The increasing volumes of data generated by social networking, cloud computing, e-commerce, and online video broadcasting necessitate the implementation of higher data rates. As the current 4G network encounters congestion and potentially struggles to accommodate the substantial data demand, there is a growing interest in millimeter wave (mmWave) technology. The 30-300 GHz mmWave spectrum is characterized by its broad bandwidth and low latency; it is having many applications in communication domains, also includes 5G cellular. Despite its atmospheric attenuation and non-line-of-sight (NLOS) propagation, the majority of nations have begun to implement mmWave 5G in the band of 28/38 GHz as a result of its reduced path loss exponent, minimal signal spread, and decreased atmospheric attenuation. While the patch antenna (single-element) is a compact and easily transportable choice for mmWave applications, its radiation efficiency, gain, and bandwidth are all subpar. Array antennas have effectively addressed these limitations by exhibiting significant enhancements in bandwidth, gain, and radiation efficiency. It is still limited in the maximum data rates it can accommodate. The rate of data can be increased by a factor of one thousand using Multiple-Input-Multiple-Output (MIMO) technology, which is enabled by geographical diversity and multiplexing techniques. As a result, comprehension of the structures of MIMO antennas operating at mmWave is imperative for the continued enhancement of performance. In comparing the efficacy of these designs, bandwidth, isolation, efficiency, gain, and radiation pattern are considered. In this paper, the most recent planar MIMO antenna designs, which are categorized as defected ground structures, Slot/Patch/Stub, MIMO Antenna Array, Dielectric Resonator Antenna, and Meta-Surface/Metamaterial Structures, are described. This paper also addresses the effects that slots, partial ground, and decoupling structures have on levels of isolation, bandwidth, and impedance matching. A comprehensive analysis of the design considerations and subsequent advancements is also provided in this paper.

The design and analysis of a compact coplanar waveguide (CPW) fed wearable slot antenna with four notched bands for Ultra-Wideband (UWB) applications are presented in this paper. The antenna is printed on a 0.1-millimeter-thick Liquid Crystal Polymer (LCP) substrate, providing flexibility for wearable applications. Split Concentric Rings (SCRs) engraved on the radiating patch and branches in L form loaded on the ground plane provide the antenna's notched features. The impedance bandwidth of the measured antenna ranges from 2.46 GHz to 12.52 GHz, with a fractional bandwidth (FBW) of 134.1%，and it exhibits notched bands covering specific frequency ranges, ranging from 2.84 GHz to 3.93 GHz for WiMAX applications, 4.84 GHz to 5.41 GHz for WLAN downlink, 5.66 GHz to 6.26 GHz for WLAN uplink, and 6.94 GHz to 7.79 GHz for X-band satellite communication. Furthermore, the gain of the proposed antenna varies between 1.5 and 6 dBi, excluding the notched band. The antenna is tested, and the flexibility performance is good. In a word, the fabricated antenna shows promising prospects for wearable applications.

In this paper, a generalized manner is developed for the problem of the scattering of H-polarized electromagnetic waves from a shallow cavity with an arbitrary profile. Considering a proper auxiliary border and employing the region-matching technique, some close-form expressions are derived to compute the fields inside and outside the cavity. Next, we apply this approach to two cavities with different shapes and verify it by the Method of Moments (MoM).

Aiming at the problems of poor population diversity, slow speed of late identification and low identification accuracy of traditional grey wolf algorithm (GWO), a chaotic adaptive search grey wolf optimization algorithm (CASGWO) for parameter identification of permanent magnet synchronous motor is proposed in this paper. Firstly multiple low-dimensional chaotic mappings are combined; a composite chaotic system Tent-Logistic-Cosine is obtained; uniform populations are generated. So the population diversity and global search capability are improved. Then a segmented nonlinear search method is proposed, where the nonlinear decay factor quickly converges to the vicinity of the optimal solution in the first segment and slows down the convergence rate for local search in the second segment. Thus, the convergence rate is accelerated while the local search capability is enhanced. Finally, the adaptive inertia weights are adjusted according to the fitness values of different wolf pack iterations, and ω wolves approach the leader wolf pack with smaller fitness values at a faster speed. Therefore, the speed of search is again improved, and the local search ability of the algorithm is again enhanced. Experiments show that when identifying multiple parameters of resistance, inductance, and permanent magnet flux of a permanent magnet synchronous motor, the CASGWO method has good global and local search capability, with faster identification speed and higher identification accuracy than the traditional grey wolf algorithm.

A novel ultra-compact dual-band reconfigurable microstrip phase shifter designed by using a dual-composite right/left handed D-CRLH technique of metamaterial is introduced. The paper proposes detailed studies between the simulation and the fabricated prototype results. Moreover, the study of the proposed phase shifter explains a shifting range from 0° till 360° by submitting four mounted surface switches in different spots of the fingers. Switches have fixed states shifting to provide the controlling of the requested range. The switches were chosen to be from PIN Diode as it has many compatible characteristics which are explained in the proposed paper. The reconfigurable phase shifter designed with high quality factors and low insertion loss 0.25 and 0.2 at 5.7 GHz and 7.5 GHz respectively with a very compact size area 8 x 11 mm², beside that the proposed shifter support the application of wide band usage especially for network access point, Wi-Fi, WiMAX network and wireless LAN connections in addition to the application of point to point microwave radio links and X-band of satellite & space communications.

To address the issues associated with the conventional permanent magnet synchronous machine, particularly difficulties in adjusting the air-gap flux barrier and the limited range of constant power speed regulation, this paper introduces a novel approach. It combines the intensifying-flux effect with the permanent magnet synchronous machine to propose a new design known as the reverse salient permanent magnet synchronous machine (RS-PMSM) with a multilayered flux barrier. This innovation serves to enhance the working performance of the permanent magnets. The paper's structure includes an initial introduction to the RS-PMSM, outlining its structure and operational principles. Following this, an optimization approach employing NSGA-II is used to define the RS-PMSM's optimization model. The objectives of this optimization encompass torque, torque ripple, and the reverse salient pole ratio. The study then proceeds to conduct a comprehensive set of performance analyses and comparisons, involving the initial machine, the optimized machine, and a conventional machine. The performance metrics considered include no-load air-gap flux density, reverse electromotive force, torque characteristics, speed range, and efficiency. Finally, the study verifies the design rationality of the RS-PMSM, highlighting its potential to address the challenges posed by traditional permanent magnet synchronous motors.

Prolonging the shelf life of bread through cost-effective methods becomes imperative in times of a pandemic when numerous countries are grappling with extended lockdowns. This study explores the application of microwave food processing to identify pathogens by inducing rapid, selective heating within the material. A critical issue in microwave food processing is the uneven distribution of heat, creating cold spots that amplify pathogen growth, thereby increasing the risk of foodborne illnesses such as acute poisoning, diarrhea, fever, abdominal pain, and, in severe instances, even death. In this context, we propose a method for pathogen detection using polyethylene terephthalate (PET), which involves subjecting the bread to high thermal irradiation. To achieve this, a low-profile inset-fed PET-based microstrip patch antenna operating at 4 GHz is employed to detect pathogens by analyzing variations in S-parameters. The suggested PET antenna introduces a flexible approach to pathogen detection, especially at the edges and corners, owing to the conformable choice of substrate.

This paper proposes an application of ultra-wideband antenna in conjunction with supervised machine learning to detect the existence of breast tumor. The microstrip line fed octagonal shaped UWB antenna is designed by using Ansys high-frequency structure simulator 2022 R2. It is fabricated on double sided copper FR4 epoxy glass substrate of size 40 mm × 40 mm and tested by using vector network analyzer N9916A. The antenna structure is optimized over the frequency spectrum of 3.1 GHz to 10.6 GHz to obtain minimum value of return loss. The optimized structure provides bandwidth spectrum of 8.38 GHz covering the frequency range of 2.76 to 11.15 GHz with maximum gain of 5.3 dB at 8 GHz. The homogenous artificial breast phantoms with and without tumor are fabricated using different chemical compositions. The dielectric traits of skin, fatty, glandular and tumor layers are analyzed. Microwave sensing for detecting the presence of breast cancer uses the disparity between tumor and breast tissues, requiring consideration of dispersiveness to accurately assess the dielectric characteristics of the breast model due to its lossy dispersive nature. The three sets of reflection characteristics of the entire system comprised of antenna with phantoms are recorded by using VNA with a gap of week to constitute the dataset. The ultrasonic gel serves as a medium for matching between the breast model and antenna. Further, the supervised machine learning approach is used to improve the detection accuracy. Supervised learning, a key category of machine learning, uses labeled data to predict unseen data. The Logistic Regression, Support Vector Machine, K-Nearest Neighbors, Random Forest and Multilayer Perceptron algorithms are applied on the measured data to classify the healthy and tumorous tissues. The random forest proven to be best fit on the data with auc score of 98.05%.

A compact dual-feed multiple-input multiple-output (MIMO) antenna is designed for sub-6 GHz 5G applications with isolation enhancement. The proposed dual-polarized MIMO antenna formed by each patch uses two inset-feed lines placed orthogonal to each other with symmetric conditions, which excite each port to resonate at the same frequency (3.65 GHz). The stub is identified diagonally based on plated through-hole technology between orthogonal ports. The structure employs a half mode and maintains minimum inter-port isolation (≤-12 dB) of each patch, followed by another patch to form an 8-element miniaturized MIMO antenna. High isolation (≤-15 dB) is achieved with the help of a decoupling structure placed between the antennas in the ground plane. Measurements of a fabricated prototype validate the simulation results. The diversity performances of MIMO antenna parameters like envelope correlatio coefficient (ECC), diversity gain (DG), and Mean Effective Gain (MEG) are also found within acceptable ranges.

A novel compact planar duplexer is proposed. It consists of three dual-mode E-shaped microstrip resonators and works well on the WCDMA system with uplink band of 1940 MHz-1955 MHz and downlink band of 2130 MHz-2145 MHz. The high rectangular coefficient of the duplexer makes its frequency selectivity high, and its small size is convenient for further miniaturization. In the product test, the duplexer is found to meet the band requirements very well with high isolation levels of -44 dB and -48 dB at the first and second frequency centers, respectively, which are better than those with similar frequency bands in the references.

This paper proposes the design of a microwave equalizer based on SIR loading with internal coupled-line. By loading a ring-type stepped impedance resonator (SIR) with internal coupled-lines, a microwave equalizer with positive slope transmission characteristics is presented. The frequency response is synthesized using a second-order SIR, and a detailed theoretical derivation of the equalizer is presented. A prototype of the equalizer is fabricated and measured to validate its expected performance, with the measurements showing good agreement with the predictions. The microwave amplitude equalizer demonstrates the necessary gain slope across its entire operational frequency range. Finally, a potential design scheme for a microwave amplitude equalizer is proposed.

Photovoltaic (PV) systems represent an extremely intriguing alternative in order to provide dry and semi-arid regions in remote locations with water. In this case, a maximum power point tracking (MPPT) unit that aims to regulate the (PV) panel connected converter duty cycle is necessary to ensure that it operates as efficiently as possible under various operating situations. This study introduces a sliding mode technique-based MPPT control unit with the goal of enhancing photovoltaic pump (PVP) system performance. It discusses this for a number of scenarios, including the presence or absence of batteries, operation under various radiation conditions, and operation in consideration of constant speed and variable load torque. The outcomes of the MATLAB simulation demonstrated that the proposed methodology is preferable compared to the incremental conductance method for the various scenarios, and it achieves better efficiency and lower voltage ripples.

Photonics crystal sensors, sensitive to light, play a crucial role in discerning minute alterations in a material's refractive index, finding widespread application, such as in monitoring drinking water quality. Our objective is to fashion a sensor based on a 2D photonics crystal structure and scrutinize optical transformations induced by variations in the bacteria's refractive index as light traverses the sensor structure. Leveraging Rsoft's simulation capabilities, we assessed transmission spectra, observing shifts in the bacteria's refractive index and their consequential impact on the light signal's frequency and wavelength within the sensor structure. The simulations unequivocally demonstrate that fluctuations in the bacteria's refractive index significantly affect the light signal's frequency and wavelength. Consequently, the study underscores the efficacy of the Rsoft-designed optical sensor in discerning bacterial presence in contaminated water, achieving an average sensitivity of 834 nm/RIU. In conclusion, the study establishes the success of the optical sensor crafted with Rsoft software in detecting bacteria in polluted water. By monitoring optical alterations during light traversal, variations in the bacteria's refractive index are translated into discernible shifts in the light signal's frequency and wavelength, facilitating effective bacteria detection.

In this article, a metamaterial SRR and CSRR based octagonal ring-shaped multiband antenna is presented. The proposed antenna structure is designed with the implementation of slotted radiating patch with metamaterial cells for resonating at penta-bands to cover the 5G Sub-6 GHz NR frequency bands n48/n78/n79/n96, 3.5 GHz worldwide interoperability for microwave access, 5 GHz wireless local area network, 10.03-14.29 GHz upper X band and 15.74-19.98 GHz upper Ku band wireless applications. The proposed antenna with a compact dimension of 33×22×1.6 mm³ is fabricated to validate the simulated results with measured ones. The radiation characteristics is identified in stable and uniform manner for all the penta resonant bands.

A dual-port microstrip sensor based on a complementary split ring resonator (CSRR)-derived structure is proposed to measure the permittivity and permeability simultaneously in this paper. The coupling among meandered conductive ring, interdigital capacitor, and microstrip line is used to obtain the relatively independent distribution area of the highest intensity of the electric field and magnetic field. It can be utilized to distinguish the influence of permittivity and permeability on the resonant frequency point. A numerical model was established for extracting the magnetic and dielectric properties, and the sensor was processed and tested. The findings demonstrate that the sensor can measure permittivity and permeability in a single operation by taking advantage of the resonant properties of low and high frequencies. The relative errors of the measured permittivity and permeability are controlled within 4.43% and 3.41%, as well as the sensitivity values S_fm and S_fe of 7.24 and 3.06, indicating excellent overall performance.

In this research work, a Z-shaped printed slot microstrip antenna with variations in feed location has been presented to realize broadband and compact antenna. The Z-shaped slot has been realized by placing two right angle triangle shaped patches in opposite directions inside rectangular shaped slot. Further by aligning the microstrip line as feed along the length and width of Z-shaped slot, the broadband and compact antenna respectively has been realized. The antenna is fabricated using an FR4 substrate having electrical dimension of 0.48λ₀ × 0.4λ₀. The antenna offers 407 MHz (27%) measured impedance bandwidth for broadband and 22% of reduction in size for compact configurations. The parametric analysis, equivalent circuit analysis and temperature as an environmental testing parameter of proposed designs are presented and validated in this paper.

An antenna operating between 300\,MHz and 700\,MHz, designed to be used on a ground penetrating radar installed on an Unmanned Aerial Vehicle (UAV) for the exploration and characterization of the buried ice deposits on Mars, is presented. To this end, a lightweight, high-gain Vivaldi antenna having compact dimensions and high operating bandwidth has been taken into consideration. This antenna, equipped with circular-loaded rectangular slots etched on its radiating arms, exhibits improved performance in terms of size, return loss, gain, and fidelity factor with respect to a conventional antipodal Vivaldi antenna. Experimental measurements performed on a prototype of the Vivaldi antenna with slots showed a return loss lower than -12 dB with realized gains between 4 dBi and 6.5 dBi in the 300-700 MHz frequency band.

This article presents a quad port multi-input multi-output (MIMO) antenna based on arrays of rectangular dielectric resonators for intelligent automotive applications. The proposed MIMO antenna configuration is formulated by integrating four rectangular dielectric resonator antenna (RDRA) arrays. Two RDRAs are configured as E-plane arrays and the other two as H-plane arrays. Each array consists of two radiating elements, evenly spaced apart. Direct microstrip line (DML) feeding, a novel kind of feeding technique to cope up with back radiation issue which occurs owing to discrete grooves on ground plane is employed to feed RDRA. The orthogonal mode in individual arrays (H-plane and E-plane) results in increased isolation. The overall dimension of the suggested quad port MIMO antenna is (2.21λ₀×1.32λ₀). The prescribed RDRA array operates at 5.9 GHz with an impedance bandwidth of 6.9% for Port1 and 8.1% for Port2, respectively. The measured isolation is more than -24 dB. For this MIMO antenna measured peak gain of 9.6 dBi is noticed. Various MIMO performance metrics such as the total active reflection coefficient (TARC), diversity gain (DG), channel capacity loss (CCL), and envelope correlation coefficient (ECC) have been studied in detail and discussed in this article. It is noteworthy that these measurements continue to fall within allowable threshold ranges, indicating the appropriateness of the prescribed MIMO antenna for the intended applications in intelligent automotive system.

To increase the stopband width of the filter, a second-order wide-stopband substrate-integrated waveguide filter is suggested. This filter is designed by utilizing a DGS structure and the weakest electric field approach. To suppress the modes, the filter sets the inner and outer coupling windows at the modes' weakest electric fields (TE₁₂₀/TE₂₁₀, TE₂₂₀). Additionally, a new nested U-shaped DGS structure is implemented to suppress the TE₁₃₀ mode, hence expanding the stopband width of the filter. The filter has been processed and measured, and the findings indicate a 4.5 GHz center frequency, a -3 dB bandwidth of 240 MHz, a relative bandwidth of 5.3%, an insertion loss of -1.2 dB in the passband, and a -22 dB stopband, which can be extended up to 9.4 GHz (i.e., 2.1 times the center frequency). The simulated and measured results demonstrate good alignment. Compared to other SIW filters, the current filter achieves a wider stopband while using fewer orders and implementing a straightforward design method, providing potential value for applications.

The performance requirements for filters in the microwave frequency band are particularly stringent, particularly in terms of high bandwidth and out-of-band rejection. However, meeting these requirements within the constraints of a compact size presents a significant challenge. A coupled step-impedance resonator bandpass filter is proposed. The filter combines U-shaped branches and L-shaped branches to create multiple resonance points while expanding the bandwidth, and the in-band ripple is also improved by this folded structure that greatly reduces the filter size. The microstrip filter measures only 9.6 mm × 8.8 mm × 1.1 mm, has a center frequency of 4.65 GHz, and achieves a relative bandwidth of 60.2%. The filter can be used in 5G n77 (3300~4200 MHz), n78 (3300~3800 MHz), n79 (4800~4960 MHz), and WLAN (5150~5850 MHz) bands. In addition, the filter has a left-side rectangular coefficient of 1.12, insertion loss <0.4 dB, and return loss better than 17 dB.