Frequency Of Antenna Research Articles

Fast ion studies in the extended high-performance high βP plasma on EAST

Abstract Comprehending and optimizing fast ion behaviors is critical for the enhancement of performance in Experimental Advanced Superconducting Tokamak (EAST). This study explores the potential benefits of several factors that can improve the fast ion confinement. First, experiments show the change in the direction of the NBI2 from counter-I p to co-I p leads to a significant reduction in fast ion losses. TRANSP/NUBEAM simulation and tomography results based on fast-ion D-alpha measurements reveal that after the neutral beam injection (NBI) upgrade, the beam ion prompt loss is reduced by approximately 50%. Second, the upgraded ion cyclotron resonant frequency (ICRF) antenna at the N-port features twice the coupling resistance of the original antennas at EAST. This improved ICRF power coupling has enhanced the synergistic heating effect of NBI + ICRF, where the ICRF wave field accelerates beam ions at the harmonics. Experiments demonstrate that NBI + ICRF synergistic not only enhances plasma neutron yield and β P, but also accelerates beam ions to hundreds of keV. Further, the electron density and the neutral beam voltage have been optimized to reduce the fast ion slowing-down time and beam ion losses. Experimental and simulation results indicate that increasing the electron density reduces beam ion losses and enhances the bootstrap current fraction. While higher beam voltage results in a slight decrease in beam power absorption, it can increase the fraction of bootstrap current. With the understanding of these optimization of fast ion confinement, experiments have demonstrated fully non-inductive operation at high density (n e/n G ∼ 0.67, β P ∼ 3.1, β N ∼ 2.1, H 98,y2 ∼ 1.2) even without the support of co-I p beam NBI2. This investigation presents a potential regime to enhance fast ion confinement and extend performance in the high β P plasma for future experiments.

Machine learning‐driven design of dual‐band antennas using PGGAN and enhanced feature mapping

AbstractThis paper presents a systematic antenna design methodology that integrates machine learning, leveraging the progressive growth technique of Progressive Growing of GANs (PGGAN) to generate images of various dual‐band PIFA‐like antenna structures. The process involves using data augmentation methods to generate 4180 antenna samples. In the latent space, the authors employ Latin Hypercube Sampling to maintain diversity and combine it with the Hough Transform to enhance the edge features of the antennas while providing labelling functionality. This labelling method strengthens the relationship between antenna frequency and wavelength characteristics. The paper clearly outlines the design process, starting from the simulation of two types of single‐frequency PIFA‐like antennas (2.45 and 5.2 GHz, respectively) to the completion of PGGAN's generation task, resulting in a novel dual‐band Wi‐Fi PIFA‐like antenna structure. The measurement results of the dual‐band antennas exhibit excellent consistency with the simulation results.

Combining Microstrip Meander Line and Dipole Antennas: Dual-Band Solution for PIR Equipment

One of the aviation navigation tools is the Instrument Landing System (ILS), which functions to provide guidance signals to aircraft in the final approach position toward the runway. The ILS consists of three components: the Localizer, Glide Path, and Marker Beacon. To ensure aviation safety and security, navigation equipment must be regularly inspected through Ground Inspection. With current technological advancements, Ground Inspection is being conducted using UAVs or drones. One of the components to be installed on the UAV is the PIR, which requires two antennas of different lengths to receive signals from the Localizer and Glide Path.In this study, a dual-band antenna was developed that combines a dipole antenna and a meander line microstrip antenna for frequencies 108-112 MHz and 328.6-335.4 MHz, using CST Studio Suite 2021 software and FR-4 substrate material. Simulation results showed good performance with a return loss value of -19.43471 dB, VSWR of 1.238951, and a bandwidth of 2 MHz at a frequency of 110.5 MHz, and a return loss value of -27.41626 dB, VSWR of 1.119686, and a bandwidth of 2.5 MHz at a frequency of 329.6 MHz.Measurement parameter values for the VHF band were a return loss of -14.1680 dB, VSWR of 1.487, and a bandwidth of 14.6 MHz. Meanwhile, for the UHF band, there was a shift in the resonance frequency to 368.5 MHz with a return loss value of -15.4202 dB, VSWR of 1.408, and a bandwidth of 11.4 MHz. In this antenna design, a dual-band combination of a dipole and a meander line microstrip antenna with dimensions of 320 mm was achieved, capable of operating in both the VHF and UHF frequency bands simultaneously. However, this antenna can only operate at the Localizer working frequency.

Dual magnetoelectric antenna array with enhanced bandwidth and sensitivity for low-frequency communications

The magnetoelectric coupling effect demonstrated immense potential for miniaturizing antenna applications. However, due to the resonant nature of magnetoelectric (ME) antennas, their bandwidth tended to be relatively narrow. To address this limitation, our study introduced an array design based on coupled ME antennas. A tri-layer FeGa–PZT8–FeGa laminate structure was employed to construct the ME antennas, which utilized inter-array coupling to broaden the frequency range. Both the central frequency and sensitivity of the array structure were theoretically analyzed, and two methods for extending the frequency were proposed. By coupling two ME antennas of similar frequency in the series mode, the arrayed ME antennas exhibited enhanced sensitivity, increasing from 0.225 and 0.247 to 0.413 mV/nT, and an expanded bandwidth from 0.92–1.03 to 1.4 kHz, indicating improved performance through combined configuration. On the other hand, by coupling two ME antennas of different frequencies together in the series mode, a dual-frequency (97.8/98.97 kHz) ME antenna array was formed. The communication capabilities of the ME antenna array under weak magnetic fields were demonstrated using amplitude shift keying and frequency shift keying modulation methods. The designed array of ME antennas elevated low-frequency communication performance and possessed excellent magnetic field detection capabilities, thereby offering a cost-effective technological pathway for bioelectronic and marine communication design.

Passive wireless RFID strain sensor for directional-independent structural deformation monitoring

The advancement of Radio-frequency identification (RFID) sensor technology presents a novel approach to monitoring the health of structures. However, the traditional RFID antenna sensor encounters issues with limited sensitivity and strain measurement capabilities in a single direction. In this investigation, we propose, model, analyze, and test an enhanced wireless and passive RFID strain sensor that offers improved sensitivity to strains and quantifiable measurements in orthogonal directions. Theoretical analysis based on multiphysics elastodynamics and electromagnetics illustrating the resonant response and distribution of current field density between two sets of orthogonally installed sensors under applied stress. Our findings reveal that the RFID strain sensor exhibits characteristics to electromagnetically induced transparency like (EIT-like) effect, enabling independent and intensified measurement of strains both horizontally and vertically. Experimental data demonstrates a linear correlation between the shift in resonant frequency of the sensor antenna and transverse strains as well as longitudinal strains, with sensitivity coefficients measuring −1.76 kHz με−1 for transverse strain and 2.17 kHz με−1 for longitudinal strain respectively. Consequently, by accurately analyzing variations in resonant frequency it becomes possible to deduce both magnitude and direction of strains on the antenna effectively laying groundwork for future engineering applications.

A novel miniaturized metamaterial inspired frequency reconfigurable antenna with switchable polarization for sub 6 GHz band

Abstract A metamaterial-inspired frequency reconfigurable antenna with switchable polarization realized for 2.4 GHz, 3.5 GHz, and 5.8 GHz frequencies, is reported in this work. Initially, a conventional rectangular patch is designed to resonate at 3.5 GHz. A regular square-shaped SRR (Split Ring Resonator) is a metamaterial-inspired structure that excites additional resonance at 5.8 GHz, without increasing the antenna form factor. Further, a parasitic patch is introduced to create one resonance at 2.4 GHz. Reconfigurability of frequency and polarization is achieved using MPP4203 series PIN diodes. The antenna is simulated using CST Microwave Studio Suite 2019. The designed antenna, characterized by reflection coefficient and bandwidth is analysed for three diode states. The devised antenna operates at 2.4 GHz, 3.5 GHz, and 5.8 GHz, with a maximum bandwidth of 346.2 MHz at the 5.8 GHz frequency band. The radiator outperformed other similar antennas reported in the literature in terms of antenna size, bandwidth, and frequency cum polarization reconfigurability.

Investigating enhanced electrical conductivity for antenna applications through dual metallization on 3D printed SLA substrates

The advancement of 3D printing (additive manufacturing) has gained interest in variety of applications, especially for antenna fabrication. The demand for cheap, reliable, and high-performance antenna fabrication methods is essential in order to cope with the demand of wireless communications industry. In this work, the focus was emphasized on enhancing the electrical conductivity of the 3D printed substrates fabricated by stereolithography (SLA) 3D printer. The 3D printed substrate went through a dual metallization approach, involving sputtering and electrodeposition techniques for the fabrication of conductive metal layers. The parameters for the sputtering were fixed for all the substrate while current density during electrodeposition process was varied at 25 %, 50 %, 75 % and 100 % from recommended value of current. The results showed that the current density during the electrodeposition determined the conductivity performance of the metal layers and established a significant correlation with the surface morphological. Three different frequencies comprised of 2.4 GHz, 3.5 GHz and 5.0 GHz were selected to simulate and fabricate a microstrip patch antenna using the optimized current density which was valued optimal at 75 % (52.5 mA). The percentage of accuracy between simulated and measured frequencies of antenna, portrayed that the measured values were slightly higher than the simulated approximately about 5.14 to 6.67 %. Therefore, the integration of additive manufacturing or 3D printing techniques for antenna could address the critical necessity for fast and economical solution in wireless systems.

MEDEA: A New Model for Emulating Radio Antenna Beam Patterns for 21 cm Cosmology and Antenna Design Studies

In 21 cm experimental cosmology, accurate characterization of a radio telescope’s antenna beam response is essential to measure the 21 cm signal. Computational electromagnetic (CEM) simulations estimate the antenna beam pattern and frequency response by subjecting the EM model to different dependencies, or beam hyperparameters, such as soil dielectric constant or orientation with the environment. However, it is computationally expensive to search all possible parameter spaces to optimize the antenna design or accurately represent the beam to the level required for use as a systematic model in 21 cm cosmology. We therefore present the Model for Emulating Directivities and Electric fields of Antennas (MEDEA), an emulator that rapidly and accurately generates far-field radiation patterns over a large hyperparameter space. MEDEA takes a subset of beams simulated by CEM software, spatially decomposes them into coefficients on a complete, linear basis, and then interpolates them to form new beams at arbitrary hyperparameters. We test MEDEA on an analytical dipole and two numerical beams motivated by upcoming lunar lander missions, and then employ MEDEA as a model to fit mock radio spectrometer data to extract covariances on the input beam hyperparameters. We find that the interpolated beams have rms relative errors of at most 10−2 using 20 input beams or less, and that fits to mock data are able to recover the input beam hyperparameters when the model and mock are derived from the same set of beams. When a systematic bias is introduced into the mock data, extracted beam hyperparameters exhibit bias, as expected. We propose several extensions to MEDEA to potentially account for such bias.

A Gain‐Enhanced Multiband Frequency and Pattern Reconfigurable Antenna for Wi‐Fi 6E and 5G New Radio Wireless Standards

A Gain‐Enhanced Multiband Frequency and Pattern Reconfigurable Antenna for Wi‐Fi 6E and 5G New Radio Wireless Standards

A Machine to Listen to the Sky: Transducing Space Weather

A Machine to Listen to the Sky: Transducing Space Weather delves into the intersection of art, science, and technology by capturing electromagnetic signals from natural and man-made sources. Using custom-built Very Low Frequency (VLF) antennas, Tapper explores the invisible soundscape created by space weather and terrestrial activity, including solar radiation lightning, and power grids. His work investigates how these signals interact with the Earth’s ionosphere, transforming scientific phenomena into artworks disseminated through workshops, installations, and field recordings.

Выбор сопротивления нагрузки приемной электрически малой антенны по критерию минимальной неравномерности группового времени запаздывания принятого сигнала

The accuracy of determining coordinates in terrestrial radio navigation systems (RNS) depends on the receiving antenna frequency response irregularity: received signal power and group delay time (GD). Due to the limited space on the carrier, the RNS receiving antennas are small and cannot be effectively matched with feeder over the entire operating frequency band. The paper considers two options for the RNS receiver input circuit. First is a classical matching scheme and second is direct connection of the antenna to the receiver input. It is shown that the most uniform frequency characteristics are achieved when the antenna is connected directly to reciever. In this case, the maximum received signal power occurs when the antenna input resistance module and the load resistance are equal. At the same time, high load resistance increases the frequency response irregularity. Therefore, the choice of load resistance should be made compromising manner, taking into account signal level, available input amplifier gain and the allowed frequency response irregularity.

Microstructural, dielectric, electrical, electromagnetic, and magnetic property enhancements in GdIG /TrIG/ Mn0.2Co0.3Zn0.5Fe2O4 ferrites composites for electronic devices application

Gadolinium garnet ferrite (GdIG) and terbium garnet ferrite (TrIG), known for their favourable magnetic and dielectric characteristics, were combined with doped zinc spinel ferrite (GdIG)x-(TrIG)y/Mn0.2Co0.3Zn0.5Fe2O4(1-x-y) (at x=1 y=0, x=0 y=1, x=y=0.5, x=y=0.25, x=y=0) to achieve improved permittivity, permeability and magnetic properties with reduced magneto-dielectric losses. Our study details the synthesis process and the resulting enhancements in structural, magnetic, and dielectric properties of the prepared samples. Analysis of the X-ray diffraction (XRD) patterns confirmed the presence of a crystalline structure characterized by both cubic spinel and cubic garnet phases in the composites. The microstructures of the composites were analysed with field emission scanning electron microscopy (FESEM), revealing the variation in a grain size from 0.11 μm to 0.96 μm at x =y=0.5. A thorough link between the crystal structure and XRD spectra, transmission electron microscope (TEM), and selected area electron diffraction (SAED) patterns have all been investigated in order to enhance the characterisation of the samples. At 1KHz, the composites exhibit highest electrical resistivity values of 5.9×106 Ωm and 2.6×106 Ωm. With the incorporation of spinel ferrites in garnet ferrite composite (x=y=0.25) the highest value of dielectric constant (885.2) and low value of dielectric loss (0.07) at 100 KHz has been obtained. Permeability values, derived from permittivity data, showed an increase in real permeability values of from 1.4×1012 to 9.2×1017 for x=y=0.5 to x=y=0.25 composite. Vibrating sample magnetometer (VSM) further confirm that the composite x=y=0.25 has highest magnetic saturation (148.8 emu/g), coercivity (502 Oe) and microwave operating frequency (33.6 GHz). The observed high dielectric constant, low loss values, switching field distribution and good magnetic properties suggest the potential suitability of these samples for various electronic devices like: high frequency devices, antennas, switching devices and magnetic recording devices.

Theoretical investigation of HTS compact microstrip antennas printed on anisotropic substrates using hybrid cavity model

This work explores the effects of a compact, superconducting C-shaped patch printed on uniaxial anisotropic substrate, utilizing two uniaxial substrate materials: boron nitride and magnesium fluoride. This study employed the superconducting material BSCCO (2212 BSCCO crystal), with a critical temperature of 95 K. Using the hybrid cavity model, we identified and extracted two key parameters: the resonance frequency of conductive elements and the superconducting resonance frequency. We analyzed the impact of the operating temperature on the resonant frequency of a C-shaped superconductivity microstrip antenna, as well as the effect of the uniaxial substrate material and its thickness on the surface resistance and surface reactance. The results showed that temperature significantly affects the resonant frequency of the compact antenna. Our research highlighted the importance of selecting the correct operating temperature for a superconducting microstrip antenna to ensure optimal performance in compact microstrip antenna designs.

A Review of the Applications of Through-the-Earth (TTE) Communication Systems for Underground Mines

AbstractUnderground mining accidents have the potential of leaving miners trapped in unknown and life-threatening locations for an extended period of time. The lives of the trapped and unaccounted-for miners are at risk and require emergency rescue. But, the primary tracking systems are highly susceptible to damage during accidents and are most likely to be defunct and inoperable post-accident. This prompted the need for a robust and reliable post-accident communication and locator system. Subsequently, the through-the-earth (TTE) communication systems were developed and tested in underground mines. Under ideal conditions, these systems are capable of post-accident full-duplex two-way voice, text, and data communication and fingerprint detection of the geolocations of the trapped miners. This is achieved through a wireless link established by the transmission of electromagnetic and seismic waves between surface and underground, even in challenged underground environments. Unlike the primary tracking systems, the TTE communication systems do not require extensive shaft-to-workplace backbone infrastructure. This has made the TTE systems to be less susceptible to damage and therefore suitable for post-accident communication. Instead, the Earth’s crust acts as the signal transmission medium which forms an uplink and downlink communication path. This is achieved by injecting an electric current into the ground using electrodes, by transmitting magnetic fields from a radiating loop antenna, or by inducing fingerprint geolocations using seismic waves. Range and data rates are the critical requirements for the effectiveness of these systems and are dependent on factors such as the antenna design, frequency, and rock properties. This study provides a review of the applications of the different types of TTE communication systems, their evolution, factors that affect them, and techniques for improving their efficiencies and capabilities. These systems present the mining industry with an opportunity to improve safety by providing post-accident communication and locating trapped miners as quickly as possible. This will improve their survival chances and ultimately reduce fatality rates in the mining industry.

WITHDRAWN: A Novel Wideband Circular Polarized Filtering Antenna based on Left Hand Metamaterial

Across a broad frequency range, this reconfigurable antenna can be used for 5G, multi-function radars and automobile applications. To obtain ultra-wideband (UWB), the monopole antenna patch is suitably etched, and a stub is inserted to the feed line. In the meantime, an electromagnetic band gap (EBG) and rectangle slots are added in the partial ground to expand its operational bandwidth, which ranges from 2.7GHz to 23GHz. Size shrinkage rises to 65% when step feed is used in conjunction with partial grinding. Loading left-hand metamaterial (LHM) behind the monopole patch and etching slots at the corners of the rectangular patch results in circular polarization and an increase in gain. By placing a filter across the feedline, the recommended antenna's frequency and bandwidth can be adjusted as needed, enabling bandwidth reconfiguration. The via loaded in the patch extends the axial ratio (AR) bandwidth from 5GHz to 21GHz.The recommended antenna's step feed has a vertical slit that improves impedance matching over a wide operating spectrum.

Characterization of plasma parameters and neutral particles in microwave and radio frequency discharges in the Toroidal Magnetized System.

A characterization of plasma parameters and neutral particle energies and fluxes has been performed for radio frequency and microwave discharges in the Toroidal Magnetized System (TOMAS). A movable triple Langmuir probe was used to study the electron densities and temperatures, and a time-of-flight neutral particle analyzer was used to measure the energy and fluxes of neutral particles, as a function of the total injected power and the antenna frequency used to generate the plasma. The experimental results can provide information on the behavior of neutral particles at low energies in wall conditioning plasmas.

Design and research of high-frequency electromagnetic wave detection antenna for discharge of transmission lines

Abstract Overhead lines have a wide range of applications in power systems. When early insulation faults occur in the long-term operation of overhead lines, corona discharge may occur. Timely detection of corona discharge can guide maintenance personnel to discover and eliminate faults in a timely manner. The height and distribution of overhead lines are relatively high, and close-range detection cannot quickly locate the discharge area. Using radio frequency antennas to measure the electromagnetic wave signals generated by corona discharge can achieve long-distance positioning detection of corona discharge. This article uses a log-periodic antenna as the detection antenna and simulates the antenna structure to prove that its directionality, gain, and measurement frequency band meet the design requirements. Finally, the discharge detection performance of the antenna is verified through experiments.

Doppler sensitivity and resonant tuning of Rydberg atom-based antennas

Radio frequency antennas based on Rydberg atom vapor cells can in principle reach sensitivities beyond those of any conventional wire antenna, especially at lower frequencies where very long wires are needed to accommodate the increasing wavelength. They also have other desirable features such as consisting of nonmetallic, hence lower profile, elements. This paper presents a detailed theoretical investigation of Rydberg antenna sensitivity, elucidating parameter regimes that could cumulatively lead to a sensitivity increase 2–3 orders of magnitude beyond that of currently tested configurations. The key insight is to optimally combine the advantages of two well-studied approaches: (i) three laser ‘2D star configuration’ setups that, when enhanced with increased laser power, to some degree compensate for atom motion-induced Doppler broadening, and (ii) resonant coupling between a pair of near-degenerate Rydberg levels, tuned via a local oscillator to the incident signal of interest. The advantage of the star setup is subtle because it only restores the overall sensitivity to the expected Doppler-limited value, compensating for additional significant off-resonance reductions where differently moving atom sub-populations destructively interfere with each other in the net signal. An additional unique advantage of local oscillator tuning is that it leads to vastly narrower line widths, as low as ∼10 kHz set by the intrinsic Rydberg state lifetimes, rather than the typical ∼10 MHz scale set by the core state lifetimes. Intuitively, with this setup the two Rydberg states may be tuned to act as an independent high-q cavity, a point of view supported by a study of the frequency-dependence of the antenna resonant response. There are a number of practical experimental advances, especially larger ∼1 cm laser beam widths, required to suppress various extrinsic line broadening effects and to fully exploit this ‘Rydberg superheterodyne’ response.

Low‐cost and easy‐to‐embed 7‐bit 360° phase shifter with transitions for large‐scale phased arrays

AbstractIn this letter, a low‐cost and easy‐to‐embed 7‐bit 360° phase shifter with transitions is presented for applications to beamforming in the large‐scale phased array. In the proposed 360° phase shifter, the topology of the reflection‐type phase shifter (RTPS) is employed, composed of a 3‐dB branchline coupler terminated with two tunable parallel L–C loads. First, a two‐step phase extraction process for RTPS is applied to design the RTPS rapidly with competitive performance, including 360° phase range and low insertion loss. A huge amount of parameter sweep is reduced in the design and test. Meanwhile, the parameter of inductors in the tunable loads is investigated effectively, to achieve the minimal phase step. Second, aiming at the enhanced performance of beamforming and improved flexibility of integration, the stripline is adopted in the design of the phase shifter, avoiding the interference on antenna radiation effectively. To facilitate the integration with antenna and radio frequency connectors of the input and output signals, a stripline‐to‐microstrip line transition with electromagnetic bandgap structures is adopted. By this means, the complexity and cost of fabrication are decreased. Finally, fabricated in the low‐cost printed circuit board technology, our proof‐of‐concept design operated from 2.4 to 2.5 GHz is measured and achieves a 386.8° phase shift range with an insertion loss of 2.21 ± 0.82 dB at 2.45 GHz.

Phonon–Polaritonic Resonances on Nanopillars of Hexagonal Boron Nitride for Surface‐Enhanced Infrared Absorption

Phonon polaritons (PhPs) in hexagonal boron nitride enable sharp midinfrared optical resonance with strong spatial confinement, making them promising for surface‐enhanced infrared absorption (SEIRA) spectroscopy. Here, using colloidal nanosphere lithography, hBN nanopillar antennas are fabricated and their PhP resonances in a cost‐effective way are demonstrated. By varying the diameters of the hBN nanopillars, the PhP resonance can be readily tuned to match the molecular vibrations of CBP (4,4′‐bis(N‐carbazolyl)‐1,1′‐biphenyl) molecules. Upon frequency matching, the coupling between the PhP resonance and the molecular vibration shows pronounced mode splitting, illustrating the SEIRA behavior with a coupling strength approaching the strong coupling regime. However, with slight frequency mismatching around 10 cm−1, the coupling strength decreases significantly, indicating a high sensitivity of the SEIRA activities to the resonance frequency of hBN nanopillar antennas. The findings provide a new method for the fabrication of PhP nanoantennas and may promote the development of PhPs in SEIRA‐based midinfrared sensing applications.