Two unsupervised methods, fuzzy c-means (FCM) and $k$-means, as well as three supervised methods, support vector machine (SVM), neural network (NN), and convolutional neural network (CNN), are applied to classify sea-ice type of first-year ice (FYI), multi-year ice (MYI) and open water, by using L-band polarimetric synthetic aperture radar (PolSAR) images in winter and advanced-melt phases, respectively. Different input vectors, pending on different scenarios, are also proposed to increase the accuracy rate. The efficacy of different algorithms in conjunction with different input vectors are analyzed and related to the underlying physical mechanisms.

An Electric Ring Resonator (ERR) loaded Sierpinski Square Gasket Fractal (SSGF) antenna for multiple frequency band application is proposed, fabricated, and measured. The CPW-fed antenna consists of a Multi-mode Electric Ring Resonator (MERR) which is fixed on reverse side of the substrate and iterated Sierpinski gasket fractal derived from a square patch which is stamped on top of an FR4. Multi-bands can be obtained by placing a single multi-mode ERR beneath the CPW structure of the antenna. Each resonating frequency band can be easily tuned by properly changing the dimensions of the ERR structure. Instead of ERR's quasi-lumped capacitance, reconfigurability of the low, middle, and high frequency bands can be achieved by using a pair of Digital Variable Capacitors (DVCs)inserted into the middle of the ERR's rings corresponding to the chosen mode. The bandwidth is enhanced using four iterations of square radiating patch, modified feed line, and multi-mode electric ring resonator-loaded ground plane. More specifically, the impedance matching of the CPW fed antenna is improved by introducing transitions between the microstrip feed line and the Sierpinski square gasket. The numerical results show that the proposed antenna has good impedance bandwidth and radiation characteristics in the operating bands at 3.08/5.81/8.02/12.13/15.56\,GHz which cover the frequency spectrum of WiMAX, WiFi/WLAN(IEEE 802.11a), IEEE 802.16e, X-band uplink, S/C/X/Ku and K band with return loss of better than 10 dB.

With the progress of technologies though the years, the extent of electromagnetic radiations has increased in our environment, so there are increased concerns about health for wireless device users. It has become a necessity to use devices with low Specific Absorption Rate (SAR) to reduce human exposure to the effects of Electromagnetic Fields (EM fields). In this article, the design of a circular microstrip antenna (CMSA) with and without an electromagnetic band gap (EBG) structure is proposed. It is evident from simulated results that CMSA with EBG gives low SAR as compared to CMSA without EBG for the proposed prototype. M-shaped unit cell structure of EBG is designed for 1812 MHz resonance frequency, and a bandwidth of 244 MHz is achieved using CMSA with EBG for LTE Band 3. SAR is reduced by 76.25% when CMSA is used with EBG in comparison to CMSA without EBG.

GBSAR has been widely used in landslides monitoring for its high precision in deformation monitoring and portable characteristic in natural environments. When monitor slides in mountainous areas, GBSAR cannot only work in positive mode, and its antennas may be directed to the target with a large squint angle. Unfortunately, normal range doppler imaging algorithm is not used well in such applications. Thus, a correction method of RD algorithm for SAR imaging with a squint angle has been proposed in the paper. Because the monitoring target may be far away from the view center of the GBSAR, echo of the target may be side lobe resided, when it is received by the radar's sensor. Simultaneously, distance between the sensor and imaging target changes with the azimuth time. Therefore, target in the SAR image would not be focused in one range bin if no range correction method was used. Thus, phase correction methods were used in the paper. The phase error was corrected in range domain and azimuth domain, respectively. It avoids 2D FFT processing. Thus, it may use few time and work. In this way, the GBSAR would have real time processing ability in the future. In the paper, a GBSAR was designed and used in slide monitoring applications in western mountains of Beijing. The experiment result shows that the system can measure target's micro deformation in mm levels with a high precision.

Wireless Power Transfer (WPT) based on resonant magnetic coupling is an attractive technology for enabling the wireless recharge of electric devices and systems. One of the main drawbacks of this technology is related to the dependence of the efficiency and the power delivered to the load on possible variations of the coupling coefficient and load impedance. In order to alleviate the effects of this dependence, the optimization of appropriate adaptive matching networks is proposed in this paper. The three power gains usually adopted in the context of two-port active networks are assumed as figures of merit in the optimization process. It is theoretically and experimentally demonstrated that the maximum realizable gain of the link is achieved when the conjugate image impedance matching is realized by appropriate matching networks at both the input and output ports of the WPT link.

In severe multipath channels, depolarization of wireless signals has been shown to be a three dimensional effect. This work herein presents and applies a 3D Stokes vector framework for such depolarization. Empirical data are used to illustrate the capabilities of this framework (specifically, polarization purity indices and direction of propagation) to describe depolarization behavior for three different wireless channels.

Conical scanning radiometric imaging system is good at large field view but suffers from visual nonlinear distortion. The distortion is caused by azimuth and elevation sampling in sphere coordinate, especially for short range and large views. An outdoor experiment is carried out on a building, and the raw image is obtained with obvious distortion. The key to correct distortion is solving the range in relationship between sphere coordinate and Cartesian coordinate. For the a specific building, it is approximately treated as a plane object, and its height is assumed known to solve the range and parameters for plane fitting. Once the coordinates of all pixels are determined, the object is represented in Cartesian coordinate, and the nonlinear distortion is corrected. If any size information for object is unknown, an arbitrary plane is also competent for distortion correction. The difference is that the correcting result is a projection onto this plane instead of real location. However, the projection is also compatible with human vision.

A planar endfire circularly polarized quasi-Yagi antenna with the feasibility of obtaining a wider bandwidth and relatively smaller size is proposed and demonstrated. With a planar double-sided printed complementary structure, the proposed endfire circularly polarized (CP) antenna, consisting of a vertically polarized planar quasi-Yagi array and a horizontally polarized planar quasi-Yagi array with a common driver, is designed, analyzed, and fabricated. Good agreement between simulated and measured results is observed. Simulation and measurement results reveal that the proposed antenna can provide an impedance bandwidth of 16.3% (5.02-5.91 GHz) and a 3 dB axial ratio (AR) bandwidth of 17.4% (5-5.95 GHz). Meanwhile, the proposed antenna has endfire gains from 5.4 dBic to 7.4 dBic with an average endfire gain of 6.3 dBic, and front-to-back (F/B) ratios ranging from 10.2 dB to 16 dB with an average F/B ratio of 11.9 dB. Additionally, the measured effective CP bandwidth of 16.3% (5.02-5.91 GHz) not only meets the need for certain Wi-Fi (5.2/5.8 GHz) or WiMAX (5.5 GHz) band communication application, but also provides the potential to implement multiservice transmission.

In plasma physics, the interaction with electromagnetic waves is related to the electrons contained in the plasma. So to analyze this interaction, the behaviour of electrons contained must be understood and modeled. In this paper, a new TLM formulation for dispersive media called the exponential time differencing (ETD) transmission line matrix (TLM) technique is introduced to model the interaction with dispersive media. To verify the high accuracy and efficiency of this method, the reflection and transmission coefficients of electromagnetic wave through a non-magnetized collisional plasma slab are computed and compared to the analytical solution. As the electron density in plasma can be distributed as Epstein formula, and its distribution is a function of the grads coefficient σ, and the effect of this parameter and the electron collision frequency ν_c on the reflection coefficient is calculated. The results show that with different values of σ and ν_c, the reflection coefficient is affected and can be reduced.

A novel compact ultra-wideband (UWB) bandpass filter (BPF) with quad-notched bands and wide upper-stopband performance using quad-mode stepped impedance resonator (QMSIR) is proposed in this paper. Firstly, the resonance properties of the proposed QMSIR are studied. The proposed QMSIR is found to have the advantages of introducing quad notched bands and wide upper-stopband performance. Then, the proposed QMSIR is employed to achieve four desired notched bands. To validate the design concept, a novel super compact UWB BPF with quad notched bands respectively centered at frequencies of 5.2 GHz, 5.8 GHz, 7.0 GHz, and 8.0 GHz is designed and measured. The predicted results are compared with measured data, and good agreement is reported.

In this paper a novel design to reduce mutual coupling in circular patch antennas is proposed. A circular MIMO antenna with a dumb-bell shape parasitic element is inserted between the two circular patch antennas thereby reducing the mutual coupling. It has been observed that the proposed design produces a multi-band characteristics at 3.1 GHz, 6.2 GHz & 7.7 GHz. At the tri-band frequencies impedance bandwidths (IBW's) are around 90 MHz, 320 MHz, and 540 MHz. The process involves cutting rectangular slits on each side of a circular patch and placing a dumb-bell shaped parasitic structure to reduce the transmission coefficient (S₁₂) to -40.75 dB. It is observed that the antenna parameters are greatly improved in terms of ECC, diversity gain, directivity, group delay and peak gain which are 0.005, 9.973 dBi, 6.14 dBi, 10.81±1 nsec and 3.59 dBi. The results of experimental validation and numerical analysis are presented. The antenna design can be used for wireless communication as well as all C-band applications.

This paper presents a novel design methodology for the design and optimization of a miniaturized multiband microstrip patch antenna (MPA) suitable to be used in wireless communication systems. Two design steps were used to do that. In the first step, an initial antenna is designed by a trial and error approach to nearly operated in the desired frequency bands, but the level of impedance matching (S₁₁<-10 dB) for one or more bands is unsatisfactory, or some bands are uncovered by the antenna. Then, the second design step is beginning after that aiming to achieve optimized antenna by applying an optimization algorithm to effectively fine-tune the impedance matching of the initial deigned antenna to closely satisfy all the desired frequency bands. As an illustrative example, the proposed optimization methodology was used for designing a miniaturized multiband MPA suitable for operating at five different frequency bands, 915 MHz (RFID band), 1850 MHz (GSM band), (ISM-Industrial, Scientific, Medical), 2.45 and 5.8 GHz, and 3.5 GHz (WiMAX band). The proposed MPA used here is composed of two patch structures printed on both sides of an FR4 substrate occupying an overall size of just 28×28 mm². The final optimized antenna is fabricated, and its simulated and measured results were coinciding with each other validating the design principle. Moreover, simulation antenna performance parameters, surface current distribution, realized peak gain, and efficiency besides the radiation patterns at the desired frequency bands are obtained using CST MWS.

A miniaturized TM21 mode circular patch antenna is introduced. The miniaturization is realized by loading the patch with four symmetric radial slits, which facilitate elongating the current path and thus reducing the resonant frequency and the patch size. In particular, the eigenvalue of the proposed higher order mode is reduced to that of a conventional dominant TM11 mode antenna, resulting in about 40% reduction in the radius. The effects of the slit geometry on miniaturization and resonant frequency are studied. The measurement results are also presented, which are in good agreement with the simulation ones. Such miniaturized TM21 patch antennas with conical radiation patterns have manifold applications in phased array antennas for booming communication demands.

In order to solve the high harmonic content of permanent magnet synchronous motor (PMSM) for fitness car, a PMSM with built-in permanent magnet bridge is proposed in this paper. Compared with surface mounted permanent magnet synchronous motor (SM-PMSM), the proposed motor with permanent magnet bridge structure has lower harmonic content. The performance and magnetization angle of the proposed motor are compared and analyzed in detail. The results obtained from finite element analysis show that the permanent magnet bridge can increase the air gap magnetic field intensity, and different directions of magnetization will affect the amplitude of fundamental wave of air gap magnetic density. Moreover, it can reduce the total harmonic distortion (THD) and make the magnetic density waveform more sinusoidal. It is very beneficial to the smooth output of torque of fitness car.

The design guidelines have been proposed for achieving efficient wireless Electric Vehicle (EV) charging system under non-ideal practical scenarios. The effects of operating parameters have been investigated by addressing the fundamental hurdle to the widespread usage of magnetic resonance coupling (MRC) based wireless EV charging system. From both experimental and simulated results, it has been perceived that the power transfer efficiency (PTE) depreciates rapidly as the charging condition deviates from the ideal one. It is observed that PTE can be managed to enhance from the deteriorated value to an acceptable level through proper consideration of separation air gap of the charging coils, frequency of operation with acceptable horizontal offsets, suitable coil models, position of metallic object and coil properties. To maintain the maximum PTE even under non-ideal scenario, an automated frequency tuning method has also been delineated. The corroborated experimental and simulated results can provide a complete strategic plan in the design of an efficient practical wireless power transfer system to be utilized for EV charging system.

A compact wideband circularly polarized (CP) square slot antenna for universal ultra high frequency (UHF) RF identification (RFID) handheld reader applications is proposed, fabricated, and tested. The antenna is coplanar waveguide (CPW) fed by an inverted Z-shaped feeding line. By inserting four stubs in diagonal directions and two inverted T-shaped strips inside the square slot, broadband CP operation, wide axial ratio bandwidth, and good impedance matching are achieved. The measured < -10 dB impedance bandwidth is from 706 MHz to 1007 MHz (301 MHz, 35.1%). The measured 3-dB axial ratio (AR) is 427 MHz (745-1172 MHz, 44.5%). The maximum measured gain of the proposed antenna is 4.8 dBi. The proposed antenna has wide impedance bandwidth, wide axial ratio bandwidth, and small size. The dimensions of the antenna are only 120×120×1.6 mm³. The impedance bandwidth and AR bandwidth performances of the proposed antenna can easily cover the UHF RFID band as whole.

The paper presents a new method of dispersion compensation. It aims to reduce the dispersion effect of the wave throughout its propagation in the cable. The main objective is to improve the defects localization accuracy in electrical cables. This suggested method can be applied to any test signal injected in the line under test.

In this article, a microstrip-fed stepped open slot antenna is presented which is suitable for GSM 1800, WiFi, WiMAX, PCS, and ITM-2000 applications. The proposed geometry is composed of a circle-shaped tuning stub, a feed structure, and deformed ground plane. The proper tuning of resonating modes (f_r1, f_r2, f_r3 and f_r4) and wideband frequency response are acquired by adjusting the dimension of stairs, tuning the stub and an elliptical slot. The experimental result demonstrates that this antenna covers the frequency range from 1.375 to 5.6 GHz with measured fractional bandwidth (BW(%)=200 * (f_h - f_l)/(f_h + f_l) of 121.14% for S₁₁<-10 dB. This antenna also exhibits resonance at frequencies (measured) 1.625, 2.52, 2.82, 3.75, 4.67, and 5.42 GHz. After investigating the surface current distribution, the mathematical equations are deduced for simulated resonating frequencies of 1.35, 2, 3.8, and 5.22 GHz. Due to asymmetry in structure, asymmetric far-field patterns are found in E-plane with omnidirectional patterns in H-plane.

This paper proposes and implements a novel class of inductor-capacitor-capacitor wireless coordinative DC motor drives, which not only performs selective wireless power to motors, but also achieves power equalization to ensure the same operation for isolated robotic arms. The key is to make use of the selective wireless power transfer with several resonant frequencies and then use only one transmitter with the inductor-capacitor-capacitor compensation network to provide multiple-frequency transmission without relying on the switched-capacitor array. In order to provide simultaneous and independent wireless power to different motors and hence achieve the desired coordinative motion, a time-division multiplexing scheme and burst firing control are newly employed. Thus, the wireless power transfer system with multiple receivers can achieve better flexibility and simplicity. Both finite element analysis and experimental results are given to verify the validity of the proposed inductor-capacitor-capacitor wireless coordinative DC motor drive. As a result, the motors can achieve independent motion with 1200 rpm and simultaneous motion with 400 rpm when the torque is 10 Ncm, and the operating frequencies are set at 110 kHz and 130 kHz.

A compact dual-band substrate integrated waveguide (SIW) crossover with high isolation is proposed. Two identical slots are etched on the ground plane to achieve dual-band response and compact size. The passbands are generated below the cutoff frequency of the SIW due to the electric dipole behaviour of the slots. In-line ports are also employed to obtain good transmission and high isolation. To validate the concept, a dual-band crossover operating at 2.4 GHz and 5.4 GHz is designed, fabricated, and measured. The crossover size including in-line ports is 43.2×43.2 mm², equivalent to 0.43λ_g×0.43λ_g, here λ_g is the guided wavelength at the first operating frequency. The tested insertion loss and isolation at the two operating frequencies are smaller than 0.27 dB and greater than 40 dB, respectively.