In this research work, a new and simple design method of a compact slot antenna with dual notched bands is demonstrated for ultra-wideband (UWB) wireless networks. The presented antenna design is printed on a low-cost FR-4 substrate. Initially, an antenna with improved impedance bandwidth is designed. This is archived by employing the an extra slot with two T-shaped strips which increases the upper-frequency band of the design from 9 to 15 GHz. Later, undesirable bands including 4 GHz C-band, worldwide interoperability for microwave access (WiMAX) at 3.5/5.5 GHz (3.3 to 3.7 GHz and 5.15-5.85 GHz), wireless area network (WLAN) systems at 5-6 GHz (5.15-5.35 and 5.725-5.825 GHz) are eliminated by modifying the upper layer of the antenna using the protruded L-shaped strips inside the square radiation stub and the protruded E-shaped strip inside the feed-line. The proposed antenna offers quite good fundamental properties in terms of impedance bandwidth, gain, fidelity, radiation pattern, etc. A good agreement is observed between the measured and simulated results. Due to the simple structure and excellent performance of the design with controllable band-notch function, the presented microstrip antenna is useful for modern UWB wireless networksand can be an attractive

In this paper, local meteorological data of one year have been used to calculate the surface atmospheric radio refractivity (N) and estimate the vertical refractivity gradient (dN₁) as well as the geoclimatic factor (K) in the lowest atmospheric layer above the ground surface in the station Kuujjuaq (Quebec, Canada). In this region, the climate is arctic, characterized by very long and very cold winters (on average the temperature is below -20˚C for almost 240 days per year). The precipitations are almost nonexistent, and the vegetation is scarce. Average daily, monthly, seasonal, and yearly variations of the N, dN₁, and K are estimated and analysed. The obtained values of these indices are compared to the corresponding values provided by the ITU. The results show that the more negative values of dN₁ lie in the summer season. This is mainly due to the important variations of the temperature and humidity during this season. However, the estimated values lie in the limits mostly corresponding to standard refraction.

This article describes a compact split ring monopole antenna loaded with a Hexagonal Split Ring Resonator (Hex-SRR) for Wireless Local Area Network (WLAN) and Radio frequency Identification (RFID) applications. The resonance frequency of the proposed antenna is obtained by making use of a split ring structure and a metamaterial element Hex-SRR. The prototype antenna is printed on an FR-4 substrate having a dielectric constant (ε_r) of 4.4 with dimensions of 21×21×1.6 mm³. The split in the ring radiating element is used to achieve good impedance matching, and the Hex-SRR creates a new resonance frequency of 5.8 GHz. This paper includes equivalent circuit investigation, operating mechanism, and band characteristics of Hex-SRR as well as negative permeability details. The fabricated antenna provides an impedance bandwidth of 1180 MHz (5.23-6.41 GHz), which is suitable for WLAN and RFID applications. Good similarity is inferred between the simulated and measured results of the proposed antenna.

A study on the use of non-ionizing and non-thermal millimeter electromagnetic radiation in tumor chemotherapy was conducted. DNA released from sarcoma 45 tumor (tDNA) and healthy rats (hDNA) in water-saline solution was irradiated during 90 min by frequencies at both resonates for oscillations of water molecular structures (at 64.5 GHz and 50.3 GHz) and non-resonance (48.3 GHz). Non-irradiated and irradiated tDNA and hDNA binding constants with anti-tumorous drugs doxorubicin (DX) and netropsin (NT) were studied. The absorption spectra of non-irradiated and irradiated complexes of DNA with DX and NT were obtained by spectroscopic method. From the absorption spectra, binding constants at 290 K, 300 K, and 310 K temperatures have been determined. According to our calculations doxorubicin and netropsin with irradiated DNA form were more stable complexes and much stronger with tDNA irradiated at resonant frequencies: it was observed doxorubicin and netropsin binding selectivity to irradiated tDNA in-vitro experiments. For a DNA irradiation at resonant frequencies of 64.5 GHz and 50.3 GHz the binding constant K to DX and to NT is almost an order of magnitude higher than for the non-irradiated DNA. The obtained data suggest that the irradiation of malignant tumors by non-thermal (ultra-weak intensity) millimeter electromagnetic waves in combination with anticancer drugs may be promising for clinical oncology. The same antitumor effect can be achieved at much lower doses of medicines (considerable dose reduction). This is essential from the point of view of the application of gentle therapies for patients and the reduction of expenses associated with acquisition of expensive medicines.

A new compressive sensing-based direction of arrival (DOA) estimation technique for source signal detection in the presence of unknown noise, based on the generalized correlation decomposition (GCD) algorithm, is presented. The proposed algorithm does not depend on the singular value decomposition nor on the orthogonality of the signal and the noise subspaces. Hence, the DOA estimation can be done without an a priori knowledge of the number of sources. The proposed algorithm can estimate more sources than the number of physical sensors used without any constraints or assumptions about the nature of the signal sources. It can estimate coherent source signals as well as closely-spaced sources using a small number of snapshots.

We present a three-dimensional finite element (FEM) field-flux eigenmode formulation, able to provide accurate modeling of the propagation characteristics of periodic structures featuring graphene. The proposed formulation leads to a linear eigenmode problem, where the effective refractive index is an unknown eigenvalue; the electric field intensity and magnetic flux density are the state variables; and graphene's contribution is efficiently incorporated via a finite conductivity boundary condition. The FEM formulation is spurious-mode free and capable of providing accurate dispersion diagrams and field distributions for arbitrary propagation directions, as opposed toother analytical or numerical approaches, while also efficiently dealing with graphene's dispersive nature. The novelty of the presented approximation is substantiated by computational results for structures incorporating graphene of random periodicity, both within passbands and bandgap frequencies.

Urban heat islands (UHIs) threaten the ecological environment and human health. A large number of studies have focused on surface UHIs (SUHIs) across different spatial and temporal scales around the world with the development of satellite remote sensing technology. However, the influences of heterogeneous urbanization processes and background climates on SUHIs are still unclear and are important for targeted mitigation policies. A systematic review of the current status of SUHI studies, particularly from the perspective of comparisons among different regions, is urgently needed. We first introduce the commonly used satellite-retrieved data products and quantification methods used in SUHI studies. Subsequently, we summarize the potential driving factors of SUHI and compare the specific findings for different regions. Finally, we point out the deficiencies in the existing research and propose several prospects for the consideration of future SUHI studies. Additional global-scale research should be conducted using more advanced spatial statistical models. This can help better explore the spatially heterogeneous relationship between the SUHI and its associated driving factors. The effects of urbanization and climate from different regions should be further explored. Moreover, the problems of imperfections in the satellite data and from dynamic land use should not be ignored.

Drawing on the ideas of stator permanent magnet motors, hybrid planetary gears are integrated into permanent magnet motors using hybrid excitation on the stator side, and a new type of stator-hybrid magnetic planetary gear motor for steering systems is proposed. The magnetic gear motor overcomes the shortcomings of the existing magnetic gear structure and performance, and has the advantages of high reliability, strong torque transmission capacity and large transmission ratio. At the same time, it can adjust the levitation force and power in real time as the working conditions change, improving motor efficiency. This paper focuses on the topology and working principle of the stator-excited planetary magnetic gear motor. According to the finite element analysis, the magnetic field distribution is obtained, and the rationality of the magnetic field is analyzed. Theoretical analysis and experimental results show that the magnetic circuit of the stator-hybrid excitation planetary gear motor is correct, and the torque can meet the design requirements. This method provides reference and application value for the development of high performance and low cost permanent magnet planetary gear motors.

The design of an eight-port MIMO antenna at the sub-6-GHz (LTE 42/43 and 46) bandsfor fifth-generation (5G) smartphone is presented. First, based on the Babinet's principle, a microstrip slot antenna (MSA) is designed from its counterpart complementary structure, microstrip patch antenna (MPA) to operate over the LTE 46 band. In order to make the MSA to operate at the specified three LTE bands, a proposed single antenna, namely RMSA, is achieved by adding a strip-ring resonator within the grounded slot of MSA which shows a good measured impedance bandwidth (S₁₁ ≤ -6 dB) of 3.28 ~ 3.84 GHz and 5.14 ~ > 6.0 GHz. Then, eight similar antenna elements of RMSA are printed on a smartphone printed circuit board (PCB). An FR4 substrate is used as the system PCB with an overall dimension of 80 × 150 × 0.8 mm³. Two techniques, namely polarization and pattern diversity, are exhibited by designing the MIMO system due to the orthogonal arrangement of microstrip lines feeding the RMSAs. Simulated and experimental results are conducted to examine the performance of the designed MIMO antenna. Good isolation, acceptable gain, and efficiency are obtained over the bands of interest which verify the suitability of the proposed system for MIMO smartphone applications.

This paper introduces a new simple-structured dual circularly polarized (CP) antenna design for fifth-generation (5G) front end systems. The antenna configuration consists of a crescent-shaped slot radiator fed by a pair of rectangular 50-Ohm microstrip lines. The antenna is designed on an FR-4 dielectric substrate with an overall size of 48 × 48 × 1.6 mm³ to operate at 3.5 GHz, a 5G candidate band. A wide dual CP characteristics supporting both left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP) is achieved in the frequency of 3-4.2 GHz. In addition, the mutual coupling (S₂₁) between two ports of the proposed antenna is better than 15 dB. A prototype sample of the proposed design is fabricated and measured to validate the design concept. The antenna offers sufficient efficiency, gain level, and axial ratio bandwidth which make it suitable for different 5G front end applications such as cognitive radio, base station, satellite communications, imaging, and radar systems.

The goal of this paper is to present, for the first time, calculations of the magnetic penetration case of a first principles multipole-based cable braid electromagnetic penetration model. As a first test case, a one-dimensional array of perfect electrically conducting wires, for which an analytical solution is known, is investigated: we compare both the self-inductance and the transfer inductance results from our first principles cable braid electromagnetic penetration model to those obtained using the analytical solution. These results are found in good agreement up to a radius to half spacing ratio of about 0.78, demonstrating a robustness needed for many commercial and non-commercial cables. We then analyze a second set of test cases of a square array of wires whose solution is the same as the one-dimensional array result and of a rhomboidal array whose solution can be estimated from Kley's model. As a final test case, we consider two layers of one-dimensional arrays of wires to investigate porpoising effects analytically. We find good agreement with analytical and Kley's results for these geometries, verifying our proposed multipole model. Note that only our multipole model accounts for the full dependence on the actual cable geometry which enables us to model more complicated cable geometries.

When multiple antennas, operating at different frequencies, are installed on a single platform where the typical inter antenna spacing is a few wavelengths at the lowest frequency, the mutual coupling between the antennas can be optimized by the suitable selection of frequencies and the separation of adjacent antennas. This paper characterizes the dependency of mutual coupling between monopoles on the frequency and separation of the radiating/interfering monopole as well as on the size and shape of the ground plane. The out of band (off-band) characteristics of the monopoles are studied, and the effect of frequency offset between the adjacent monopoles on off-band mutual coupling is summarized. The off-band mutual coupling is reduced by more than 15 dB when the adjacent antenna frequency is selected to be near the fourth harmonic. In the case of smaller ground planes, better isolation of more than 20 dB is possible at intermediate antenna spacing than at the edges. The effect on radiation pattern of an antenna by the proximity of nearby antennas is also studied. The operating frequency/resonant length of the nearby antenna and the inter antenna spacing are found to be the key factors causing variation in radiation pattern. Lower off-band interfering antenna of bigger size is found to have significant effect on radiation pattern at spacing less than 2λ. Analysis has been carried out using FEKO, whose findings are validated using another software HFSS and measurements.

The complete analytical formulation of periodic structures using metamaterials formed with split ring resonators (SRRs) is developed. The periodic structure modeling is based on coplanar waveguide transmission line method and network parameters. The full effect of mutual inductances in the array design is integrated for the first time using curve fitting techniques with electromagnetic simulator. The simplified equivalent circuit including the effect of mutual inductance is presented. The proposed formulation is then used to design a unit cell composed of two SRRs of the sensor array. The analytical method is then verified with simulation results. The prototype of the unit cell has then been manufactured and measured at different frequencies. The analytical, simulation, and measurement results are compared, and agreement has been confirmed.

Near-field magnetic measurement is a simple but effective way of researching the magical electromagnetic properties of metamaterials. However, till now, the experiments in the field of metamaterials have involved only far-field macroscopic and near-field electric measurements because of the difficulty in isolating interference from electric fields. In this research, we design and fabricate a near-field magnetic probe with about an one-tenth wavelength size and 20 dB E-field rejection ratio, which can be combined with a parallel double-plate device integrating a system for measuring anisotropic vector magnetic field. As a verification measurement of plane waves and cylindrical waves, it got the clear vector field distribution characteristics and good anisotropy. Next we used the dipole to measure the typical metal split ring structure of the metamaterial. The measurement of the distribution of magnetic fields contributes to revealing the interaction mechanism between electromagnetic waves and metamaterials as well as the relationship between microscopic structural elements and macroscopic electromagnetic properties.

Microwave technology has been widely used in rubber industry. In order to solve the problem of uneven temperature distribution, a novel control method of adaptive multi-dimensional Taylor network combined with Cuckoo Search is proposed in this paper. The adaptive multi-dimensional Taylor network control method is used to obtain the suitable output powers and phase difference under unknown system parameters. Cuckoo Search algorithm is utilized to optimize the whole situation and find the best fit input variables at sampling points. To verify the proposed control strategy, the dielectric permittivity of nitrile butadiene rubber composites is measured, and the control process is simulated based on measured values. The simulation results show that the proposed method can well control the temperature rising process with little difference between the average temperature and reference trajectory.

This study addresses the problem of adaptive polarimetric detector (APD) and optimal polarimetric design for the distributed multiple-input-multiple-output radar in compound-Gaussian clutter with inverse-gamma distributed texture component. We derive the APD by maximizing a posteriori estimation and performing a generalized likelihood ratio test. The false alarm probability for the detector is analyzed to validate the corresponding constant false alarm rate property. Furthermore, based on the concepts of game theory, we formulate an optimal polarimetric design as a two players zero-sum game, which further improves the performance of the proposed detector. Simulation results show that the proposed detector outperforms its counterparts, and the optimal polarimetric design algorithm can efficiently enhance the detection performance.

In this paper, a double-side hybrid excitation flux-switching (DSHE-FS) motor employing a double stator structure with special multi-excitations is presented. The high space utilization improves the torque density and power density of DSHE-FS motor. The addition of non-rare-earth permanent magnet material reduces the consumption of rare-earth permanent magnet material. The double-side field windings enable the motor to have more flexible magnetic modulation properties. To investigate the principle of motor operation and flux regulation, the equivalent magnetic circuit method is employed. In order to achieve higher operation performances of the motor in different driving modes, the multi-objective optimization with coupled multi-physical field calculation is carried out. The multi physical comprehensive sensitivity function is defined which couples the electromagnetic performance optimization objective and mechanical performance objective. Then multi-objective genetic algorithm (MOGA) method was used to find a feasible solution set. Response surface (RS) method and parameter scan method are used to further determine the five important dimensions. The electromagnetic characteristics of optimized DSHE-FS motor are evaluated and compared in detail. Moreover, the mechanical analysis is conducted for the cupped rotor of DSHE-FS motor to validate the operation security. Theoretical analysis and simulation results verify the rationality of the DSHE-FS motor and the proposed optimization design method.

Spatial transform techniques like transformation optics and conformal mapping have arisen as the dominant techniques for designing metamaterial devices. However, these techniques only produce the electrical permittivity and permeability as a function of position. The manner in which these functions are converted into physical metamaterial lattices remains elusive, except in some simple or canonical configurations. Metamaterial lattices designed by spatial transforms are composed of elements of different sizes, orientations, and designs. The elements must be distributed and oriented in a manner that makes the final lattice smooth, continuous, have uniform density, be free of unintentional defects, and have minimal distortions to the elements. Any of these would weaken or destroy the electromagnetic properties of the lattice. This paper describes a general purpose method to generate such arbitrary metamaterial lattices. Inputs to the algorithm are the permittivity and permeability functions as well as the baseline metamaterials that can provide the necessary permittivity and permeability values. In prior research, we reported a simple finite-difference technique for calculating the permittivity and permeability functions for arbitrary shaped devices using transformation optics. The present work is illustrated by generating an electromagnetic cloak of arbitrary shape that was designed using the previously reported technique. The final metamaterial cloak is simulated using the finite-difference time-domain method and performance compared to other cloaks reported in the literature.

The Lienard-Wiechert potentials show explicitly that charge acceleration, i.e., a change in charge velocity, causes radiation of an electromagnetic field. The goal of this discussion is to explore the rate of energy loss due to radiation from current and charge flowing on a circular loop as a function of the loop's curvature and wire radius. The results presented are obtained using a thin-wire, time-domain (TWTD) computer model for Gaussian-pulse excitation. Some results for a straight wire are also presented for comparison. Analytical estimates for the curvature and wire-radius effects are developed from best-fits expressions to the computed results.

This paper describes an experiment in a wind-wave pool in Brest, France, to characterize surface films when observed at moderate incidence from X-to-K radar bands. Measurements of the radar backscattered field were carried out for various seawater surface states and incidence angles. From this meaningful database (mainly lying in simultaneous acquisitions in X-, Ku-, and K-bands), an inversion method is proposed to characterize the elasticity modulus of the surface film. This process is based on the minimization of the cost function correlating the values given by a physical model of the damping ratio and the measured ones. The resulting oil parameters are found in overall good agreement - but still qualitative - with the various released oils. Nonetheless, the inversion method does not work properly for the rapeseed oil slick when higher wind speeds are considered, and this failure is explained. In addition, it can be seen that the results can be applied in an ocean context by comparing the modeled normalized radar cross section (NRCS) in an ocean context (given by the Bragg scattering and the Elfouhaily spectrum) and the measured NRCS.