In this paper, the effect of corrosion on the magnetic behavior of a magnetic material used as a magnetic circuit in the induction machines is studied. With this objective, the magnetic properties of the samples with corrosion and without corrosion were evaluated by the study of hysteresis loops using a homemade vibrating sample magnetometer (VSM). The magnetic parameters extracted from the hysteresis loops such as saturation magnetization, coercive, remanent magnetization, squareness ratio, magnetic permeability, and hysteresis area were analyzed. It was shown that more energy is required to demagnetize the sample with corrosion than the sample without corrosion, and the hysteresis loss in the case of the sample with corrosion is more than the case of the sample without corrosion. These mean that when the corrosion is presented in the magnetic circuits of the induction machine, the hysteresis loss increases, consequentially reducing the machine efficiency.

In this paper, a compact dual-band MIMO antenna for WI-MAX and WLAN applications with improved isolation is proposed. The proposed design consists of two counter facing F shaped monopoles placed closely to each other with edge to edge spacing of 10 mm (0.1167λ₀ at 3.5 GHz). Each monopole element operates over 3.5 and 5.8 GHz bands. The isolation over the operating dual bands is achieved by using an elliptical slot and a rectangular parasitic strip. S₁₁ < -10 dB is achieved over 3.2-3.8 GHz and 5.7-6.2 GHz with S₁₂ < -20 dB. The overall dimension of the proposed antenna is 30 × 26 mm². The proposed antenna has correlation coefficient < 0.03, diversity gain > 9.8 dB with stable radiation pattern over the operating dual bands. The measured results are in good agreement with the simulated ones. The proposed antenna is a suitable candidate for MIMO applications.

A pair of broadband double-sided parallel-strip line (DSPSL) to coplanar waveguide (CPW) vertical transitions are presented. The transitions are composed of CPW open end with connected grounds forming two strips of the DSPSL with single via connection. The connected grounds of CPW, which forms top strip of the DSPSL are of two dierent shapes resulting in two transitions (Types 1 & 2). Simulated results for the back-to-back transitions, using the multilayer solver of CST Microwave Studio, show good agreement with the measured ones.

As a kind of complex targets, the non-rigid vibration of an aircraft as well as its attitude change and the rotation of its rotating parts will induce complex nonlinear modulation on its echo from low-resolution radars. If these nonlinear modulation features which reflect the physical characteristics of an aircraft target can be extracted effectively, then they are helpful to target classification and recognition. However, the echo translational component and background clutter have a very adverse effect on the extraction of such features. On basis of introducing the ensemble empirical mode decomposition (EEMD) algorithm, the paper firstly performs the decomposition of real recorded aircraft echo data from a low-resolution radar by EEMD and distinguishes the false component, body translational component and micro-motion component by calculating waveform entropy in the Doppler domain. Secondly, it carries out characteristic analysis and feature extraction further on the echo micro-motion component separated and extracts three features of the micro-motion component, including Doppler domain waveform entropy E_mc, normalized equivalent Doppler spectrum width BW₀, and normalized frequency interval between the adjacent maximum spectral peaks on both sides of the spectrum center Δf₀. The analysis results show that EEMD can be used to separate the body translational component and micromotion component of an aircraft echo effectively, and the proposed features (E_mc, BW₀ and Δf₀) can be used as effective features for aircraft target classification and recognition.

A modified three-way in-phase equal Gysel power divider/combiner (PDC) and a method for implementation this novel three-way Gysel PDC on plane structure are proposed in this article. To obtain accurate values of the line impedance,the derivation of the exact equations is based on even-odd mode analysis. An experimental prototype is realized. The results show that this three-way Gysel PDC has good matching, isolation and magnitude-phase balances with high power handling capabilities.

This paper presents a novel 2D meta-surface wall to increase the isolation between microstrip patch radiators in an antenna array that is operating in the teraherz (THz) band of 139-141 GHz for applications including communications, medical and security screening systems. The meta-surface unit-cell comprises conjoined twin `Y-shape' microstrip structures, which are inter-digitally interleaved together to create the meta-surface wall. The proposed meta-surface wall is free of via holes and defected ground-plane hence easing its fabrication. The meta-surface wall is inserted tightly between the radiating elements to reduce surface wave mutual coupling. For best isolation performance the wall is oriented orthogonal to the patch antennas. The antenna array exhibits a gain of 9.0 dBi with high isolation level of less than -63 dB between transmit and receive antennas in the specified THz-band. The proposed technique achieves mutual coupling suppression of more than 10 dB over a much wider frequency bandwidth (2 GHz) than achieved to date. With the proposed technique the edge-to-edge gap between the transmit and receive patch antennas can be reduced to 2.5 mm. Dimensions of the transmit and receive patch antennas are 5×5 mm² with ground-plane size of 9×4.25 mm² when being constructed on a conventional lossy substrate with thickness of 1.6 mm.

This paper presents a CPW-fed UWB band-notched antenna having continuously tunable WiMAX rejection band and fixed WLAN rejection band. As the WLAN frequency band is fixed all over the world, it is made fixed with the use of a newly designed resonator in the radiating patch. As the main problem is that the WiMAX band is different in different countries of the world, between 3 and 4 GHz, it is made continuously tunable by using a novel miniaturized implemented resonator in the partial ground plane with variable capacitors. Altering the values of these capacitors tunes the 3-4 GHz rejection band continuously.

Design and experimental optimization of a 5 cm-diameter electron cyclotron resonance (ECR) Ion Thruster was carried out. The experimental results with the shorten discharge chamber demonstrated that its maximum efficiency, specific impulse, and thrust were 38%, 4300 s, 2.3 mN with the power of 130 W, respectively. The beam current was increased with the increment of the propellant flow rate and screen grid voltage. In addition, the performance of the thruster was associated with the distance of the antenna and screen grid. However, the optimum distance depended on the input microwave power which was about 20 W.

The rapid quantification method of human serum glucose was established by using the Fourier transform infrared spectroscopy (FTIR) and attenuated total reflection (ATR). Based on the optimal predicting effect, a subtraction band model combining with optimal single continuous wave band was developed. The spectrum (1600-900 cm^-1) was selected as the base band. Then, window subtracted partial least squares (WSPLS) based on the spectrum was carried out, and the optimal two continuous bands were found. The results show that the prediction effect of the base band model is obviously better than that of the whole spectral model, and WSPLS model is even better than base band model. Finally, an independent test set was tested for model verification. V-SEP and V-R_P were 0.831 mmol/L and 0.882, respectively by the compensation model.

Objective: In this paper we present a study of a novel method to noninvasively monitor temperature noninvasively during thermotherapy, for instance, in cancer treatment using M-sequence radar technology. The main objective is to investigate the temperature dependence of reflectivity in UWB radar signal in gelatine phantoms using electrically small antennas. Methods: The phantom was locally heated up, and consequently changes of signal reflectivity were observed. Results: An approximate linear relationship between temperature change and reflectivity variations was formulated. To show the potential of this approach we used an M-sequence MIMO radar system. The system was tested on breast-shape phantom with local heating by circulating water of controlled temperature. For two dimensional imaging the Delay and Sum algorithm was implemented for two-dimensional imaging. Significance: The article is a study of temperature measurement using UWB radar system for possible usage in thermotherapy.

In this work, a wide-angle and wide-band transmission-type circular polarizer based on a bi-layer anisotropic metasurface is proposed, in which the unit cell consists of two layers of identical patterned metal films deposited on the two sides of a homogeneous dielectric layer, and the geometric pattern of the metal film is a square aperture surrounding a concentric square-corner-truncated square patch. The simulated results show that the polarizer can realize a linear-to-circular polarization conversion at both x- and y-polarized incidences in the frequency range from 7.63 to 11.13 GHz with a relative bandwidth of 37.3%, and it can maintain a stable polarization conversion performance under large-range incidence angles. Moreover, it has no asymmetric transmission effect, and the transmission coefficients at x- and y-polarized incidences are completely equal. Finally, one experiment is carried out, and the simulated and measured results are almost in agreement with each other.

This paper aimed to take closer steps towards real wearability by investigating the possibilities of designing and fabricating highly efficient and fully flexible wearable microstrip patch antenna for operating frequency of 5.8 GHz as a center frequency. Two types of conducting materials have been used for conducting parts: conventional metal plane and woven electro-textile material, while a non-conducting jeans fabric has been used as antenna substrate material. The dielectric constant ε_r = 1.78, and loss tangent tanδ = 0.085 of the jeans substrate measured by using two different methods. Also, the electromagnetic properties of the electro-textile are studied in details. The conductivity of e-textile cell is equal to 2.5×10⁶ S/m and the surface impedance of e-textile cell equal to 0.0395+J18.4 Ω. Furthermore, the proposed wearable antenna may be attached to human body, so the specific absorption ratio (SAR) must be calculated. Finally, the proposed design is simulated by CST simulator version 2016, fabricated using folded copper and measured by Agilent8719ES VNA.

A microstrip patch antenna can be readily installed on any non-planar surface due to its conformal property, and this feature enhances its applicability in many areas. Moreover, in some specific applications, it is desirable and mandatory to provide protection of antenna from the unfriendly surroundings. Therefore, the present work focuses on the antenna with a dielectric cover and analyzes its effect on directivity, gain, and bandwidth at various superstrate air gaps. Two antenna models of single and dual elements are considered here separately, and both are conformal to the cylindrical surface. The antenna parameters are studied under varying superstrate gaps with equal intervals up to a quarter wavelength under fixed cylindrical curvature. It is noted that there is a significant improvement of 6% and 12% in bandwidth at quarter wavelength gap as compared to simple single and dual antenna models without dielectric loading, respectively. Also, both the calculated and measured results show the other important constructive effect of superstrate on the antenna performance.

This paper presents a novel approach of sensing the defect response after craniotomy on cranial surgery phantom models utilizing a short pulsed radar technique. The proposed antenna has demonstrated that the short pulse can be radiated without antenna's own distortion, which is a desirable characteristic for sensing defect response. The layered microwave head phantom has been developed for the purpose of emulating the healing stages of cranial surgery after craniotomy. The fabricated phantom has been validated with reference values reported in literature. The longitudinal scan has been performed for various skull thicknesses as a preliminary study. The one-dimensional pulsed profile has been obtained to achieve the pulse compression so that the defect response can be highlighted. The results obtained in this paper have the potential that the microwave based technique can be utilized for monitoring the healing stages for the future work.

A new structure design of a dual-band suspended microstrip meshed patch antenna integrated with a polycrystalline silicon solar cell for Ku-band satellite applications is proposed and presented. This antenna element is a basic building block for a Ku-band meshed array antenna used for two-way satellite internet and TV applications at rural and remote locations. The antenna covers the operating frequency range from 11.7 GHz to 12.22 GHz downlink band and from 14.0 GHz to 14.5 GHz uplink band allocated by the ITU to the Regions 1 and 2. While achieving 500 MHz bandwidth across each band, fully covering the Ku-band uplink and downlink frequency bands, the antenna offers a single element gain of 6.05 dBi in the downlink band and 7.61 dBi in the uplink band. The antenna has been fabricated and measured, and good agreement is achieved between the experimental and simulated results. In addition, a good compromise between RF performance and optical transparency is obtained. The overall visible light transmission is found to be approximately 87%. A compact low-profile antenna element is also achieved.

The main objective of the current work is to develop a Very Low Frequency (VLF) monitoring system for characterizing low layer ionosphere. Low layer ionosphere is important for communication, and some researchers stressed that lower layer ionosphere can be a precursor to earthquake event. The VLF monitoring system composed of a 1-m antenna, a preamplifier to amplify the signal, an ADC converter and a data acquisition system. The optimization of 1-m antenna received dual frequencies 19.2 kHz and 19.8 kHz from South Vijayanarayanam, India and North West Cape, Australia, respectively. Subsequently, a low pass filter was designed in the preamplifier to pass VLF signals from 0-30 kHz. The results revealed that the system was able to characterize diurnal variation: sunrise and sunset and detect changes in the lower layer ionosphere region due to Solar activity.

Intentional Electromagnetic Interference (IEMI) is one of the applications of High Power Electromagnetics (HPEM) for causing intentional interference in military targets such as C⁴I (Command, Control, Communication, Computer and Intelligence) targets and segments of civilian systems like critical VSAT's (Very Small Aperture Terminals), power grid and communication network, weather and air-traffic control radars etc. HPEM essentially consists of generation of intense electromagnetic waves either as High Power Microwave (HPM) or Ultra Wide Band (UWB) waves to cause electromagnetic interference. High power UWB waves are promising candidate for IEMI application. One such UWB source, developed for the purpose of radiating high intensity, fast rise time, short pulses, is the Half Impulse Radiating Antenna (HIRA) which covers a frequency range of 100 MHz to 6 GHz. In this paper, characteristics of UWB source i.e., HIRA, such as characteristics of electric field in both boresight and off-boresight, far field boundary and radiation pattern were computed. The UWB pulse dispersion through civil infrastructure and their coupling to power cables were studied experimentally.

Statistics of monthly and diurnal variations in the occurrence of rain fades are needed to give a detailed insight for system design of these services. This paper analyses the performance on three years of rain rate and rain attenuation measurement to study the empirical determination of power law coefficients calculated for monthly distribution of rain attenuation from the knowledge of rain rate at 19.8 GHz link for COMS1 in South Korea. The received signal data for rain attenuation and rain rate were collected at 10 second intervals over a three year period from 2013 to 2015. The comparison of measured data for monthly variation illustrates the suitability for the estimation of signal in Ka-band whose appropriateness is verified through the comparison with prominent rain attenuation models namely ITU-R P. 618-13 and empirically generated regression coefficients values for ITU-R P. 838-3. A monthly variation of the coefficients has been indicated, and the empirical measured data were compared with the ITU-R P. 838-3 derived regression coefficients. Moreover, the statistics analyzed to 6 hour contiguous periods of the day are also shown. Furthermore, the paper presents an overview of the redicted monthly variation of rain attenuation estimation of 2013 year for Ka band in 19.8 and 20.73 GHz from 12.25 GHz link which are obtained from the ITU-R P. 618-13 frequency scaling method, and these predictions are compared with experimentally measured values. These statistics can be useful for communication systems whose service quality and design require seasonal and diurnal variation.

In this paper, a dual-band antenna in orthogonal polarization with stacked configuration is proposed. The proposed antenna introduces two layers of radiating patches to realize the dual frequency characteristic. A pair of novel 180˚ broadband microstrip baluns, printed on the backside of the bottom substrate, are utilized to feed the antenna. By employing wideband feeding mechanisms for the two input ports, high input port isolation and wide impedance bandwidth are successfully realized. The proposed antenna is fabricated and measured. It exhibits a characteristic of two resonant frequencies, from 2.75 to 4.01 GHz with a relative bandwidth of 37.3% and over 8.1 dBi gain at two ports, and the upper band f2 is from 4.4 to 5.21 GHz with a relative bandwidth of 16.9% and over 5.8 dBi gain at two ports. The port isolation is below -35 dB, and the cross-polarization level is below -20 dB at broadside across the whole band.

A 3-mm wave interferometer is designed and developed to measure the electron density online at the central chord of Aditya tokamak, unambiguously. The scheme used for this has the advantages in operating the interferometer without a source frequency modulation and easy data processing. The central chord of a 3-mm wave homodyne interferometer system is modified to make a quadrature circuit by using phase shifters and magic tees. This is used to produce the sine/cosine fringe signals. These outputs are amplified and converted into pulses and passed to wired logic up/down fringe counter. Digital synchronous logic circuit is implemented in a Complex Programmable Logic Device (CPLD), followed by digital to analog converter (DAC) and scaler which produces a voltage proportional to increase or decrease in plasma density in real time. The paper presents about this technique and test results of the fringe counter with artificial signals. The chord averaged plasma density n_e = 0.9 × 10¹³ cm^-3 is measured online at Aditya tokamak using this interferometer.