Abstract The dielectric properties and electromagnetic wave absorbing performance of granular polysilicon have important influences on microwave smelting efficiency. In this study, the dielectric parameters (dielectric constant, dielectric loss factor and loss tangent) of granular polysilicon were measured from room temperature (25 °C) to 800 °C at 2450 MHz by using the cylindrical cavity perturbation

(2020). Editor’s message: the challenge of virus sanitizing with microwaves. Journal of Microwave Power and Electromagnetic Energy: Vol. 54, No. 4, pp. 271-272.

Abstract The complex relative permittivity study of samples of liberdux® syrup dissolved in distilled–deionized water is presented. It should be mentioned that excess of this syrup as pharmaceutical residual in water is considered an emerging contaminant. The study covers liberdux® concentrations from 0% v/v to 100% v/v, which were measured from 500 MHz to 20 GHz. For each sample, the parameters of

Abstract Dielectric properties of a set of glasses having the composition (70-x)%V2O5 - x%ZnO − 10%SrO − 20%FeO is studied in terms of their permittivity and electric modulus. The dielectric data are collected at the frequencies 120, 103, 104 and 105 Hz and in the temperature range 300 − 523 K. The electric moduli are treated with different theoretical models. Good fitting to the experimental data

Abstract In the present work, microwave energy was used for casting Al 7039 alloy at 2.45 GHz in the ambient cavity environment. Effects of input power and insulation of the mould assembly during irradiation on charge melting and mould preheating were studied. Five different casts were produced at 1000 W, 1200 W, 1400 W, 1400 W with an insulated pouring basin and 1400 W with insulated mould assembly

Abstract Three-stub waveguides are common impedance matching devices which are essential for a wide range of high-power microwave applications. Based on equivalent circuit analysis method, this article presents a novel matching algorithm which can be applied for three-stub tuners to implement continuous, automatic and real-time impedance matching. Equivalent model of a stub waveguide is firstly established

Abstract Many simulations employed in microwave heating simplify the geometric model of the microwave cavity to reduce the complexity of the model. Some detailed design features of the cavity, such as magnetron and cavity depression, are usually ignored. This study built detailed geometric models (DGM) and simplified geometric models (SGM) to investigate the changes in the electric field in a microwave

(2020). Editor’s message: a glance to virtual conferences. Journal of Microwave Power and Electromagnetic Energy: Vol. 54, No. 3, pp. 183-185.

The effects of different drying methods (hot air drying (HAD), microwave drying (MD), and hot air-microwave combined drying (HAMCD) processes) on the drying characteristics, rehydration ability, colour, texture, moisture state, microstructure, and energy characteristics of tilapia fillets have been investigated. The best rehydration and recovery ratios of tilapia fillets were obtained using HAMCD (58

This paper presents a stable, accurate and wideband microwave fractional order differentiator (MFOD) based on infinite impulse response filter. The fractional order differentiator (FOD) design problem is formulated in the z-domain. This formulation alliances with the transmission line elements in cascading. Real coded genetic algorithm (RCGA), particle swarm optimization (PSO) and cuckoo search algorithm

Microwave-assisted hydrodistillation and conventional hydrodistillation (MAHD and HD) were used for a comparative study of extraction Callistemon citrinus Skeels leaf essential oils. The time required for a MAHD method is 75 minutes that for HD method is 3.5 hours, so MAHD requires lesser time. The increases in yield of extracted oil by MAHD (0.84%) is found compared oil extracted by HD (0.6%). Essential

In this paper, the electromagnetic shielding effectiveness results of the plain weave composite fabric and the analytical solution of metal mesh were investigated. The composite fabric made of cotton yarns twisted with 50 µm copper filaments was used in the experiment. As the fabric was weaved and stretched, it had square shaped apertures which had length of 1.2 mm. The electromagnetic shielding effectiveness

In order to exploit the use of remote sensing, microwave heating/drying and water stress in the agricultural sector, it is necessary to determine the dielectric properties of plant materials (branches, leaves, roots, fruits). In this way, the yield and quality of agricultural products can be increased. In this study, dielectric parameters of the sweet cherry and sour cherry leaves are measured by waveguide

The use of polyols as green solvents in conjunction with microwave heating (MH) has become a very attractive synthetic protocol nowadays. However, among the needs of this area, as well as any other that uses MH, figure the electromagnetic properties of the materials. In this context, the contribution of this work is provide dielectric data of three polyols: glycerol, 1,2-propanediol and 1,3-propanediol

There are five stages in acid coagulation of milk and most studies miss out on a stage or two depending on the experiments performed. Dielectric studies of milk and various physico-chemical studies on the formation of yogurt are well studied and established. However, most of the papers deal with either a limited range of frequencies in the dielectric studies and hence are unable to reflect all the

(2020). Editor’s message: microwave processing of modern materials. Journal of Microwave Power and Electromagnetic Energy: Vol. 54, No. 2, pp. 81-82.

Abstract Little published information exists examining the effect of heating methods on nutrient retention in single-serve frozen meals, which can have instructions for conventional and microwave ovens. In peer-reviewed references, there are no recent studies that address this question. This work compares the effect of two reheating methods on nutrient retention of a frozen single-serve meal that has

The thin layer drying of Eri silkworm pupae using microwaves combined with hot air was conducted. Several empirical models simulating thin layer drying of Eri silkworm pupae were selected and analyzed. Microwave power between 100 and 200 W and drying temperatures between 50 and 70°C were used in the study. The comparison between experimental results and those of the models indicated that the Page’s

This work aims to improve the uniformity and efficiency of microwave heating. A dual-port simulation model based on the finite element method was built, and two pins were applied to the heating cavity. The impact of dual frequency and pins on the coefficient of variation (COV) and heating efficiency were investigated. The results demonstrated that the uniformity of dual-frequency heating can be improved

(2020). Editor’s message: experiments with microwave kitchen ovens. Journal of Microwave Power and Electromagnetic Energy: Vol. 54, No. 1, pp. 1-2.

Abstract Ce-substituted strontium hexagonal M-type SrCexFe12-xO19 ferrites (x = 0.0, 0.03, 0.05, 0.07, and 0.1) and various concentrations of poly(N-vinilpyrrolidone) (PVP) polymer were prepared by citrate sol-gel auto-combustion route, and their structural and magnetic properties were studied. The Fourier transform infrared spectroscopy (FT-IR) revealed bands at 437, 549, and 598 cm−1, related to

Abstract In this study, a simultaneous cooled-microwave (MW) system operating in isothermal conditions under constant and continuous MW irradiation was designed using outside cooling for glycerin. To design an appropriate simultaneous cooled-MW experimental system, many simultaneous cooling methods, cooling liquids and MW experimental systems have been tried. Among these MW systems, the coil-cooled-MW

Abstract The ionic strength (I) of a solution is a measure of the concentration of ions or a measure of the intensity of the electric field in a solution. In water treatment, the ionic strength allows the determination of total dissolved solids concentrations. In this work, different concentrations of MgSO4*7H2O in water are considered. This produces several levels of ionic strength. This varies from

Abstract This study aimed to understand the microwave thermal regeneration mechanism of asphalt pavement and improve its regeneration quality. Asphalt mixtures containing moisture were regarded as a porous medium to study the multi-physical distribution law of asphalt mixtures in the microwave heating process. Mass and heat transfer models of moisture and a heat transfer model of asphalt mixtures were

Abstract In this study, four textural classes of soil (Clay, Clay Loam, Loam, and Loamy Sand) were used to investigate the dielectric properties of soils, using a vector network analyser with an open-ended coaxial probe kit at room temperature (25 ± 2°C) in the 700–7000 MHz microwave frequency range. Four levels of soil moisture content (oven dry, 33% field capacity, 66% field capacity and 100% field

(2019). Editor’s message: Communication applications and perception of microwave effect. Journal of Microwave Power and Electromagnetic Energy: Vol. 53, No. 4, pp. 213-214.

Abstract This research studied the effects of power level and aspect ratio by numerical and experimental analysis in the microwave heating process. The sample was congee frozen rice. A three-dimensional model developed to solve Maxwell’s equations and Fourier’s heat equations using the finite element method in COMSOL Multiphysics software. The simulated temperature results were validated experimental

Abstract Squalene is a triterpene of pharmaceutical interest, due to its antioxidant and anticancer properties. Amaranth oil is a source of plant origin with high squalene content which is extracted by conventional methods that involve high cost, time-consuming and create large amounts of waste by-products or CO2 emissions. In this study, the microwave-assisted extraction (MAE) was used to obtain amaranth

Abstract The health benefits of Indian gooseberry have resulted in a tremendous growth in its consumption in the form of tasty candy and marmalade prepared by drying process. The candy production process is limited by high drying time and plant size requirements as most of the processing production plants are equipped with conventional drying methods. Hence, the paper presents computational model defining

Abstract For industrialized processes, microwave techniques for quality control and pasteurization methods may be required. For this reason the precise knowledge of the dielectric characteristics of foods are of prime importance. In this paper, we present the dielectric properties of pulque, a Mexican traditional drink. Three different pulque flavors (natural, strawberry and coconut/pineapple) are

Abstract In this paper, an all-metal sectoral waveguide (SWG) mode converter has been proposed for TM01 to TE11 mode conversion, suitable for high-power application with high mode conversion efficiency and beam stability. Describing its operating principle, electromagnetic (EM) analysis has been carried out to observe the propagation behaviour in the different structure regions of the mode converter

(2019). Editor’s message: applied science and engineering for solving society needs. Journal of Microwave Power and Electromagnetic Energy: Vol. 53, No. 3, pp. 143-144.

Abstract P2O5–ZnO–Na2O glasses doped with various concentrations of NiO in the range from 0 to 6 mol % are prepared. The measurements of the electric properties of the samples are studied at different temperatures and frequencies. It is found that the dielectric constant decreases with increasing frequency as well as the electric modulus shows relaxation behaviour. The effect of different NiO concentrations

Abstract The present study investigates the treatment of membrane concentrate leachate by thermal-activated persulfate catalysed with Ag(I). Activation of persulfate was done by microwave/conventional heating. The persulfate activation with microwave (MW) and conventional heating (CH) processes was compared with Taguchi multi-response optimization as robust design approach. Parameters affecting the

Abstract The investigation of injection locking of cooker magnetron by a solid-state microwave power source is reported. Experimental results show that a 2.45 GHz cooker magnetron can be locked in continuous wave operation. In the frequency-locking bandwidth, the magnetron output frequency can be tuned by adjusting the injection source. The maximum frequency-locking bandwidth of 12 MHz and noise of

Abstract To liberate magnetite from ludwigite, the dielectric properties of ludwigite are investigated by cavity perturbation method at 2.45 GHz from 20 to 800 °C. The results show dielectric properties of ludwigite with temperature can be divided into three stages: at the first stage (20–200 °C), the dielectric constant (ε′), dielectric loss factor (ε″) and loss tangent (tan δ) increase approximately

Abstract Microwave heating in white corn (Zea mays L.) against Sitotroga cerealella was applied as a post-harvest treatment. Power levels of 293, 390 or 475 W were applied to batches of 250 g until reaching the target temperature of 50 °C in the grain centre and held for 3 min, followed by air-forced cooling during 3.5 min. One batch was left as a control without treatment. Thermocouples and thermal

Abstract In many agricultural and industrial applications, moisture content needs to be determined in real time while the material is moving. For granular and particulate materials, density-independent calibration functions were used in microwave moisture sensors to minimize the effect of bulk density changes. Three of these calibration functions expressed in term of the attenuation, phase shift and

Abstract Dielectric properties of Huimin siderite ore were investigated by using the self-made high-temperature cavity perturbation method from room temperature to approximately 1000 °C at 2.45 GHz. The dielectric properties of the siderite ore remain constant from room temperature to 400 °C, then there is a rapid increase in both the dielectric loss factor and loss tangent from 400 °C to 600 °C, due

(2019). Editor’s Message: Global Meetings and the International Year of the Periodic Table of Chemical Elements. Journal of Microwave Power and Electromagnetic Energy: Vol. 53, No. 2, pp. 67-68.

Abstract Apertures and slots of the enclosures come into prominence for heat allocation, ventilation, I/O cable, etc. These slots and apertures induce the coupling route of electromagnetic interference (EMI) from the inside to outside. So, electromagnetic shielding is usually used to decrease the emissions or to the progress of equipment immunity. In this paper, an effect of an aperture shape on the

Abstract This study is concerned with the development of model-free adaptive control (MFAC) of microwave heating process for the industry application of microwave energy. Precise control of the material's time–temperature profile is essential for preventing thermal runaway. To achieve good tracking performance a data-driven MFAC with input constrain is proposed since it is hard to establish an accurate

Abstract Dielectric properties of canola seeds, corn, paddy rice, soybean and wheat were studied to determine the dependence of dielectric properties on frequency, moisture content and density of powdered seeds. In this context, several tests were done to find the relationship between the dielectric properties of the seeds at different frequencies (0.6–3 GHz) and at different moisture contents. Experimental

Abstract Nanocrystalline Mg-ferrites have been synthesized by sol-gel auto combustion method using citric acid as fuel agent at different Calcination temperatures (200 °C, 400 °C, 600 °C, and 800 °C). The physical properties of nano Mg-ferrite were investigated using X-ray diffraction (XRD) analysis, scanning electron microscopy, Fourier-transform infrared spectroscopy, and LCR-Hitester for structural

Abstract In microwave heating process, electric field intensity is the main parameter that controls the temperature rise in the material. With this parameter and available material properties, temperature changes are predictable. In this study, a new setup based on a domestic microwave oven was developed and uniform microwave radiation at 2450 MHz was lunched normal to the base of pre-prepared cylindrical

Abstract Materials with negative permittivity are opaque for electromagnetic wave such that the transmitted signal cannot travel through them. To combat this phenomenon, we propose a novel high transmission mechanism using periodic placed split-ring resonators and metallic wires to construct a transparent sandwich structure. This structure consists of three layers of materials, where the material with

Abstract A new type of reconfigurable sensing cavity is designed for measurement of complex dielectric permittivity of materials. This circuit is based on an Epsilon Near Zero (ENZ) tunnel integrated on a substrate, and it uses liquid metal switches to reconfigure two tunneling frequencies (2.4 GHz, and 3.5 GHz). As opposed to conventional narrow channel ENZ structures, our tunnel offers high unloaded

Abstract In this study, the microwave drying of fabrics at 2.45 GHz was investigated experimentally. The effect and efficiency of microwave drying on different fabrics at powers of 700 W and 300 W are discussed. The loss tangent of the fabrics was measured to analyze the relationship between drying efficiency and the fabric characteristics. By investigating the breaking tensile strength variation and

Abstract The present work envisages assessment of microwave assisted extraction (MAE) followed by comparison with that of conventional methods for effective extraction of colchicine from Gloriosa superba tubers. Subsequently, optimum conditions for MAE were determined using response surface methodology by employing Box-Behnken design. The observed optimal conditions for efficient extraction of colchicine

(2019). Editor’s message: computer simulation and scaling-up. Journal of Microwave Power and Electromagnetic Energy: Vol. 53, No. 1, pp. 1-2.

Abstract A Multiphysics numerical model was developed using COMSOL Multiphysics to study the effect of size, shape and position of catalyst bed within the microwave reactor (2450 MHz). The dielectric properties of HZSM-5 catalyst were measured at different frequencies and nine different temperatures ranging from 25 °C to 370 °C. The heat transfer in porous media was coupled with RF electromagnetics

Abstract Dielectric constants and loss tangents of four common edible oils – mustard oil, olive oil, sesame oil and canola oil are measured in the 9–15 GHz range using cavity perturbation. Accuracy of the measurement is enhanced by determining the sample volume through mass and density measurements, instead of dimensional measurements. Results show that the dielectric properties vary with oil type

Abstract This article investigated and compared the dielectric properties of urine between pregnant women and non-pregnant women. Urine samples were collected from 30 pregnant women and 30 non-pregnant women. Dielectric properties of the urine were measured between 0.2 and 50 GHz at temperatures of 25, 30 and 37 °C. The composition of urine and human chorionic gonadotropin (hCG) were also determined

(2018). Editor’s message: Terms in journal papers. Journal of Microwave Power and Electromagnetic Energy: Vol. 52, No. 4, pp. 253-254.

Abstract In this work, the drying of amaranth and quinoa seeds using microwave technology has been studied for the first time. The main objective of this study was to analyze the influence of the power density of the microwave oven on the drying time, germination rate and field survival of these seeds. The tests were performed in a domestic microwave oven at three power densities (0.875, 1.75 and 3

Abstract Dielectric property of laterite ores plays a key role in the determination of its treatment effect by microwave. However, till date, to our knowledge, there is no article reported on the dielectric property of laterite ores up to the nickel–iron alloy extraction temperature of around 1200 °C, which impedes the efficient application of microwave power in the nickel–iron alloy extraction. This

(2018). Editor’s message: speculating from forced relationships. Journal of Microwave Power and Electromagnetic Energy: Vol. 52, No. 3, pp. 159-161.

Abstract Forced degradation studies are essential to determine the drug stability, elucidate the main degradation routes, and monitor the degradation products in qualitative/quantitative terms. Over the years, the pharmaceutical industry has been using a traditional and conventional method that employs a stove as the heating source; this requires a lengthy process and high energy. Recently, a new forced

Abstract The study investigates the use of scattering parameters measurement to retrieve the permittivity, permeability, refractive index and intrinsic impedance of materials over the wide range of frequencies. The approach is demonstrated for thin as well as thick materials to clarify the complex branching problems of the logarithm and sign ambiguities. The special requirement of simulation and measurement

Abstract In this paper, a new feeding mechanism to excite the various radiating modes in rectangular dielectric resonator antenna for multiband application has been presented. TE1,2,2y and TEδ,4,2y modes have been explored with the possibility of a radiating mode in rectangular dielectric resonator antenna with good radiation efficiency and stable radiation pattern. New feeding scheme consists of two