on performances due to the magnetization saturation and the nonlinear mechanical behavior that occur from high-field driving have not been paid enough attention. This work presents a unique equivalent-circuit-based numerical method to analyze the near-field resonance radiation performances of ME antennas driven by high electric fields. In this method, we establish an equivalent circuit of the converse magnetoelectric effect for a ME laminated composite to describe the operating principle of acoustically actuated electromagnetic radiation. The equivalent parameters related to resonance characteristics are determined by fitting the circuit model to the data from frequency response measurements of the near-field magnetic flux density. The validity of the model is verified by comparing the theoretical predictions with the experimental results, in the view of the volume fraction dependence of the mechanical resonance-related radiation characteristics of the fabricated ME composites. Based on the proposed model, the influence of driving voltage amplitude on near-field radiation performances is further analyzed by experimental fitting to the model, and the potential limiting factors of ME antennas are discussed according to the driving-amplitude dependence of parameters obtained from the fit. This work provides an effective and engineering-friendly approach to predict the evolution of ME antenna performances, leading a way to improve the performance limit for resonant magnetoelectric coupling.