Radiation Pattern Of Antenna Research Articles

Ошибка установки углового положения радиолокационного объекта, замещаемого двухточечной моделью, при использовании антенны с разностной диаграммой направленности

The issues of estimating systematic errors in setting the angular position of the apparent radiation center of a radar object simulated by a two-point model when using antennas with difference radiation patterns are considered. The dependence of the angular error on the model parameters, such as the spacing of the emitters, the expected position of the apparent center of radiation and the coefficients of the antenna radiation pattern approximation, is established. The angular error of the bearing is determined by including it in the direction finding characteristic of the antenna as a correction to the angular position with further analytical expression. Calculations were performed for the sum and difference directional diagrams, on the basis of which the error values were compared. The ratio of the approximation coefficients for the sum and difference radiation patterns of the antenna is determined. The obtained analytical results can be used in solving applied problems related to the development of matrix simulators and forecasting the accuracy characteristics of simulation complexes.

Design of Low-Cost RF Detector for Electric Field Determination in Antenna Radiation Pattern Measurement

Antenna pattern measurement is a requirement for antenna characteristics determination. However, such sophisticated set-up measurement demands skilled authority. This project employed a low-cost RF detector (MAX4003) to capture the E-field and consequently assist in acquiring data for antenna radiation pattern. By fabricating a 3.0V circuit with MAX4003 and connecting to an Arduino, this compact module creates a basic interface between the antenna under test and user’s measurement PC. The results show the measured voltage from the RF detector is in good agreement with the manufacturer’s datasheet for 1.8GHz and 2.1GHz operating frequencies. The input power is also directly proportional to the output power. The project was further tested by conducting a full 360° antenna radiation pattern measurement. The results established a satisfying comparison to theoretical radiation pattern. Overall, the system benefits to individual such as students and researchers to replicate the same method in order to have a compact and attainable antenna measurement system.

Evaluation of a double-lens dielectric radome using a microstrip patch antenna for electromagnetic applications

The advancement of increasingly powerful antennas has increased the complexity of radome electromagnetic (EM) design and analysis. The antenna systems are protected from environmental influences by radomes, which are dielectric and electromagnetically transparent structures. Because the presence of the radome affects the performance parameters of the antenna, such as the radiation pattern, reflected power, and side lobe level, its design should not be done independently of the antenna analysis. The great majority of ground-based hemispherical radomes are used for satellite communication antennas, commercial and military radars, telemetry systems, and other uses. Patch antennas, reflector antennas, phased array radars, and other antenna systems are used in these applications. The operational effectiveness of a radome architecture for housing multiple patch antenna systems is proposed and evaluated. The proposed line of work includes antenna-radome interaction analyses, electromagnetic designs for radome walls, and radiation patterns for reflector antennas. COMSOL Multiphysics was used to develop the EM radome and examine the antenna-radome interaction. The findings of a comprehensive analysis into the differences in radiation patterns produced by patch antennas with and without radomes are presented in this article. At a frequency of 1.62 GHz, a plot and investigation of the far-field gain of the microstrip patch antenna with and without radome were done. The radome is estimated to add 0.09 dBi to the gain boost experienced by the microstrip patch antenna.Abbreviations: EM, Electromagnetic; DSF, Dielectric space frame radome; IFR, Induced field ratio; RF, Radio frequency; VSWR, Voltage standing wave ratio; FEM, Finite element method; SRR, Split ring resonator; CATR, Compact antenna test range; DUT, Device being tested; LHM, Left-handed metamaterials; PML, Perfectly matched layer; PTFE, Polytetrafluoroethylene.

Potential characteristics of direction finder with interference compensator and a direction finder with an adaptive antenna array with limitations in the event of interference in the main lobe of the antenna pattern

The displacement of the bearing estimate in a direction finder with an adaptive noise compensator, its sensitivity and the sensitivity of a direction finder with an adaptive antenna array with restrictions have been studied depending on the antenna radiation pattern, the angular position of the signal and local interference, the correlation of distributed noise and spectral densities of signal power, noise and interference. A comparative analysis of the accuracy and sensitivity of these direction finders in the event of interference in the main lobe of the antenna pattern was carried out for a linear equidistant antenna array.

Electrical properties of acetone imprinted hematite nanomaterials doped with Pd & Ag for gas sensing and simulation of their wireless devices

This article presents a novel technique for wireless hydrothermally improved gas sensor devices enhanced by molecular imprinting technique (MIT) for hematite nanomaterials with the existence of acetone using different ratios (10 %, 15 %, and 25 %) as well as doping with palladium/ silver to detect the imprinted gas. α-Fe2O3 are characterized utilizing field emission scanning electron microscope (FESEM), photoluminescence, Fourier transforms infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photo-spectroscopy (XPS), and High-Resolution Transmission Electron Microscopy (HRTEM), Thermogravimetric Analysis (TGA) and utilizes Brunauer-Emmett-Teller (BET) to ascertain their shape, optical properties, and values for surface area and thermal characteristics, respectively. Depending on the preparation conditions, non-regular cubes and rods have typical particle sizes ranging from 25 to 120 nm, acetone imprinted and doped with palladium sample (Ap) offers smaller particles than acetone imprinted sample (A15) making adsorption easier. Where XRD showed all diffraction peaks for α-Fe2O3 as well as XPS authorized the oxidation state, also FTIR showed the characteristic peaks of the stretching mode Fe-O which indicates the formation of α-Fe2O3. Lower defects for (Ap) as it has the highest intensity of 176.15 a.u. in the photoluminescent spectrum, for TGA analysis results explain that pure sample has more thermal stability and lower weight loss. Six hematite films are fabricated using the spin coating technique where acetone molecules are presented during the synthesis process of the nanomaterials to imprint their shapes on the surface of hematite. By measuring the response of the gas sensors and their electrical properties, the I-V curve for Ap showed a rectifying behavior and its shunt resistance (Rsh) is higher than series resistance (Rs) which ensures a high response of (115 %). To develop a wireless gas sensor COMSOL Multiphysics software 5.3(a) software is used for the simulation of three devices model by depositing a layer by specified dimensions of hematites (A15, As, and Ap) with their different electrical conductivities on the surface of rectangular patch antenna by showing geometry, the microstrip patch antenna bandwidth, resonant frequency, scattering parameters, and radiation patterns in the E-plane and 3-D far-field pattern and directivity is calculated also, Sp gives improved reflection coefficient, gain quality factor and directivity due to its high electrical conductivity.

Compensation of phased array antenna electrical performance based on improved genetic algorithm

Phased array antennas are frequently subjected to surface distortions due to environ-mental factors during operation. Such distortions can lead to a deterioration in the electrical performance of the phased array antenna. This study provides an in-depth analysis of the impact of array distortions on electrical performance indicators. An electronic compensation approach, employing an enhanced genetic algorithm, is proposed to mitigate the effects of these distortions. The conventional genetic algorithm has been augmented with an elimination mechanism to boost convergence. This method compensates for amplitude and phase by calculating each element's amplitude and phase of the excitation current, thereby enhancing the convergence performance. Simulations this approach, simulations of rectangular microstrip patch antennas are conducted to validate the effectiveness of this approach. The simulation outcomes reveal that the proposed method significantly improves the antenna's radiation pattern and all performance indicators, confirming its efficacy.

Highly isolated electrically compact UWB MIMO antenna for wireless communications applications

A multiple-input multiple-output Ultra-Wide Band (UWB) antenna with a compact size of 0.8λ x 0.7λ is proposed. The presented structure is constituted with patch geometry on a planar surface. The radiator consists of three counter U-shaped conducting strips united with a patch structure where two are positioned nearby and the third geometry covers the remaining conducting strips. A corrugated design has been created on a ground plane in which zigzag pattern slots are engineered to receive high isolation of more than 20 dB. The configured antenna radiates over a wide frequency spectrum of 3.10 GHz–11.85 GHz. It offers a fractional bandwidth of 195 % with a gain of 2.80 dBi, 3.08 dBi, and 2.72 dBi for targeted resonances. The antenna radiation patterns and MIMO diversity parameters are also presented. The acceptable values of ECC (<0.05 abs), MEG (−6 dB to −8 dB), CCL (<0.02 bits/sec/Hz) were found. The fabricated model was tested inside an anechoic chamber environment to receive the measured response with optimum accuracy through multiple iterations. The measured response shows a strong correlation with numerically computed responses finding the presented antenna suitable for WiMAX, WLAN (max protocol) and radar applications.

Decoupled Dipole Arrays Empowered by Invisible Complex Poles in Epsilon‐Near‐Zero Metamaterials

AbstractEvanescent waves, characterized by an exponential decay in propagation, have witnessed significant advancements in far‐field imaging and near‐field sensing applications. However, incoming evanescent waves can excite guided resonance inside a dielectric slab, resulting in a rapid growth of transmission coefficient toward infinity at the pole points. Such evanescent‐wave excited resonance benefits super‐resolution applications yet causes severe crosstalk in highly integrated multi‐channel devices. Here, the invisible complex poles are discovered in the transmission spectra of epsilon‐near‐zero (ENZ) metamaterials and demonstrate the striking suppression of near‐field crosstalk enabled by the anomalous transmission beyond the critical angle. Equipped with an ENZ metamaterial spacer, collinear dipole arrays exhibit 9.2 dB improvement in near‐field isolation among interior dipoles at a distance of less than one wavelength. Experimental measurements show negligible influence on the intrinsic impedance matching and radiation patterns of the dipole antennas. The discovered field divergence effect from the disappearance of real‐valued pole singularity in ENZ metamaterials offers an alternative solution for highly compact arrays in full duplex communication and multiple‐input multiple‐output technology.

28/38 GHz compact rhombic-shaped antenna for future generations of mobile communications

ABSTRACT It is mandatory for the modern antennas to be designed to operate in the millimetre-wave (mm-wave) range of the electromagnetic spectrum for future generations of mobile communication requires multiband operation of a single antenna. The present work proposes a dual-band antenna to operate at 28 and 38 GHz . The design stages of the proposed antenna and examples of the parametric study performed to arrive at the final antenna design are demonstrated and discussed in detail. The proposed antenna is constructed as a main patch with parasitic element that is capacitively coupled to the main patch through a narrow slot. The main patch is a rhombic-in-shape and excited through a microstrip live with inset feed. This rhombic shaped patch antenna is originally designed to operate at 28 GHz . To achieve the dual-band operation, the geometry of the main patch is modified and is loaded by a parasitic element. The antenna is fabricated for experimental assessment through measurement of the antenna impedance, radiation patterns, maximum gain and radiation efficiency. The proper operation at 28 and 38 GHz is confirmed by experimental verification of the simulation results. Both the simulation and measurements show that the proposed antenna has 50 Ω -matched impedance over the frequency bands 27.7 − 28.4 GHz and 37.7 − 38.4 GHz . The proposed antenna has been designed to enhance the communications system performance when used in the mobile networks through noise rejection by limiting the operation within relatively narrow bands around the resonant frequencies. The values of the maximum gain obtained at 28 and 38 GHz are 6.98 and 8.8 dBi , respectively. The radiation efficiencies of the proposed antenna are 89 % and 87 % , respectively, and the total efficiency is also calculated.

Direction-dependent Effects on Global 21 cm Detection

Cosmic dawn represents a critical juncture in cosmic history when the first population of stars emerged. The astrophysical processes that govern this transformation need to be better understood. The detection of redshifted 21 cm radiation emitted from neutral hydrogen during this era offers a direct window into the thermal and ionization state of the Universe. This emission manifests as differential brightness between spin temperature and the cosmic microwave background. The SARAS experiment aims to detect the sky-averaged signal in the frequency range 40–200 MHz. SARAS’s unique design and operational strategy to float the antenna over a water body minimizes spectral features that may arise due to stratified ground beneath the antenna. However, the antenna environment can be prone to configuration changes due to variations in critical design parameters such as conductivity and antenna tilt. In this paper, we connect the variations in antenna properties to signal detection prospects. By using realistic simulations of a direction- and frequency-dependent radiation pattern of the SARAS antenna and its transfer function, we establish critical parameters and estimate bias in the detectability of different models of the global 21 cm signal. We find a correlation between the nature of chromaticity in antenna properties and the bias in the recovered spectral profiles of 21 cm signals. We also find stringent requirements for transfer function corrections, which can otherwise make detection prospects prohibitive. We finally explore a range of critical parameters that allow robust signal detection.

Rejection of Surface Clutter in Far Sidelobes for Airborne Radars

In airborne radar, false alarms caused by surface clutter returns through antenna sidelobes need to be suppressed to detect the target of interest. Sidelobe blanking is widely used to reject false alarms. Ideally, an auxiliary antenna radiation pattern should cover entire sidelobes of the main antenna radiation pattern. However, this may not always be satisfied, especially in the case of far sidelobes (FSL) of the main antenna, for various reasons. In this work, rejection techniques for false alarms caused by surface clutter returns through FSL are proposed. The distortion of the measured angle and velocity of the surface clutter are explained, and a measurement process for estimating the true location and velocity of the clutter is derived. Subsequently, two techniques for false alarm rejection are presented. The first technique is based on the look-up table (LUT) of FSL, which is robust but not practical due to the time and cost required to build a LUT with sufficient resolution. In the second technique, false alarms are rejected when they satisfy predefined criteria derived from their common characteristics, and flight test results confirm that false alarms can be effectively rejected by applying the second technique.

A Compact and Flexible Monopole Antenna with Controllable Bandwidth

In this paper, a compact antenna with flexible and controllable bandwidth characteristics is proposed. To ensure wide coverage along with an omnidirectional radiation pattern, a monopole structure was utilized as the primary radiating element of the proposed antenna. The monopole was fed using a coplanar waveguide technique to achieve a single-layer design. To alter the operating bandwidth, defined by a reflection coefficient of less than -10 dB, a single stub was directly connected to the feeding transmission line. By controlling the stub's length, matching performance in the high-frequency range was found to undergo significant degradation, indicating that the operating bandwidth could be controlled. Furthermore, for validation, two antenna prototypes were fabricated and measured under different circumstances. In the unbending mode, the design without the stub achieved a wideband of 51.6%, while the other design with the stub exhibited a narrower band of about 19.6%. Additionally, the antennas worked efficiently when operating in bending mode. It is also worth noting that the antenna gain and radiation pattern remained stable across the entire operating bandwidth.

Radiation Behavior of Synthesized LiTi Ferrite Based Microstrip Antenna in X Band

The paper comprehensively explores the development, characteristics, and antenna applications of lithium titanium (LiTi) ferrite. Utilising a solid-state reaction technique, the study examines the substrate’s electrical, magnetic, and structural properties in detail. Additionally, it assesses the far-field radiation patterns of a magnetically-biased LiTi ferrite-based antenna. Key findings point to a noticeable reduction in mutual coupling and radiated power, along with an isotropic redistribution of minor side lobes. Comparative analysis with RT-duroid substrates in X band frequency spectrum highlights the LiTi ferrite-based antenna’s remarkable 62.85 % miniaturization and consistent directivity, along with a superior quality factor. These findings emphasise LiTi ferrite’s potential for compact, high-performance applications in demanding environments. LiTi ferrite’s advantages in miniaturisation and stability position it for specific applications, despite trade-offs in bandwidth, gain, and impedance compared to RT-duroid substrates.

H-Shape Microstrip Patch Antenna: Design, Simulation, and Characterization

This paper presents the design, simulation, and characterization of an H-shape microstrip patch antenna intended for high-frequency applications. The proposed antenna is modeled using Computer Simulation Technology (CST) Microwave Studio, a powerful tool for simulating electromagnetic fields and optimizing antenna parameters. The H-shaped configuration is chosen to enhance the antenna's radiation characteristics, bandwidth, and gain, while minimizing size and surface wave effects. The design process involves parameter optimization, including substrate selection, patch dimensions, and feed point configuration, to achieve superior performance. Detailed simulation results are presented, demonstrating the antenna's return loss, VSWR, gain, and radiation pattern. The antenna operates efficiently with stable resonance, offering low return loss and high radiation efficiency. The simulation results confirm that the H-shape microstrip patch antenna is well-suited for various wireless communication systems, showing potential for integration in compact, high-performance devices. This paper serves as a step towards further optimization and practical implementation of H-shape microstrip antennas in advanced RF systems.

Ear-to-Ear Propagation Model—Antenna Radiation Pattern Optimization and On-Body Far-Field Formulation

Ear-to-Ear Propagation Model—Antenna Radiation Pattern Optimization and On-Body Far-Field Formulation

Design of Controlled Radiation Pattern Antenna Using Bent Monopole Antenna Array for Anti-Jamming Application

Design of Controlled Radiation Pattern Antenna Using Bent Monopole Antenna Array for Anti-Jamming Application

Experimental demonstration of a silicon nanophotonic antenna for far-field broadened optical phased arrays

Optical antennas play a pivotal role in interfacing integrated photonic circuits with free-space systems. Designing antennas for optical phased arrays ideally requires achieving compact antenna apertures, wide radiation angles, and high radiation efficiency all at once, which presents a significant challenge. Here, we experimentally demonstrate a novel ultra-compact silicon grating antenna, utilizing subwavelength grating nanostructures arranged in a transversally interleaved topology to control the antenna radiation pattern. Through near-field phase engineering, we increase the antenna’s far-field beam width beyond the Fraunhofer limit for a given aperture size. The antenna incorporates a single-etch grating and a Bragg reflector implemented on a 300-nm-thick silicon-on-insulator (SOI) platform. Experimental characterizations demonstrate a beam width of 44°×52° with −3.22 dB diffraction efficiency, for an aperture size of 3.4 μm×1.78 μm. Furthermore, to the best of our knowledge, a novel topology of a 2D antenna array is demonstrated for the first time, leveraging evanescently coupled architecture to yield a very compact antenna array. We validated the functionality of our antenna design through its integration into this new 2D array topology. Specifically, we demonstrate a small proof-of-concept two-dimensional optical phased array with 2×4 elements and a wide beam steering range of 19.3º × 39.7º. A path towards scalability and larger-scale integration is also demonstrated on the antenna array of 8×20 elements with a transverse beam steering of 31.4º.

Dynamic SNR, Spectral Efficiency, and Rate Characterization in 5G/6G mmWave/sub-THz Systems with Macro- and Micro-Mobilities

The performance of 5G/6G cellular systems operating in millimeter wave (mmWave, 30–100 GHz) and sub-terahertz (sub-THz, 100–300 GHz) bands is conventionally assessed by utilizing the static distributions of user locations. The rationale is that the use of the beam tracking procedure allows for keeping the beams of a base station (BS) and user equipment (UE) aligned at all times. However, by introducing 3GPP Reduced Capability (RedCap) UEs utilizing the Radio Resource Management (RRM) Relaxation procedure, this may no longer be the case, as UEs are allowed to skip synchronization signal blocks (SSB) to improve energy efficiency. Thus, to characterize the performance of such UEs, methods explicitly accounting for UE mobility are needed. In this paper, we will utilize the tools of the stochastic geometry and random walk theory to derive signal-to-noise ratio (SNR), spectral efficiency, and rate as an explicit function of time by accounting for mmWave/sub-THZ specifics, including realistic directional antenna radiation patterns and micro- and macro-mobilities causing dynamic antenna misalignment. Different from other studies in the field that consider time-averaged performance measures, these metrics are obtained as an explicit function of time. Our numerical results illustrate that the macro-mobility specifies the overall trend of the time-dependent spectral efficiency, while local dynamics at 1–3 s scales are mainly governed by micro-mobility. The difference between spectral efficiency corresponding to perfectly synchronized UE and BS antennas and time-dependent spectral efficiency in a completely desynchronized system is rather negligible for realistic cell coverages and stays within approximately 5–10% for a wide range of system parameters. These conclusions are not affected by the utilized antenna array at the BS side. However, accounting for realistic radiation patterns is critical for a time-dependent performance analysis of 5G/6G mmWave/sub-THz systems.

Dual-Polarized Dipole Antenna with Wideband Stable Radiation Patterns Using Artificial Magnetic Conductor Reflector.

This paper presents a wideband dual-polarized dipole antenna structure operating at 1.7-3.8 GHz (76.4%). For a traditional 4G dipole antenna that covers the band 1.71-2.69 GHz, it is difficult to maintain the satisfactory impedance matching and normal stable radiation patterns within the 5G sub-6 GHz band 3.3-3.8 GHz, mainly due to the fixed antenna height no longer being a quarter-wavelength. To solve this, a connected-ring-shaped metasurface structure is proposed and deployed to operate as an artificial magnetic conductor (AMC). As a result, stable antenna radiation patterns are obtained within the whole band 1.7-3.8 GHz. For verification, this wideband dipole antenna using AMC is implemented and tested. The measured results show that the proposed antenna has an impedance bandwidth of 80.7% (1.7-4.0 GHz). It has an average measured in-band realized gain of 7.0±1.0 dBi and a stable 70±5 half power beam width (HPBW) within the 4G/5G-sub 6GHz bands 1.71-2.69 GHz and 3.3-3.8 GHz.

Quad-port 28/38 GHz Antenna with Isolation Improvement for 5G Wireless Networks

A 28/38 GHz quad-port cross-shaped antenna printed on a 0.203 mm Roger RO4003 substrate is designed and fabricated for 5G networks. The antenna consists of a rectangular patch radiator with three triangle slots to enhance the antenna's impedance matching. The four elements are arranged in a cross-shaped layout to achieve the desired compactness of 29 mm × 24.2 mm × 0.203 mm. A thin parasitic strip is inserted between the second and fourth elements to enhance the port isolation. The designed antenna is simulated by utilizing the CST simulator. The antenna achieved S11 < -10 dB at 28 / 38 GHz, with isolation ≥ 20 dB. Furthermore, the E- and H-planes within the anechoic chamber are evaluated to validate the MIMO antenna radiation patterns and gain. The MIMO parameters are calculated, simulated, tested, and its outcomes are under the standard level which confirms the MIMO diversity feature. The ECC of the structure is < 0.001, the DG ≥ 9.95 dB. and the CCL was ≤ 0.2 bit/s/Hz across the dual working band.