Radiation Characteristics Of Antenna Research Articles

Dual nanocomposite materials that enhance the radiation characteristics of flexible circular antenna

A novel dual nanocomposite filled circular shaped flexible slot antenna is introduced for WLAN/WiMAX/5G/Wi-Fi applications. The circular radiating patch is given two slots that are filled with nanocomposite materials PANI/CCo and PDMS/AgNW, which enhances antenna radiation properties in both lower and upper band independently. The antenna is fabricated deploying a coplanar waveguide (CPW) fed system that encompasses a patch featuring a circular shape and CPW ground combined with a circular ring shape. The dual band is formed by introducing a narrow rectangular slot on the circular radiating patch and is designed for a mid-frequency 3.85 GHz, of two resonance frequencies. Different bending radii are used to evaluate antenna flexibility, and findings are in good match for a flat antenna. With good radiating qualities over the whole dual band, the suggested fabricated antenna covers the 2.4/5.2/5.8 GHz WLAN, 2.5/5.5 GHz WiMAX, 2.3/2.6 GHz 5G, 2.4/4.9/5.2/5.5/5.8 GHz Wi-Fi, and 5G SUB 6 GHz bands.

Parametric study of a dual-band quasi-Yagi antenna for LTE application

Due to small size and lightweight properties, the development of microstrip (MS) patch antennas for wireless communication has become one of the mobile application devices in demand in recent years. This has helped to reduce reliance on wired cables. In this paper, a study has been performed on MS antenna by developing a quasi-Yagi structure on a fire retardant-4 (FR-4) substrate with a MS to coplanar strip line (CPS) transition feeding technique. The antenna is designed by using computer simulation technology (CST) to achieve the desired resonant frequency and bandwidth. The proposed dual band quasi-Yagi antenna has impedance bandwidths of approximately 0.3 GHz and 0.22 GHz resonating at 1.80 GHz and 2.60 GHz, respectively, which makes it suitable for long-term evolution (LTE) applications. Eight-director elements in four pairs are constructed to achieve directivity with magnitudes of 6 dB and 8.3 dBi at both resonant frequencies, 1.80 GHz and 2.60 GHz, respectively. Different parametric studies have also been performed to characterize the antenna radiation characteristics. The return loss, voltage standing wave ratio (VSWR), front to back (F/B) ratio and far-field radiation are analyzed and discussed.

Development and Research of a Medium Vertical Dipole Electromagnetic Pulse Simulator

In this paper, the design of a self-developed EMP simulator with a 5 m height and an inverted conducting mono-cone antenna with a cone half-angle of 32° is introduced. The experimental region of the simulator is a circular area of 25 m in diameter around the cone vertex. Two feeding modes, feed-in over the ground and feed-in under the ground, are realized by two different high-voltage pulse sources. It can be concluded through radiation field testing that the radiation field waveform generated by the simulator has a rise time of 2–3 ns and a half-width of about 25 ns, meeting the specifications of the EMP experimental waveform in the IEC61000-2-9 standard. Meanwhile, the differences between the engineering implementation of the simulator and its ideal structure during the design process can lead to some distortion issues in the antenna radiation characteristics and the electromagnetic radiation field it generates. The radiation field waveform and the distribution of the EMP field generated by the simulator under different feeding methods, antenna wire quantities, antenna end processing methods, and different antenna resistive loading were studied, and the changes in the radiation field waveform and field distribution with different angles and distances of the monitoring point were analyzed. Based on the measurement results, the radiation characteristics of the antenna and the factors that affect the waveform of the field were studied and analyzed. Through the aforementioned work, a comprehensive understanding of the performance, radiation characteristics, and engineering factors affecting the electromagnetic environment generated by the simulator has been obtained. On this basis, the parameters of the antenna wire quantity, antenna end processing method, and test point position of the designed simulator were reconfirmed and optimized. In summary, this work has important reference significance for mastering the development technology of such simulators, understanding their antenna radiation characteristics, and conducting EMP-related assessments and effect experiments in the future.

A reconfigurable graphene patch antenna inverse design at terahertz frequencies

This article investigates the inverse design of a reconfigurable multi-band patch antenna based on graphene for terahertz applications to operate frequency range (2–5THz). In the first step, this article evaluates the dependence of the antenna radiation characteristics on its geometric parameters and the graphene properties. The simulation results show that it is possible to achieve up to 8.8 dB gain, 13 frequency bands, and 360^circ beam steering. Then and due to the complexity of the design of graphene antenna, a deep neural network (DNN) is used to predict the antenna parameters by given inputs like desired realized gain, main lobe direction, half power beam width, and return loss in each resonance frequency. The trained DNN model predicts almost with 93% accuracy and 3% mean square error in the shortest time. Then, this network was used to design five-band and three-band antennas, and it has been shown that the desired antenna parameters are achieved with negligible errors. Therefore, the proposed antenna finds many potential applications in the THz frequency band.

Practical approach of measuring of angular bearing errors for radiotransparent radomes with complex shape in the “antenna – radome” system in the entire possible scanning ar-ea of the airborne radar antenna system

A nose radiotransparent radome (RTR) plays the role of a dielectric lens of a complex shape, which can significantly affect the radiation characteristics of the airborne radar antenna of an aircraft located under it. Modern radars, as a rule, are built on the basis of antenna systems with electronic beam control – phased antenna arrays. The phasing of the array is carried out in the most different (available for a given phased array) spatial directions. One of the parameters that define the operation of the radar under the RTR is the error in determining the angular position of the targets found by the radar. With complex forms (with one plane of symmetry) of the nose RTR, the resulting angular bearing errors (ABE) depend significantly on the spatial position in which the radar antenna is currently phased. In some cases, bearing errors must be taken into account when operating the radar. This becomes especially important in direction finding and tracking of targets remote to the limit for radar aircraft. In this case, the data on the values of the ABE depending on the current coordinates of the array phasing become relevant. The aim of the article is to present a simple technique that makes it possible to practically measure the ABE in the system “antenna – RTR” in a significant area of electronic scanning by the antenna beam. The technique for measuring the ABE has been developed, which was tested on the basis of an antenna-measuring collimator complex (“compact test site”). Mathematical expressions have been given for calculating both components of ABE (in the phased antenna array angular coordinate system) based on the measured data. At the initial stage, the technique has been tested on the basis of a specially made quick-detachable model-simulator of the radome, which has the ability to introduce arbitrary ABE. With the help of this model, a comparison of the results of measurements obtained on the basis of the proposed method and the method associated with the measurement of dynamic spatial radiation patterns (RP) has been performed. A good correlation of data has been noted for different methods, but on one physical model-simulator of the RTR, which allows us to speak about the correctness of the chosen approach. Subsequently, the correctness of the proposed method has been confirmed by the data collected when working with the system “phased antenna array – RTR” (teardrop shape). In this case, the calculated components of the ABE have been compared with the results of direct measurements by the difference method, when each of the orthogonal components is calculated by measuring the angle of displacement of the minimum of the corresponding difference pattern, obtained before and after the installation of the RTR. The developed technique of preliminary measurement of angular bearing errors over a significant part of the surface of a real RTR makes it possible, if necessary, to compensate the measured ABE in aircraft radar computers, thereby increasing the accuracy of determining the spatial coordinates of targets in space.

Design of Frequency-Reconfigurable Antenna on Dielectric and Magnetic Metamaterial Composite Substrate

Reconfigurable planar antennas are essential in multifunctional wireless communication devices. This letter presents the design of a frequency-reconfigurable patch antenna printed on a composite substrate made of a dielectric and a magnetic metamaterial (MMM). The MMM comprises magnetized ferrite slabs with embedded split-ring resonators (SRR). The constructive coupling between the resonances of the magnetized ferrites and SRR is optimized to achieve promising reconfigurable properties. The proposed frequency-reconfigurable antenna demonstrates a 158% increase in the frequency tuning range. Furthermore, the simulated results are experimentally verified, and the composite substrate shows slight effects on the antenna radiation characteristics.

High-Efficiency Diagnosis of Antenna Radiation Characteristics Based on Scanning Optic-Induced Plasma Scattering Technology

This article presents an innovative quasi-real-time antenna near-field diagnosis method, by scanning a laser-induced plasma on a silicon wafer and imaging the field with the synchronously produced scattered signals. Several approaches have been devised to adapt to the antenna diagnosis scenarios. By using the multilayer matching approach, the issue of multiple reflection disturbance between the aperture and silicon wafer is avoided, especially for large aperture antennae at high frequencies. The accuracy of near-field distribution is improved, and far-field patterns can be transformed directly. The experimental results of a Ka-band 20 dB standard antenna agree well with the simulation results. Diagnosis of radiation states in the reactive near-field region is demonstrated, and the resonate modes of a 2.4 GHz Wi-Fi patch antenna at different frequencies are clearly observed. The experiments of a TM01 mode antenna verify the full polarization diagnosis ability of the method, and the linear polarization component is measured with the help of a polarization grid. The demonstrated diagnosis method has the advantages of high efficiency, ultraclose measurement distance, and superresolution and provides a highly promising and widely available method for antenna diagnosis.

A Novel Compact Ultra-Wideband Frequency-Selective Surface-Based Antenna for Gain Enhancement Applications

This article presents a compact ultra-wideband (UWB) circular monopole antenna with a frequency-selective surface (FSS) for gain enhancement. The proposed antenna has a circular patch with circular cuts at the edges and is excited by a microstrip feed. The bottom plane is truncated and further modified by two triangular cuts at the sides and one rectangular cut in the middle to improve the radiation characteristics of the UWB antenna. The antenna is designed on an FR-4 substrate with a thickness of 1.6 mm, a relative permittivity of 4.3, and planner dimensions of 30 mm × 30 mm. To improve the proposed antenna’s gain, an FSS is designed that consists of periodic unit cells of metal printed on the upper layer of an FR-4 substrate with dimensions of 0.11λ × 0.11λ at the lowest operating frequency of 3.3 GHz. The FSS shows a very low transmission coefficient and linearly reducing reflection phase with increasing frequency over a frequency range of 3.3–10.8 GHz. The gain of the proposed antenna is increased from 3 dB to 8.1 dB at 9 GHz by placing the antenna on the FSS. Moreover, the prototype of the proposed antenna is fabricated, and the experimental results are measured, which show close agreements with simulated results. The FSS-based antenna has directional radiation patterns, making it a potential candidate for ground-penetrating radar and UWB applications.

A Novel Compact Filtering Antenna for 5.0-GHz WLAN Communication System

The proposed antenna presents a microstrip filter antenna with both filter out-of-band rejection characteristics and antenna radiation characteristics for WLAN communication system. The antenna consists of four U-shaped microstrip resonators, one Γ-shaped antenna, and one parallel coupling line. The Γ-shaped antenna has the filtering function as the last order resonator, and the parallel coupling line integrates the filter and antenna as the conductance converter. After simulation and test, the results show that the center frequency of the filter antenna is 5.25 GHz, the fractional bandwidthis 8.0% (5.0 − 5.42 GHz), the in-band gain changes smoothly, the maximum in-band gain is 3.059 dBi, the gain at 150 MHz outside the passband rapidly decreases to 10.0 dBi, and the overall out-of-band gain drops to below −24 dBi. The filter antenna has a simple structure and thin substrate, which optimizes the overall size of the filter and antenna, reduces the transmission loss between them, and is applicable to the RF front-end of wireless communication systems.

A Miniaturized Dual-Band Short-Ended ZOR Antenna with Backed Ground Plane for Improved Bandwidth and Radiation Efficiency

This paper presents a miniaturized planar dual-band short-ended metamaterial antenna with the backed ground plane to improve antenna bandwidths and radiation characteristics. The proposed dual-band metamaterial (MTM) antenna has been made up of the composite right- or left-handed transmission line (CRLH-TL) concept. Here, the backed ground plane has been employed to generate an extra coupling capacitance (CC), which shifts the ZOR frequency in the lower band while also improving ZOR matching and increasing the impedance bandwidth of the higher-order mode. In this proposed MTM antenna, interdigital capacitance (IDC) has been used in place of a simple series gap, which shifts the higher-order impedance bandwidth into a lower frequency band for second-band Wi-MAX applications (3.3–3.7 GHz). The proposed antenna offers a short-ended MTM, and hence the ZOR frequency is controlled by a series of LC lumped parameters. The proposed antenna offers dual-band behavior with measured −10 dB impedance bandwidths of 5.55% and 41.57% at centered frequencies of 2.70 GHz and 4.33 GHz, respectively. The overall electrical size of the designed antenna is 0.225λ0 × 0.144λ0 × 0.0144λ0 at ZOR (f0 = 2.70 GHz), where λ0 is the free space wavelength; therefore, it is applicable for different Wi-MAX application bands (2.5–2.7 GHz/3.3–3.8 GHz). Furthermore, the proposed dual-band MTM antenna provides compactness, low loss, stable gain, and radiation efficiency, and also offers omnidirectional radiation patterns in the E-plane and dipolar type radiation patterns in the H-plane, respectively.

A triband EBG loaded microstrip fractal antenna for THz application

Future wireless communication needs antenna with multifunctional operation. This paper focuses on Terahertz Antenna that could be easily integrated with micro and nano devices. In this paper, an octagonal shaped Microstrip Fractal Antenna loaded with the EBG structure is designed for tri-band terahertz application. Triple band characteristic achieved by fractal radiating patch is loaded with Electronic Band Gap (EBG). The antenna is working on triple band characteristics at 948 GHz, 984GHz and, 1040 GHz with overall dimensions of 700x900 µm2. The result and performance show that the recommended antenna will be compatible with compact wireless devices and Monolithic Microwave Integrated Circuit (MMIC). All simulation work has been done using electromagnetic software Ansoft High Frequency Structure Simulator (HFSS) and CST studio suite. The electromagnetic features like S11 parameters, VSWR, gain, efficiency and the radiation characteristics of such antenna are also explored. The simulation results show that this antenna has 9 dB realized gain at 0.948 THz resonating frequency.

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.

ИССЛЕДОВАНИЕ ХАРАКТЕРИСТИК РАЗВЕРТЫВАЕМОЙ КОСМИЧЕСКОЙ ЗЕРКАЛЬНОЙ АНТЕННЫ С РАЗРЕЖЕННОЙ ОТРАЖАЮЩЕЙ ПОВЕРХНОСТЬЮ

The article presents the results of a study of the characteristics of a space parabolic mirror with a deployable reflector. A model of the reflector truss structure formed by two asymmetric parabolic networks with tension cables is presented. Three variants of the sparse structure of the reflecting film of the reflector are presented, differing in periodically repeating hexagonal holes with different sizes. A complex electrodynamic modeling of the radiation characteristics of a parabolic mirror antenna with a developed model of a truss-bearing structure and the proposed structures of reflective films, allowing to reduce the mass of the reflector and increase the reliability of the antenna system, are carried out. The estimation of the frequency dependences of the characteristics of the variants of the parabolic mirror antenna model is given. Recommendations on the use of sparse reflective films for small, medium and large apertures of deployable reflectors are proposed.

Optimized multibeam synthesis of time-modulated microstrip arrays

The capability to form the main beam of antennas improves the energy efficiency of wireless systems and enhances radar systems' effectiveness in detecting and tracking objects. The time-modulated array can generate multibeam with arbitrary directions in different spectral parts. This work synthesizes several linear arrays to achieve particular main beams and additional restrictions. We modify the pulse durations and the switch-on instants of the switches in each antenna element in an optimization procedure. The parameters are varied through the simulated annealing by minimizing certain cost functions. We designed three linear arrays: model 1 consists of six elements and has two beams. Model 2 is the improved version of model 1 by rejecting the sidelobes of other spectral contributions at the main beam under consideration. Model 3 consists of sixteen elements and has three different beams. The analytical results were verified by modeling the arrays in the form of microstrip arrays in a numerical simulation with HFSS. We obtained very accurate verification. Distinctive devitations at the region ϑ<-60<sup>o</sup> and ϑ>60<sup>o</sup> originate from the radiation characteristics of microstrip antennas, which focus the energy upwards to the region around ϑ=0<sup>o</sup>.<br /><br />

Low-profile high gain circularly polarized CRLH transmission line inspired antenna with artificial magnetic conductor for wearable applications

AbstractIn this work, a compact, wideband, circularly polarized wearable antenna is proposed using asymmetric coplanar strip feeding for wireless health monitor applications in the ISM frequency band. The proposed antenna consists of a composite right/left transmission line (CRLH TL) inspired structure to achieve compactness and a rectangular ring slot is created in the metallic ground to enhance the CP radiation of the antenna. A 5 × 5 artificial magnetic conductor unit cell-based metasurface is designed which is operating at 2.4 GHz as a ground plane for the CRLH-based CP antenna. Implementation of AMC-based metasurface as a ground plane results in enhancement of radiation characteristics of CRLH TL antenna. The proposed antenna has a small footprint of 50 × 50 mm2 with measured impedance bandwidth of 2.3–3.2 GHz. The 3 dB axial ratio bandwidth of the proposed antenna is 2.36–2.78 GHz with peak gain of 5.89 dBi. Simulation and experimental results show that proposed AMC-based antenna is robust in terms of structural deformation. Further, to validate the performance of the antenna for biomedical applications, we have simulated the proposed antenna with human phantom model. The proposed antenna exhibits stable scattering and radiation characteristics with the phantom body environment and due to the inclusion of AMC structure, the proposed design satisfies maximum specific absorption rate value given as per the IEEE standard safety guidelines.

Design Analysis of 5G Microstrip Antenna

5G communication network has three distinct characteristics, although not limited to; enhanced network coverage, low latency and massive device connectivity. 5G mobile system has broad spectrum to support high data rates. Such device must deploy corresponding radiating structures to meet the changing technological advancement. In this paper therefore, a microstrip patch antenna operating at 3.6GHz frequency is designed and simulated for 5G application. The choice of frequency of operation is influenced by the broad prospects for 5G. The substrate is the flame resistant four (FR4) with a dielectric constant of 4.6 and a loss tangent of 0.023. The results include; plots of the voltage standing wave ratio, radiation pattern, return loss and radiation efficiency. The result further showed that, the parameters influencing the radiation characteristics of the patch antenna are the relative permittivity of the dielectric material, the position of the slot on the patch, the ground plane, substrate type as well as the dimensions of the feed and patch. The microstrip antenna thus can be effectively deployed for 5G application.

Reduced-Size Series-Fed Two-Dipole Endfire Antenna

The conventional series-fed endfire dipole antenna has a wide impedance bandwidth and is inexpensive to manufacture. However, it has a disadvantage: its size is large because of the large inter-dipole spacing, which is required to satisfy the endfire condition for good antenna radiation characteristics. Here, we propose a two-dipole endfire antenna with a reduced size. The miniaturized endfire antenna was designed using a meander line to reduce the interdipole spacing while ensuring that the endfire condition was satisfied. Furthermore, the overall width of the antenna was reduced using a bent dipole and a corrugated ground plane. The electrical size of the proposed antenna was only 0.33

Reconfigurable Radiation Angle Continuous Deflection of All-Dielectric Phase-Change V-Shaped Antenna.

All-dielectric optical antenna with multiple Mie modes and lower inherent ohmic loss can achieve high efficiency of light manipulation. However, the silicon-based optical antenna is not reconfigurable for specific scenarios. The refractive index of optical phase-change materials can be reconfigured under stimulus, and this singular behavior makes it a good candidate for making reconfigurable passive optical devices. Here, the optical radiation characteristics of the V-shaped phase-change antenna are investigated theoretically. The results show that with increasing crystallinity, the maximum radiation direction of the V-shaped phase-change antenna can be continuously deflected by 90°. The exact multipole decomposition analysis reveals that the modulus and interference phase difference of the main multipole moments change with the crystallinity, resulting in a continuous deflection of the maximum radiation direction. Thus, the power ratio in the two vertical radiation directions can be monotonically reversed from −12 to 7 dB between 20% and 80% crystallinity. The V-shaped phase-change antenna exhibits the potential to act as the basic structural unit to construct a reconfigurable passive spatial angular power splitter or wavelength multiplexer. The mechanism analysis of radiation directivity involving the modulus and interference phase difference of the multipole moments will provide a reference for the design and optimization of the phase-change antenna.

Directive properties of radiating source systems in massive electromagnetism

We investigate the problem of electromagnetic radiation in massive electromagnetism with focus on the directive radiation characteristics of Proca antennas (sources embedded into Proca metamaterial domains.) It is theoretically demonstrated that the recently proposed nonlocal Proca metamaterial implies the existence of point nonlocal sources possessing a perfectly isotropic radiation pattern. Based on rigorous analysis, we derive exact expressions for the directive radiation patterns of arbitrary discrete distributions of Proca source systems, i.e., radiating arrays emitting massive photons. Examples of linear discrete Proca arrays are given and comparison with massless photon radiation sources is provided.

Side lobe level reduction of metasurface transmit array

This paper presents a study on the side-lobe level (SLL) reduction with transmission type metasurface (MTS) using the concept of non-uniform array technique and transmit array antenna. According to the non-uniform antenna array technique, the SLL can be controlled by controlling the amplitude and phase distribution simultaneously. Initially, transmit array concept is used to design the MTS. The radiation characteristics of the MTS antenna are analyzed by exciting with a rectangular patch antenna at a fixed feed position. The simulation results show a gain of 17.6 dB with SLL of −18.3 and −19 dB in ϕ = 0° and 90°-planes, respectively. Later, non-uniform array techniques are used to reduce the SLL by introducing various amplitude distribution functions on the MTS for a fixed focal distance. The MTS incorporates the amplitude tapering functions such as Kaiser, Hamming, Hanning, and Blackman distribution functions. The resulting SLLs are analyzed, and the achieved SLLs are far from the theoretical values. In order to further reduce and control the SLL, the Gaussian distribution function is used, which minimizes the SLL by optimizing the standard deviation(σ). A MTS with 16 × 16 unitcells is fabricated and measured with an optimized σ = 0.31. The measured SLL are −25.1 and −26.3 dB in ϕ = 0° and 90°-planes, respectively.