Antenna Array Pattern Research Articles

Искажения диаграмм направленности фазированных антенных решеток под влиянием периодических и флуктуационных помех.

Issues related to determination of distortions of directional patterns of phased antenna arrays under the influence of periodic and fluctuating multiplicative (modulating) noise are in the focus of the paper. Expressions are obtained for instantaneous directional patterns in terms of voltage and power, as well as the average value of the directional pattern in terms of voltage under the influence of periodic multiplicative noise. So far, since the phase ratios in these instantaneous diagrams change over time, the pattern of the grating fluctuates. The condition is defined under which the structure of the grating pattern «crumbles». At the same time, lower frequencies of acting multiplicative noise lead to distortion of the diagram: its main maximum expands, the level of side lobes increases and lateral reception directions are «smoothed». It is noted that in synthesized arrays, «scattering» of the directional pattern can occur at relatively small values​ of the frequency of multiplicative noise. In lattices with delay lines, periodic multiplicative noise does not cause significant distortion of the directional patterns. Expressions are obtained for determining average directional patterns by voltage and power under the influence of fluctuating multipath noise, including those obtained using correlation function of noise modulation. It has been shown that under the influence of stationary multiplicative noise, the beam pattern on the power of the grating with phase shifters is a convolution of the undistorted diagram on an undistorted scale and the energy spectrum of the noise modulation function. The upper limit of increasing the width of the main lobe of the beam pattern caused by multiplicative noise is determined. It is also shown that as the noise correlation time decreases and the phase distortion depth increases, the diagram expands and its side lobes smooth. It is noted that for distortions of the directional pattern of synthesized arrays, all the basic provisions for phased antenna arrays with phase shifters are true. For lattices with delay lines in the presence of multiplicative noise, the maximum of the average power of the beam pattern does not shift regardless of the shape of the energy spectrum of the noise modulation function. Multiplicative noise can cause only some expansion of the main lobe of the diagram and smoothing of the zero reception directions. Distortions of the grating pattern when exposed to slow fluctuation multiplicative noise are shown. These distortions are determined by changes in the phase and amplitude of the signal over time corresponding to the time shift between the signals in the individual elements of the array, and with slow multiplicative noise, the distortions are small. It is also shown that slow multiplicative noise leads to some reduction in the maximum beam pattern and to smoothing the pattern in the area of the side lobes. In the presence of such noise, the zero reception directions disappear.

WITHDRAWN: Array pattern synthesis for desired side lobe level using modified differential evolution

Abstract In this work, a linear array antenna pattern is synthesized which has desired side lobe level using optimal value of element current with the help of Differential evolution. The problem is solved through the optimization approach and a modified version of Differential Evolution has been presented to meet the objectives. Hierarchical approach of differential evolution has been applied to explore the solution domain while a new mutation strategy has been presented to converge the solution faster. For different level of side lobes, experiment has been done for various number of antenna elements. Comparative performances are shown over the existing form of self adaptive Differential evolution as well as with particle swarm optimization. It is been observed that, the proposed method has delivered the superior and outstanding performances of the array pattern containing the desired side lobe level.

Directional pattern of an antenna array with non-equidistant arrangement of receiving elements

This article presents an analysis of the directional pattern of an antenna array with a non-equidistant arrangement of receiving elements. This problem is relevant for the synthesis of antenna arrays with the required location of zeros and maxima in the radiation pattern. The analysis is suitable for obtaining an analytical expression describing the directional pattern of a flat phased antenna array, the receiving elements of which are located on the antenna curtain.

Taylor Expansion and Matrix-Based Interval Analysis of Linear Arrays With Patch Element Pattern Tolerance

In this study, a novel interval analysis (IA) approach for linear arrays with element pattern tolerance is proposed. This study differentiates itself from the classic interval analysis (CIA) method because it focuses on the effects of the array element (e.g., patch) pattern tolerance on the antenna array pattern; the tolerance may be caused by fabrication errors in the element. The closed-form pattern expressions of the element (e.g., patch) and array are deduced by the interval arithmetic method. To mitigate the interval extension (also referred to as the overestimation problem) caused by the dependency problem, Taylor expansion and matrix-based interval analysis (TMIA) methods are proposed and implemented in this study. A set of numerical examples is reported and analyzed to indicate the effectiveness of the proposed TMIA approach with the results of Monte Carlo (MC) and CIA methods, as well as to indicate its potential capabilities and advantages in the actual application of industrial antenna arrays.

Antenna radome based on metal-dielectric gratings as angular filter at microwaves

This article is devoted to the analysis of numerical study results of printed angular filters scattering characteristics. It is shown these angular filters may be used as antenna radomes. Numerical results are obtained by full-wave simulation of frequency-selective surfaces with dielectric covers. The numerical research results of the scattering characteristics of a printed angular filter as antenna radome based on metal-dielectric gratings are presented. A comprehensive numerical study of microwave angular filters based on multi-element multilayer printed reflect arrays has been carried out. Constructive solutions for metal-dielectric structures in integral design, realizing the functions of angular filters, are found. These solutions are based on performed numerical studies. The problems of constructive implementation of multilayer planar spatially selective as angular filters are considered. These angular filters are integrated into the radiators and feeders of modern multi-element printed phased arrays. The problems connected with creation of such arrays are also considered. The numerical simulation results for angular filters based on metal gratings with dielectric covers are obtained. These results can be used to select the most rational options for the topology of metal-dielectric gratings. Such solutions may be useful for design of multifunctional radomes in microwave antenna systems. Based on the obtained numerical data, the possibilities of using flat gratings as angular filters in the composition of antenna radomes are considered. The spatial frequency-selective structures proposed in this work are performed as multi-planar printed gratings. These gratings are designed to ensure electromagnetic compatibility of closely spaced radio electronic sets. These radio electronic sets operate in close frequency ranges. They contain antenna arrays. These arrays are placed under the antenna radomes. At the same time, the installation of angular filters in the antenna radomes makes it possible to eliminate the appearance of unwanted grating lobes in the radiation patterns of sparse antenna arrays of promising radioengineering sets at microwaves.

Pencil and Shaped Beam Patterns Synthesis Using a Hybrid GA/l₁ Optimization and Its Application to Improve Spectral Efficiency of Massive MIMO Systems

The synthesis of pencil beam and arbitrarily shaped beam patterns of linear antenna arrays (LAA) using reduced number of antenna elements attracts the attention of researchers in recent years. In this paper, a hybrid beamforming technique based on the combination of the genetic algorithm (GA) optimization technique and the l <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> minimization method denoted as (GA/l <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> ) is introduced for LAAs synthesis. The proposed GA/l <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> beamforming technique optimizes both the elements excitations and interelement spacing to synthesize the desired LAA pattern with a minimum number of antenna elements. The GA/l <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> technique provides an excellent approximation to the desired radiation pattern with high accuracy and low complexity (less number of iterations and computational time) compared to the other synthesis approaches introduced in the literature. In addition, as an application of this work, the proposed GA/l <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> technique is used to build up a proposed hybrid precoding and beamforming (HP-BF) structure for Massive Multi-input Multi-output (M-MIMO) systems. In this structure, the transmit antenna array is synthesized for maximum gain realization using the existing number of antenna elements. In the HP-BF structure, the proposed GA/l <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> technique is used to make full use of the existing transmit array elements to synthesize the radiation pattern of much larger size and higher gain arrays without the need for additional elements. Thereby, significant savings in the number of antenna elements and their corresponding radio frequency (RF) chains are achieved, which reduces the system complexity. In addition, the array gain maximization will maximize the received signal to noise ratio (SNR) giving rise to higher system performance in terms of spectral efficiency (SE) and power utilization.

Nonequidistant antenna arrays synthesis based on genetic algorithm

A new approach to the synthesis of nonequidistant antenna arrays with uniform distribution based on the Genetic Algorithm of the global extrema search is introduced and analyzed. The technique is demonstrated for various uniform antenna array structure. The radiation pattern of the nonequidistant antenna array is formed using the Genetic Algorithm to reduce a side lobe level. A mathematical formula is presented to highlight the operation of objective function minimization.

Wideband antenna array pattern based on reinforcement epoxy materials &amp; breast cancer diagnostic by composites

Abstract In this study, it is proposed to measure the numerical values of the depths of cancer tissues in the cancer organ. The creation of broadband antennas and the identification of cancer organs is a primary objective. A ΨU -shaped 2 × 2 grid antenna with a geographical coordinate has been modelled using mathematical modelling; simulated by Advanced Design Simulator (ADS); optimised using Moments of Methods (MoM); designed using Microwave Monolithic Integrated Circuits (MMIC) as the prototype and analytic microwave analysis by Agilent N99917A Analyzer represented Microwave Analyzer. It contains 18.64 × 17.92 × 1 mm3 compact dimensions. The model consists of the 2 × 2 array with four ΨU -shaped radiation slots, printed on a dielectric thickness of 1 mm of FR4 material and conductive ground level. The wideband spectrum from 4.5 GHz to 5.5 GHz was transmitted to 5.26 GHz operating frequency. In addition, the broadband antenna, a structure with a low profile and four number of radiating slots, is available. These broadband antennas have been developed for the application of breast cancer detection, which is the secondary provision of study. These broadband antennas with a dielectric model similar to the human breast are available on Debye test beds. These broadband antennas have impressed the materials for coupling that serve as the coupling medium. The findings were higher than the air medium. The higher and lower dielectric strength was demonstrated in these coupling materials. The average of distributed answers has been obtained. Distances between the cancerous organ and transceivers antennas, dielectric intensity and travelling times of spreading answers respectively have been determined by the degree of cancer present in the cancerous organ with the assistance of speed of propagation. This distributed response was therefore obtained in the Debye test bed from the cancer organ. Therefore the numerical depth value, which is validated under existing Debye test beds, and the coverage of the cancerous organ depth.

Using a phased antenna array with control coupling for nulls forming in the radiation pattern

A simple nulls forming method in the radiation pattern of a phased antenna array considered. Presented the basic calculation ratios confirmed by the simulation results are. The possibility of applying the method to form extended nulls in the radiation pattern is shown.

Investigation of a Radiation Pattern Frequency Dependence of a Subarrayed Slotted Waveguide Antenna Using CAD Ansys HFSS

Introduction. A resonant slotted waveguide antenna allows providing broadside radiation, which coincides with the normal line to the longitudinal axis of the array. Such an antenna can be well-matched in a very narrow frequency band. Even a slight deviation from the operating frequency leads to a significant distortion of the radiation pattern. In this regard, the distortion of the radiation pattern is becoming an urgent task. Aim. The main objective of this work is to preserve the radiation pattern of the resonant slotted waveguide antenna with longitudinal slots in the broad face in operating bandwidth. Materials and methods. Subarraying was performed to preserve the undistorted radiation pattern of the slotted waveguide antenna array in the operating bandwidth. The antenna model and its directional properties were analyzed in CAD Ansys HFSS using Visual Basic Scripting Edition macros. Results. Three slotted waveguide antennas’ models, consisting of two, four, and eight subarrays were developed in Ansys HFSS CAD. The effect of subarraying on the radiation pattern at the center frequency and the upper and the lower operating frequencies is studied. It is shown that the growing number of subarrays leads to a more stable radiation pattern in the operating bandwidth. Conclusions. Full-wave electromagnetic simulations have shown that subarraying of a resonant slotted waveguide antenna is a useful measure that preserves undistorted radiation pattern in the operating frequency band. Usage of Visual Basic Scripting Edition macros allows to minimizing the time spent creating a model in CAD Ansys HFSS.

Analysis of the Target Detection Performance of Air-to-Air Airborne Radar Using Long-Range Propagation Simulation in Abnormal Atmospheric Conditions

In this paper, we propose the analysis of the target detection performance of air-to-air airborne radars using long-range propagation simulations with a novel quad-linear refractivity model under abnormal atmospheric conditions. The radar propagation characteristics and the target detection performance are simulated using the Advanced Refractive Effects Prediction System (AREPS) software, where the refractivity along the altitude, array antenna pattern, and digital terrain elevation data are considered as inputs to obtain the path loss of the wave propagation. The quad-linear model is used to approximate the actual refractivity data, which are compared to the data derived using the conventional trilinear refractivity model. On the basis of the propagation simulations, we propose a detection performance metric in terms of the atmosphere (DPMA) for intuitively examining the long-range propagation characteristics of airborne radars in air-to-air situations. To confirm the feasibility of using the DPMA map in various duct scenarios, we employ two actual refractive indices to observe the DPMA results in relation to the height of the airborne radar.

Control Parameter Based Comparative Study of Radiation Properties of TMCCAA and TMHSCAA

Two different configurations have been considered for the optimal design of radiated electric field pattern characteristics of antenna arrays. Time-modulated concentric circular antenna array (TMCCAA) and time-modulated half symmetric circular antenna array (TMHSCAA) have been dealt with for the comparative analysis of control parameters of the radiation properties of the antenna array. Collective animal behaviour (CAB), an evolutionary approach, is applied as the optimisation tool. The effect of different control parameters of the radiation pattern of TMCCAA is compared by taking two different cases. In the first case, i.e., Case-1, only one parameter (switching time sequence) is used as the control parameter for the optimisation of the radiated electric field pattern of TMCCAA. In the second case, i.e., for Case-2, three control parameters, switching ON-OFF time of each ring, inter-element spacing, and ring radii are optimised. In the second array, the effect of different control parameters of the radiation pattern of Time-Modulated Half Symmetric Circular Antenna Array (TMHSCAA) is compared by taking two different cases. Simulation results obtained for 20- elements TMHSCAA with uniform amplitude and spacing are analysed. Optimized SLL values obtained for the Case-1 and Case-2 of TMCCAA are -24.68 dB and -46.15 dB, respectively.

2D/3D Shaped Radiation Patterns of Sunflower and Conformal Antenna Arrays Using Phase Synthesis

2D and 3D beam synthesis from different antenna array arrangements are investigated in this paper. Planar sunflower, conformal cylinderical and spherical helical array arrangements are studied. The particle swarm optimization (PSO) technique is used to predict the phase distribution on the array elements. The beam synthesis is achieved by comparing the array factor with a predetermined mask with both upper and lower limits according to the intented application requirements. Different 2D and 3D masks are used in beam synthesis as pencil, flat-top, and cosecant single beam are predicted. The planar sunflower antenna array is investigated due to its high gain, low side-lobe level (SLL) below − 20 dB and its compact size. The phase distribution of sunflower array is estimated using PSO to radiate dual-beams in different planes. Dual-beam with pencil, flat-top, and cosecant beams are obtained with different half-power beam widths. 3D conformal antenna arrays of cylindrical and spherical helical arrangements are studied. Each 3D conformal array consists of four arms shifted in position by 90° orintation angle. Each arm is designed to radiate single beam in a specific direction. Four-beams are considered to radiate in the directions of θ1,2,3,4 = 30°, and ϕ1 = 0°, ϕ2 = 90°, ϕ3 = 180°, and ϕ4 = 270° with SLL optimized below − 17 dB. The array arrangements analysis is based on the array theory formulation, through the implemention of the estimiated equation using a home programmed MATLAB code.

Side Lobe Suppression of Concentric Circular Antenna Array Using Social Spider Algorithm

This paper presents an efficient method to improve the far-field radiation pattern of concentric circular antenna array (CCAA) design using two stochastic optimization algorithms known as social spider algorithm (SSA) and modified social spider algorithm (MSSA). Low side lobe level (SLL) plays a crucial role in reducing the interference with the other frequency components along the entire side lobes of the far-field radiation pattern. SSA and MSAA are the state-of-the-art evolutionary optimization techniques which are applied here to determine the optimal current amplitude and the inter-element distance between two consecutive antennae of the 3-ring CCAA. In this paper, the optimal results achieved by using SSA, MSSA for (4, 6, 8) elements and (8, 10, 12) elements 3-ring CCAAs, with and without centre elements are reported. The results achieved by employing SSA and MSSA show a considerable improvement in SLL reduction as compared to the uniform and the other array patterns reported in the state-of-the-art literature.

An Implementation of Interactive Application for the Synthesis of Communication Systems with Antenna Arrays

Introduction. Modern radar and communications systems contain phased array antennas. One of the synthesis problems of such systems is the formulation of requirements for components, modules and units which are comprised in it. To solve this problem, one needs to build a coverage area and to analyze an impact of characteristics of its parts. The quality of analysis and synthesis of such complex systems can be enhanced by use of interactive data visualization, which requires a fairly quick calculation of characteristics.Aim. Development of an interactive application for increasing the synthesis capabilities of communication systems containing antenna arrays and for improving the characteristics of systems of interest.Materials and methods. To accelerate the calculation of radiation patterns, the antenna array pattern in a form suitable for the fast Fourier transform algorithm was used. To find the required amplitude-phase distributions, Kotelnikov series expansion and genetic algorithm were used.Results. In the developed application, amplitude-phase distribution, directivity pattern of a linear equidistant array and coverage area were displayed. An interactive change of the amplitude-phase distribution at radiation elements and synthesized radiation patterns in given directions were possible. With introduction of changes to the radiation pattern, the amplitude-phase distribution and the array radiation pattern itself changed in directions other than the specified one. The coverage area was rebuilt when any of the characteristics changes. If necessary, the coverage area display could be turned off. The paper provides an example of using the application in the synthesis of a communication system with an aircraft.Conclusion. The use of the developed application allows one to extend the capabilities and significantly reduce the analysis and synthesis time of the communication secondary radar systems with antenna arrays too. Besides, the application is used for training specialists for industry enterprises.

Failure Correction of a Linear Array of Coupled Parallel Vertical Dipole Antennas

In this paper, a cuckoo search algorithm based on the combined characteristics of the brood parasite behavior and Levy flights is applied to correct the radiation pattern of a linear antenna array composed of parallel dipoles with faulty elements. An effort is made to restore the radiation pattern similar to one without any faulty elements, and the difference in the values of side lobe level and wide null depth of both patterns, as well as the voltage standing wave ratio obtained from the new voltage excitations become diminished. The examples presented in this paper show the effectiveness of this algorithm in correcting the radiation pattern of a linear array of 36 and 120 dipole antennas with four and ten failed elements, respectively. The results show that the matching condition and the wide null control produced by Cuckoo Search algorithm are more efficient in comparison with the benchmark failure correction algorithm. The approach adopted herein may be applied to other array configurations as well

Generalized characteristics of expanded sector beams formed by phased antenna arrays obtained by scaling phase distributions

This paper considers specific features of the phase synthesis of expanded sector beams formed by phased antenna arrays by the method of fan partial diagrams. Partial radiation patterns are formed by pairs of adjacent emitters. The synthesis results have the property of scaling, which allows many expansion options to be obtained on the basis of one expansion option. This is achieved by multiplying the phase shift values of the signals from all emitters by the same value. It is shown that, when the beam expands along the sum channel, a radiation pattern with an extended angular distance between the maxima is formed in the difference channel. An analysis of the initial sections of the difference radiation patterns in the formation of expanded beams of the sum radiation pattern was conducted. The behaviour of the generalized characteristics of expanded beams across the range of expansion coefficients was analysed. The conclusion was made about the possibility of timely and predictable control of the width of the difference radiation pattern of a phased antenna array

Design of Crescent Shaped 64-Elements Flexible Patch Antenna Array for the Application of Uterine Tumour Detection

In this paper, a crescent shape 64 (8 × 8) elements microstrip patch array, using rubber substrate is designed and simulated to function at 4 GHz for the application of uterine tumour detection. A comparison using various combinations of antenna array elements is also presented. The centre-to-centre patch element distance is kept 0.5λ (λ = guided wavelength) for the antenna array to control mutual coupling. Electromagnetic simulator Ansoft HFSS 13 is used for the simulation. Characteristic analysis e.g. return loss(RL), radiation pattern of patch antenna array have been investigated. This antenna is placed on human uterine phantom model and simulated to detect uterine tumour. 64-elements antenna array has been fabricated also. In this paper, RL of -26.8384 dB &amp; antenna gain of 21.0271 have been achieved for the proposed array. Human uterine phantom model is designed and simulated by CST Studio Suite 2019.

IWORMLF: Improved Invasive Weed Optimization With Random Mutation and Lévy Flight for Beam Pattern Optimizations of Linear and Circular Antenna Arrays

The beam pattern synthesis of antenna arrays is one of the most significant optimization problems in the electromagnetics community, and it affects the performance of wireless communication systems. In this article, we formulate the beam pattern optimization problems, and propose an improved invasive weed optimization with random mutation and Levy flight (IWORMLF) algorithm to synthesize the beam patterns of linear antenna arrays (LAAs) and circular antenna arrays (CAAs). IWORMLF introduces the random mutation operator and the Levy flight mechanism to enhance the efficiency and to balance the exploration and exploitation of the algorithm for optimization problems. Several simulations are conducted to evaluate the performance of the proposed approach. First, IWORMLF is tested by a variety of benchmark functions, and the results indicate that it achieves the best performance in most of the functions compared to some other algorithms. Second, IWORMLF is utilized for the maximum sidelobe level (SLL) reduction and the joint maximum SLL and mainlobe beamwidth reductions. The results show that it achieves better performances in terms of the convergence rate, stability, and accuracy compared to some evolutionary algorithms for these optimization cases. Third, the efficiencies of the improved factors are verified. Finally, electromagnetism simulations are conducted to evaluate the performance of IWORMLF for the beam pattern optimizations with considering mutual coupling.

A Highly Efficient Spectrum Sensing Approach Based on Antenna Arrays Beamforming

In cognitive radio (CR), the sensitivity of the spectrum sensing (SS) algorithms depends mainly on several factors such as the receiver sensitivity, the antenna gain, the antenna efficiency and the SS algorithm itself. Researchers depend mainly on a single antenna element and sometimes on a uniform linear antenna (ULA) arrays to increase the system sensitivity. But actually the ULA suffers from the large side lobe level which in turn reduces the antenna gain. Furthermore, the separation between elements in the ULA is almost chosen to be half wavelength at the operating frequency which results in a dense array of close elements. If this separation increases slightly in order to reduce the mutual coupling between elements, the side lobes will increase and thus the realized gain is reduced more and more and as a consequence, the SNR will be reduced also which has a direct effect on the sensitivity of the system. In this paper, a low complexity and highly efficient SS technique based on antenna arrays beamforming and the generalized likelihood ratio test (GLRT) denoted as BF/GD is introduced. The proposed beamforming approach allows the utilization of the limited number of ULA elements and their corresponding RF chains to synthesize the desired radiation patterns of larger size antenna arrays for maximum gain realization. The desired pattern is realized by optimizing the excitation coefficients and inter-element spacing of the array. Consequently, the enhancement in the realized array gain will lead to a direct increase in the received signal-to-noise ratio (SNR) which significantly improves the sensitivity and the SS capability of the CR receiver without the need for extra hardware.