Radiation Pattern Of Antenna Array Research Articles

Efficient Radiation Pattern Prediction of Array Antennas Based on Complex-Valued Graph Neural Networks

Antenna design with the traditional numerical methods is a highly computationally expensive task. In this letter, a complex-valued graph neural network (GNN) with residual connections is proposed to efficiently predict radiation pattern for antenna arrays with different geometric structures. The model uses GNN as a backbone, and the topological structure and excitation of the antenna array are encoded into a graph representation. Complex weights and residual connections are designed to improve the accuracy of the model. Experiments are conducted on five kinds of arrays under amplitude–phase control. The experimental results show that the average mean absolute percentage error and the average root-mean-square error of the model on five types of the antenna array are 1.86% and 0.032, respectively, while the time efficiency of the model is six orders of magnitude faster than that of the traditional full-wave simulation.

Arrays of combined antennas with equal-amplitude distribution of bipolar voltage pulses

The paper presents the comparative characteristics of the radiation pattern of the combined antenna arrays excited by a bipolar pulse and harmonic oscillations near the central frequency of the spectrum of ultrawideband radiation. Particular attention is paid to the 3x3 array radiation source with maximum efficiency.

Antenna array control system with combination of strength and flexible scanning programs

The structure of the antenna array control system with a combination of strengh and flexible scanning programs is proposed, characterized by the introduction of additional modules of statistics and expert assessments in the feedback circuit between the secondary processing module and hardware and software complexes for the formation of transmitting and receiving antenna array radiation patterns. The implementation of this structure allows for the formation of an additional transmitting and several receiving beams to confirm marks that do not meet the specified detection criterion. An algorithm for controlling an active phased array antenna has been developed, characterized by a procedure for additional confirmation of marks with a low signal-to-noise ratio due to the formation of additional transmitting and receiving beams. The estimates of the gain from the implementation of the proposed structural scheme of the antenna array control system and the algorithm of its functioning are obtained.

High‐efficient optimisation method of antenna array radiation pattern synthesis based on multi‐layer perceptron network

With the increasing complexity of the application environment of antenna arrays and the increasing requirements for antenna array radiation patterns, efficient optimisation methods of antenna array radiation pattern synthesis have always been the challenges of the research. This paper proposes a method of utilising a multi-layer perceptron network to optimise the radiation patterns of antenna array. The optimisation requirements of the antenna array radiation pattern are described by defining the objective mask function, which is designed to shape the target radiation pattern by desired features. Simulation experiments have been designed with a variety of antenna array layouts, of which the radiation patterns with different requirements were successfully synthesised and optimised. The results show that the proposed method has high efficiency and satisfactory optimisation effect in dealing with the problem of complex radiation pattern requirements.

A Proposed Method for Synthesizing the Radiation Pattern of Linear Antenna Arrays

The design of antenna arrays is one of the most challenging optimization problems in recent research interests. In this research work a new method of optimization proposed. This method called “Characteristics Evolution Optimization” is based on parallel processing of streams of binary digits, and hence it can perform well in parallel processing digital systems. In this article, a 16 - element linear antenna array has been taken into consideration, and the performance of the proposed technique for synthesizing the radiation pattern of the array has been investigated and compared with other existing techniques, such as DE (Differential Evolution), IWO (Invasive Weed Optimization), and PSO (Particle Swarm Optimization). Various variants of Invasive Weed Optimization have been investigated as well. It has been observed that the proposed method (Characteristics Evolution optimization) outperforms the other optimization techniques significantly in different aspects.

Development of a New Method for Pattern Synthesizing of Linear and Planar Arrays Using Legendre Transform With Minimum Number of Elements

In this article, a novel beam shaping technique is developed to synthesize the array factor (AF) radiation pattern of linear and planar antenna arrays. The proposed method is established based on the expanding of AF using Legendre transform in conjunction with an integrand operator. A system of linear equations is derived and its solution is obtained using least-square method (LSM) for the required pattern. In addition, an iterative procedure is introduced to reduce the number of elements of the primary designed array for a specified mean square error (mse). Then, the proposed method is applied to synthesize the AF of planar and ring antenna arrays. To verify the performance of the proposed method, a few comprehensive well-known linear, planar, and ring arrays are examined. The obtained results show that the introduced method can be used to design the AF pattern of many types of practical arrays with good accuracy.

DESIGN OF 6G COMMUNICATION SYSTEM AT THZ FREQUENCY BANDS

Toward increasing the data rates further, Teraherk (THz) frequency bands (0.1 -10 THz) became the central aspect of sixth-generation (6G) networks that support massive connectivity, low-latency, highly secure communications, data rates [hundreds of gigabytes per second (Gbps)], and denser networks. THz transmission is a complementary wireless technology for high-speed wireless extension of the optical fibers for 6G. The availability of materials for antenna fabrication and feasibility in designing ultra-massive multi-input-multi-output (U-mMIMO) systems motivates one to explore its peak performance at THz frequency bands. In this paper, a multiuser U-mMIMO system was designed with hybrid beam-forming features and its performance was tested at 0.142 THz bands for different numbers of base station antennas and modulation orders. Each user had one or more number of independent data streams, and the total number of users considered in the multiuser U-mMIMO system were 4 and 8. The metrics we considered in evaluating the performance were error vector magnitude, antenna array radiation patterns, and equalized symbol constellations. The results of simulations strongly recommend exploring the THz frequency bands for building next-generation wireless systems that satisfy the needs of the near future.

A Proposed Method for Synthesizing the Radiation Pattern of Linear Antenna Arrays

The design of antenna arrays is one of the most challenging optimization problems in recent research interests. In this research work a new method of optimization is proposed. This method called "Characteristics Evolution Optimization" is based on parallel processing of streams of binary digits, and hence it can perform well in parallel processing digital systems. In this article, a 16 - element linear antenna array has been taken into consideration, and the performance of the proposed technique for synthesizing the radiation pattern of the array has been investigated and compared with other existing techniques, such as DE (Differential Evolution), IWO (Invasive Weed Optimization), and PSO (Particle Swarm Optimization). Various variants of Invasive Weed Optimization have been investigated as well. It has been observed that the proposed method (Characteristics Evolution optimization) outperforms the other optimization techniques significantly in different aspects.

Performance of microstrip patch antenna for single and array element with and without EBG

In this paper, a compact single patch antenna and microstrip array antenna with EBG structures at 6 GHzhave been compained. A surface wave effect is often considered undesirable, since it increased the side lobes, and decreased the antenna gain and effeciency. This problem can be solved by utilizing EBG to suppress of such waves. Above the antenna substrate, the mushroom-like EBG were proposed. The side lobes have been improved from −6.8 dB to −16.5 dB, and better directivity was achieved from 5.77 dBi to 10 dBi and the efficiency improved from (80%) to 95% by using EBG with rectangular antenna. Additionally, the array antenna radiation pattern with EBG was improved to −23.5 dB, and the directivity and effeciency have been improved to 14.3 dBi and to 91.5 respctively. These antenna structures have a great eventuality for use in C band application.

Low-Cost Beamforming Concept for the Control of Radiation Patterns of Antenna Arrays Installed onto UAVs.

This paper presents a low-cost architecture that allows for beamforming with antenna arrays installed onto unmanned aerial vehicles (UAVs). Beam switching is proposed to improve the antenna gain towards the ground station with two three-element arrays installed below the wings of the UAV. The electromagnetic modeling of the complete structure (UAV and integrated antennas) was performed with commercial electromagnetic simulator Ansys HFSS. The radiation patterns were synthesized with particle swarm optimization (PSO). By employing lumped surface-mount device (SMD) components and switches, the design of the feeder to deliver proper excitation coefficients to the antennas is presented, and its performance was assessed by simulations. The proposed approach is demonstrated to be very effective with low-cost production.

Средняя диаграмма направленности и способ снижения среднего уровня боковых лепестков цифровой антенной решетки.

n the development of the existing statistical theory of antennas, new analytical relations are obtained for estimating the average radiation pattern of a digital antenna array. These ratios take into account the variance of rounding errors of the weight coefficients, errors in the amplitude and phase calibration of the antenna, jitter noise and rounding errors of the signal at the output of the analog-to-digital converter. It is shown that most of the factors affect the average level of the side lobes, as in analog antenna arrays. However, the variances of the phase calibration errors and the jitter noise determine the contribution of the new term, which has symmetry in the angular coordinate and has an extremums in the direction of the main beam of the antenna array and in the direction that is mirrored relative to the main beam. It is established that the variances of rounding errors depend on the signal-to-noise ratio and, when performing numerical studies, should be estimated based on the results of experimental studies. It is shown that digital processing in a sliding window reduces the average level of the side lobes by separating the spectral components of the signal and noise.

An Efficient Approach for Sidelobe Level Reduction Based on Recursive Sequential Damping

Recently, antenna array radiation pattern synthesis and adaptation has become an essential requirement for most wireless communication systems. Therefore, this paper proposes a new recursive sidelobe level (SLL) reduction algorithm using a sidelobe sequential damping (SSD) approach based on pattern subtraction, where the sidelobes are sequentially reduced to the optimum required levels with near-symmetrical distribution. The proposed SSD algorithm is demonstrated, and its performance is analyzed, including SLL reduction and convergence behavior, mainlobe scanning, processing speed, and performance under mutual coupling effects for uniform linear and planar arrays. In addition, the SSD performance is compared with both conventional tapering windows and optimization techniques, where the simulation results show that the proposed SSD approach has superior maximum and average SLL performances and lower processing speeds. In addition, the SSD is found to have a constant SLL convergence profile that is independent on the array size, working effectively on any uniform array geometry with interelement spacing less than one wavelength, and deep SLL levels of less than −70 dB can be achieved relative to the mainlobe level, especially for symmetrical arrays.

Алгоритм оценки характеристик направленности антенной решетки с электрическим сканированием в системе координат наблюдения

An algorithm is proposed for estimating the parameters of the antenna array radiation pattern with electric scanning in the observation coordinate system associated with the phasing direction of the antenna elements. It is shown that in this coordinate system, the concentration of coordinate lines near the phasing direction is maximal. This allows for a relatively small number of observation points to study in detail the parameters of the main beam and the first side lobes of the antenna array, as well as to evaluate the coefficient directivity. The simplest quadrature formula is acceptable for calculating the coefficient directivity in the selected observation coordinate system. The relations for calculating the antenna array radiation pattern taking into account the direction of the beam departures are given. It is shown that taking into account the directivity of individual elements during scanning leads to beam departures, which are convenient to track in the observation coordinate system. Procedures are proposed for estimating the beam width based on linear interpolation of sections of the radiation pattern where the level -3dB intersects. A procedure for estimating the level of side lobes is proposed, which does not include a procedure for searching the area of side lobes. The relations that establish the relationship between the observation coordinate system and the coordinate systems used in radar are given. The results of numerical studies that demonstrate the possibility of visualizing the radiation pattern and its cross-sections in the local coordinate system of the radar system, in the antenna coordinate system, and in the observation coordinate system are presented. This article is the first in a line of research in terms of determining the scientific and methodological apparatus for constructing adaptive algorithms for the diagram-forming scheme of the digital antenna array of radar stations and helps to determine the potential achievable characteristics of newly developed radar stations.

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.

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.

Combined adaptive antenna array and adaptive channel equalizer, based on multichannel fast recursive least squares algorithms

An adaptive antenna array (AAA) is a sort of directional antennas, which is able to suppress the signals of the interference sources. The AAA works well if there is no multipath propagation of the information signal. A device, which removes the multipath effects, is an adaptive equalizer. However, the independent AAA and equalizer do not work well if the interferences and multipath exist simultaneously. The purpose of this paper is to present a new efficient solution of the task by using of the AAA, whose weights are shared with the weights of the fractionally-spaced feed-forward (FF) part of the equalizer. The array output signal is combined with that of the feed-backward (FB) part of the equalizer. The array and such distributed equalizer operate as an indivisible adaptive filter, providing good performance and ability to receive the multipath information signals in the presence of the signals of the external interference sources. Because the FF part of the equalizer operates at the up-sampled rate, which is a few times higher than the information symbols rate, but the FB filter operates at the symbol rate, the computationally efficient fast recursive least squares (RLS) algorithms cannot be used directly in the considered adaptive unit. To solve this problem, it is proposed to use polyphase representation of the FF part of the equalizer. In this case, the architecture of the adaptive unit is viewed as a multichannel adaptive filter with unequal number of weights in channels. The paper presents the architecture of the adaptive unit and the details of its equalizer part. The mathematical description of a multichannel fast adaptive filtering algorithm, called stabilized fast a posteriori sequential technique (FAEST), fitted for the weights calculation of the considered unit is also presented. The verification of the proposed adaptive unit has been carried out via simulation, using a linear array with sixteen omnidirectional antennas, which operates in the conditions of –30 dB signal-to-interference ratio (SIR), 10…30 dB signal-to-noise ratio (SNR), receives the phase shift keying (8-PSK) desired signal, passed through a two-rays communication channel with about –65 dB gaps in the channel amplitude-frequency response. In the steady-state, the proposed adaptive unit demonstrates about –100 dB radiation pattern gaps towards the interference sources and the transient response with less than 500 symbols duration. The simulation demonstrates the ability of the proposed unit simultaneously to steer the main lobe of antenna array radiation pattern towards the desired signal source without a priori search of its angular location and to remove the signals of the external interferences and intersymbol interference in the array output signal. Due to these properties, the proposed AAA/equalizer can be used in equipment of modern mobile communication systems.

Use of graphics processors to cardinally acceleration the calculation procedure of large subaperture active phased antenna arrays radiation pattern

For traditional APAA with a rectangular and triangular grid of nodes, in which partial emitters are installed, simple analytical formulas are known that express the dependence of the array radiation pattern (ARP) on the angular coordinates. If the grid of nodes is irregular, or in a regular grid there are failures of individual digits in the control elements (phase shifters, attenuators, delay lines) or in power amplifiers, then these formulas are not applicable. Therefore, it is necessary to address to general relations of additive summation of the specific contribution to the ARP of the field generated by each emitter separately. In large arrays, their number can range from several to many tens or even hundreds of thousands. Further, if it is necessary to synthesize a given type of array RP, it is necessary to form special types of the amplitude-phase distribution of the signal on the emitters. The procedures for synthesizing such distributions require hundreds or even thousands of repeated calculations of the array RP, which may require several million angular points to analyze in the upper hemisphere of radiation. The article shows that using parallel computing with the help of programming technology on graphics processors (GPU), produced by NVIDIA and CUDA technology in a system designed to quickly create high-performance codes in the extended C language, C++ is able to speed up the calculations of the large antenna ARP by 2…3 orders of magnitude, even on standard office computers. When using modern CPUs (AMD Ryzen Threadripper PRO 3995 WX) and GPU (NVIDIA GeForce 3090), the acceleration in calculations can additionally increase by hundreds of times. At such computing speeds, even the problems of antenna synthesis and statistical analysis of the characteristics of the array RP will be solved almost in real time. An example of a statistical estimation of the ARP parameters of a large subaperture array with 1280 emitters, used in the COSMOSkyMed system, when random failures of the inverse type occur in the phase shifter digits. The use of graphics processors allows us to solve problems such as the synthesis of an array RP having a prescribed shape, and the statistical analysis of the characteristics of the array in the event of various failure options in its elements, as well as mechanical distortions of the aperture shape, in almost real time.

Design and Analysis of Phased Array System by MATLAB Toolbox

An array of antennas mounted on vehicles, ships, aircraft, satellites, and base stations is expected to play an important role in fulfilling the increased demand of channel requirement for these services. In this paper toolboxes of MATLAB will use for the phased array system for different purposes of extraction of information about a validate results for antenna array and a comparison is made between different antenna array geometries, also this paper provides the background of the newly developed MATLAB Phased Array Toolbox. So, some effective parameters like the changing element spacing and the number of elements and the geometrical shape of the array on the antenna array radiation pattern along with the gain have been studied. The Phased Array Toolbox of MATLAB has also been used to validate the results.

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.