Antenna Model Research Articles

A Novel Chrysanthemum-Like Fractal Structure Multi-Band Antenna for Mobile Terminals

This paper incorporates the structural characteristics of chrysanthemums in nature and fractal geometry theory into the antenna structure design and a novel-structured fractal multiband fractal microstrip antenna with a chrysanthemum petal structure is proposed. The antenna can cover commercial frequency bands from the second to fourth generation (4G), satellite navigation, wireless local area networks, and Bluetooth. The antenna radiator imitates the structure of chrysanthemum’s petals in nature, and a basic arc shape is iterated many times according to a certain proportional coefficient. After simulation and comparison, the second iteration can achieve the best antenna performance, and the antenna adopted the coplanar waveguide feeding method to broaden the antenna bandwidth. The antenna covers three effective frequency bands of 1.58–2.68 GHz (64.7%), 2.76–4.01 GHz (33.9%), and 4.68–5.35 GHz (13.4%). The antenna dielectric board is made of FR-4 material, the dielectric constant is 4.4, and the actual size is 41 × 29 × 1.6 mm3. The antenna performs fractal iteration at a small size, and the approximate calculation of the frequency band is completed by comparing the ratio of each ring to the current vector diagram. The design of the antenna is to use HFSS for antenna modeling and parameter optimization, and the model under different conditions were compared and analyzed. By comparing the test results of the antenna prototype with the simulation structure in the electromagnetic anechoic chamber, the rationality of the antenna is verified.

Taguchi-RBF Neural networks Based Optimization of Phased Array Antenna With Coupling Effects

In the antenna array synthesis problems, most of the works in literature utilize isotropic elements. Thus, the mutual coupling effects between the array elements are neglected. It is obvious that an array antenna synthesized by neglecting the coupling effects cannot be used in the real world applications due to the possible mismatch between the desired and realized radiation patterns. In this paper, a novel method based on neural network algorithm RBF (Radial Basis Function ) for the synthesis and model of Antipodal Vivaldi antenna with mutual coupling effect is presented. The synthesis in implementation’s method for this type of array permits to approach the appropriated radiation pattern while considering the mutual coupling between its elements. The neural network is used to estimate the array elements’ excitations. The architecture of the neural network based on the radial basis functions (RBFs) is introduced and simulation results are presented. Results show that there is an agreement between the desired specifications and the synthesized one. The proposed optimization approach offers an efficient and robust synthesis procedure.

Influence of Dielectric Plate Parameters on the Reflection Coefficient of a Planar Aperture Antenna

In this article, an aperture antenna excited by a waveguide with a circular cross-section and covered with a dielectric plate was analyzed via simulation calculation and verified via measurements. The influence of the geometrical and electromagnetic parameters of the dielectric plate on the reflection coefficient S11 of the antenna opening was systematically analyzed. The geometrical parameters taken in this analysis are the thickness d and the width/length h1/h2 of the dielectric plate. The electromagnetic parameters used in this analysis are the real and the imaginary part of permittivity (εr, tan δ) and the electrical conductivity of the dielectric plate (σ). The simulation calculation and analysis included other structural and electromagnetic parameters of the dielectric plate (density of the radome material, relative permeability, and magnetic loss tangent (ρ, µr, and tan δµ, respectively)), but the results show that in the range of real values of these parameters for the materials used for the dielectric plate, they had no significant influence on the reflection coefficient. The results show that impedance-matched antennas with very low values of the reflection coefficients S11 at the resonant frequency can be realized by changing the geometrical and electromagnetic parameters of the dielectric plate material. The results are presented for a circular aperture antenna on a planar grounded plane with a dielectric plate on the opening, and the achieved lowest values of the S11 parameter were −45.17 dB (simulated) and −43.93 dB (measured) at the frequencies of 1.7820 GHz and 1.7550 GHz, respectively. The estimated values of the dielectric plate parameters in this case are thickness d = 11.08 mm (0.67 λ); width × length of grounded plane and dielectric plate h1 × h2 = 423 × 450 mm2 (2.51 × 2.67 λ); relative permittivity 2.5, tan δ = 0.09, μr = 1, tan δμ = 0.00, ρ = 1200 kg·m−3; and electrical conductivity σ = 0 S/m. The simulation calculation results were verified by measuring the reflection coefficient S11 on the created laboratory model of the aperture antenna with the dielectric plate and showed a very good match.

A Novel Low-Cost Compact High-Performance Flower-Shaped Radiator Design for Modern Smartphone Applications

This manuscript examines the design principle and real-world validation of a new miniaturized high-performance flower-shaped radiator (FSR). The antenna prototype consists of an ultracompact square metallic patch of 0.116λ0 × 0.116λ0 (λ0 is the free space wavelength at 3.67 GHz), a rectangular microstrip feed network, and a partial metal ground plane. A novel, effective, and efficient approach based on open circuit loaded stubs is employed to achieve the antenna's optimal performance features. Rectangular, triangular, and circular disc stubs were added to the simple structure of the square radiator, and hence, the FSR configuration was formed. The proposed antenna was imprinted on a low-cost F4B laminate with low profile thickness of 0.018λ0, relative permittivity εr = 2.55, and dielectric loss tangent δ = 0.0018. The designed radiator has an overall small size of 0.256λ0 × 0.354λ0. The parameter study of multiple variables and their influence on the performance results has been extensively studied. Moreover, the impact of different substrate materials, impedance bandwidths, resonance tuning, and impedance matching has also been analyzed. The proposed antenna model has been designed, simulated, and fabricated. The designed antenna exhibits a wide bandwidth of 5.33 GHz ranging from 3.67 to 9.0 GHz at 10 dB return loss, which resulted in an 83.6% fractional impedance bandwidth; a maximum gain of 7.3 dBi at 8.625 GHz; optimal radiation efficiency of 89% at 4.5 GHz; strong intensity current flow across the radiator; and stable monopole-like far-field radiation patterns. Finally, a comparison between the scientific results and newly published research has been provided. The antenna's high-performance simulated and measured results are in a good agreement; hence, they make the proposed antenna an excellent choice for modern smartphones' connectivity with the sub-6 GHz frequency spectrum of modern fifth-generation (5G) mobile communication application.

Directional antennas modelling and coverage analysis for UAV networks with blockage effects in urban environment

AbstractIn recent years, the use of unmanned aerial vehicles (UAVs) as flying base stations (BSs) has attracted widespread attention in both academia and industry. Most of the existing research on UAV networks in dense urban environment focus on omnidirectional antenna patterns, which results in severe interference and overlapping between coverage area due to dominant line‐of‐sight (LOS) links. This paper proposed a directional antennas model with tunable beamwidth and blockage effects in urban UAV networks, and derive the coverage probability of UAV networks in dense urban environment by stochastic geometry tools, where UAVs and users are deployed according to independent Poisson point process (PPP). Specifically, a realistic and mathematically tractable directional antenna pattern is adopted and radiation gain is modelled by a continuous function of the elevation angle . In addition, the blockage effects of the buildings are considered by establishing a three‐dimensional blockage model where buildings are distributed according to PPP with heights followed by Rayleigh distribution. Numerical results match well with simulations and provide optimal deployment parameters for UAV deployments.

Design and Modeling of Ultra-Compact Wideband Implantable Antenna for Wireless ISM Band

This paper proposes a wideband ultra-compact implantable antenna for a wireless body area network (WBAN). The proposed patch antenna works in the industrial, scientific, and medical (ISM) bands. The proposed patch antenna with an ultra-compact size (5 × 5 × 0.26 mm3) was designed with 29% wide bandwidth (about 670 MHz). This wide bandwidth makes the antenna unaffected by implantation in different human body parts. The miniaturization process passed many steps by adding many slots with different shapes in the radiating element as well as in the ground plane. A 50 Ω coaxial feeding excites the antenna to maintain matching and low power loss. The specific absorption rate (SAR) was calculated for health considerations. The result was within the standard limits of IEEE organizations and the International Commission on Non-Ionizing Radiation Protection (ICNRP). The antenna was tested in tissues with multiple layers (up to seven layers) and at various depths (up to 29 mm). The link margin was calculated, and the proposed antenna enables 100 Kbps of data to be transferred over a distance of 20 m and approximately 1 Mbps over a distance of 7 m. The proposed antenna was fabricated and tested. The measured S11 parameters and the simulated results using the Computer Simulation Technology (CST Studio) simulator were in good agreement.

Antenna Array Performance in Microwave Imaging Technique for Brain Tumor Detection

Recent advancements in microwave tomography (MT) imaging studies have stimulated interest in antenna array development for medical imaging. An antenna and a model of the human head are required for the medical MT system, particularly in detecting brain tumors. Previous studies have shown that antenna arrays are more reliable as compared to a single element of patch antenna in detecting brain tumors. In this study, a single patch antenna is first designed to work at 3.2GHz using CST Studio software. To evaluate the effectiveness of antenna arrays in microwave imaging systems, the patch antenna is then improved into a 2x1 and 4x1 array. The gain, directivity, return loss (S11), Voltage Standing Wave Ratio (VSWR), and bandwidth are compared between single and arrays of antenna models. It has been proved that 2x1 and 4x1 antenna arrays resulted in higher performance. With a maximum gain of 7.11 dB, the 4x1 rectangle patch antenna has 11.3 dBi directivity, -13.88 dB return loss, and 91.1 MHz bandwidth, meanwhile single patch antenna has a gain of 3.34 dB, 5.68 dBi directivity, - 17.33 dB return loss, and 132 MHz bandwidth. Overall, a 4x1 patch antenna is made reliable and sensitive to be used in detecting brain tumors as higher gain and directivity may be useful to penetrate multilayer human head.

A novel frequency reconfigurable antenna for smart grid applications in TV white space band

<span>This paper presents the design and analysis of a frequency reconfigurable, aperture coupled rectangular patch antenna for use in smart grid applications in TV white space bands. The proposed antenna model has been realized on multi-substrate layers of Polylactic acid (PLA) material (</span><em><span>εr</span></em><span>=2.65, </span><em><span>tanδ</span></em><span>=0.003) with a ground plane sandwiched in between them. An aperture has been made in the ground plane for coupling energy to the patch. The overall system dimensions are 270×270 mm. The feature of frequency reconfigurability has been achieved by incorporating a switch and varying the reactance of the feed line on the bottom substrate. A rectangular slot on the long feed line improves impedance matching. The ON and OFF states of the switch provide two operating frequency bands namely 630.13 to 636.7 MHz and 619.16 to 625.3 MHz respectively. The proposed aperture coupled reconfigurable system operates with a maximum gain of 6.4 dB and average efficiency of 78.5% in both bands. The measured results are satisfactory and the proposed antenna will be suitable for operation in the smart grid environment.</span>

Connectivity Improvement of Hybrid Millimeter Wave and Microwave Vehicular Networks

The network connectivity while traveling in a vehicle is an important issue, which needs to be addressed by mobile vehicular networks. This paper proposes a novel scheme to improve the connectivity of mobile vehicular networks. In particular, the paper proposes a medium access control (MAC) layer hybrid mmWave and microwave scheme for vehicular networks, and leverage their capabilities to improve the vehicle’s connectivity. The novel computational model is derived to evaluate the connectivity for the proposed scheme. The model is used for performance analysis of vehicles moving on a multi-lane highway road and getting connectivity with road-side-units (RSUs) deployed along the roads. Our analysis considers that reference VN has perfect channel state information. It is assumed that the RSU radiates ubiquitously on the road surface using microwave radio access technology (RAT), while it radiates directionally towards reference VN using mmWave RAT. For mathematical analysis, the directionality in mmWave RAT is well approximated by a sectored antenna model. The analysis for the proposed scheme is compared with the existing mmWave network and packet data convergence protocol (PDCP) layer hybrid scheme. The analysis claims that the proposed hybrid scheme significantly improves the connectivity performance in mobile vehicular networks over the existing schemes. The computation results are validated with the simulation results. Also, the paper offers parametric analysis for connectivity probability with vehicle speed and slot duration to enable its practical implementation in 5G/6G technologies.

Metamaterial inspired square gap defected ground structured wideband dielectric resonator antenna for microwave applications

A metamaterial inspired dielectric resonator antenna (DRA) with square gap defected ground structure is proposed in the present work. Antenna has wideband characteristics with coverage of several commercial communication applications of Wi-Fi, WLAN, and satellite communications from 3.5 to 11.6 GHz. The metamaterial behavior of the proposed structure providing good impedance characteristics with peak realized gain of 7.7 dB and peak efficiency of 87% with dual band circular polarization from 4.2 to 6 GHz and 9.2–11.4 GHz respectively. The prototyped antenna model 1 without DRA providing good matching characteristics results and producing huge bandwidth of 8.1 GHz and the impedance bandwidth of 108%. DRA loaded antenna providing dual band circular polarization with axial ratio bandwidths of 36% and 28% respectively for wide range in the microwave communication applications.

The study of the radiating module of the energy management system of buildings

Purpose. Improving the toolkit of interaction between sensors and the building control system using a triangular microstrip antenna. Methodology. Mathematical modeling by the method of finite differences in the time domain. Findings. The proposed technical solution consists in choosing the optimal design of the radiating module in the form of a triangular microstrip antenna, by means of mathematical modeling, the values of the geometric dimensions of the triangle, the thickness of the dielectric layer and the value of its dielectric constant, the overall dimensions of the radiating module, which ensure optimal coordination of the antenna with the power feeder in the form of a microstrip line. The developed computer model of the triangular microstrip antenna using the finite-difference method in the time domain allows conducting research on the parameters of this antenna that provide stable wireless communication between the system of sensors and the home automation control unit. The condition for increasing the degree of matching the impedance of the antenna and the supply line is the choice of the method of powering the antenna. It was established that the most optimal way of feeding a triangular antenna is the method of connecting the microstrip line to the middle of the side of the triangle, compared to the way of connecting the power line to the top of the triangle. The width of the microstrip power line was optimized according to the criterion of minimizing the module of the reflection coefficient at the antenna input. A study of the degree of matching the impedance of the antenna at operating frequencies of 2,4 and 7 GHz was carried out. At a frequency of 7 GHz, the magnitude of the reflection coefficient module is -23,6776 dB. The three-dimensional and two-dimensional radiation patterns of this antenna are calculated. The radiation pattern has an almost spherical shape, that is, it allows placing the radiating module in any orientation relative to the earth's surface. This allows the triangular microstrip antenna to be used as a radiating module of the building energy management system and the smart home system. Originality. The study of the ways of feeding the triangular microstrip antenna allows to find the optimal coupling of the antenna with the power line, which ensures the formation of radiation characteristics that ensure effective interaction between the sensors and the building's energy management control system. Practical value. The radiation characteristics of a triangular microstrip antenna obtained as a result of the study make it possible to use it to organize a wireless communication channel in a 4% operating frequency band.

A distributed active patch antenna model of a Josephson oscillator.

Optimization of Josephson oscillators requires a quantitative understanding of their microwave properties. A Josephson junction has a geometry similar to a microstrip patch antenna. However, it is biased by a dc current distributed over the whole area of the junction. The oscillating electric field is generated internally via the ac-Josephson effect. In this work, I present a distributed, active patch antenna model of a Josephson oscillator. It takes into account the internal Josephson electrodynamics and allows for the determination of the effective input resistance, which couples the Josephson current to cavity modes in the transmission line formed by the junction. The model provides full characterization of Josephson oscillators and explains the origin of the low radiative power efficiency. Finally, I discuss the design of an optimized Josephson patch oscillator capable of reaching high efficiency and radiation power for emission into free space.

OAM mode purity improvement based on antenna array

Orbital Angular Momentum (OAM) waves are characterized by helical wave fronts and orthogonality between different modes. Therefore, OAM waves have huge potential in improving wireless communications' channel capacity and radar imaging's resolution. Consequently, the generation and application of OAM waves have attracted a lot of attention. And many methods are proposed to generate OAM waves. Although antenna array is the most popular method of generating OAM waves, OAM waves generated by antenna array have redundant modes. However, all advantages of OAM waves are closely related to infinite OAM modes. Thus, to better apply OAM waves to wireless communications and radar, it is very important to reduce unnecessary OAM modes and improve the OAM mode purity. In order to improve the OAM mode purity, two combined antenna arrays composed of X direction antenna and Y direction antenna array are proposed in this paper. The X direction antenna array and the Y direction antenna array are supplied by the excitations with the same amplitude and fixed phase shift. The overall phase shift of the X direction antenna array is π/2 more or less than that of the Y direction antenna array. The results of formulas and antenna models in CST show that the combined antenna arrays can generate OAM waves with less redundant modes in x component, y component and z component. Besides, the z component carries pure OAM modes.

MeterGPX: A Smart Multimeter Embedded with Multigene Genetic Programming Model for Multiarray Antenna Transmitter

Genetic programming (GP) is an evolutionary algorithm used to produce high-quality solutions to various problems. It has seen few claims in circuitry and the development of antenna designs. The application of GP in the model of embedded digital systems on multi-channel antenna arrays of subsurface imaging equipment has not yet been investigated. This study focuses on designing and developing a digital multimeter embedded with a multigene genetic programming (MGGP) model for multi-array transmitter antenna used for subsurface imaging operating at a low frequency of 3.5 kHz to 18.5 kHz using Arduino microcontroller for prototyping. The electrical outputs of a transmitter antenna system employed in a subsurface imaging device require live measurement and monitoring during operation for data logging purposes. The amount of transmitted voltage, produced current, and operating frequency are significant parameters for mapping the underground resistivity, thus the produced GP models are functions of the three parameters. GP fitness function was determined through MATLAB software. The output current signal from the transmitter were imitated in Proteus simulation software using a current source in the designed current measuring circuit. This produced linear and nonlinear relationships of the electrical outputs where GP modeling was beneficially applied. The application of GP in with the microcontroller provided an accurate reading of frequency, current and voltage produced by the multi-array transmitter antenna. These measurements were displayed using LM016L LCD display. Moreover, this embedded digital multimeter on transmitter antenna avoids utilizing costly high voltage measuring devices.

Correction to: Terahertz Micro-Strip Patch Antenna Design and Modelling for 6G Mobile Communication

Correction to: Terahertz Micro-Strip Patch Antenna Design and Modelling for 6G Mobile Communication

Numerical Modeling and Computer Simulation of a Meander Line Antenna for Alzheimer's Disease Treatment, a Feasibility Study.

Alzheimer's disease (AD) is a brain disorder that eventually causes memory loss and the ability to perform simple cognitive functions; research efforts within pharmaceuticals and other medical treatments have minimal impact on the disease. Our preliminary biological studies showed that Repeated Electromagnetic Field Stimulation (REFMS) applying an EM frequency of 64 MHz and a specific absorption rate (SAR) of 0.4 - 0.9 W/kg decrease the level of amyloid-β peptides (Aβ), which is the most likely etiology of AD. This study emphasizes uniform E/H field and SAR distribution with adequate penetration depth penetration through multiple human head layers driven with low input power for safety treatments. In this work, we performed numerical modeling and computer simulations of a portable Meander Line antenna (MLA) to achieve the required EMF parameters to treat AD. The MLA device features a low cost, small size, wide bandwidth, and the ability to integrate into a portable system. This study utilized a High-Frequency Simulation System (HFSS) in the design of the MLA with the desired characteristics suited for AD treatment in humans. The team designed a 24-turn antenna with a 60 cm length and 25 cm width and achieved the required resonant frequency of 64 MHz. Here we used two numerical human head phantoms to test the antenna, the MIDA and spherical head phantom with six and seven tissue layers, respectively. The antenna was fed from a 50-Watt input source to obtain the SAR of 0.6 W/kg requirement in the center of the simulated brain tissue layer. We found that the E/H field and SAR distribution produced was not homogeneous; there were areas of high SAR values close to the antenna transmitter, also areas of low SAR value far away from the antenna. This paper details the antenna parameters, the scattering parameters response, the efficiency response, and the E and H field distribution; we presented the computer simulation results and discussed future work for a practical model.

Влияние неоднородной теплозащиты на характеристики излучения антенны космического аппарата

Introduction: Knowledge of the electrical characteristics of the onboard antenna on the trajectory of the descent of the spacecraft makes it possible to assess the presence or absence of radio communication. Under conditions of aerodynamic heating, the thermal protection of the onboard antenna heats up unevenly in thickness and becomes electrically inhomogeneous. Purpose of the work: Determination of the radio technical characteristics of the onboard antennas of the returning spacecraft with the effect of high-temperature heating on the thermal protection of the antenna based on calculations using the developed mathematical model of the antenna with thermal protection. Methods: Expressions for the structure of the radiation field of a rectangular waveguide under the above conditions were derived by the WKB method. Of the well-known analytical methods of solution, it is possible to use the method of integral transformations and the method of eigenfunctions. Both of these methods were used in this work. Results: The obtained theoretical results are new, they allow predicting the radio technical characteristics of the onboard antenna, taking into account uneven heating across the thickness of the thermal protection at low temperature gradients. A mathematical model of the spacecraft's onboard antenna on the descent trajectory has been developed, taking into account the inhomogeneity of thermal protection under conditions of aerodynamic heating. Practical significance: The development of a mathematical model of the main radio technical characteristics of onboard antennas, taking into account the impact of high-temperature aerodynamic heating, as well as the results of numerical calculations, can be applied in the development of recommendations for choosing thermal protection and recommendations for reducing the effect of temperature changes in the electrical parameters of thermal protection on the characteristics of onboard antennas and reducing time loss of radio communication or loss recovery.

Circuit-Level Modeling and Simulation of Wireless Sensing and Energy Harvesting With Hybrid Magnetoelectric Antennas for Implantable Neural Devices.

A magnetoelectric antenna (ME) can exhibit the dual capabilities of wireless energy harvesting and sensing at different frequencies. In this article, a behavioral circuit model for hybrid ME antennas is described to emulate the radio frequency (RF) energy harvesting and sensing operations during circuit simulations. The ME antenna of this work is interfaced with a CMOS energy harvester chip towards the goal of developing a wireless communication link for fully integrated implantable devices. One role of the integrated system is to receive pulse-modulated power from a nearby transmitter, and another role is to sense and transmit low-magnitude neural signals. The measurements reported in this paper are the first results that demonstrate simultaneous low-frequency wireless magnetic sensing and high-frequency wireless energy harvesting at two different frequencies with one dual-mode ME antenna. The proposed behavioral ME antenna model can be utilized during design optimizations of energy harvesting circuits. Measurements were performed to validate the wireless power transfer link with an ME antenna having a 2.57 GHz resonance frequency connected to an energy harvester chip designed in 65nm CMOS technology. Furthermore, this dual-mode ME antenna enables concurrent sensing using a carrier signal with a frequency that matches the second 63.63 MHz resonance mode. A wireless test platform has been developed for evaluation of ME antennas as a tool for neural implant design, and this prototype system was utilized to provide first experimental results with the transmission of magnetically modulated action potential waveforms.

MULTIFREQUENCY STACKED PATCH ANTENNA ANALYSIS

In this paper, the theoretical and simulated results of a quad-band patch antenna without any air/foam gap between the dielectric layers are discussed. The design idea uses a skated dielectric layers to achieve a multi-frequency operation. The antenna under study includes four patches patterned on the top of layered dielectric substrates and is stacked vertically. Two pairs of spaced slits are embedded at the patch's radiation edges of the bottom and second patches to adjust the resonant frequencies. The resonant frequencies of the different patches are obtained at 4 GHz, 5 GHz, 6 GHz, and 7 GHz. According to the cavity theory and equivalent circuit approach, a theoretical model of the multilayer stacked patch antenna (MLSPA) is determined. Theoretical and simulated return loss plot is presented to validate the proposed design. The antenna parameters such as radiation pattern, gain, voltage standing wave ratio (VSWR), and beam-width are also discussed. Good impedance matching and radiation characteristics at the four operating bands make this antenna a good candidate for many applications. The antenna simulations are performed using a high frequency structure simulator (HFSS) 15.0 tool.

Approximation of the solution of an internal problem of electrodynamics by the method of eigenfunctions

The problem of constructing approximation models of radiating and reradiating structures based on the eigenfunction method is considered. The ambiguity of the solution of this problem is noticed. Techniques are proposed which can be used in developing approximation models. An expression is presented for estimating the error introduced by the approximation model. As an example, one of the possible options for constructing an approximation model for a tubular antenna is given. The results of numerical simulation are presented. Keywords: method of eigenfunctions, method of moments, singular integral equations, approximation model, tubular antenna.