Radiation Pattern Of Antenna Research Articles

Traffic-Aware Coordinated Beamforming for mmWave Backhauling of 5G Dense Networks

We study the problem of downlink Coordinated Beamforming for dense fixed-wireless millimeter wave (mmWave) networks under a Centralized/Cloud Radio Access Network (C-RAN) setting. To compensate for the increased mmWave path loss, we consider directional transmissions via antenna array analog beamforming, which leads to a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">discrete</i> set of available beams. We apply the Lyapunov optimization framework to propose a throughput-optimal policy which explicitly accounts for stochastic traffic and channel fluctuations and dynamically performs joint Base Station-to-user association and analog beam selection. Our model makes minimal assumptions and considers realistic mmWave antenna radiation patterns, while it can be easily extended to include additional MAC and PHY layer controls. Since this flexibility comes at the cost of high computational complexity, we also propose two heuristic policies offering reduced complexity. Their performance is compared against a baseline Round-Robin (RR)-based policy, while a theoretical <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">worst-case</i> performance bound is derived. Extensive simulations show the optimal Lyapunov policy achieving a stable throughput increase of more than 2X <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">per user</i> compared to the RR policy, while the proposed heuristics incur only a 20-30% performance penalty with respect to the optimal Lyapunov policy with 60X-900X computational time savings.

A novel high gain dual band ear bud shaped patch antenna for under water communications

AbstractThis article elucidates a high gain dual band ear bud shaped patch antenna with mm wave technology. The pivotal characteristic of this design is to provide higher gain and less interference at higher frequencies. It operates at a frequency of 40.59 and 52.002 GHz. The major advantage of this design is that it produces the circular polarization in entire band of frequency; moreover this antenna is useful for under water communication. The proposed design introduces two splits, imprinted at the walls of patch to get a wide band. For an optimal design, a future antenna parametric analysis was carried out. The proposed design is developed with the aid of HFSS software; we measured major parameters S11, VSWR, gain and radiation patterns in free space and underground environment. In the results, the predicted antenna radiation pattern is seen for E‐plane and H‐plane at various frequency bands. The gain 3D polar plots and current distribution plots are presented, including a comparison of previous work to the current work. We assure that the suggested design is applicable for under water communication.

Impact of Antenna Pattern on TOA Based 3D UAV Localization Using a Terrestrial Sensor Network

In this article, we explore the fundamental limits of the 3-dimensional (3D) localization of unmanned aerial vehicles (UAVs) in conjunction with the effects of 3D antenna radiation patterns. Although localization of UAVs has been studied to some extent in the literature, effects of antenna characteristics on 3D localization remains mostly unexplored. To study such effects, we consider a scenario where a fixed number of radio-frequency (RF) sensors equipped with single or multiple dipole antennas are placed at some known locations on the ground, and they derive the time-difference-of-arrival (TDOA) measurements from the time-of-arrival (TOA) data collected for the UAV that is also equipped with a dipole antenna. We then use these measurements to estimate the 3D location of the UAV, and to derive the Cramer-Rao lower bounds (CRLBs) on the localization error for various orientations of the dipole antennas at the transmitter and the receiver. Namely, we consider vertical-vertical (VV), horizontal-horizontal (HH), and vertical-horizontal (VH) radiation patterns in a purely line-of-sight (LoS) environment and a mixed LoS/Non-line-of-sight (NLoS) environment. We show that the localization accuracy changes in a non-monotonic pattern with respect to the UAV altitude and identify the respective critical altitudes for each of the VV, VH and HH orientations. Subsequently, we propose a multi-antenna signal acquisition technique that mitigates the accuracy degradation due to the antenna pattern mismatches, and we derive the localization CRLB for the multi-antenna scenario. Our numerical results characterize achievable localization accuracy for various antenna configurations, UAV heights, and propagation conditions for representative UAV scenarios.

Simulation of T shape MSPA for UWB Application

Using the CADFEKO tool, a T-shaped Microstrip patch antenna (MSPA) with an epoxy substrate was designed and simulated to achieve the best possible result. MSPA is frequently utilized because of its numerous benefits, including its light weight, low volume, and low manufacturing cost. The antenna's bandwidth, gain, return loss, VSWR, and radiation pattern were assessed. Maximum impedance is attained at 6.85 GHz, antenna gain is 8dB, directivity is 4.5, and return loss is -10.80dB at 5.725 GHz and 12.48dB at 10.6 GHz for the T-shape rectangular Microstrip patch antenna for ultra-wideband applications. 50Ω is used to power the T-shaped Microstrip antenna. The simulated results of the proposed antenna are good radiation patterns. The return loss is less than -10 dB and VSWR is less than 2 throughout the UWB band. At 3.1 to 10.6 GHz resonant frequencies, the S11are -10.80dB,-12.48dB, and antenna efficiency is 100 % due to all losses being zero.

Проекционный метод решения дискретизированных обратных задач в области антенных измерений

In the article, the problems of determining and monitoring antenna parameters, solved using measurements in the near field, are presented in a unified formulation corresponding to the gene-ralized inverse radiation problem in the form of an integral equation of the first kind. Within the framework of the numerical approach to the solution, the equation is discretized, and then the solution is sought approximately as a solution to the normal system of equations. It is shown that an approximate solution to the discretized problem that satisfies the normal system is also a solution to an equation with an orthogonal projector on its right-hand side. On the basis of this formulation, a new method of iterative projections is proposed. The efficiency of the method is demonstrated by the example of solving the problem of reconstructing the radiation pattern of a horn antenna from near-field data calculated for the electrodynamic model of the antenna in the HFSS program. The results of the proposed method are compared with the results of solving the problem by the method of decomposition in singular numbers.

A 5G filtering antenna simultaneously featuring high selectivity and band notch

This paper presents a compact and low-profile filtering antenna featuring simultaneously bilateral high selectivity and 5G band notch functionality. The bilateral high selectivity of this quasi-Yagi antenna is achieved by using innovative ground etches instead of microstrips on the top layer. Independent U-shaped split ring on the top layer endows the filtering antenna with an additional property, namely the band notch functionality. By modifying the arm length of split ring, the notched band can completely cover 5G sub-6 GHz (3.4–3.8 GHz). Moreover, the gain of end-fire filtering antennas mostly varies around 4.5 dBi within operational band. The radiation patterns of the proposed antenna ensure a desired antenna performance at different frequencies. The results of the measurements of the S-parameter as well as the gain and the radiation pattern of filtering antenna are consistent with respective simulation results.

A Wideband Monoconical Antenna for Airborne Applications With a Null-Filled Radiation Pattern

A wideband monoconical antenna with a null-filled radiation pattern for airborne applications is presented. A rotating current distribution, which radiates an electric field at the null point (<i>&theta;</i> &#x003D; <i>&phi;</i> &#x003D; 0&#x00B0;) of an omnidirectional radiation pattern of a conventional monoconical antenna, is formed using the proposed slotted structure in a monoconical radiator. In the proposed design, the null point is effectively filled over the 1:12 impedance-matched frequencies, while the size of the reference monoconical antenna is maintained. A figure of merit composed of the electric field intensity in the main radiation area (0&#x00B0; &#x2264; <i>&theta;</i> &#x2264; 45&#x00B0; and 0&#x00B0; &#x2264; <i>&phi;</i> &#x2264; 360&#x00B0;) and the profile of the antenna shows that the proposed antenna performs better than a conventional monoconical antenna or a fan-dipole antenna used in airborne applications. The impedance and radiation performances of the proposed antenna are verified experimentally from a 5.85:1 scaled built prototype.

Suppression of Cross-Band Coupling Interference in Tri-Band Shared-Aperture Base Station Antenna

A triband shared aperture (TBSA) antenna is proposed to meet the new requirements of base station antennas for multiband antennas fusion. The proposed TBSA (P-TBSA) antenna is composed of a lower band (LB, 790–960 MHz) antenna, two columns of middle band (MB, 1710–2170 MHz) subarrays, and a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4\times 8$ </tex-math></inline-formula> array antenna operating at N78 band (higher band (HB): 3.4–3.6 GHz). The LB antenna is located in the center of a shared reflector. The MB subarrays are located around the LB antenna with a side-by-side scheme. The HB array antenna is located below the MB and LB antennas for multi-input–multioutput (MIMO) application. The cross-band coupling interference existing in the P-TBSA antenna can be divided into scattering interference and common-mode interference, which will seriously deteriorate its performance. To suppress the scattering interference, an LB crossed dipole antenna with low radar cross Section (RCS) at both MB and HB and an MB crossed dipole antenna with low RCS at HB are designed. In addition, the method of “path extension” is used to suppress the common-mode interference. By taking the above measures, the distorted radiation pattern of the P-TBSA antenna is significantly recovered.

A simple cavity method which increases bandwidth of cylindrical dipole antennas to almost 100%

A broadband dipole antenna and an integrated cavity section responsible for increasing bandwidth are introduced, designed, and successfully fabricated. This simple and highly effective cavity is added at the dipoles input, where the concentric coaxial feed line becomes its inner conductor, and the dipoles cylinder becomes its outer conductor. This coaxial-fed dipole antenna could be easily fabricated due to its simple mechanical structure. A version of this type of dipole antenna, with a total length of less than 38 cm (0.44λ) and a radius of about 5 cm, is designed once symmetrically and once with an asymmetrical down-tilted radiation pattern. The new proposed cavity part can increase the antenna's bandwidth up to 100%, which is highly superior compared to conventional counterparts. Furthermore, the antenna's radiation pattern is stable throughout the bandwidth. The minimum realized gain at the solid angle of θ (for instance, θ between 90 and 120°) is perfectly above zero within the frequency range. The antenna measurement results are in acceptable agreement with the simulations.

An Algebraic Comparison of Synthetic Aperture Interferometry and Digital Beam Forming in Imaging Radiometry

Digital beam forming (DBF) and synthetic aperture interferometry (SAI) are signal processing techniques that mix the signals collected by an antenna array to obtain high-resolution images with the aid of a computer. This note aims at comparing these two approaches from an algebraic perspective with the illustrations of simulations conducted at microwaves frequencies within the frame of the Soil Moisture and Ocean Salinity (SMOS) mission. Although the two techniques are using the same signals and sharing the same goal, there are several differences that deserve attention. From the algebraic point of view, it is the case for the singular values distributions of the respective modeling matrices which are both rank-deficient but do not have the same sensitivity to the diversity of the array’s elementary antennas radiation patterns. As a consequence of this difference, the level and the angular signature of the reconstruction floor error are significantly lower with the DBF paradigm than with the SAI one.

Ergodic Outage and Capacity of Terahertz Systems Under Micromobility and Blockage Impairments

Terahertz (THz) communications systems are expected to become a major enabling technology at the air interface in sixth-generation (6G) cellular systems. However, utilizing extremely narrow antenna radiation patterns at both base station (BS) and user equipment (UE) sides, these systems are affected by not only dynamic blockage but micromobility of UEs. To alleviate the impact of both factors one may utilize the multiconnectivity mechanism allowing for UE to remain connected to several BSs simultaneously and switch between them in case the active connection is lost. In this work, we develop a mathematical framework to characterize the outage probability and spectral efficiency associated with different degrees of multiconnectivity in dynamic blockage and micromobility environment for different beamsearching design options. Our results demonstrate that the presence of UE micromobility may have a positive impact on system performance. Particularly, multiconnectivity allows improving outage and spectral efficiency for small and medium blockers density (up to 0.5 bl./m²) up to that of an ideal system with zero beamsearching times. Furthermore, higher gains are observed for higher degrees of multiconnectivity (e.g., greater than two) as compared to the system with only blockage impairments. For higher blockers densities, however, the reverse effect is observed.

Study of the radiation pattern of a rectangular horn antenna in the operation of multimode propagation of electromagnetic waves

The object of research in the work is the process of radiation of electromagnetic waves and the directional properties of a rectangular horn antenna in a multimode operation. The existing problem is that in practice when developing and researching horn antennas, only the single-mode mode of their operation is taken into account. The fundamental mode of the rectangular waveguide that feeds this horn antenna is chosen as the base mode of the emitted electromagnetic wave. Radiation of higher types of electromagnetic waves is not taken into account. To take into account the impact of higher types of electromagnetic waves on the directional properties of a rectangular horn antenna, it is proposed to investigate a multimode mode consisting of three types of magnetic waves H10, H20, and H30. Horn antennas have high-quality wide-range properties and make it possible to obtain a maximum frequency coverage ratio of 1.5–1.8. In this paper, the directional properties of a rectangular horn antenna are determined by the example of calculating and modeling normalized radiation patterns of a standard horn-type for a wide frequency range with an average frequency of 12 GHz and a frequency overlap factor of 1.67. It has been established that when emitting three higher types of waves, it is possible to simultaneously improve the characteristics and directional properties of a horn antenna by changing the amplitude of each component of the constituent waves of electromagnetic radiation. The work aimed to study the normalized radiation patterns of a rectangular horn antenna to improve its directional properties. It was found that with increasing frequency, starting from the middle frequency of the operating frequency range, the radiation pattern of a rectangular horn antenna expanded. That is, the opening angle increased in the direction of the main radiation, with a decrease in the radiation amplitude, the level of the side and rear lobes increased, which leads to a deterioration in the characteristics of the horn antenna. For the selected geometric dimensions of the horn antenna in the frequency range of 12–12.5 GHz in the multimode mode, it was possible to provide almost the same beam width in the horizontal and vertical planes at the level of 13.2–13.6°.

Received power modelling in ultra‐dense networks

In received power modelling for system level simulations, the relative orientation of the transmitter and receiver antennas are not generally considered. By doing that, a constant gain of the receiver antenna, independently of the angle of arrival, is implicitly assumed. This is usually of minor relevance for small or low-dense scenarios. However, in ultra-dense deployments, especially those based on cell-free massive multiple-input–multiple-output architectures where users interact with all access points, the consideration of the antennas relative orientation comes to the forefront. In this paper, the impact of whether to take the receiver antenna gain into account or not for ultra-dense indoor environments with ceiling-mounted antennas are studied. A simple approach to take this gain into account using the antenna effective area is provided. Finally, this approach is compared with that based on antenna radiation patterns.

A novel pattern reconfigurable dual beam Vivaldi antenna with water-based absorbers

In this paper, a novel orthogonal dual-beam Vivaldi antenna loaded with metamaterial lenses (MLs) is designed as the original antenna. Then, we designed two simple water-based absorbers (WBAs) containers using 3D printing technology, which can be mounted on the ML. WBA filled with water can absorb electromagnetic waves radiated from antenna aperture, while empty WBA does not affect antenna radiation. The antenna radiation pattern can be reconstructed by selectively injecting water into WBAs. The proposed antenna can realize three radiation states in the operating frequency band, including radiation along the X direction and Y direction at the same time (state 1), radiation along X direction (state 2), and radiation along the Y direction (state 3). The proposed antenna has an operating frequency range from 3 GHz to 6 GHz, which realizes the coverage of the 5G sub-6 GHz main frequency band. Finally, the measured results of the antenna are consistent with the simulated. The work in this paper has potential application value in the 5G communication system and point-to-point communication system.

Design of a low-frequency miniaturized piezoelectric antenna based on acoustically actuated principle

An acoustically actuated piezoelectric antenna is proposed for low frequency (LF) band in this paper. The proposed antenna is theoretically calculated, numerically optimized by the finite element method (FEM), and experimentally analyzed. The measurement results show that the near-field radiation pattern of the piezoelectric antenna is similar to that of the electric dipole antenna. The radiation efficiency of the piezoelectric antenna is 3–4 orders of magnitude higher than that of electrically small antenna (ESA), with their sizes being the same size, and the maximum transmission distance obtained experimentally is 100 cm, which can be improved by increasing the input power. In addition, the gain, directivity, and quality factor of piezoelectric antenna are also analyzed. In this paper, traditional antenna parameters are creatively used to analyze the performance of piezoelectric antenna. The research conclusions can provide reliable theoretical basis for realizing LF antenna miniaturization.

Radiation Pattern Nulling in Phased Array Antennas Using Superior Discrete Fourier Transform and Dolph‐Tschebyscheff Based Synthesis Techniques

AbstractThis study proposes an improved method for sector nulling in the radiation pattern of rectangular phased array antennas using two different synthesis techniques; an orthogonal Discrete Fourier transform and a quasi‐orthogonal Dolph‐Tschebyscheff based technique. In traditional synthesis techniques, broad elemental beams serve as local field basis functions (FBFs) in an array. Instead, the proposed methods produce low sidelobe narrow beams as FBFs. A set of these FBFs can effectively constitute the array's radiation pattern in a confined angular region. By properly weighting these FBFs, sector pattern nulls in a designated angular range are synthesized without severely distorting the patterns outside this area. The FBFs' optimal weights can be efficiently calculated using a nonlinear minimum least squares error technique, which is later transformed into the array's elemental excitation coefficients. Along with faster convergence, this technique allows control over peak sidelobe level, null depth, and width, making it suitable for GPS anti‐jamming, 5G communications, and other applications requiring interference suppression.

A novel and effective technique to reduce electromagnetic radiation absorption on biotic components at 2.45 GHz

ABSTRACT A strong evidence of the effects of radiation absorption on the living community together with a better solution to reduce the radiation intensity without compromising the usage of wireless communication systems is presented. This study analyses the radiation effects on living things and validates the proposed techniques for specific absorption rate (SAR) value reduction at 2.45 GHz. To reduce these radiation impacts on the living community, proper shielding from the radiation and effectively reorienting antenna radiation patterns are the solutions suggested. An analogous antenna configuration in wireless communication systems – a coplanar waveguide fed loop antenna is considered and an open loop resonator (OLR) optimized in ANSYS HFSS at 2.45 GHz is incorporated on the back side of the proposed antenna for achieving SAR value reduction. Theoretical and experimental validation is carried out by measuring the variation in absorption power on each vegetable sample using vector network analyzer E5080A. The existence of OLR on the back side of the antenna reduces the absorption power upto 2 dB. From experimental validation, the proposed technique provides 88% to 98% reduction in SAR value when tested in each sample. Along with this OLR exhibits the capability to enhance the shielding characteristics to the controlled environment of experimental setup for analyzing the stages of seed germination, which helps in reducing the reported radiation effects and growth retardation. The proposed method of EMR reduction with miniaturized planar resonator can be effectively used in the communication systems operating at 2.45 GHz for creating a reduced radiation environment.

Analytical Investigation of Body-Centric Communication Links Based on Path Loss in Indoor Environment

In this paper, a detailed analysis has been carried out related to body-to-body communication links in an indoor office environment using compact ultra-wideband wearable antennas. The links have been analysed on the basis of path loss magnitude variation and statistical information which are dependent on the orientation and distance. Four orientations of the transmitter and receiver are chosen, namely facing front, back, side right, and side left. The distance between the links is varied up to 5 m to consider the effect of separation between the Tx and Rx. The path loss magnitude has been classified into three ranges, which mainly represent direct path propagation (R1:40–55 dB), partially obstructed/high multipath links (R2:55–60 dB), and totally obstructed links (R3 > 60 dB). The presence of path loss in the range R1 is highest (35%) for the case when the Tx is facing front for B-to-B links due to the high chance of direct line-of-sight propagation between the Tx and Rx. The percentage of occurrence of PL (>60 dB) is highest (95 %) for the scenario in which the Tx is facing back for B-to-B links which is due to the obstruction caused for all the orientations of the receiver. The difference in PL statistics and modelling is observed for various B-to-B links that are attributed to the fact of the presence of two human subjects and the corresponding orientations. This leads to variation in the antenna radiation pattern which in turn affects the propagation characteristics and the channel parameters.

Direction of Arrival Estimation Based on Received Signal Strength Using Two-Row Electronically Steerable Parasitic Array Radiator Antenna.

In this paper, we present a novel approach to direction-of-arrival (DoA) estimation using two-row electronically steerable parasitic array radiator (ESPAR) antenna which has 12 passive elements and allows for elevation and azimuth beam switching using a simple microcontroller, relying solely on received signal strength (RSS) values measured at the antenna output port. To this end, we thoroughly investigate all 18 available 3D antenna radiation patterns of the antenna measured in an anechoic chamber with respect to radiation coverage in the horizontal and vertical direction and propose a generalization of the power-pattern cross-correlation (PPCC) algorithm involving a high number of multiple calibration planes (MCP) as well as specific combinations of radiation pattern sets. Additionally, a new way of RSS-based DoA estimation accuracy assessment, which involves thorough testing conducted along the elevation direction when RF signals impinging on the antenna arrive from arbitrary θ angles, has been reported in this paper to verify the overall algorithm’s performance. The results obtained for different signal-to-noise ratio (SNR) levels indicate that two-row ESPAR antenna can produce, even for low SNR values, accurate DoA estimation in the horizontal plane without prior knowledge about the elevation direction of the unknown RF signals by using appropriate combinations of only 12 3D antenna radiation patterns.

Минимизация нижней границы Крамера-Рао для построения антенных решеток с направленными излучателями для повышения точности оценок угловых координат радиосигналов

The use of antenna arrays equipped with digital signal processing units is a promising way to increase the throughput, noise immunity of modern wireless information transmission systems. The spatial diversity of the antenna is the main advantage of this approach which makes it possible to estimate the spatial coordinates of radio signals with subsequent beamforming. It is well known that the insufficient knowledge of the influence of the array geometry together with various types of antenna elements (such as a dipole, a patch, etc.) may be a cause reducing the accuracy of such systems. The article describes an approach aiming at reducing direction-of-arrival estimation errors of radio signal sources by means of optimal antenna array geometries. In particular, the Cramer-Rao lower bound is used for the task. The quantity sets a limit below which one or another algorithm for estimating the spatial coordinates of signal sources cannot descend for a particular geometry of the antenna array. The expressions based on the Cramer-Rao lower bound are derived which describes the dependence of the variance of direction-of-arrival estimation errors on the location of the array elements in the Cartesian coordinate system, i.e. along the x, y, z axes. In addition, the function of the radiation patterns of individual antennas is taken into account in the obtained formulas. Additionally it is considered that the antenna elements are directional. Therefore, the proposed technique is aimed at reducing the variance of direction-of-arrival estimation errors of statistical algorithms with superresolution by minimizing the obtained new formulas. As a result, the optimal locations of antenna elements along the x, y, z axes are calculated. In the paper, new geometries of antenna arrays have been obtained according to the proposed approach. In particular, two- and six-element arrays are researched, which are compared with equally spaced cylindrical ones. Graphs of the error variance of the Cramer-Rao boundary are presented, as well as a statistical study of the MUSIC method. It is shown that the magnitude of errors is reduced by new antenna arrays in all the researching scenarios. Thus the antenna arrays geometries obtained in this paper allow improving the accuracy of algorithms for estimating the angular coordinates of radio signals with superresolution.