In order to satisfy the requirements of 2G/3G/4G wireless communication, two kinds of base station antennas with wideband, dual-polarized and three-modes are proposed in this paper. Firstly, a pair of diamond dipoles is placed in an orthogonal way to realize dual-polarizations, then a pair of Y-shaped branches is added to generate a new mode. The Y-type coupling feeding can increase the impedance bandwidth without increasing the size of antenna. The antenna achieves an impedance bandwidth of 51.75% (1.69-2.87 GHz) with a return loss lower than -14 dB. The antenna also has a stable radiation performance. The gain is greater than 8.6 dBi, and the port isolation is less than -27 dB over the entire frequency band. Then based on above antenna, a C-type slot notched antenna is added to improve anti-interference ability. Finally, band stop characteristics are obtained by etching a C-type slot line resonator on two dipoles. The results show that the bandwidth is 1.7-2.69 GHz, and the sharp notched band is 1.8-1.95 GHz. The C-type slot line here can be regarded as a quarter wavelength resonator in series. Moreover, the isolation of the port is less than -28 dB, and the 3 dB beamwidth in the bandwidth is 66±5˚. Both antennas are fabricated and have dual polarizations, simple structure, and good radiation performance, which can be used in the next generation of wireless communication.

Transverse electromagnetic (TEM) cell is usually used to evaluate the electromagnetic immunity and electromagnetic radiation disturbance of the equipment under test (EUT) and integrated circuit (IC). Affected by the structure of the TEM cell, high-order modes and reflection will be generated in the high frequency range, which will limit the higher frequency applications of the TEM cell. In this paper, the TEM cell specified in IEC61967-2 standard is improved by adopting several methods, including segmented impedance matching, slitting outer conductor, slotting inner conductor, adding absorbing materials and adding an external shielding box. The results show that the improved TEM cell voltage standing wave ratio (VSWR) is less than 1.2 in 0-3.4 GHz, less than 1.3 in 0-3.75 GHz, and less than 1.5 in 0-4.06 GHz; at the same time, the S-parameter characteristics are better.

This paper presents the design and measurements of a dual-band Triple H-Defected Ground Structure (Triple H-DGS) antenna. DGS has proven to be successful in the design of multiband antennas; however because of the lack of a standard approach, the determination of the exact position of the Triple H-DGS requires rigorous and lengthy numerical computations. The aim of the current work is to present a state-of-the-art innovative, efficient, and accurate solution based on Machine Learning (ML) techniques. The design is based on Substrate Integrated Waveguide (SIW) technology which provides low cost, small size, and convenient integration with planar circuits. The antenna is fabricated on a Roger 5880 substrate with a thickness of 1.6 mm, relative dielectric constant of 2.2, and tangent loss of 0.0009. The proposed antenna was developed using a hybrid solution based on CST Microwave Studio assisted by ML, and the fabricated prototype was measured using both ROHDE & SCHWARZ ZVB20 network analyser and an anechoic chamber setting. The measurement results show good agreement with the simulation. The antenna demonstrates a dual-band performance at centre frequencies of 12.67 GHz and 14.56 GHz, for which the respective antenna gains are 7.03 dBi and 7.38 dBi, and antenna directivities of 7.77 dB and 8.13 dB, respectively. The antenna total efficiencies are 95.25% and 95.60%, at the corresponding centre frequencies. The developed ML based technique shows good accuracies of about 98% in the determination of the DGS position and saves more than 99% of the computational time. The developed antenna is compact, simple in structure, and can be used for different applications in the Ku band.

The time-harmonic scattering problem from an isotropic multilayer coated 3-D object is considered. The coating is modeled by an impedance boundary condition (IBC) prescribed on the outer surface of the coating. The standard Leontovich IBC is local and constitutes a poor approximation for low index materials. A possible remedy is to employ high order IBCs (HOIBCs) involving tangential differential operators multiplied by coefficients. A generic HOIBC formulation (termed here IBC3) with five coefficients is considered here. Sufficient uniqueness conditions (SUCs) are derived for the corresponding Maxwell's problem (i.e. Maxwell's equations in free-space, radiation condition at infinity and IBC3 on the surface). The IBC3 coefficients are obtained by minimizing, with the SUCs as constraints, the error between either the exact and IBC3 impedances (local planar approximation) or the exact and IBC3 Mie series coefficients (local spherical approximation). Finally, the IBC3 is numerically implemented in a well-posed EFIE+MFIE formulation. Numerical results obtained on 3D objects demonstrate the high accuracy achieved with the constrained IBC3.

Resistive random access memory (RRAM) devices are promising candidates for next generation high capacity data storagedue to their superior properties such ascost-effective fabrication, high operating speed, low power consumption, and long data retention. Particularly, the two dimensional (2D)-materials-based RRAM has attracted researchers' attention because of its unique physical and chemical properties without the constraint of lattice matching. In this review, the switching mechanisms and modeling of RRAM devices based on the 2D materials such as hexagonal-boron nitride (h-BN) and graphene are discussed. Firstly, the monolayer and multilayer h-BNRRAMs are introduced, and their mechanisms and compact model are further described. Then, the mechanisms of graphene electrode-based RRAM (GE-RRAM) for different applications are also introduced and compared. Furthermore, the electrical conductivity, multi-physic and compact models of GE-RRAM are introduced. This review paper provides the guidance for the design and optimization of the 2D-materials-based RRAM in the next generation memories.

A dual-element miniaturized multiple-input-multiple-output (MIMO) antenna with a defected ground plane and a tapered microstrip feed line is introduced in this article. It achieves a bandwidth (BW) of 10.8 GHz (7.2-18 GHz), frequency ratio (FR) of 2.5, and average isolation of 15 dB over the entire operating band. The proposed antenna is right hand circularly polarized (RHCP) and achieves an axial ratio of < 3 dB in the frequency band ranging from 7.2 to 8.9 GHz. The performance characteristics of the proposed antenna are analyzed in terms of the envelope correlation coefficient (ECC), mean effective gain (MEG), total active reflection coefficient (TARC), isolation between the ports, and channel capacity loss (CCL), and the values obtained are 0.1607, 9.99 dB, ±3 dB, -11 dB, -7 dB, 0.20 bits/sec/Hz respectively. The proposed MIMO antenna is fabricated on an FR-4 dielectric substrate of dimension 10.6×10.3×1.6 mm³ and has good agreement between simulated and experimental results. The proposed antenna can be used for C, X, and Ku band applications.

In the present day scenario, the need for 5G technology is increasing daily, so we design a reconfigurable antenna working in the millimeter-wave range (25 GHz-30 GHz). The antenna is designed using HFSS software, and the antenna is loaded with compact planar metamaterial. This design includes 9 unit cells arranged in a 3 x 3 array, and each unit cell is made up of a hexagonal patch surrounded by a split ring resonator. Apart from this two-unit cells are connected using pin diodes. By operating these two pin diodes in different modes we get four different characteristics. The designed antenna radiates at 27 GHz with a gain of 3.75 dB to 4 dB. The designed antenna is compact and easy to fabricate with dimensions of 30 mm x 23 mm.

Controlled mutual attraction or repulsion, by the aid of light beam, between two or more particles, is regarded as the reversal of optical binding force. It has emerged as an important tool in the area of optical manipulation, facilitating clustering or aggregating between homodimer and heterodimer arrangements of particles. Despite a vast array of works being done in this area, dielectric-plasmonic hybrid dimer pair has not received any attention yet. To the best of our knowledge, in this letter, we have provided the very first proposal of a generic way to attain the controlled broadband reversal of optical binding force between dielectric and plasmonic hybrid dimer pair. A simple optical setup consisting of a plasmonic substrate placed underneath the hybrid dimer pair has been proposed, where the reversal of optical binding force can be attained by the incidence of a non-structured laser beam in both near- and far-field regions. Furthermore, we have demonstrated that the magnitude of this binding force can be enhanced, simply by altering the angle of incidence of the source of illumination. The force reversal has been attained based on two physical phenomena - mutual attraction and repulsion between the charges formed within the hybrid pair and the reversal of current density in the plasmonic object.

The object of this paper is a permanent magnet synchronous linear motor (PMLSM), whose control method is based on a model-referenced adaptive system (MRAS), and it analyses the speed identification of a permanent magnet synchronous linear motor without position sensors. The article proposes a new model-referenced adaptive method, which utilises a sliding-mode variable structure control method (SMC), to replace the PI control algorithm utilised in conventional model-referenced adaptive algorithm. The control system of the PMLSM is therefore designed and studied based on the change of the adaptive law in model-referenced adaption. the mathematical model of the PMLSM itself is chosen as the reference model, and the feedback magnetic chain model of the motor output is chosen as the adjustable model, replacing the conventional current model and simplifying the control algorithm. The sliding mode surface of the sliding mode variable structure control algorithm is constructed using the reference model and the output error of the adjustable model. Through theoretical analysis and simulation models built by MATLAB/Simulink simulation software, the simulation results show that the designed PMLSM speed induction-free control system MRAS speed observer based on the sliding mode variable structure has strong robustness and excellent dynamic static performance. The advantages verified by the new algorithm achieve the experimental purpose of the expected assumptions.

In this paper, the bandwidth of a bowtie antenna is improved to meet the requirements of Ground Penetrating Radar (GPR) applications that need a fractional bandwidth greater than 100% and are able to operate at low frequencies. This was done using several modification steps, which were the use of Antipodal technique for its advantages in reducing the complexity of the feeder network to achieve good matching with a standard 50-Ω SMA connector, bending the four corners of the arms and adding a triangular slot in each arm. The simulation was carried out using CST Microwave Studio to study the effect of each modification step on improving the bandwidth. The simulation results of the new antenna achieved a fractional bandwidth of 138% within the frequency range (1-5.45) GHz at the values of return loss (S11≤-10 dB). The new antenna was also fabricated, and the return loss was measured and showed a good agreement with the simulation results.

Utilizing spread spectrum time domain reflectometry (SSTDR) to detect, locate, and characterize faults in photovoltaic (PV) systems is examined in this paper. We present a method to obtain the model parameters that are needed to produce digital twin SSTDR responses for PV systems. The digital twin SSTDR responses could be used to predict faults within the PV systems. The model parameters are the reflection and transmission coefficients at each impedance discontinuity in the PV system along with the propagation coefficients across each PV cable segment. We obtain model parameter by applying inverse modeling techniques to experimental SSTDR data associated with PV systems. Our model parameters can be used in any digital twin simulation method for modeling reflectometry in frequency-dependent and complex loads. For validation, we used the model parameters in a graph network simulation engine and adapted it to be used for SSTDR digital twin simulations in PV systems. We produced simulations for 0 to 10 PV modules connected in series. We also simulated SSTDR responses for open circuit disconnections in a PV setup containing 10 PV modules in series. Results show that all but one simulated disconnect locations match experimental disconnection locations of the same setup with an error of less than 5%.

This proposal presents a novel design of a reconfigurable antenna with frequency, polarization, and pattern diversities for wireless body area networks. The design makes use of a 3.2 mm thick FR4 substrate of 39X36 mm² dimensions with a square patch and partial ground structure. The antenna operates in sixteen different modes and resonates at various frequencies ranging from 2.456 to 14.384 GHz. The proposed model has the capability to exhibit elliptical as well as linear polarization with different radiation patterns. For suitability of the proposed design in healthcare applications its SAR analysis has been performed along with other antenna characteristics like reflection coefficient, gain, radiation pattern, and axial ratio. Four PIN diodes have been used to switch the antenna operational modes.

Pneumothorax can cause chest tightness, chest pain, and respiratory failure, which can be life-threatening in severe cases. Therefore, early diagnosis and treatment of pneumothorax are crucial. Magneto-Acousto-Electrical Tomography (MAET)is an imaging technique in which ultrasound and electromagnetism are mutually coupled. It has the advantages of high spatial resolution and high image contrast. In this paper, we use MAET to study porous and air-containing lung tissue. We first simulate the characteristics of the MAET signal as the degree of pneumothorax increases. The relationship between the size of the ultrasonic probe and the size of the pneumothorax was discussed. The simulation results show that the reflection and attenuation values of the MAET voltage signals increase as the pneumothorax size gradually increases, regardless of whether the ultrasound transducer size is larger or smaller than the pneumothorax size. Finally, the MAET experimental platform was built to validate the simulation results of MAET signals. The results of the experiment and simulation are consistent with each other. The research of this paper has a certain reference value for the detection of pneumothorax using MAET.

In this paper, a Substrate Integrated Waveguide (SIW) band pass filter loaded with a square Complementary Split Ring Resonator (CSRR) etched with Defected Ground Structure (DGS) is proposed. SIW is a promising candidate for the design and development of various microwave and millimeter wave components useful in communication systems. Due to the evanescent mode propagation and TE₁₀ mode of the cavity, dual band (5.57/7.84 GHz) filtering is achieved with a 3-dB fractional bandwidth (FBW) of 6.8% and 4.1% respectively. The dual bands achieve a low insertion loss of 1.8 dB and 2 dB respectively. Cursor head DGS improves the out of band rejection to a greater level. The configuration is investigated with its corresponding circuit and simulated using Computer Simulation Technology (CST) software. The prototype is fabricated using a Rogers substrate with ε_r of 3.5 and tested. This prototype finds its application in C band satellite communication systems. The measured results are consistent with the simulated ones.

In this paper, a low profile Frequency Selective Surface is presented, for obtaining electromagnetic shielding in four distinct frequency regions. The designed structure consists of three rectangular strips Resonators, Jerusalem cross in the top side and diagonal metallic strips on bottom side of the dielectric. The proposed structure provides electromagnetic shielding at 9.9 GHz, 12.3 GHz, 13.5 GHz, and 16.4 GHz frequency regions. Besides these frequency regions, we also obtain five transparent windows suitable for telemetry application. The prototype of the proposed structure is fabricated. It is observed that the measured results are nearly similar to simulated results because of minor fabrication errors. Furthermore the proposed low profile structure can be deployed for applications like radoms, spatial filters, antenna reflectors and RCS reductions.

In this paper, a full-360° reflection-type phase shifter (RTPS) using a trans-directional (TRD) coupler with multi-resonance loads is presented. It features the characteristics of wide bandwidth, small size, and wide phase shifts with a compact structure and inherent DC blocking. Influences of the multi-resonance loads on the phase shifts and insertion losses of the RTPS are analyzed, and design procedures are given for guidance. For validation, a prototype is designed at 2 GHz. The overall size is 0.56λ_g × 0.17λ_g. Measured results show a bandwidth of 20% under the criterion of more than 10-dB return loss. Meanwhile, a relative phase variation of 425° with a maximum insertion loss of 3.6 dB is achieved when the varactor capacitance is varied among 0.35 pF~3.2 pF.

This work discusses the effect of reconfigurability on a Sierpinski-carpet fractal microstrip patch antenna. The implementation of reconfigurability is achieved by modeling a PIN diode as a lumped RC element on HFSS (High Frequency Structure Simulator) simulation tool. The proposed antenna design is also fabricated and tested. It is highly miniaturized having a dimension of 9.5 mm × 7.4 mm and a significantly high impedance bandwidth which is desirable for most wireless communication applications. The resultant Fractal Reconfigurable Antenna (FRA) exhibits good performance parameters having frequency reconfigurability rendering it useful for Ku/K/Ka band applications.

A Negative Group delay (NGD) triple passband filter with a lossy Meander Step Impedance Resonator (MSIR) is introduced in this article. The size miniaturization technique by increasing the number of meander turns is presented. In the process of filter design, the calculation of the total inductance value of the meander section is discussed in a simplified way. At the same time, the electrical and physical lengths of each section of meander resonator are calculated. The proposed filter has three passbands at 2.4, 5.0, and 7.4 GHz. The Group Delay (GD) in the three pass bands is -2.5 ns, -2.1 ns, and -2.0 ns, respectively. The more the number of meander turns is, the more the NGD will be. The proposed design is well equipped to be used in feed-forward and feed-back power amplifier applications. The frequency response exhibits satisfactory Return Losses (RLs) of -24, -25, and -22 dB at these three passbands. Four Transmission Zeros are generated at 3.35, 3.98, 6.2, and 8.31 GHz using an absorptive Folded SIR (FSIR) structure which improve the stopband performance. The overall dimension of the filter is (20.7 x 12) mm = (0.16 x 0.09)λ_g.

A wideband interdigital Metal-insulator-metal (MIM) capacitor is created and built in a two-layer low temperature co-fired ceramic (LTCC) substrate. To reduce the amount of stopbands and eliminate unexpected spurs which restrict the bandwidth, short-interconnection that interconnects the open ends of interval fingers is proposed. The increment of bandwidth and capacitance of the proposed interdigital MIM capacitor is 206% and 25%, respectively. The proposed interdigital capacitor has a wider frequency applicational range and a compact size of only 8.2×6.2 mm. Performance discussion and comparisons are also carried out.

In this paper, a single-feed cylindrical dielectric resonator antenna (DRA) with wide angular circular polarization is proposed. It is composed of a cylindrical cavity loaded cylindrical dielectric resonator (DR), an orthogonal slot with curved arms, and an off-centered L-shaped microstrip line. By inserting the slot with curved arms and a cylindrical cavity, the 3-dB axial ratio beamwidth (ARBW) can be increased, and symmetric radiation can be obtained. For validation, a prototype is designed at 1.7 GHz and fabricated. The overall size is 0.39λ₀ × 0.39λ₀ × 0.13λ₀. The measured results show that it exhibits a 10-dB impedance bandwidth of 33.3% (1.45~2.03 GHz) with a circularly polarized (CP) bandwidth of 16.1% (1.54~1.81 GHz). Symmetric radiations are obtained, and the 3-dB ARBWs in the xoz and yoz planes are more than 150° over the CP bandwidth.