A newly synthesis method of planar array antenna for wireless power transmission (WPT) is introduced in this paper. The whole array aperture is divided into several subarrays which can reduce the complexity of the feed network and the cost of the array antenna. Invasive Weed Optimization (IWO) algorithmis used to optimize the subarray division and the excitation amplitude of each subarray. The maximum beam collection efficiency (BCE) and maximum sidelobe level outside the receiving area (CSL) are considered as the evaluation index. The synthesis results show that the proposed method can obtain higher BCE and lower CSL.

We demonstrate the recovery of simple geometric and permittivity information of breast models in an experimental microwave breast imaging system using a synthetically trained machine learning workflow. The recovered information consists of simple models of adipose and fibroglandular regions. The machine learning model is trained on a labelled synthetic dataset constructed over a range of possible adipose and fibroglandular regions and the trained neural network predicts the geometry and average permittivty of the adipose and fibroglandular regions from calibrated experimental data. The proposed workflow is tested on two different experimental models of the human breast. The first model is comprised of two simple, symmetric phantoms representing the adipose and fibroglandular regions of the breast that match the model used to train the neural network. The second, more realistic model replaces the symmetric fibroglandular phantom with an irregularly shaped, MRI-derived fibroglandular phantom. We demonstrate the ability of the machine learning workflow to accurately recover geometry and complex valued average permittivity of the fibroglandular region for the simple case, and to predict a symmetric convex hull that is a reasonable approximation to the proportions of the MRI-derived fibroglandular phantom.

Pattern synthesis usually involves determining the strengths of the current sources in a given array that yield a specified pattern. Demonstrating that this pattern can be produced by an actual array of physical elements is a step that is rarely included in the discussion. The purpose of this article is to examine how well a numerical model of these sources will match the desired pattern when mutual interactions between the array elements are taken into account. An investigation of this process is described here using NEC (the Numerical Electromagnetics Code), although any wire-antenna computer code could be used. Modeling wire antennas in codes like NEC typically involves specifying the input or exciting voltage of the antenna to find the induced current from which the far field can be obtained. The pattern-synthesis problem for a specified array geometry, by contrast, requires instead finding the exciting voltages that will induce the synthesized currents needed to produce the pattern of interest. The radiation pattern that results can then be compared with the desired pattern to determine how well the physical array performs. Several examples of this approach are included here to demonstrate the process.

A novel low-profile GNSS microstrip circular polarization antenna is proposed and analyzed. Circular polarization is realized by asymmetric structure patch, and arc structure loaded on the main radiator can keep two modes orthogonal over a wide-angle range, so that the antenna has an extremely wide 3 dB axial ratio beamwidth (ARBW). The far-field AR beamwidths obtained are 232° and 212° respectively in the main plane of φ=0° and φ=90°. In φ=45° and φ=135°, 3 dB AR beamwidths are 241° and 244°, far exceeding the 120° required for satellite applications. In the whole CP band, 78.95% of the beam width exceeds 180°. The profile is only 0.0156λ₀, which is suitable, especially, for portable wireless systems or devices. The return loss bandwidth of -10 dB is 5.13% (1.52 GHz-1.6 GHz), which covers BeiDou Navigation System B1 (1.561 GHz). The axial ratio bandwidth is 1.28% (1.55 GHz-1.57 GHz), and the in-band peak gain is 4.09 dBi.

This paper presents a highly directive pattern reconfigurable antenna array capable of switching single or multiple beams of high directivity in multiple directions. Each element is individually capable of providing radiation pattern of directivity 12 dB and realized gain of 10.2 dB. Here, eight directive array elements are arranged in a circular fashion resembling a fan along with a switching arrangement to obtain beam switching in the horizontal plane. Two or more elements can be excited simultaneously to obtain patterns in multiple directions. In another configuration, the elements are arranged around a cylindrical support resembling an umbrella structure to obtain azimuthal switching at a desired tilt. The ability to reconfigure patterns in desired direction facilitates their usage as base station antennas providing desired angular coverage to intended users only, resulting in least signal interference.

A novel mid-infrared (MIR) biochemistry sensor using two suspended GaAs waveguides based on an asymmetric Mach-Zender Interferometer (MZI) is proposed. The propagation properties and refractive index (RI) sensing performances of MZI are investigated by the finite element method (FEM). The simulation results show that the maximum waveguide sensitivities (S_wg) of the TE and TM modes in the suspended GaAs waveguide are ~1.2 and ~1.0. This design of the GaAs waveguide using the suspension structure is to enhance the interaction between the vanishing field and the measured material. The RI sensitivity of the asymmetric MZI structure increases with the length of the sensing arm, which can reach 854.5 nm/RIU with a Q of 208.2 after parameter optimization. The two arms of the MZI are designed as width-asymmetric structures to make the sensor more sensitive to the measured material. The asymmetric MZI sensing structure has high RI sensitivity and compact structure, which provides a feasible scheme for biochemical sensing.

The article presents a compact size and high isolation with 2×2 MIMO, double flare horn shaped antenna for K and Ka bands of mm-wave applications. The overall size of the MIMO antenna 0.19λ×0.19λ×0.01λ mm³ at a lower frequency has been designed, simulated, fabricated and tested. The proposed MIMO antenna components are arranged parallel with identical shaped to provide a high level of inter-element isolation and 50 W micro strip line feed. The antenna covers 18.61-20.01 GHz in the K-band (18-26.5 GHz) and 21.52-33.91 GHz in the Ka-band (26.5-40 GHz) with impedance bandwidths of 7.2% and 44.5% respectively at port-1 and port-2. Maximum peak gain of 6.5 dBi & 8.1 dBi respectively at port-1 and 6.5 dBi&7.9 dBi at port-2 is observed respectively. Diversity characteristics such as envelope correlation coefficient, diversity gain, total active reflection coefficient and channel capacity loss are determined to validate the considered MIMO antenna's work qualities. The isolation of more than 35 dB indicates that the proposed structure is suitable to use a dual-port MIMO antenna. The recommended structure's investigation revealed a steady performance and a high degree of agreement between simulated and measured findings.

The integration of directed energy weapons (DEWs) into modern military platforms is of considerable interest to those examining the impact of emerging technology on the future fighting force. Hence the performance prediction of DEWs is of importance. The purpose of this study is to develop a simple framework where the minimum number of DEWs deployed in an operational setting can be determined, to achieve a desired level of performance.

The proposed work focuses on the mathematical interpretation of Electromagnetic Shielding Effectiveness (ESE) of age-dependent human Head Models (HMs) of seven tissues (Skin, Fat, Bone, Dura, Cerebrospinal fluid (CSF), Gray matter, and White Matter) with the impact of the mobile phone holding position on the RF radiation absorption by the human head. The ESE is first simulated and estimated using the Transmission Line Method approach: a. for only layered human Head Models (HMs) in the absence of mobile position with variation in Oblique Angle of Incidence (OAI) in Transverse Electric Polarization (TEP) and Transverse Magnetic Polarization (TMP), b. in the presence of mobile phone position and Polarization. c. by incorporating the Transparent Conductive Metal Mesh Polyethylene terephthalate (PET) film (Copper grid PET Film) as a shielding material in the presence and absence of Polarization and mobile phone holding positions. The Copper grid PET Film is composed of optical PET film laminated with Copper (Cu) and Nickel (Ni) Transparent Conductive Mesh Coatings (TCMCs) to form a transparent laminated mesh. The radiation absorption characteristic, Specific Absorption Rate (SAR), is evaluated numerically at four Sub-6 GHz frequencies from the obtained ESE data to draw collation at the least SAR absorbed by the age-dependent HMs, considering the water contents of tissues. Out of adult and child HMs, the child HM absorbed the higher RF SAR. However, with the transparent PET/Cu/Ni Laminated Mesh (LM), at 5.47 GHz, the SAR by the brain's white matter in child HM is highest in TEP with no shield considered is 10 W/kg. With transparent LM, the SAR obtained is 2.8e-12 W/kg in TEP in no mobile phone tilt condition at 89˚ OAI. With the user mobile tilt at 15˚ and 30˚, the SAR absorbed by the brain WM is 2.62e-12 W/kg and 2.1e-12 W/kg, respectively at 89˚. Hence, the SAR absorption is the least in any direction (azimuth or elevation) when the mobile phone is tilted to 30˚ in TE Polarization using the transparent PET/Cu/Ni laminated mesh. Therefore, the usage of transparent PET/Cu/Ni laminated mesh in TE Polarization saw the least SAR absorbed, whether the mobile phone is tilted either towards or away from the head when the mobile phone is moved to 15˚ or 30˚ tilted position.

A compact Sub-6 GHz Multiple-input Multiple-output (MIMO) antenna based on a complementary split-ring resonator (CSRR) and electromagnetic bandgap (EBG) is proposed in this paper. The antenna has an interesting structure and a compact size of 38×38 mm². Four identical antenna elements are deposited orthogonally to each other, using polarization diversity and adding decoupling structures, so that good isolation and miniaturized size can be obtained. The isolation is less than -17.5 dB in the operating bandwidth of 3.28-3.62 GHz and -19.5 dB in 4.78-5.04 GHz. The simulation results are consistent with the measured ones, indicating that the antenna is suitable for Sub-6 GHz communication equipments.

Variations of modified E-shape microstrip antennas are proposed which realize wideband and circularly polarized responses inside the same impedance bandwidth but in separate frequency regions. The offset pair of slots in E-shape patch tunes the spacing in between TM₀₂, TM₁₀ and TM₁₁ mode frequencies, and for the design in 900 MHz frequency band, it yields the total impedance bandwidth of 34.15%, in which circularly polarized bandwidth of 4.75% is present towards the higher frequency region. In comparison with the wideband E-shape or its circularly polarized variation, proposed configurations yield larger total impedance and same axial ratio bandwidth, but without overlapping bands for the wideband and circularly polarized regions. A compact half E-shape microstrip antenna is proposed, which yields total impedance bandwidth of 38.8%, with a circularly polarized bandwidth of 5.3%, present towards the higher frequency region. Further, the wideband E-shape variations are presented on a thinner substrate by using a bow-tie shape ground plane profile. Against the conventional ground plane design, it offers more than 12% increase in the bandwidth for 0.03λ_g reduction in the substrate thickness. Thus, as against the reported E-shape variations, proposed study presents a new design feature of traditional E-shape patch that provides separate regions for the wideband and circularly polarized responses, occupying the same impedance bandwidth.

A compact triple band monopole antenna with a simple modified C-shape structure for vehicle-to-everything (V2X) application is presented. The proposed multiband vehicle antenna with three C-shaped round stubs structure satisfies the worldwide interoperability for microwave access (WiMAX), wireless local area network (WLAN), and wireless access in vehicular environment (WAVE) bands. The three resonant frequencies are implemented with three C-shaped round stubs, and they are simply controlled by adjusting the round stub length without influence each other. The presented antenna demonstrated good impedance bandwidth and nearly omnidirectional radiation patterns over the whole operating bands. The field communication tests by connecting the vehicular communication module were also performed and verified in the view of automotive vehicle antenna application.

Despite recent advances, fast and reliable Human Activity Recognition in confined space is still an open problem related to many real-world applications, especially in health and biomedical monitoring. With the ubiquitous presence of Wi-Fi networks, the activity recognition and classification problems can be solved by leveraging some characteristics of the Channel State Information of the 802.11 standard. Given the well-documented advantages of Deep Learning algorithms in solving complex pattern recognition problems, many solutions in the Human Activity Recognition domain are taking advantage of those models. To improve the time and precision of activity classification of time-series data stemming from Channel State Information, we propose herein a fast deep neural model encompassing concepts not only from state-of-the-art recurrent neural networks, but also using convolutional operators with added randomization. Results from real data in an experimental environment show promising results.

This article presents a dipole antenna using an I-shapes adding technique on both sides of the antenna's body. To increase the using frequency range to be wider, with horn waveguide for gain enhancement and harvest energy by matching circuit. Which is compatible with the voltage multiplier circuit at RF frequency (510-790 MHz) in a TV digital system. When taken to measure the effect of the antenna, it was found that the antenna operates at a frequency range of 60.24% (450-838 MHz), a 67.79% increase from the base dipole antenna, which has the gain enhancement of 10.23 dB from adding the horn waveguide 60.99%. By has a pattern of energy radiating in a specific direction, and when the antenna is used with an energy harvesting circuit to get energy or power from the front direction of the TV digital antenna at a distance of 10 km, capable of harvesting energy up to 7.33 uW.

Graphene has become one of the most essential materials in recent years due to its numerous advantages and benefits. Because of its features, graphene is becoming more widespread in a variety of applications, particularly in electrical devices. In this research, graphene thick film paste (GTP) has been used to fabricate a microstrip bandpass filter (BPF). To obtain graphene nanoparticle powder, graphene oxide (GO) was synthesized from nanoparticle graphite using the Improved Hummers Method (IHM). The graphene oxide (GO) was chemically reduced to reduced graphene oxide or graphene (rGO) using ascorbic acid as the reducing agent. The structural and morphological properties of three nanoparticle powders, G, GO, and rGO, were investigated. An X-ray Diffractometer (XRD) (Rigaku Miniflex) with a diffraction angle of 10˚ to 60˚ was used to differentiate and determine the structure of crystalline materials. Thermal stability of the samples was identified using thermogravimetric analysis (TGA). The synthesized rGO has been used to fabricate BPF circuit. The obtained nanoparticle rGO was mixed with an organic carrier composed of linseed oil, m-xylene, and α-terpineol to form GTP. The GTP was screen printed on RT duroid 5880 substrates to form BPF circuit. The BPF circuit that was created was tested for paste-to-substrate adhesion. Then, the fabricated BPF circuit was tested using vector network analyzer (VNA) and compared with conventional BPF to obtaine scattering parameter results which include return loss, insertion loss, and bandwidth. The graphene BPF circuit demonstrated a good performance with return loss and insertion loss at -27.481 dB and -0.725 dB, respectively, and a bandwidth of 1.5916 GHz while conventional return loss was -26.750 dB and insertion loss value the same as graphene which is -0.725 dB and bandwidth 0.7077 GHz. From the result graphene BPF showed better result than conventional BPF.

In this paper, the transport characteristics of gold/silver mixed chain nanostructures with different proportions of infinite length in the range of 270-810 nm are studied, and the corresponding band gap characteristics and other transport characteristics are analyzed. We introduced an analytical model to determine the complex dielectric constant of an arbitrary composition Au-Ag alloy, and combined this with the experimental data to study the propagation characteristics of the infinite-length gold-silver mixed-chain nanostructures with various compositions. As the gold content exceeds Au:Ag(1:2), the coupling coefficient between the forward and reverse waves becomes smaller, and the reverse wave cannot provide enough energy to transfer to the forward wave. The scattering ability of the scattering unit weakens, the frequency range of the propagation state widens, and it exhibits good propagation characteristics. By gradually increasing the proportion of metal in the alloy, we can explore the variation of the propagation characteristics of the alloy. At present, the change of metal propagation characteristics has not been studied from this point at home and abroad, so we found for the first time that frequency modulation can be realized through this method (regulating the attenuation or cutoff frequency range, namely the band gap range). We also studied a cylindrical finite array chain composed of 40 nanorods under five types of experimental data and discussed the wave guiding ability of the finite array chain under the excitation of a plane wave of a specific wavelength.

Bond wires aging is one of the most common failure modes of insulated gate bipolar transistor (IGBT) module. Real-time monitoring of bond wires status is an important guarantee for the stable operation of power electronics system. In this paper, a method of monitoring the aging state of bond wires in IGBT module based on the spectrum characteristics of electromagnetic radiation (EMR) signature is proposed. Firstly, the turn-off process of IGBT module is analyzed, and the behavior model of IGBT module in the stage of rapid current change is established, which shows that EMR interference in buck converter mainly occurs during the turn-off process of IGBT module. Secondly, the relationship between the aging degree of bond wires and differential mode (DM) interference signal is deduced. Thirdly, the IGBT module is equivalent to a magnetic dipole, which proves that the change of DM interference signal will cause the change of EMR signal, thus demonstrating the feasibility of using EMR signal to monitor bond wires aging. Finally, a buck converter composed of IGBT module is used as the equipment to be tested. The EMR signal is extracted by the near-field probe, and the EMR signal spectrum is used to monitor the aging degree of the bond wires. The experimental results show that with the deepening of the aging degree of bond wires, the spectrum amplitude of EMR signal increases.

This work studies the correlation between 14-elements of a sub-6 GHz MIMO antenna for mobile terminal, operating in the 3.10 to 3.85 GHz frequency band. Envelope correlation coefficient (ECC) was used to assess the relationship between MIMO antenna elements. A total of 91 ECC values were considered at every frequency point for the 14-element antenna, which was performed under two propagation scenarios: (i) a uniform environment, and (ii) a Gaussian environment. For the latter, three angular spreads (AS) of 20˚, 30˚, and 40˚ and incident angle of every 10˚ in both elevation and azimuth coordinates are considered. The resulting ECC in the uniform environment is below 0.15 over the entire operating frequency band, indicating that the 14 elements are minimally correlated. However, in a Gaussian environment, the ECC is evaluated at 3.25 GHz. For the AS values of 20˚, 30˚, and 40˚. The average number of ECC values below the 0.3 threshold is 48, 67, and 81 out of 91 total ECC values, respectively. Finally, a relation is derived between the number of ECC values below 0.3 and the lowly-correlated number of antenna elements. It is seen that at a wider angular spread of 40˚, the number of equivalent lowly-correlated elements is 12 with 87% from all considered incident wave directions.

This paper investigates the design method, characterization, and innovative uncertainty analysis of bandpass (BP) type negative group delay (NGD) passive cell. The lumped passive topology under study consists of a resistor and a passive RLC-series network. The voltage transfer function (VTF) based circuit theory introducing the BP NGD specification analytical expressions is established in function of the R, L and C lumped component parameters. The BP NGD performance is evaluated by figure of merit (FOM) formula. To demonstrate the BP NGD function, the design method was applied to a proof-of-concept (POC) operating at 125-kHz RFID standard center frequency. The BP NGD theory is validated by both AC simulation and measurement of POC and discrete component-based circuit prototype. Experimental BP NGD results in good agreement with calculation and simulation are obtained with NGD value of -36.77 μs, 8% NGD bandwidth, and an attenuation lower than -9.6 dB. Innovative expressions of BP NGD parameter uncertainties are established versus the POC circuit parameters. The BP NGD specification variations are interpreted with respect to the influence of constituting component uncertainties via comparison between the established NGD uncertainty theory and co-simulated sensitivity analyses.

In application to active microwave remote sensing, the counterwise RL (left-hand circularly polarized transmitting and right-hand circularly polarized receiving) and LR polarized bistatic scattering are generally stronger than the likewise LL and RR ones, respectively. In this paper, we investigate the circularly polarized propagation over terrain profile at 1.575 GHz and 900 MHz in application to wireless communication. Completely different from common sense in remote sensing, however, numerical simulations show that field strengths for likewise polarizations are larger than those for counterwise polarizations. For further verification, circularly polarized bistatic scattering from terrain is also provided, which is consistent with previous conclusion that the counterwise LR polarized one is larger. Physical mechanism of such a contradictory behavior is explicated by local Fresnel reflections, and physical insights are offered for terrain propagation of circular polarizations. It is suggested that the likewise configuration be adopted in wireless communication, although the counterwise is adopted in microwave remote sensing.