Characteristics Of Antenna Array Research Articles

A combination of asymptotic and numerical methods in calculating the characteristics of a convex quasi-periodic phased antenna array with account the interaction of elements of an arbitrary type

Approximate asymptotic expressions are obtained for the partial radiating elements pattern and the active reflection coefficient of a large-sized quasi-periodic convex phased array antenna (PAA), using as a basis the results of a numerical solution for the electromagnetic field in a single PAA cell under periodic boundary conditions on the lateral surface of the cell. These expressions can be used to create mathematical software for modelling such phased arrays, taking into account the interaction of radiating elements, based on a combination of direct numerical methods, such as the finite element method, to analyse the field in a single cell of the phased array with the calculation of the characteristics of the phased array as a whole using analytical asymptotic expressions. Numerical results of applying the method are presented for calculating the characteristics of multi-element spherical phased array of slot radiating elements and conical phased array of slot and director radiating elements.

Methods for optimizing the characteristics of antenna elements and arrays simulating aggregative behavior and evolution of living be-ings in nature

Rigorous analytical solutions to antenna synthesis problems have been obtained for several of their simplest designs, while numerical solutions to specific versions of these problems in a strict electrodynamic formulation for the required practical structures take so much time in most cases that obtaining an optimal solution in an acceptable time is not always possible. For this reason, approximate methods for solving various technical problems, including antenna problems, based on significantly simpler operators than in electrodynamics have become widespread. This allows for a significant gain in time and optimal solutions to synthesis problems in a reasonable time by direct, targeted enumeration of the space of combinations of parameters characterizing the problem under consideration. If it is necessary to increase the accuracy of the solution obtained in this way, approximate methods allow one to select from a possible number of options a significantly smaller number with the best values of the objective function for subsequent analysis of these options by strict methods. A significant place among approximate optimization methods is occupied by evolutionary algorithms (EA), which have been developed since the second half of the last century. They imitate the behavior and evolution of various biological communities, generally obeying the theory of evolution and Darwin's natural selection. The article provides a brief overview of modifications of both well-known algorithms and the control parameters they contain: the genetic algorithm (GA), the method of swarm of biological entities (PSO), the method of differential evolution (DE), with the help of which a number of problems on the synthesis of antennas with discretely and continuously changing parameters have been solved, and a relatively new algorithm – the method of grey wolves (GWO). An example of implementation using the PSO/FDTD optimization algorithm of a dual-frequency and broadband microstrip antenna with an E-shaped plate has been given. A mathematical model and a block diagram of the modified IGWO algorithm have been presented. The superiority of its characteristics in terms of the accuracy of determining the global extremum and the speed of convergence over such well-known algorithms as GWO, SCA, SSA, PSO, FPA, MFO and BA has been shown based on testing these algorithms on twenty-three reference functions.

An Efficient MLFMA for Accurately Analyzing Electromagnetic Radiation and Coupling Characteristics of Large-scale Antenna Arrays Mounted on Platform

A multilevel fast multipole algorithm (MLFMA) for analyzing electromagnetic radiation and coupling characteristics of large-scale antenna arrays mounted on the platforms is presented in this paper. Compared with the method of moments (MoM), the MLFMA can be used to calculate larger scale problems with limited resources. First, waveport model of the MLFMA based on the equivalence principle and mode matching theory is established to efficiently and accurately simulate the antenna array. Then, a preconditioning approach for solving the radiation problems with the waveports is designed to improve convergence of the MLFMA. An initial guess construction method is proposed to accelerate the MLFMA computation for the multi-excitation problems, which can reduce the iteration time by at least 50%. Numerical results demonstrate accuracy and efficiency of the proposed method.

Research into the Impact of Phase Shifter Failures on the Characteristics of Slotted Waveguide Array Antenna

Introduction. Currently, the impact of phase shifter (PS) failures on the characteristics of phased antenna arrays, slotted waveguide array antenna (SWAA) in particular, represents a significant problem. A review of publications shows that insufficient attention has been paid to PS failures.Aim. To investigate the characteristics of a SWAA in the event of PS failures, when their phase takes a value equal to zero instead of the required value.Materials and methods. The methods of statistical modeling methods were used to study the impact of failures on SWA characteristics. Calculations were carried using the Mathcad 15 software package.Results. An algorithm for statistical modeling of the impact of PS failures on SWAA characteristics is proposed. A relationship that connects the radiation pattern with the volume of the statistical sample and the number of failed PSs is given. The malfunctions of emitters from 5 to 35 out of 50 elements were studied. Changes in the following characteristics were obtained: standard deviation – from 0.064 to 0.18, radiation pattern width – from 8 to 18 %, the level of side lobes – from 13 to 59 %, radiation power – from 0.9 to 0.3.Conclusion. The results obtained can be used in radio-electronic systems with antenna arrays at the stage of their development. Future work will address PS failures with phases being established randomly and with random values, as well as the case of PS failures where power does not pass into the emitter. Another important direction concerns compensation of distortions resulting from failures of antenna elements.

Investigation of mutual coupling coefficients in dual-polarized antenna arrays

Background. Antenna arrays are widely used in various fields of radio engineering, such as radio and telecommunications, satellite communication systems, etc. One of the important characteristics of an antenna array is its radiation pattern. The estimation of impedance matrices, scattering matrices, and partial radiation patterns is usually performed based on the results of numerical electrodynamic modelling. In the case of a large number of antenna elements, such modelling and optimization of the array requires significant time.
 Aim. To investigate the mutual coupling between dual- polarised antenna elements included in a linear antenna array.
 Methods. Modelling of antenna arrays based on cross-dipole elements was performed using methods of electrodynamic modelling software. The study of the mutual coupling of antenna elements in the antenna array and verification of the developed mathematical model were carried out by numerical methods.
 Results. A physical interpretation of that there is no almost interaction between the elements operating in orthogonal polarizations, and the coefficients of mutual coupling decrease with increasing distance between antenna elements is given. Proposed a simplified model of mutual coupling, which reduces the computational complexity of the problem of determining the mutual coupling matrices.
 Conclusion. It is developed a mathematical technique that allows to calculate the characteristics of antenna arrays with a large number of antenna elements, meanwhile electrodynamic modelling is carried out only for an isolated antenna element and a two-element array.

Application of dielectric and ТЕМ horns in phased antenna arrays

The effect of the dielectric layer and metal horns on the characteristics of waveguide phased antenna arrays was studied using the finite element method. The geometric dimensions of the horns were optimized for better matching of the antenna array when scanning at an angle θ. Graphs illustrating the dependence of beam width and directivity on the number of elements in one side of the square array are plotted. Radiation patterns of the antenna array are plotted for different numbers of elements on one side of it.

The Influence of Random Internal Waves on the Characteristics of a Horizontal Antenna in a Shallow Sea

The effect of random internal waves on the gain and pattern of a horizontal antenna array in a shallow sea has been investigated. An algorithm for calculating the correlation matrix of the point source field at the grating aperture is proposed. The antenna gain is analyzed for different spatial processing methods: the beam forming method, the optimal linear processing method, and the optimal quadratic processing method. The effect of internal waves on the directivity pattern is described by the dispersion of the angular response of the grating. Numerical simulation results are presented for a model summer-type waveguide and an exponential Brunt–Väisälä frequency profile. The empirical internal wave spectrum proposed earlier from the SWARM95 experiment is used. The dependences of the antenna array characteristics on the number of its elements, orientation with respect to the source, radiation frequency, and the acoustic characteristics of the bottom are analyzed.

Onboard Phased Array Antenna of the Millimeter Wave Range

The requirements for the characteristics of phased antenna arrays of radar systems designed to probe the Earth’s surface from an aircraft are determined. The design features of an onboard pass-through phased array antenna with a monopulse irradiator are considered. The results of the calculation of the directivity characteristics and the magnitude of the gain coefficient losses of the phase-controlled antenna array are presented.

A Survey of On-Body Antenna Arrays: Future improvements, new designs, and lessons learned [Bioelectromagnetics

This manuscript presents a survey of the existing literature on on-body antenna arrays. They can be used to enable wireless communication to and from different on-body nodes in a wireless body area network (WBAN) and are also used in medical applications. The design process and the required characteristics of on-body antenna arrays are discussed. On-body antenna arrays should be small, lightweight, and low profile to ensure user comfort. The different types of on-body antenna arrays are discussed as well. On-body antenna arrays differ in the type of antenna element and in the geometric configuration of the array. The gain normalized to the area for the antenna arrays is compared, and it is found that, in the current state of the art, this quantity reduces with increasing frequency from 36 to 0.7 dBi. From our literature review, we draw important lessons that can be used to develop future on-body antenna arrays.

Two-Port Dual-Band Filtering Network and Its Application on Filtering Antennas

This letter presents a two-port dual-band filtering network, which can be integrated with antennas for dual-band filtering antenna applications in sub-6 GHz systems. The proposed network consists of a slotline resonator and two stub groups, featuring second- and third-order resonant characteristics at the lower and upper frequencies. Analysis by establishing equivalent circuits is carried out to verify the performance of the network. Moreover, the proposed filtering network is integrated with a 2 × 2 antenna array. Notice that the 2 × 2 antenna array serves as the final resonator of the filtering network during the integration. A prototype working at 3.5 and 4.9 GHz is fabricated for verification purposes. The filtering antenna array features sharp roll-off at the edges, with low insertion loss, high polarization purity, and wide fractional bandwidth of 11.7% at 3.5 GHz and 13.5% at 4.9 GHz.

Comparison of copper and graphene-assembled films in 5G wireless communication and THz electromagnetic-interference shielding

Since first developed, the conducting materials in wireless communication and electromagnetic interference (EMI) shielding devices have been primarily made of metal-based structures. Here, we present a graphene-assembled film (GAF) that can be used to replace copper in such practical electronics. The GAF-based antennas present strong anticorrosive behavior. The GAF ultra-wideband antenna covers the frequency range of 3.7 GHz to 67 GHz with the bandwidth (BW) of 63.3 GHz, which exceed ~110% than the copper foil-based antenna. The GAF Fifth Generation (5G) antenna array features a wider BW and lower sidelobe level compared with that of copper antennas. EMI shielding effectiveness (SE) of GAF also outperforms copper, reaching up to 127 dB in the frequency range of 2.6GHz to 0.32 THz, with a SE per unit thickness of 6,966 dB/mm. We also confirm that GAF metamaterials exhibit promising frequency selection characteristics and angular stability as flexible frequency selective surfaces.

Tuning the Angular Characteristics of Biomimetic Antenna Arrays

Tuning the Angular Characteristics of Biomimetic Antenna Arrays

Spatiotemporal Search for Pulsed Radiation in the Photon Flux Detection Mode with Prolonged Observation Time of the Decomposition Element

The development of science and technologies of microwave frequencies (UHF) has contributed to the fact that the use of ultrawideband (UWB) pulsed signals has emerged as a separate scientific and technical area of radiophysics, requiring a deeper study of the methods of formation, emission, reception and processing of such signals. Aperture radiators are mainly used to transmit UWB signals. This type of emitters is a variety of modifications of mirror antennas, horn antennas of various shapes and profiles, open waveguides, planar and conformal antenna arrays, as well as lens antennas. The classical theory of analysis of radiation and propagation of electromagnetic signals is well known, but its application to the synthesis of UWB emitters in the time domain often becomes too cumbersome and incorrect. Progress in the fields of radar, communications, and radio astronomy in the 1960s stimulated the creation of aperture theory based on physical optics approaches. This theory makes it possible to analyze and calculate the characteristics of mirror radiators and antenna arrays with sufficient accuracy for practical application. It is often possible to use the aperture theory to analyze some horn emitters that have a large radiation surface relative to the spatial dimensions of pulsed signals.

Appraising the Effect of Null-fill to the Broadcast Coverage of Four-bay Collinear Array

Null-fill is a method of improving the signal level in areas where pattern nulls occur. To take advantage of itin improving FM broadcast coverage, factors such as antenna height in relation to the average terrain, the number of bays in the array and the location of the target area are considered. It is therefore important to understand the radiation characteristics of the antenna system after the application of null-fill. This paper presents an analysis of the radiation characteristics of a four-bay FM collinear antenna array composed of circularly polarized elements with varying upper and lower bank power ratios. The analysis leads to the discussion of the capabilities and limitations of null-fill with the different bank ratios. Results show that, in the elimination of pattern nulls, the bank power ratio of 95:5 produces the best results. Also, irrespective on the value of the bank ratio, there exists a pattern null near the tower base. If left uncorrected, this pattern null poses reception difficulty in that area. An explanation on the existence of this kind of null and a method of eliminating it is worth considering in future studies. Keywords—Broadcast antenna, Collinear array, FM antenna, Null-fill, Pattern null, Polarization

An Improved Combination Method of MoM and UTD for Calculating the Radiation Characteristics of Antenna Arrays Mounted around Electrically Large Platform

An improved method, namely, combined UTD with MoM, is studied to calculate the disturbed pattern of array antennas mounted around an electrically large platform. Each array unit is fed in turns in an MoM processor and then substituted into the UTD process to pursue the calculation of the disturbed pattern. When solving the current coefficient in MoM, the linear superposition principle is used to realize the separate feeding of each array unit. The proposed method can avoid unreliable UTD results when an equivalent phase center of the antenna is sheltered, and it can improve the RMS error from more than 15 dB to about 1 dB in the T-shaped example given. No large amount of computing resources are needed for the proposed method; the accuracy, efficiency and necessity are illustrated by examples given.

Effects of Mutual Coupling on Gain and Beam Width of a Linear Array of a Dielectric Resonator Antenna for Main Beam Scanning Applications.

The effects of mutual coupling on the scanning characteristics of a four-element linear rectangular dielectric resonator antenna array (RDRA) are investigated for different inter-element spacing in this work. In particular, the gain and half-power beam width (HPBW) of an RDRA are studied for various scan angles in the E- and H-plane configurations. It is shown that for both the E and H planes, mutual coupling has an adverse effect on the performance of both phased array configurations. The H-plane array, however, is more stable than the E-plane array in terms of a gain and beam width performance comparison. The HPBW increases and gain decreases more in the E plane than the H plane when the scan angle is increased.

Design of an Interface Layer Using CPW between an Array Antenna and TRM in X-Band Radar Systems to Minimize Leakage Fields and Improve Transmission Characteristics

In this paper, we propose an interface layer using the coplanar waveguide (CPW) between an array antenna and transmitting receiver modules (TRMs) for X-band military ship radar systems. To improve transmission characteristics, the interface layer with the CPW has three transition parts: Transition part A is between the sub miniature push-on (SMP) connector and the interface layer. Transition part B is the CPW in which the thickness gradually increases. Transition part C is for connecting the interface layer and the antenna. The measured reflection and transmission coefficients of the fabricated interface layer are −22.4 dB and −0.82 dB, respectively. To verify the proposed interface layer, we then apply the layer to a 2 × 2 X-band array antenna and measure the array antenna characteristics, such as reflection coefficients, array antenna gain, and half-power beam widths (HPBWs). The measured reflection coefficient is under −10 dB from 8.6 GHz to 10.2 GHz, and the bore-sight array gain of the 2 × 2 array antenna is 10.5 dBi at 9.5 GHz. In addition, the measured HPBWs under the same conditions are 47.8° and 39.1° in the zx- and zy-planes, respectively. The results demonstrate that the proposed interface layer using the CPW is suitable for X-band radar systems.

Method of Electrostatic Analogy

It is considered the analysis method for electromagnetic fields and directional characteristics of antenna arrays consisting of parallel linear radiators based on the calculation of the electrostatic fields of charges located on parallel wires. It is demonstrated the advantage of using radiators with in-phase current distribution. It is shown that the application of radiators with in-phase current distribution allows to decrease the length of antenna array and to provide the high directivity in a wide frequency range. It is stated the task of optimization of considered arrays by methods of mathematical programming.

A Compact 4×4 Filtering Microstrip Patch Antenna Array With Dolph-Chebyshev Power Distribution

This paper proposes a compact 4×4 filtering microstrip patch antenna array with Dolph-Chebyshev distribution implemented by multilayer structure. The proposed antenna array features good filtering performance but contains no extra filtering parts in the feeding or the radiating element. The whole antenna array consists of four 1×4 antenna subarrays, each subarray is composed of four patch antennas which are coupled-fed by a single microstrip line. Inside the desired passband, by properly choosing the coupling area along the microstrip line, the patches are induced in-phase currents therefore achieving the excellent radiation characteristics. On the other hand, the four patches can’t be properly excited outside the passband which would enable radiation suppression performance. In order to implement a 4×4 filtering microstrip patch antenna array with low sidelobe level (SLL), four subarrays are combined and fed by Dolphy-Chebyshev excitation method. Finally, the proposed antenna array is implemented, fabricated and measured. The maximum measured gain in the passband is 14.7 dBi, and the radiation suppression outside the passband is better than 25 dB.

Broadband D-Band Patch Antenna Array in Wafer-Level Package Based on BCB Process

This paper presents a broadband stacked patch antenna array in wafer-level package based on benzocyclobutene (BCB) process for D-band wireless communications. The BCB material is not only used as a substrate for the antenna, but also as an interconnection layer, enabling low-loss interconnection with RFICs through vias and transmission lines. By introducing a BCB polymer-filled back cavity and carefully developing the feeding network, the designed antenna achieves a relative bandwidth of 18.9 the 2W2 stacked antenna array features a stable high-gain broadside radiation pattern. The pairwise antiphase feeding technique is adopted to suppress the cross-polarization level. In order to acquire high-speed data transmission, a dual-polarization MIMO implementation is presented. The port isolations are greater than 35 dB across the whole operating band.