Antenna Model Research Articles

Medical Communication Systems Utilizing Optical Nanoantenna and Microstrip Technology

Many technical approaches were implemented in the antenna manufacturing process to maintain the desired miniaturization of the size of the antenna model which can be employed in various applied systems such as medical communication systems. Furthermore, over the past several years, nanotechnology science has rapidly grown in a wide variety of applications, which has given rise to novel ideas in the design of antennas based on nanoscale merits, leading to the use of antennae as an essential linkage between the human body and the different apparatus of the medical communication system. Some medical applications dealt with different antenna configurations, such as microstrip patch antenna or optical nanoantenna in conjugate with sensing elements, controlling units, and monitoring instruments to maintain a specified healthcare system. This study summarizes and presents a brief review of the recent applications of antennas in different medical communication systems involving highlights, and drawbacks with explores recommended issues related to using antennas in medical treatment.

Simulation and Suppression Measure Analysis of Electromagnetic Radiation Interference Due to Frequency Converters in Coal Mines

Nowadays, due to their characteristics of high efficiency and energy saving, frequency converters are used in coal mine excavation machines and ventilation machines. They can cause serious electromagnetic radiation interference with the surrounding monitoring, sensing and other equipment. Therefore, it is necessary to explore the electromagnetic interference characteristics of mining converters. By choosing a ZJT-75/660SF mine frequency converter as the research object, an antenna model was established, and the method of moments was used to solve the problem. The electromagnetic radiation characteristics of the frequency converter were analyzed, and a field experiment was conducted to verify the effectiveness of the model by comparing the simulation and experimental data. According to the analysis of the electromagnetic intensity distribution characteristics of the near field and far field, the near-field intensity is concentrated in the inner part of the converter, but the far-field intensity has obvious directional characteristics, which are found to provide a reference value for the location of the underground mining converter. Finally, a method is proposed to improve electromagnetic radiation disturbance by changing the structure of the converter’s heat dissipation hole, and the feasibility of this method is verified.

A Complementary Overview and Challenges in Radar Cross Section Modeling of Phased Array Antennas

The radar cross-section (RCS) is a critical factor in the design and performance of modern airborne weapon systems. These systems utilize phased array antennas due to their low profile, advanced beamforming, and angle measurement capabilities. The effect of phased array antennas on platform RCS can be crucial. Addressing the RCS of phased array antennas involves solving both structural and antenna mode scattering. Each component presents different challenges for computation and requires specific RCS reduction techniques. This short review delves into various existing methods for computing antenna and structural mode RCS and offers insights into their application. Simulating the RCS of large array antennas presents significant challenges due to the high demands on computing resources. Additionally, this review highlights existing solutions aimed at reducing the simulation times and memory usage in RCS modeling while maintaining accurate results. However, further advancements are necessary to simulate large scale array antennas more efficiently and accurately.

Class-E, active electrically small antenna with enhanced bandwidth-efficiency product and high radiated power at the high-frequency (HF) band

Antennas operating at the high-frequency (HF) band (3–30 MHz) are frequently electrically small due to the large wavelength of electromagnetic waves (10–100 m). However, the bandwidth-efficiency products of passively matched electrically small antennas (ESAs) are fundamentally limited. Wideband HF waveforms using bandwidths of 24 kHz or more have recently received significant attention in military communications applications. Efficiently radiating such signals from conventional passive ESAs is very challenging due to fundamental physical limits on bandwidth-efficiency products of ESAs. However, active antennas are not subject to the same constraints. In this work, we present the design and experimental characterization of a high-power, class-E active ESA with enhanced bandwidth-efficiency product compared to that of passively matched ESAs. Specifically, the proposed class-E active ESA can radiate wideband HF signals with bandwidths of 24 kHz or more at 3 MHz (fractional bandwidths of ≈1%–4%), with total efficiencies ranging from 40% up to 80% depending on the modulation type and radiated power levels approaching 100 W. Our approach uses a highly efficient, integrated class-E switching circuit specifically designed to drive an electrically small, high-Q HF antenna over a bandwidth exceeding 24 kHz at 3 MHz. Using a high-Q RLC antenna model, we have successfully demonstrated wideband binary ASK, PSK, and FSK modulations with the proposed class-E active ESA. Experimental results indicate that the bandwidth-efficiency product of this class-E active ESA is 5.4–9.8 dB higher than that of an equivalent passive design with the same data rate and bit-error-rate.

Design of a UWB patch antenna and performance evaluation in detecting brain tumors

In this study, a patch antenna is designed for easy fabrication and effective operation across a wide frequency range, making it particularly valuable for detecting brain tumors within a human head phantom using the monostatic technique. The study presents the proposed antenna's modeling in four stages, analyzing all essential parameters where a substrate material consisting of FR 4 is used. The antenna has a patch area of 0.27 λ × 0.21 λ and operates at 7.5 (free space), 7.48, and 7.47 GHz with a wide bandwidth of 3.188 GHz (free space), whereas in measurement, it operates in free space at 6.79 GHz with a bandwidth of 3.24 GHz, which is also categorized as an ultra-wide band. A comparative analysis is carried out between the proposed patch antenna and previous studies utilizing FR4 and similar substrate materials to enhance understanding. In this research, the analysis includes a human head phantom model, assessing key performance criteria such as SAR, return loss, and VSWR. The time-dependent analysis provides in this study insights into the dynamic behavior of the system in detecting brain tumor. The proposed antenna has been evaluated and yielded a maximum specific absorption rate (SAR) of 0.420985 W/kg for 1 gram of tissue in the head phantom. The performance of the patch antenna is evaluated using CST software, while the fabricated PCB antenna is tested in real-world conditions to ensure dependable operation in practical applications. The main challenge addressed in this work is achieving accurate brain tumor detection within a human head phantom model in a CST environment and using a UWB patch antenna fabricated via PCB technology.

FSS inspired two port CP MIMO antenna with enhanced gain for X-band applications

In this work, a dual-port circularly polarized (CP) Multiple Input Multiple Output (MIMO) antenna equipped with frequency selective surface (FSS) for X-band applications is designed and analyzed. The antenna system aims to enhance gain, a critical parameter like isolation radiation pattern, etc. In wireless communication systems working in the X-band frequency range. The present MIMO antenna consists of two parts that provide coverage for the whole frequency band of 7.6–11.6 GHz, specifically for X-band communication applications. As a decoupled network, the meander line architecture greatly improves isolation. The MIMO antenna's measurements include 25 × 30 × 1 mm3. To improve the antenna's peak gain even further, a FSS is placed below the present MIMO antenna at 10.5 mm. The whole volume of the FSS-inspired composite structure is 50 × 60 × 11.6 mm3. By correctly incorporating the FSS array with the antenna's structure and utilizing its frequency-selective properties, gain improvement can be attained. Without FSS, the antenna's gain is 4.8 dBi and it is enhanced by 21 % and the maximum value of gain is 15 dBi in the desired frequency spectrum. The efficiency of the proposed FSS-inspired structure is >84.2% in the operating frequency band. To evaluate the MIMO performance of the current antenna, several attributes are evaluated. On the evaluation, it is found that the present MIMO antenna has an envelope correlation coefficient (ECC) < 0.004, a diversity gain (DG) over 9.99, measured mean effective gain (MEG) below 3 dB, and CCL of less than 0.4 bits/s/Hz throughout the resonant frequency spectrum. Through modeling and experimental testing, the current MIMO antenna model is created and verified.

Plasmonic metamaterial absorber for MWIR and LWIR bispectral microbolometers

Plasmonic metamaterial absorbers (PMAs) designed for multispectral imaging in the infrared (IR) with uncooled microbolometers are investigated. The study presents Fourier transform infrared spectroscopy (FTIR) measurements of PMAs consisting of metal-insulator-metal-stacks (MIM) with square-shaped micropatches as top metal layers. The measurements reveal high absorptances of 82% to 99% for distinct wavelengths within a range from 2 μm to 9.2 μm. The spectra are evaluated with respect to the lateral dimensions of the patches and to the refractive indices of the used dielectrics SiO2, Al2O3 and Ta2O5. Numerical simulations and analytical calculations of the TM010-mode using the transmission line model (TLM) for microstrip antennas show good qualitative agreement with the measurement results. Additionally, bispectral PMAs were fabricated consisting of fields of PMAs with two different patch sizes arranged in a chessboard pattern. The individual fields of this pattern correspond to microbolometers with 12 μm pitch in shape and size. Two distinct absorption maxima can be seen in the spectra measured by FTIR. The choice of materials, deposition methods and patterning processes is suitable for the integration into the existing Fraunhofer IMS's nanotube microbolometer technology to realize multispectral infrared imaging. The fabrication process is CMOS-compatible and carried out on 8-in. wafers.

Special aspects of patch antennas synthesis using genetic algorithm

Microstrip-fed patch antenna synthesis can be performed using one of the numerous optimization algorithms, such as a genetic algorithm (GA). VBA or IronPython script engines implemented in modern CAD systems make it possible to implement GA. However, the capabilities of these languages for processing matrix data are limited. The use of a MATLAB environment script could combine the capabilities of MATLAB and CAD for electromagnetic modelling. It would make it possible to generate chromosomes of individuals of a given length, build antenna models in CAD that reflect the genetic code of individuals, process modelling results in MATLAB, carry out crossing over and mutations with a given probability for obtaining patch antennas that provide a user-specified value of the goal function. The primary purpose of this work is to propose a script in the MATLAB environment that allows complete automation of microstrip antennas' structural synthesis in MATLAB - CAD using GA, as well as to study GA selection methods and their influence on the results of this algorithm. As a result, a MATLAB script has been developed, combining the capabilities of electromagnetic modelling CAD and the MATLAB environment for processing matrix data for fully automated synthesis of the microstrip-fed patch antenna. It is shown that the proposed script randomly generates an initial population, creates a CAD model corresponding to each individual, determines the value of the goal function for each individual, performs crossing over and mutations, and then iteratively repeats the above actions until the GA convergence condition is satisfied. This paper highlights that the GA convergence speed depends on the selection method chosen before crossing over. Recommendations for choosing a selection method are formulated. The results of synthesizing a microstrip antenna with a frequency band 5.2 times greater than the frequency band of the reference antenna are presented. The presented script combines the capabilities of electromagnetic modelling CAD and MATLAB to fully automate the process of structural synthesis of microstrip antennas with a given frequency response and the main lobe direction of the radiation pattern.

Multibeam Wideband Transmit Beamforming Using 2D Sparse FIR Trapezoidal Filters

A low-complexity multibeam wideband transmit beamformer using a 2D sparse FIR filter design capable of multiple beams is proposed as a digital building block for fully digital beamformers. The 2D sparse FIR filter has multiple trapezoid-shaped passbands pertaining to wideband beams aimed at particular directions. The proposed multibeam digital beamformer drives a uniform linear array of wideband antenna elements to achieve the wideband multibeam transmit-mode signals desired by the communication system. The 2D sparse FIR filter is designed to be optimal in the minimax sense using convex optimization techniques. Full-wave electromagnetic simulations using real antenna models confirm that the proposed wideband transmit beamformer can achieve multibeam transmission in the 1.3–2.8 GHz frequency range, with more than 70% fractional bandwidth. Furthermore, the adoption of the wideband transmit multibeam beamformer leads to a significant reduction in digital arithmetic (computational) complexity compared with previously reported wideband transmit beamformers of similar transfer function type, without deteriorating beam directionality and causing increases in the side-lobe level. The proposed sparse 2D FIR multibeam beamformer architecture is well-suited for both sub-6 GHz (legacy) band transmit beamforming, frequency range three (FR3) beamforming up to 28 GHz, and mmWave operation for emerging 5G/6G applications.

Rapid Tracking Satellite Servo Control for Three-Axis Satcom-on-the-Move Antenna

To overcome the possible gimbal lock problem of the dual-axis satcom-on-the-move (SOTM) antenna, a three-axis tracking satellite SOTM antenna structure appears. The three-axis SOTM antenna is realized by adding a roll axis to the azimuth axis and pitch axis in the dual-axis SOTM structure. There is coupling among the azimuth axis, pitch axis and roll axis in the mechanical structure of the three-axis SOTM antenna, which makes the kinematic modeling of the antenna difficult. This paper introduces a three-axis SOTM antenna kinematic modeling method based on the modified Denavit–Hartenberg (MDH) method, named the new modified Denavit–Hartenberg (NMDH) method. In order to meet the modeling requirements of the MDH method, the NMDH method adds virtual coordinate systems and auxiliary coordinate systems to the three-axis SOTM antenna and obtains the kinematic model of the three-axis SOTM antenna. During the motion of the carrier, the SOTM antenna needs to adjust the antenna pointing in real time according to the changes of the location and attitude of the moving carrier. Therefore, this paper designs a servo control system based on the active disturbance rejection controller (ADRC), introducing a smooth and continuous ADRC fal function to enhance the tracking speed of the servo control system and reduce the overshoot of the output response. Finally, system experiments were carried out with a 60 cm caliber three-axis SOTM antenna. The experiment results show that the proposed servo control method achieves higher antenna tracking satellite accuracy and better communication effects.

Antenna modeling based on meta-heuristic intelligent algorithms and neural networks

As wireless communication technology continues to advance, the antenna, as an essential front-end device in radio communication system, is surrounded by more and more complex electromagnetic wave environments with increasing variety, resulting in greater demand for antennas and higher design requirements. While the traditional antenna design methods suffered from the disadvantage of low design efficiency, a powerful tool for accelerating antenna design is the modelling of antennas with neural networks. Aiming to enhance the modeling accuracy of neural network, multiple novel meta-heuristic swarm intelligent algorithms are introduced and part of them are modified for the purpose of applying to optimizing network’s weights and biases so as to raise the antenna model`s prediction precision on the basis of neural network. Specifically, the intelligent algorithms and their improvement directions include the strategy of optimizing weights and biases for neural networks with seagull optimization algorithm, optimizing the weights and biases of neural network with the improved butterfly algorithm fused with reverse learning, and the artificial rabbit algorithm optimizing the neural network weights and biases. In addition, two intelligent optimization algorithms that are already more mature: the particle swarm algorithm and the genetic algorithm are added to compare with the above three algorithms. The accuracy of neural network prediction before and after the optimisation of neural network by seagull algorithm, the butterfly algorithm incorporating reverse learning, the artificial rabbit algorithm, the particle swarm algorithm, and the genetic algorithm are got through the results respectively. The results of the experiments displayed that the neural network optimized of the improved butterfly algorithm incorporating reverse learning has a prediction accuracy of 99.69 % with stable results, the optimised neural network prediction accuracy of the seagull algorithm reaches 99.51%, and the optimised neural network prediction accuracy of the artificial rabbit algorithm is 99.49 %. The remaining two traditional algorithms optimized neural network accuracy is 83.1 % and 99.43 % respectively. Therefore, the improved butterfly algorithm incorporating reverse learning is the most effective among these three new algorithms applied to the field of antenna prediction. Moreover, the running time of the network optimized by different algorithms is quite distinct, among which the neural network optimized by the improved butterfly algorithm incorporating reverse learning takes the shortest time, which increases the prediction efficiency of the network by more than 70%. In summary, the application of the fused reverse learning improved butterfly algorithm in optimizing neural network predictions yields the shortest processing time and highest accuracy. This not only enables faster and more precise antenna design but also holds greater significance for the field of antenna design and analysis.

Electrodynamic modeling of a four-channel antenna with an operating frequency band of octave

The actual problem of electrodynamic modeling of a four-channel antenna with an octave operating frequency range has been considered. The results of numerical electrodynamic modeling of a four-channel antenna have been presented. The considered antenna with an octave operating frequency range is a rectangular curtain comprising four independent non-equidistant channels. Numerical electrodynamic modeling of a four-channel antenna has been carried out in the ANSYS HFSS software package, with the convergence parameter DeltaS = 0.01. As a result of the simulation, the frequency characteristics of each channel have been obtained: VSWR, gain, reflection coefficient, directional pattern. The antenna provides a scanning angle as part of an ultra-wideband digital antenna array of at least ±30° in azimuth and from 0° to 60° in elevation. The gain of the antenna channels in the operating frequency range is not lower than 6 dB. According to the simulation results, the VSWR of each channel of the antenna in the operating frequency range does not exceed 2.55. To minimize the influence of mutual coupling of channels on the antenna characteristics, the distance from the phase centers of the curtain emitters to other elements of the ultra-wideband digital antenna array should be at least a wavelength in free space at the lower frequency of the operating frequency range. It has been shown that the considered four-channel antenna provides an octave operating frequency band and can be used as part of an ultra-wideband digital antenna array for direction finding of radiation sources.

МОДЕЛЮВАННЯ ТА АНАЛІЗ РОЗГОРТАННЯ КОСМЕТИЧНОЇ СІТЧАСТОЇ АНТЕНИ

The aim of work is to create a dynamic model of a space antenna with the pantograph structure and study the processes of its deployment using open-source software. The methods of theoretical mechanics, multi-body dynamics, computational mechanics, and computer modeling were used for this research. The object for modeling is a novel mesh antenna, which is designed for mini-satellites. The most significant difference between this antenna and others is the design of the support ring in the form of a pantograph. Using the built model, antenna deployment is simulated for different cases. Values of deployment time and cable tension during the antenna deployment are analyzed.

Dielectric Behavior Characterization of RE/BaTiO3 Using Time Domain Spectroscopy: Application on High-Performance Dielectric Resonator Antennas

We are working to design dielectric resonator antennas based on binary composites made of epoxy resin (RE) and barium titanate (BaTiO3 or BT). The composite samples are prepared at room temperature and under atmospheric pressure. The dielectric properties of these composites were assessed using time domain spectroscopy (TDS). The antennas structure are designed, simulated, and optimized using electromagnetic software Ansys, HFSS. Two types of antennas are studied. The first type consists of a cylindrical dielectric resonator that gives three antenna models in terms of bandwidths, the antennas having a single frequency band, the antennas having dual-band, and the antenna covering three frequency bands, with peak gains varying between 3.68 and 8.15 dB achieved. The second type consists of dielectric resonators composed of two adjacent identical shapes each consisting of a rectangular joined with a cylindrical with the same height. The proposed antenna achieves ultra-wideband with a relative bandwidth of 97% covering the range of 6 to 17.32 GHz, and dual-band circularly polarized ( AR<3dB ), the range of the lower band is 9.62 to 10.14 GHz and the range of the upper band is 16.74 to 16.94 GHz. The focus of this research is on creating novel antennas for applications in wireless communications systems.

X-BAND Rectangular Microstrip Patch Antenna: Design, Simulation, and Analysis

Abstract: Microstrip Patch Antennas (MPA) have shown to be the most unusual finding in the era of downsizing, despite the fact that the revolution in antenna engineering has led to the rapidly expanding communication networks. The design, modeling, and analysis of rectangular microstrip patch antennas are all included in this study. The suggested patch antennas' resonating frequency is 9 GHz, which falls inside the X band area. Ansys HFSS software was used to design them using Rogers RT/duroid 5880 material, which has a dielectric constant of 2.2. Five performance metrics were used to assess the suggested MPAs: return loss, bandwidth, VSWR, gain, and HPBW. The requested information pertains to the measurements of return loss, voltage standing wave ratio (VSWR), and half power beamwidth (HPBW). The suggested antennas are suitable for use in radar, wireless, and satellite applications.

Rigorous Analysis and Design of Resistor-Loaded Patch Antennas with Flexible Gain for Indoor Radar Sensors

A high-precision cavity model of resistor-loaded patch antenna (RLPA) with adjustable gain is proposed and rigorously studied in this article. In our analysis, the loaded resistors are perceived as controlled current sources, thus the RLPA can be solved as a modified cavity model. Accurate expressions of field distribution, input impedance, and radiation patterns are derived in this way, and a gratifying agreement has been achieved between the calculated and simulated results. Based on this approach, RLPAs for indoor motion radar are designed and analyzed. Comprehensive analysis is conducted to reveal the loading effect on radiation gain, radiation efficiency, and quality factor of RLPAs under various circumstances. Through altering the value of the loaded resistance, its radiation gain and coverage range can be flexibly adjusted. Besides, enhanced operating bandwidth and improved performance stability are also achieved due to the loaded resistors. Last but not least, several indoor motion radars based on the proposed patches are carried out and measured, which demonstrates the validity of the proposed method and design.

Antenna Shape Modeling based on Histogram of Oriented Gradients Feature

A least square support vector machine (SVM) model is proposed for shape modeling of slot antennas. The slot image is mapped into the electromagnetic response by the SVM model. A modified shape-changing technique is also proposed to describe the antenna geometry by the quadratic uniform B-spline curve and generate the slot images. In the model, the histogram of oriented gradients feature is extracted from the slot images to show the appearance and shape of the slot. The relationship between the histogram of oriented gradient features and the electromagnetic responses is preliminarily built on SVM and the transfer function. Then a radial basis function network is used for error correction. The effectiveness of the proposed model is confirmed with an example of a tri-band microstrip-fed slot antenna. Compared with the convolutional neural network (CNN), the feature extracted by CNN is substituted by the histogram of oriented gradients feature, and the proposed model shows the same accuracy and the improvement of training efficiency.

Systematic testing, simulation, and mitigation of IEMI risks in medium-voltage substations

This paper introduces a comprehensive suite of testing, simulation, and mitigation strategies aimed at evaluating and countering intentional electromagnetic interference (IEMI) risks in medium-voltage (MV) substations. Diverging from conventional IEMI testing methods, the proposed testing approach assesses the entire substation control system, offering a more precise understanding of its IEMI vulnerabilities. Additionally, a novel simulation method coupling the transmitting antenna model and the full-wave substation model is presented for IEMI estimation, which simplifies the simulation process while maintaining good accuracy. Moreover, to further fortify substations against IEMI risks, a quantitative analysis is established to determine the necessary distance between the substation building and the fencing boundary. This analysis enables the integration of protective measures during the design and construction phase of the substation, substantially mitigating IEMI risks. Through a case study using a typical MV substation, the efficacy and capability of the proposed methods are demonstrated.

Modulation of electrodes on the sensitivity of the Pockels effect

In order to improve the sensitivity of the system in the Pockels effect, a design scheme for adding antennas at both ends of the crystal is proposed. Firstly, the influence of the applied electric field on the refractive index of the crystal is explored, and the relationship between the applied electric field and the output of the system is deduced. Secondly, two different antenna models are designed (one is to connect the antenna directly to both ends of the crystal, and the other is to connect the antenna after coating on the crystal), the distribution of the applied electric field in the internal field of the crystal under different models is studied, and the corresponding input and output transfer functions are analyzed. The analysis shows that the sensitivity of the system is improved in different antenna modes, and the crystal coating has little effect on the sensitivity. In addition, the antenna model without coating is simple to install, but the internal field strength of the crystal shows a tendency to be large in the middle and small at both ends, so it is easier to produce electric field breakdown effect in the strong field. The internal field strength distribution of the coated crystal is approximately uniform field, and the field strength maximum is smaller than that of the non-coated antenna model, so crystal breakdown is not easy to occur in the strong field. Finally, the effectiveness of the theoretical analysis is verified by experiments.

Model of slot antenna for MPECVD of carbon nanostructure

A model of a slotted waveguide antenna for microwave plasma enhanced chemical vapor deposition (MPECVD) of carbon nanostructures at low pressure is developed. The performance of two slot applicator for the production of dense plasma in the working gas (argon) at a frequency of 2.45 GHz is investigated by EM field simulator. Results show that dimensions of the symmetrical slots (length l ≤ λg/2, width of d = 6-10 mm) and optimized angle (φ=32° with respect to the waveguide central line) have a strong influence on the impedance matching of the waveguide to the dielectric window and plasma column (1.5 < SWR < 2.5), and on the radiation efficiency. The dielectric plate and plasma column density were taken into account in the model in the optimisation of the dimensions of the slots. The mode structure of standing surface waves in the plasma column is investigated at three values of plasma density and results for the radial (n=1) and azimuthal wave numbers (m=3, 4, 5) are in agreement with experimental results.