A coplanar waveguide fed asymmetric rectangular antenna with sufficient WLAN-band rejection is presented for ultra-wideband applications. The antenna uses an asymmetric rectangular patch, modified feedline, and defected coplanar ground plane for obtaining ultra-wideband performance. An inverted-L shaped slit in the radiating patch is used for realizing the WLAN band-rejection. The antenna is designed on 1.6 mm thick FR-4 substrate having an area of 12×16 mm² (0.169λ_L×0.225λ_L). An impedance bandwidth of 11.49 GHz with a WLAN band-notch from 5.15-5.86 GHz is achieved. In addition to this, desirable radiation characteristics in terms of stable radiation patterns, peak realized gain of 4.5 dBi, and maximum total efficiency of 81% are achieved in the pass-band. In the notched-band, the peak gain and total efficiency reduces to -1.3 dB and 40%, respectively. Measured results agree well with simulated results. This antenna structure has fractional bandwidth of 115.18% and a bandwidth dimension ratio of 3029, which is comparable or better than that of similar structures available in the literature. The proposed antenna has desirable time domain performance in terms of fidelity factor, group delay, isolation and S₂₁ phase.

Oscillation frequency in a plasma filled rectangular dielectric resonator antenna is computed. Perturbation method for solving differential equation is applied to find oscillation frequencies of dielectric cavity resonator. Equilibrium distribution function of collisionless Boltzmann equation is slightly perturbed. Distribution function of plasma is perturbed by altering external applied electromagnetic field. Perturbed Boltzmann equation satisfies with the relaxation time approximation used for the collision. The resulting Maxwell equations are subjected to appropriate boundary condition. Multilinear algebra tensor decomposition technique is done to find eigenfrequincies of cavity resonator antenna considered in this paper. A simulation study of a ionized gas plasma antenna is done on HFSS. Numerically calculated oscillation frequency is cross verified with HFSS result and found in good agreement.

A novel method for the estimation of a forest vertical structure using Polarimetric Synthetic Aperture Radar (PolSAR) data only without the need to interferometry data is proposed in the present paper. Electromagnetic (EM) simulation is used to develop the proposed method, where the SAR pulse is simulated as a plane wave incident in the direction of the side looking angle of the SAR. For this purpose, the forest canopy layer is modeled as clouds of randomly oriented thin straight dipoles which are randomly distributed within an inclined prism volume, whereas the forest soil surface is modeled as a random rough surface. This prism has a horizontal rectangular base and parallelogram sides parallel to the direction of the incident plane wave (side looking angle of the SAR). The proposed method aims to estimate the average height of the canopy layer above the soil surface, the canopy layer thickness and the roughness of the forest ground surface. The proposed method is based on the Radar Vegetation Index (RVI) and the normalized Radar Cross Section (RCS) calculated from the PolSAR data and their relevance to the parameters of the forest vertical structure. Some examples are presented to demonstrate the capability of the proposed method using some PolSAR images obtained through EM simulation of the scattering from forest regions and by applying the theorem of SAR target composition with the Multiple Component Scattering Model (MCSM). The phase differences between the components of scattering obtained from the solution of the SAR target decomposition problem are used in the estimation process. The accuracy of the proposed method is assessed by calculating the percentage error of the estimated vertical structure and ground roughness for each resolution cell of the simulated forest region. It is shown that the percentage errors of the estimated parameters are very low, which reflects the accuracy and efficiency of the proposed method.

Quantum interactions between a single particle and nanoinclusions of spherical or cylindrical shape are optimized to produce scattering lineshapes of high selectivity with respect to impinging energies, excitation directions and cavity sizes. The optimization uses a rigorous solution derived via electromagnetic scattering formalism while the adopted scheme rejects boundary extrema corresponding to resonances that occur outside of the permissible parametric domains. The reported effects may inspire experimental efforts towards designing quantum sensing systems employed in applications spanning from quantum switching and filtering to single-photon detection and quantum memory.

An artificially two-dimensional metamaterial (ATDM) substrate is proposed as an artificial metamaterial high-constitutive parameter substrate for miniaturizing of a circularly-polarized microstrip antenna. In a circularly-polarized antenna, the electric and magnetic field directions are changing, which requires a two-dimensional metamaterial unit cell. The presented ATDM substrate raises the permeability and permittivity of the underneath substrate for a circularly-polarized patch antenna, and it is constructed of periodically arranged split-ring resonator (SRR) circuits implemented in a low permittivity dielectric underneath substrate. The ATDM attains equal permittivity and permeability material (ε_r ≅ μ_r), which neutralizes the destructive effect of the increased permittivity on the bandwidth. In addition, the ATDM structure is implemented in printed circuit board technology. The area of the ATDM antenna at 2.45 GHz is approximately 75% smaller than a usual microstrip antenna. The proposed antenna bandwidth is enhanced compared to the antennas with high-permittivity substrates. The proposed ATDM substrate antenna is fabricated and measured, and comparisons show good agreements between simulated and measured results.

The shielding cavity loaded with electronic equipment inside has a high Q value and is in overmode at relatively high frequency as a reverberation chamber (RC), but it does not have stirrers or paddles. However, the electromagnetic environment in the cavity is similar to that in the reverberation chamber working in frequency stirring mode or source stirring mode because of the certain bandwidth of the electronic equipment and the movement of the portable electronic equipment. Therefore, the electric field in the cavity can be predicted based on the theory of reverberation chamber. In order to predict the electric field in a given shielding cavity after loading additional electronic equipment, the determination method of the Q value of the cavity and the absorption cross section (ACS) of the electronic equipment, the influence of the ACS on the Q value of the cavity, and the relationship between the Q value and electric field are analyzed Firstly, the ACS and radiated emission power of the loading electronic equipment are measured in the RC. Then, the Q value of the cavity with the electronic equipment loaded inside is calculated by the known Q value of the cavity without the electronic equipment and the ACS of the electronic equipment. Finally, the electric field in the cavity loaded with electronic equipment is estimated by using the calculated Q value of the loaded cavity and the measured radiated emission power of the electronic equipment. The experimental results verify the effectiveness of the prediction method.

A novel microstrip dual-band bandpass filter (BPF) by coupling a stub-loaded hairpin resonator and two stub-loaded uniform impedance resonators (UIRs) is proposed. First, a open-ended stub is tap-connected to a meandering UIR at its centre, and these two stub-loaded meandering UIRs are further placed at symmetrical locations with respect to a stub-loaded hairpin resonator. Secondly, by introducing two parallel coupled lines at the two sides of the stub-loaded hairpin resonator, a dual-band BPF with two passbands at 2.4 GHz and 5.2 GHz is constructed. Finally, a prototype filter is designed and fabricated, and its measured results are provided to verify the predicted dual-band filter design.

The electromagnetic vibration noise level of a permanent magnet synchronous motor (PMSM) directly affects the Noise, Vibration and Harshness (NVH) performance of an electric vehicle. Taking a permanent magnet synchronous motor (PMSM) for electric vehicle driving as an example, the electromagnetic noise characteristics were studied by combining ANSYS Workbench multi-physical field finite element analysis platform. The electromagnetic vibration force of the stator teeth of the motor is the main source of electromagnetic noise. The magnetic field of the motor can be optimized by changing the slot structure of the motor rotor, so as to improve the electromagnetic vibration force of the stator teeth and reduce the electromagnetic vibration noise of the motor. In order to optimize the magnetic field, three different rotor slot structures are proposed. The most suitable slot structure is found by comparing and analyzing the magnetic field, noise field and electromagnetic force with the structure before optimization. By comparing the results before and after optimization, it can be seen that the optimized motor can effectively reduce the vibration noise of the motor and ensure the electromagnetic performance of the motor.

In this paper, a novel simple structure for all optical photonic crystal based logic gate is presented. The structure is based on coupling the input signals to a combiner and thresholding the output signal of the combiner. The unit cell of the structure is designed to achieve band gap around the communication wavelength (i.e. 1.5 μm). The presented structure reveals low cross couple between gate inputs. The structure has no symmetry between inputs, which enables realization of the gate on small footprint photonic crystal. The structure offers 0.1 μ bandwidth around the communication wavelength. The footprint of the structure is 25.59 μm × 25.31 μm.

The main intention to present this work is to miniaturize and gain enhancement of a tapered microstrip patch antenna, which resonates for Global Positioning System (GPS) of L1 band at 1.575 GHz. To accomplish this, we present a new design configuration of a Tap-Shaped Defected Ground Structure (TSDGS). It has been utilized to switch the resonant frequency from 14.5 GHz to 1.575 GHz with no adjustment of areas of the actual Tapered Microstrip Patch Antenna (TMPA). The prototype antenna is fabricated on a Roger RT Duroid substrate merely 58 × 22 mm². Conclusively, a miniaturization allowed up to 89.31%, with regard to the TMPA, is excellently accomplished. The gain of the proposed antenna is successfully enhanced with properly locating the metamaterial superstrate onto the basic patch antenna. A gain of 7 dBi improvement has been achieved. The proposed design process is done with two different solvers, ADS and HFSS.

The Coefficient of Variation (CoV) is investigated, studied, and proposed as an alternative and important performance metric to describe the effects of handset orientation on the capacity of Multiple-Input-Multiple-Output (MIMO) systems. We combine 3-D simulated radiation patterns of a base station and handset and their associated scattering parameters in two anisotropic propagation environments. The capacity is evaluated as the handset rotates about the X-Y-Z axes using standard Euler's angles. The coefficient of variation is numerically derived by rotating the handset over the Euler angles (φ, θ, ψ) in each direction every 15° about each axis over a full sphere where each rotation involves the creation of numerous instances of the propagation environment depending on the statistical robustness of the results sought. Three antenna array geometries operating at a frequency of 2.45 GHz are examined using two different propagation channel models (TGnB and TGnF) to verify the validity of the proposed approach. The derived results suggest that the proposed CoV is an effective and practical reasonable metric in selecting the best antenna system design, where ``best'' here refers to the design with the ability to reach the highest throughput of the designs considered.

A tri-band negative group delay (NGD) microwave circuit for multiband wireless applications is proposed and self-matched without the need for external matching networks. The frequency range can be influenced by the characteristic impedance of the microstrip lines. Under the condition that the microstrip circuit can be implemented with the common printed circuit board (PCB) fabrication technology, the frequency ratio of the highest NGD band to the lowest NGD band can vary between 3.8 and 10.9. For verification, a 1.2/3.5/5.8-GHz tri-band NGD circuit for Beidou B2, WiMax, and WLAN application is designed, fabricated, and measured. From the measured results, the NGD times are -1.08 ns, -1.19 ns, and -1.09 ns at three NGD central frequencies with insertion losses of 16.4 dB, 24.6 dB, and 18.9 dB, respectively. And the measured NGD bandwidths are 12.40% for the lower band, 8.60% for the center band, and 3.59% for the upper band, in which the return losses are greater than 16 dB.

A segmented three-dimensional wire monopole antenna is proposed and optimized to operate in both the Wi-Fi and Wi-Max frequency bands (2.4-2.48 and 3.3-3.7 GHz). The fabrication of the antenna employs both three dimension printing and foundry techniques. The design occupies a total volume of 33.8 mm × 30.4 mm × 37.4 mm, which is equivalent to 0.28λ₀ × 0.25λ₀ × 0.30λ₀, where λ₀ is the central wavelength of the lower band. The measurements agree with the simulations and show that the antenna has a -10 dB impedance bandwidth of 7.53% (2.36 to 2.55 GHz) and 53.87% (2.78 to 4.43 GHz) and a measured -3 dB axial ratio bandwidth of 19.06% (3.18 to 3.85 GHz) for the second band. For the first band, simulations indicate that the polarization is elliptical. The radiation pattern is a near hemispherical coverage toward the upper hemisphere. The measured maximum gain values are 5.6 and 7.3 dB for the lower and upper bands, respectively. The simulated radiation efficiency is higher than 98%.

This paper presents a humidity monitoring system with X band electromagnetic transmission. The verification is performed by comparing the gain and phase difference of intermediate frequency between 10.2 GHz and 10.4 GHz. Measurement data are analyzed to classify relative humidity levels and make decisions with ANNs. The system is simulated with electromagnetic field simulation software to analyze the ability of humidity monitoring. The structure from the simulation is developed to be a prototype system, including transmitter and receiver modules. Each module consists of an antenna, a frequency synthesizer, and a frequency mixer. The different operation frequencies of the two modules are -200 MHz and +200 MHz. The obtained intermediate frequency by mixing signals from each module is introduced into the circuit to find the gain and phase difference to compare with a relative humidity level. Humidity monitoring experiment is set in a closed plastic box to control the environment. The relative humidity level is from 55% to 95%. The decrease in gain is associated with increased relative humidity. Results found that the phase difference decreases clearly at the relative humidity from 75% to 95%. Both gain and phase difference data are used to train ANNs to optimize ANNs structure. Data are divided into 50% for training and 50% for testing. The proposed ANNs structure with a learning rate of 0.05 provides 98.8% accuracy. The optimized ANNs structure is composed of two input nodes, eight hidden nodes, and four output nodes. The four output node represents the relative humidity in 11 levels. The simulated and experimental results show that the system is able to monitor humidity effectively for applying in the greenhouse.

Resonance interaction between the electromagnetic radiation from a dipole antenna and a cylindrical density depletion aligned with an external static magnetic field in a magnetoplasma is studied in the case where the antenna is located outside such a density irregularity. A distinctive feature of the presented analysis is using a realistic distribution of the antenna current instead of the assumed one. It is shown that such an antenna can excite plasmon resonances of the density depletion, along with the resonance at the plasma frequency of the outer region. In addition, previously unrevealed resonances of the total field, which are related to excitation of complex modes of the cylindrical density depletion, are discussed. The results obtained can be helpful in understanding the basic properties of resonance interaction of the antenna fields with cylindrical density irregularities in a magnetoplasma and planning the related experiments in the ionospheric and laboratory plasmas.

There is an increasing demand in real-time imagery applications such as rapid response to disaster rescue and security screening to name a few. The throughput of a radar imaging system is mainly controlled by two parameters; data acquisition time and signal processing time. To minimize the data acquisition time, various methods are being tried and tested by researchers worldwide. Among them is the computational imaging (CI) technique, which relies on using coded apertures to encode the radar back-scattered measurements onto a set of spatio-temporarily incoherent radiation patterns. Such a CI-based imaging approach eliminates the requirement for a raster scan and can substantially simplify the physical hardware architecture. Equally important is the processing time needed to retrieve the scene information from the coded back-scattered measurements. In CI, the simplification in the hardware layer comes at the cost of increased complexity in the signal processing layer due to the indirect mapping and compression of the scene information through the spatio-temporally incoherent transfer function of the coded apertures. To address this particular challenge, this paper presents a hardware-based solution for CI signal processing using a Field Programmable Gate Array (an Xilinx Virtex-7 (XC7VX485T) FPGA chip) architecture. In particular, the proposed method consists of calculating the CI sensing matrix using the FPGA chip and storing it on the FPGA platform for image reconstruction. For the adjoint operation, the calculated sensing matrix is applied on the measured back-scattered waves from the target object. We demonstrate that the FPGA based calculation can reach 21.9 times faster speed than conventional brute-force solutions.

Corrugated substrate integrated waveguide (CSIW) based bandpass filter is designed and developed for the microwave interferometer (7.0 GHz) and ISM band (5.7 GHz-5.9 GHz) application. CSIW structure provides a cost-effective solution counter to substrate integrated waveguide (SIW). Initially, the CSIW structure is designed from the design methodology of SIW. Vias are replaced with a quarter wavelength open stub. A metallic inductive post is used for the realization of the bandpass filter from the CSIW structure. Computer simulation technology (CST) software is used for design and simulation of the proposed model. Two structures are implemented for the microwave interferometer and ISM band frequency application. The first structure resonates at the center frequency of 7.023 GHz with the fractional bandwidth of 5.26%. It provides an insertion loss value of less than 1.5 dB and a return loss better than 14 dB. Similarly, the second structure provides passband frequency, from 5.6 GHz to 6.0 GHz, with the insertion loss value less than 1.5 dB and return loss better than 18 dB at the center frequency. It can be used for the ISM band frequency application. The frequency tuning approach is also shown to change the resonance frequency for different applications. For the proof of concept, the proposed filter is fabricated and tested. The measured results are quite similar to the simulation results.

Wireless technology plays a vital role in data transfer. There is an acute need of smart wireless devices which could respond effectively for specific applications. This paper presents a defected ground plane based planar antenna. The presented antenna has the potential to operate at 2.47 GHz, 3.55 GHz, and 5.55 GHz frequencies with gains of 3.88 dBi, 3.87 dBi, and 3.83 dBi having impedance bandwidths of 14.61%, 5.42%, and 5.40% respectively. Flame Retardant 4 (FR4) is employed as a substrate. The agreement between simulated and measured results points out the utilization of the presented structure for Wi-Fi/WiMAX/WLAN applications.

This manuscript presents the design of an antenna based on nested square shaped ring fractal geometry with circular ring elements for multi-band wireless applications. The impedance bandwidth and reflection coefficient of the antenna are improved with the design of different iterations from the 0th to 2nd. The performance parameters of the antenna like reflection coefficient, VSWR, bandwidth, bandwidth ratio and current density are improved in the final iteration. It also achieves the enhanced bandwidth greater than 3 GHz at three resonant frequency bands and exhibits additional frequency band at 2.4 GHz. Likewise, the frequency band of designed fractal antenna shifts towards the lower end and helps in achieving the miniaturization of antenna. The proposed fractal antenna is designed and fabricated on a low-cost FR4 glass epoxy substrate and investigated using HFSS software. The proposed antenna is optimized for generating different parameters, and the last geometry is fabricated and tested. Further, these parameters are compared with the experimental results and found in good agreement with each other. Due to the multi-band behaviour and improved bandwidth, the proposed fractal antenna can be considered as a good candidate for several wireless standards.

Although wireless power transfer systems suffer from splitting frequency conditions under strong coupling, this could create an opportunity for initiating other frequencies for power and data transfer. This paper introduces a model of an inductive transmitter containing a transmitter and many internal resonators to diversify the magnetic link to the receiver. Using the proposed architecture and solution, the efficiency and received power can be increased, and it also supports multiple frequency diversity.