In this paper, an experimental demonstration employing the decomposition of the time-reversal operator (known as DORT) in combination with pulse inversion is reported, allowing one to detect and selectively focus on nonlinear targets. DORT is a technique based on a multistatic configuration that separates the detected targets by means of eigendecomposition of the time reversal operator allowing for selective transmission of waves towards a target of interest. Pulse inversion is a technique that enhances harmonic responses while suppressing fundamental responses. By applying DORT with pulse inversion (PIDORT), harmonic detection and selective transmission to detected nonlinear targets can be enhanced. The results from our experiment show that PI-DORT can effectively detect and separate nonlinear targets for selective transmission.

In this paper, a dual band high gain miniaturized cross shaped patch antenna is proposed for IEEE 802.11ax applications. The radiating patch size is 0.330λ₀x0.417λ₀ on a low cost Flame Retardant 4 substrate. A cross shaped radiating element is designed to cover the upper band of IEEE 802.11ax, and a four ring circular Complementary Split Ring Resonator (CSRR) is etched on the cross shaped radiating element to cover the lower band of IEEE802.11ax. Thus the dual bands of 802.11ax are achieved. In order to enhance the gain, 2x2 array hexagonal metamaterial unit cell is positioned behind the substrate. To extract the constitutive parameters of the circular CSRR, NRW (Nicolson-Ross-Wier) retrieval method is used. The measured maximum gain is approximately 6 dBi, 10 dBi for 2.4 GHz, 5 GHz, respectively. Parametric study on the geometrical dimensions is investigated using HFSS 15.0.

A novel cross polarized compact antenna system is proposed for Ultra Wide Band communications. It also covers the sub-6 GHz band for initial 5G launch. The overall antenna system is a distinctive combination of Multiple Input Multiple Output (MIMO) antenna system covering radio frequency (RF) band starting from 2 GHz to 12 GHz. This MIMO system consists of two F-shaped monopoles with slotted fractured ground planes. The two antennas are fabricated back to back with 90 degree difference. The overall volume of the MIMO antenna system is 14 mm × 14 mm × 0.25 mm. Due to its very compact design, it is suitable for mobile phones and other hand-held devices. The peak measured gain has been achieved as 4.8 dB, and the measured far field patterns are nearly isotropic. Envelope Correlation Coefficient (ECC) and Gain Diversity are presented for the proposed MIMO antenna system.

Tropical cyclone (TC) is part of the most serious natural disasters. Western Pacific is the region with the highest frequency of tropical cyclones (TCs). By simulating and correcting the brightness temperatures (TBs) of the microwave humidity and temperature sounder (MWHTS) onboard the Fengyun-3C (FY-3C) satellite, a method is proposed to observe the TCs in the Western Pacific. The Weather Research and Forecasting Model (WRF) and the fast Radiative Transfer model for TOVS (RTTOV) are adopted in our method. Then, simulated TBs are linearly corrected based on the field-of-views (FOVs), channels and latitude bands. After that, the biases of all channels are within 2 K and close to zero, and the RMSEs are less than 10-K except Channels 10 and 15. Therefore, this WRF/RTTOV method can be implemented in other TCs in the Western Pacific region. In addition, a precipitation detection algorithm is proposed and used to detect precipitation in the TC area. Compared with the FY-3C MWHTS and Tropical Rainfall Measuring Mission (TRMM) Multi-Satellite Precipitation Analysis (TMPA) precipitation products, the results indicate that our precipitation detection algorithm has reached better indicators. The potential application can lay a foundation for precipitation rate retrieval and further research.

The electromagnetic wave diffraction from the modified cone formed by a circular truncated cone whose aperture is closed by a spherical cap is considered. The problem is reduced to the solution of the mixed boundary value problem for the Helmholtz equation. The axially symmetric version of the problem, where the cone is excited by a radial electric dipole (E-polarization wave diffraction problem), is analyzed. A new approach to the solution is proposed. The solution includes the application of the Kontorovich-Lebedev integral transformation, the nonstandard procedure for derivation of the Wiener-Hopf equation and its reduction to the set of linear algebraic equations of the second kind. Their solution ensures the fulfillment of all the necessary conditions including the edge condition. The approximate equation for the sharp truncated cone terminated by the spherical cap is analyzed. The low frequency approximation as well as the transition to the plane which incorporates the hemispheric cavity is analysed. The numerical calculation results are presented.

The technique to retrieve the microwave permeability of metals from the measured constitutive parameters of composites with fine powder of these metals is developed. The technique is based on the modified Sihvola mixing rule and describes a wide range of contrasts in the component susceptibility, accounts for both the inclusion shape and the percolation threshold. These parameters are related to the Bergman-Milton shape-distribution width and to composite structure. The technique is applied to retrieve the microwave permeability of nickel. The metal permeability is calculated from the measured permittivity and permeability of paraffin-bound composites filled with nickel flakes or spheres with account for skinning in conducting inclusions. The measurements are performed using the transmission coaxial-cell in the frequency range up to 15 GHz. The effects of filling factor, inclusion shape and size on the retrieved permeability spectra are analyzed. The permeability retrieval procedure is based on parameter fitting of the selected mixing model for the measured permittivity and permeability data. The retrieved permeability is close to the data available from archived literature sources that are obtained with thick nickel wires and foils.

In this work, a novel use of the Non-Uniform Fast Fourier Transform (NUFFT) in reflectarray antenna analysis is proposed to greatly accelerate the computation of radiation patterns using a nonuniform, reduced and adaptive grid in the spectral domain. The proposed methodology is very useful for very large reflectarrays, which have very narrow beamwidths due to their large directivity, and shaped-beam reflectarrays for satellite applications such as Direct Broadcast Satellite (DBS), which might require a compliance analysis in very small angular regions. In those cases, high resolution in the radiation pattern is required, while a low resolution could be enough elsewhere to account for side lobes. However, current analysis techniques for such reflectarrays present limitations regarding large memory footprints or slow computations. The methodology presented in this work allows to overcome those limitations by performing computations in a non-uniform, reduced and adaptive grid in the transformed UV domain, achieving faster computations using considerably less memory. Numerical examples for current applications of interest are provided to assess the capabilities of the technique. In particular, the use of the NUFFT allows to compute efciently the radiation pattern in any principal plane with improved resolution for multibeam applications. Also, compliance analyses for DBS applications may be improved with the use of a reduced, multiresolution grid and the NUFFT. The proposed technique is thus suitable to greatly accelerate optimization algorithms.

A wideband composite right/left handed transmission line (CRLH-TL) antenna with cavity-backed substrate integrated waveguide (SIW) is proposed in this letter. This proposed antenna consists of a 2×2 array of mushroom unit cells, feeding line and cavity-backed SIW. By introducing SIW structure both impedance and gain of the antenna are improved. The proposed antenna has average gain of 7 dBi (peak measured gain 9.5 dBi), wide -10 dB impedance matching bandwidth of 55% from 5.2 GHz to 8.3 GHz, small size of 40 mm×50×4 mm, high integration ability, and reduced back radiation.

In this paper, a grade nested array constituted by a uniform linear array and a grade linear array with uniformly increasing inter-element is presented. The closed-form expression of the proposed array geometries and corresponding direction-of-arrival (DOA) estimation algorithm are derived. Theory analysis certifies that the proposed grade nested array can provide higher degrees of freedom (DOF) than some existing nested arrays. Some simulations are also presented to demonstrate the improved performance of the proposed nested array for DOA estimation of quasi-stationary signals.

This paper proposes a morphological ultra-wideband (UWB)-radar-based respiratory signal model. According to the detection theory, it is crucial to set up an appropriate model to fulfil the detection purpose. Previous models pay less attention on the time dimension of the respiratory signal, but the frequency domain cannot precisely describe it because of its non-linearity and non-stationarity. This model uses a morphological operator to dilate or erode the base wavelet, and the length and value of the digit in the structure element serve as the parameters in this morphological model. The result of the experiment carried out on 10 human targets with impulse radio ultra-wideband (IR-UWB) radar proves the efficiency of this model. As the UWB radar sensed human respiratory signal is nonlinear and non-stationary, the parameters in the model can be regarded as a measure of non-linearity and non-stationarity. An experiment is carried out with the simulated respiratory signal generated with the proposed model. The result shows that the detection algorithm based on Ensemble Empirical Mode Decomposition (EEMD) method has a better performance than that based on Adaptive Line Enhancer (ALE) and with the value of the digit in the structure element increases, the performance of the ALE method declines, while the EEMD method stays in a good performance, which indicates that the EEMD method has a good potential to deal with the nonlinear and non-stationary respiratory signal.

In this paper, a dual-band stub (DBS) comprising one lumped kernel circuit unit cell (KCUC) and two distributed uniform transmission lines is presented. An odd-even mode resonant frequency ratio (OEMRFR) is introduced, which can determine all the element values in the DBS circuit model. Its phase and impedance bandwidth properties are extracted based on the image parameter theory. By adjusting the OEMRFR value, the second working bandwidth and structural size can be controlled simultaneously. On the other hand, the input and output space mapping (IOSM) is exploited to realize a planar microstrip DBS by transferring the lumped KCUC into a quasi-lumped formation. The established ISOM design process is fully automated and can generate the finalized DBS layout with just a few full-wave simulations. A DBS operative at WLAN dual frequencies of 2.4/5.8 GHz with extended bandwidth is designed as an example. Good agreement between the measured and simulated results justifies both the extracted dual-band performance of the proposed DBS and its customized IOSM design process.

Magnetic resonant wireless power transfer (WPT) is an emerging technology that may create new applications for wireless power charging. However, low efficiency resulting from resonant frequency drift is a main obstructing factor for promoting this technology. In this paper, a novel method of coordinating the operating frequency and load resistor is proposed to prevent frequency drift. The system efficiency and input impedance are obtained by solving the system equivalent equations. In addition, the new resonant frequencies can be obtained by solving the input impedance equations. Moreover, the process of the coordination method is illustrated. When resonant frequency drift occurs, the system can now operate at the resonant state, and the efficiency can be improved by using the proposed method. The WPT system via magnetic resonance coupling is designed. Simulated and experimental results validating the proposed method are given.

The incorporation of Electromagnetic Band Gap (EBG) unit cells, a type of metamaterials, with a dual band array antenna is proposed. By configuring the band gap of EBG cells accordingly, the pattern of the array antenna is successfully reconfigured at lower band of 2.4 GHz while maintaining the pattern at higher band of 5.8 GHz. Three pattern directions have been achieved: initial radiation pattern, 349-degree shift and 11-degree shift of the H-field. The array antenna is also frequency reconfigurable by suppressing the radiation pattern of the antenna in four different EBG cells configurations. In pattern shifting mode, the realized gain of the antenna is satisfactorily maintained and is comparable with the standalone of dual band array antenna with the range of gains from 5.08 dBi to 6.14 dBi and 7.83 dBi at 5.8 GHz.

A low computational complexity direction of departure (DOD) and direction of arrival (DOA) estimation method is derived for bistatic multiple-input multiple-output (MIMO) radar. In this method, we propose a novel bistatic MIMO radar geometry with one transmit array and two subarrays at the receive array, based on which the cross-correlation matrix is constructed. The DODs and DOAs can be estimated without eigendecomposition, thereby signicantly reduce computational burden. Moreover, the DODs and DOAs can be paired automatically. Simulation results verify that the proposed method holds better performance than the unitary estimation of signal parameters via rotational invariance technique and joint diagonalization direction matrix method.

Improvement of properties of polymeric materials through blending is a way to obtain products with highly adapted performance for specific applications. The present work reports the design and preparation of binary blend films of poly (ethylene-co-methacrylic acid) neutralized using sodium salt (EMAANa) and nano polyaniline doped with hydrochloric acid (nano PANI-HCl) or toluene sulfonic acid (nano PANI-TSA) with the aim of achieving improved thermal stability, DC conductivity and electromagnetic interference (EMI) shielding effectiveness (SE) of EMAANa. The binary blends were prepared by solution blending using a solvent mixture of toluene/1-butanol (90:10) at 65 °C. The hybrid materials were characterized and evaluated by FTIR, UV-Vis spectroscopy, XRD spectroscopy and thermogravimetric analysis (TGA). The electrical conductivity of the PANI and PANI/EMAANa blends was measured by four-probe method. The EMI shielding effectiveness was studied using a wave-guide coupled to an Agilent Synthesized Sweeper 8375A and a Hewlett-Packard spectrum analyzer 7000 in the X band frequency range (8-12 GHz). FTIR indicates a π-π and hydrogen bonding interaction between PANI and EMAANa, enabling the PANI to be adsorbed in the ionomer. The TGA of the blends show similar weight loss pattern with nano PANI-TSA-EMAANa exhibiting slightly lower weight loss below the decomposition temperature. The TGA results show that thermal stability of the blends is better compared to pure EMAANa. The results of measurements of electrical conductivity and EMI SE demonstrates that PANI was successfully blended into the EMAANa substrate.

With combining the advantages of the hybrid excited synchronous machine and claw pole machine, hybrid excitation claw-pole synchronous machine (HECPSM) exhibits merits of controllable flux operation and independent flux paths. One novel wide range adaptive speed region control strategy is proposed in this paper, based on the analysis of the field control capability of HECPSM and the space vector control. Independent control methods of maximum torque per ampere (MTPA), space vector and minimum copper loss (MCL) control were employed for the proposed machine during three different speed regions in order to obtain satisfied performance in the whole speed range. The correctness and effectiveness of the proposed adaptive speed region control strategy and drive system design were verified by simulation and experimental results, which demonstrated that the proposed control strategy maximized the range of speed regulation while exhibiting the high efficiency.

In this paper, the impact of decoupler type has been analysed on the performance of planar inverted-F antenna (PIFA)-based multiple-input multiple-output (MIMO) antenna. A T-type and a loop-type decoupler have been employed for the isolation of the MIMO antennas, and the performances of the two cases have been compared. The decouplers have been selected based on their different coupling mechanisms with the dominant ground mode. The antennas have been designed for the ground configuration of a USB dongle operating at 2.45 GHz band. Characteristic mode analysis of the ground plane has been carried out, and the MIMO systems have been analysed based on the coupling among the antenna, decoupler and the dominant characteristic mode of the ground plane. It has been observed that the coupling between the decoupler and the ground mode significantly affects the radiation efficiency as well as the diversity performance of the MIMO antenna.

With the increasing number of mobile phone users, new services and mobile applications, the proliferation of radio antennas has raised concerns about human exposure to electromagnetic waves. This is now a challenging topic to many stakeholders such as local authorities, mobile phone operators, citizen and consumer groups. The study of the spatial and temporal variability of the actual downlink exposure is a very important requirement to find an accurate exposure assessment. In this paper, a concept of exposure areas linked to specific variations of the electric field is introduced. Then a measurement campaign of the temporal variability of the electric field in urban environment is presented, considering different technologies and mobile operators in the previously defined exposure areas. This study allowed to determine updated daytime and nighttime exposure profiles. A second result yielded the averaging duration needed to reach a stable evaluation of the electric field exposure levels, inside each exposure area and according to each technology.

This paper presents a novel dual-band bandpass filter by utilizing a new dual-mode resonator and a pair of single-mode split-ring resonators. The center frequencies and bandwidths of both passbands can be independently adjusted without affecting each other. Meanwhile, a capacitive source-load coupling is introduced to create transmission zeros near the passband edges, and the filter can obtain high skirt-selectivity. Such a dual-band bandpass filter operating at 3.5 GHz and 5.85 GHz with compact size is designed and fabricated.

In this article, a couple of UWB antennas are presented. These antennas have the shape of two overlapped circles. The presented antennas are polarization diversity antennas with and without dual band reject filters. Measurements show that the antennas work well within the whole UWB. Antennas have practical reflection parameters S₁₁ and S₂₂ lower than -10 dB, practical coupling parameters S₁₂ and S₂₁ lower than -15 dB, an Envelope Correlation Coefficient lower than 0.015 and a diversity gain between 9.97 to 9.99 dB. Simulations of the antennas are done using the CST software.