Magnetic Antenna Research Articles

Nanocomposite Embedded Electric and Magnetic Material Enhancing Antenna Radiation by Linear Relation in Radiators

The main and auxiliary radiating elements are linked by linear mathematical relation and coated with nanocomposite (NC) materials to enhance radiation characteristics. Nanocomposite-based electric material (NE) and nanocomposite-based magnetic material (NM) coated on auxiliary radiating elements to enhance the electromagnetic radiation of the proposed antenna. The radiating elements coated with NE graphene oxide (GO) and NM barium ferrite (BF) have higher electric field and magnetic field distribution respectively. The linear relation of main and auxiliary elements is verified by two substrates FR4, Teflon with correlated results. This proposed NC-coated antenna produces a bandwidth of 4.15 GHz, 4.02 dBi average gain and radiation efficiency of 95.17%, being superior to the antenna without NC coating. Fabricated antenna has 1.56–5.71 GHz bandwidth that includes 2.4/5.2 GHz WLAN, 2.5/3.5 GHz WiMAX, 2.4 GHz ISM, 5G SUB-6 GHz, 5G NR 78 and 2.4/5 GHz Wi-Fi bands.

Comparison of anomalies in the VLF spectrum of the natural electromagnetic field with data from the seismometer in a landslide-affected area

The data from a permanent monitoring station, based on a sound card as an AD/DA converter and a magnetic loop antenna for continuous recording of electromagnetic field intensities in the Very Low Frequency (VLF) range, were recorded and compared with data from a seismic station based on Raspberry Pi located in a landslide-affected area. The stations operated 24/7 and were placed in a room below ground level. Correlations were observed between seismic signals in the frequency spectrum from 0.1 Hz to 10 Hz (some extending beyond 20 Hz) and anomalies in the electromagnetic field in the VLF range. These anomalies are likely associated with micro-fracturing, piezo-electromagnetic, and triboelectric phenomena within the landslide body, producing relatively weak VLF emissions and a faint seismic signal. A single-component 4.5 Hz 395 Ohm vertical Racotech RGI-20DX geophone with electronic extension to lower frequencies (< 1 Hz) was used with a sampling rate of 100 sps (samples per second). VLF emissions cover almost the entire spectrum from 6 kHz with a peak at 14 kHz to 18 kHz. The received spectrum was divided into following sections: VLF band 4 kHz – 6 kHz; 6 kHz – 8 kHz; 8 kHz – 10 kHz; 10 kHz – 12 kHz; 12 kHz – 14 kHz; 14 kHz – 16 kHz; 16 kHz – 18 kHz. Simultaneously, there were changes in these sections analysed and compared with the seismic record within the same time interval.

Creating spatial doughnut-spot arrays and double-helix focal fields with prescribed characteristics

Spatially controllable focal fields play a pivotal role in light manipulation and provide significant opportunities for precisely manipulating light–matter interactions in a wide range of applications. In particular, the double-helix focal field—characterized by a distinctive helical structure—exhibits exceptional optical properties, thus differentiating it apart from conventional focal fields. However, the rapid construction of a double-helix focal field with controllable characteristics and a uniform intensity remains a challenging task. Based on the theory of pattern synthesis of an antenna array, we propose and realize the generation of three-dimensional doughnut-spot arrays and double-helix focal fields with specified characteristics in a 4π system by reverse-solving the radiation field of the virtual antenna. Numerical examples indicate that the desired novel focal fields, including features such as shape, orientation, length, and period, could be rapidly, conveniently, and flexibly customized by selecting appropriate parameters for the magnetic dipole array antennas. This method could reveal an avenue for enhanced light manipulation for applications in materials processing, optical lithography, and optical communications.

Matched dielectric slot waveguide as an all-dielectric terahertz magnetic dipole.

We observe that the modal field distribution of a dielectric slot waveguide closely resembles a magnetic dipole antenna. Such an aperture distribution traditionally demands metals, making it ill-suited to high frequencies due to excessive ohmic loss. By terminating a dielectric slot waveguide with a matched free-space interface, a compact all-dielectric radiating magnetic dipole is realized. In this way, we introduce general-purpose dipole antennas, which have long been a mainstay of RF and microwave ranges, into the realm of light wave photonic integrated circuits. The existence of the desired magnetic dipole aperture distribution is experimentally confirmed in the terahertz range, at ∼275 GHz, and good matching is evident in the ∼-25 dB reflection level. This is the electrically smallest radiator to ever be incorporated into an all-dielectric waveguiding platform.

Design of UWB Electrically Small Antenna Based on Distributed Passive Network Loading

In this paper, an ultra-wideband electrically small antenna based on distributed passive network loading is proposed. Based on the Vivaldi antenna theory, magnetic dipole antenna theory, and distributed loading theory, the electrically small antenna achieves the purpose of being wideband using a three-dimensional design of a planar Vivaldi antenna structure under limited space constraints. At the same time, the magnetic dipole antenna is introduced to effectively expand the low-frequency bandwidth of the electrically small antenna without increasing the aperture size. Finally, through the distributed passive network loading, the wideband-conjugated matching of the electrically small antenna is achieved without increasing the size of the electrically small antenna. The −6 dB bandwidth of the electrically small antenna is 0.2 GHz–3 GHz, and the overall size is 0.06 λ0 × 0.05 λ0 × 0.12 λ0, where λ0 is the wavelength of the lowest frequency of the antenna. One sample of the proposed UWB electrically small antenna is fabricated and tested. Good agreement between simulation results and measurement results are obtained. The design method of UWB electrically small antenna proposed in this paper can be applied to the base station antenna, low-frequency detection, microwave sensing, and microwave measurement.

Mid-range wireless power transfer: anapoles or magnetic dipoles?

For short-range wireless power transfer (WPT) one recently suggested so-called anapole antennas that practically do not create fields in the far zone, eliminating radiation loss. Enhancements of power transfer efficiency (PTE) compared to traditional WPT systems based on magnetic dipole antennas were claimed for distances of the order of one-tenth of the wavelength or smaller. In this Letter, we theoretically show that a system of two properly engineered magnetic dipole antennas grants a similar PTE for this range of distances and a higher PTE for larger distances. In addition, we demonstrate that at mid-range distances, the radiation from magnetic-dipole-based WPT systems can be made drastically lower than the radiation from a single magnetic dipole antenna. This regime offers an alternative for reduction of far-field radiation.

Numerical signal calculation and detection capability of magnetic resonance antenna with high rectangular coefficient

Magnetic resonance technology is widely used for groundwater detection due to its direct and quantitative advantages, typically employing square antennas. However, in narrow environments such as mine roadways, canyons, and dams, rectangular antennas with varying dimensions are more practical than square ones. The existing literature lacks comprehensive discussion about the response characteristics of magnetic resonance signals of rectangular antennas, particularly those with high rectangular coefficients. This paper addresses the challenges encountered in a particular application scenario by computing the magnetic resonance excitation magnetic field generated by a rectangular antenna. In addition, it determines the response characteristics of the magnetic resonance signal of rectangular multi-turn coils. We propose coefficient indices of magnetic resonance antennas with different rectangular coefficients, in conjunction with the receiving antenna's matching system to evaluate the actual detection capabilities of various rectangular antennas. Field testing validates the proposed method's effectiveness, providing a robust foundation for assessing the actual detection capability of magnetic resonance antennas and selecting appropriate antennas for specific scenarios.

Revolutionizing Connectivity: The Breakthrough of Batteryless Mouse Using Magnetic Resonant Coupling for Communication Devices

With the rapid development of electronic technology and information technology, personal computer has gradually become the public's office or entertainment tools, which also makes the computer mouse a widely used tool. However, most computer mouse on the market today come with batteries. In this context, it is necessary to design a batteryless mouse that without using power supply such as battery. In view of such demand, on the basic of theoretical analysis, this paper summarizes and designs a classical wireless transmission structure – magnetic resonant coupling and antenna that used to transmit and received power for communication devices. In order to understand the operation of wireless power transmission technology, the paper analysed antenna construction and wireless power transmission technology. The basic design parameters of the axial mode helical antenna structure are also explained. Finally, by using CST STUDIO software, axial mode helical antenna with gain of 6.45 dBi was obtained. The system's output voltage is successfully simulated at 1.516 V that can powered up the computer mouse.

Achiral Magnetic Photonic Antenna as a Tunable Nanosource of Chiral Light

Achiral Magnetic Photonic Antenna as a Tunable Nanosource of Chiral Light

Магнитное поле многовитковой цилиндрической катушки с ферромагнитным сердечником в непосредственной близости от металлических конструкций в задаче поиска людей под завалами в шахтах

Some aspects of the low-frequency magnetic field propagation in heterogeneous medium in mines are discussed in the paper. The theoretical model for calculation of magnetic field distribution in case of the parallel axis of transmitting antenna and bulk metal is developed. Metal structures are rail tracks, magnetic antenna is multiturn cylindrical coil with ferromagnetic core. Magnetic field according to proposed models principle in several stages using the method of integral equations was numerical calculated. This method of calculation of magnetic field in considered inhomogeneous space is based. The calculations of magnetic field strength of the multiturn cylindrical coil with ferromagnetic core in nearby proximity and at various distances from bulk metal were carried out. The possibility of use of low-frequency magnetic field attenuation for people search under avalanches was proved.

Motion-Induced Noise Mechanism Analysis and Reduction Algorithm of ELF Magnetic Receiving Antennas

Motion-induced noise is the main noise that limits extremely low-frequency communication for both shore-based and deep-sea submarines. This manuscript starts from the generation mechanism of motion-induced noise in magnetic antennas, and focuses on the causes of motion-induced noise in magnetic antennas on fixed platforms. The theoretical conclusion reveals that the vibration of magnetic antennas will induce their internal motion-induced noise in either differential or integral form, indicating a clear linear relationship between the vibration and motion-induced noise of magnetic antennas. Based on the generated principle of motion-induced noise presented in this manuscript, corresponding noise reduction algorithms are proposed, and an effective way to apply adaptive filtering algorithm in motion-induced noise cancellation is also presented to accurately reduce this type of noise. In different types of experiments on motion-induced noise testing, the noise reduction results obtained by different noise reduction algorithms demonstrate that the method proposed in this manuscript can achieve effective cancellation of motion-induced noise in magnetic antennas. This experimental result further confirms the research conclusions in this manuscript and provides a feasible approach for practical motion-induced noise cancellation.

High-Efficiency Wide-Angle Scanning Mechanoelectrical Hybrid Phased Array Antenna With Mechanically Reconfigurable Element Pattern

In this paper, a high-efficiency wide-angle scanning mechanoelectrical hybrid phased array antenna with mechanical-ly reconfigurable element pattern is proposed. The proposed array is composed of several linear array panels, which can be mechanically rotated. In contrast to conventional hybrid scan-ning arrays, it rotates in the elevation plane with only three fixed states enabling quick beam switching capabilities, rather than constantly rotating in the azimuth plane. The optimal element's half power beam-width (HPBW) and panel rotation angle are examined in this paper to produce the best scanning range and gain performance in the rotation plane for the array. As a proto-type, an 8×8 array formed by an equivalent magnetic dipole patch antenna, whose HPBW is properly designed to satisfy the optimal value, is configured and fabricated. Both simulated and experimental results show that the proposed array can scan its main beam from -67° to 67° in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">yoz</i> plane, -75° to 75° in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">xoz</i> plane, and its 3-dB beam coverage reaches ±82°, ±90° in the two planes. Additionally, the peak efficiency of the array can reach 75%.

Intense Pulsed Light Thermal Treatment of Pb(Zr,Ti)O3 /Metglas Heterostructured Films Resulting in Extreme Magnetoelectric Coupling of over 20Vcm-1 Oe-1.

Magnetoelectric (ME) film composites consisting of piezoelectric and magnetostrictive materials are promising candidates for application in magnetic field sensors, energy harvesters, and ME antennas. Conventionally, high-temperature annealing is required to crystallize piezoelectric films, restricting the use of heat-sensitive magnetostrictive substrates that enhance ME coupling. Herein, a synergetic approach is demonstrated for fabricating ME film composites that combines aerosol deposition and instantaneous thermal treatment based on intense pulsed light (IPL) radiation to form piezoelectric Pb(Zr,Ti)O3 (PZT) thick films on an amorphous Metglas substrate. IPL rapidly anneals PZT films within a few milliseconds without damaging the underlying Metglas. To optimize the IPL irradiation conditions, the temperature distribution inside the PZT/Metglas film is determined using transient photothermal computational simulation. The PZT/Metglas films are annealed using different IPL pulse durations to determine the structure-property relationship. IPL treatment results in an enhanced crystallinity of the PZT, thus improving the dielectric, piezoelectric, and ME properties of the composite films. An ultrahigh off-resonance ME coupling (≈20Vcm-1 Oe-1 ) is obtained for the PZT/Metglas film that is IPL annealed at a pulse width of 0.75ms (an order of magnitude higher than that reported for other ME films), confirming the potential for next-generation, miniaturized, and high-performance ME devices.

A Strong Pulsing Nature of Negative Intracloud Dart Leaders Accompanied by Regular Trains of Microsecond‐Scale Pulses

AbstractWe report the first observations of negative intracloud (IC) dart‐stepped leaders accompanied by regular trains of microsecond‐scale pulses, simultaneously detected by shielded broadband magnetic loop antennas and the radio telescope Low Frequency Array (LOFAR). Four investigated pulse trains occurred during complicated IC flashes on 18 June 2021, when heavy thunderstorms hit the Netherlands. The pulses within the trains are unipolar, a few microseconds wide, and with an average inter‐pulse interval of 5–7 μs. The broadband pulses perfectly match energetic, regularly distributed, and relatively isolated bursts of very high frequency sources localized by LOFAR. All trains were generated by negative dart‐stepped leaders propagating at a lower speed than usual dart leaders. They followed channels of previous leaders occurring within the same flash several tens of milliseconds before the reported observations. The physical mechanism remains unclear as to why we observe dart‐stepped leaders, which show mostly regular stepping, emitting energetic microsecond‐scale pulses.

Compact substrate‐integrated waveguide filtering multiple‐input multiple‐output magnetic dipole antenna with high selectivity and high isolation

AbstractA compact substrate‐integrated waveguide (SIW) filtering multiple‐input multiple‐output magnetic dipole antenna with high selectivity and high isolation is proposed. Each filtering antenna element contains a SIW cavity, a half‐mode SIW cavity, and a magnetic dipole antenna with backed ground. Meanwhile, the SIW cavity and the half‐mode SIW cavity are vertically connected through magnetic coupling, and second‐order filtering frequency responses can be obtained. Owing to the cross‐coupling between the feeding line and antenna, two radiation nulls can be created to realize high selectivity. Based on the radiation mechanism of the magnetic dipole antenna and polarization diversity, high isolation can be obtained. The measured isolation and the envelope correlation coefficient are greater than 24 dB and less than 0.004, respectively.

Research on radiation field and driving based on super-low frequency mechanical antenna array

Mechanical antennas (MAs) directly use the mechanical motion of electric or magnetic charges to excite electromagnetic waves. The radiation distance of rotating magnetic dipole type mechanical antennas is related to the volume of the radiation source, so the volume of the radiation source is too large for long-distance communication. To solve the above problem, we first establish the magnetic field model and differential equations of motion of the antenna array. Then, we design the prototype of antenna array with operating frequency of 75-125Hz. Finally, we experimentally established the radiation intensity relationship between a single permanent magnet and an array of permanent magnets. The results indicate that our driving model reduces the tolerance of the signal by 47%. Through 2FSK communication experiments, this article verifies the feasibility of extending the communication distance in the form of an array, which provides an important reference for long-distance low-frequency communication.

Analysis of electron heating due to partial resonance in an inductively coupled plasma under confronting divergent magnetic fields

We investigate the partial resonance as one of the mechanisms of the electron heating to sustain inductively coupled plasmas driven under confronting divergent magnetic fields having an electron confinement function. The dependence of the partial resonance on operating conditions is observed. The electron energy gain (EEG), defined as a measure for evaluation of the partial resonance, was calculated by a Monte Carlo method under various magnetic field strengths and RF antenna positions. It is confirmed that the partial resonance is observed in the resonant region even in low electric field and a strong magnetic field. As an attempt to utilize the partial resonance, we demonstrate enhancement of the EEG and resulting ionization in the resonant region by placing the RF antenna near a region where the magnetic field lines running through the resonant region reach.

Design, Array, and Test of Super-Low-Frequency Mechanical Antenna Based on Permanent Magnet

As a new type of super-low-frequency (SLF, 30–300 Hz) magnetic antenna, the permanent magnetic mechanical antenna (PMMA) has great potential for applications in underwater communication, underground communication, and earthquake prediction. PMMAs use large-volume permanent magnets to enhance the signal, posing a significant challenge to power consumption of the mechanical drive structure. We optimize the permanent magnets in terms of magnetization structure, magnetic material, and form factor to determine the optimal permanent magnet structure. We establish an analytical model of the magnetic torque of the array elements and the radiated field of the array to determine the optimal array form. Based on the analytical model, we analyze the effects of the array element spacing, the phase difference of the array elements, and the number of array elements on the radiated time-varying magnetic field. Finally, a 3-D array prototype operating in the frequency band of 75–125 Hz is developed for testing. The test results show that when the phase difference is less than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathrm{26}^{\circ} $ </tex-math></inline-formula> , the effect on the radiation intensity of the array is negligible. When the array element spacing is 0.15 m, the motor cannot drive the mechanical structure, and when the array element spacing increases to 0.3 m, it can operate normally. Communication experiments were conducted, and the transmission rate could reach 2 bps.

Smart Magnetic Optical Antenna for Automatic Nanoalignment and Photon Beaming from Prepatterned Single Quantum Dot Nanospot.

We present a unidirectional dielectric optical antenna, which can be chemically synthesized and controlled by magnetic fields. By applying magnetic fields, we successfully aligned an optical antenna on a prepatterned quantum dot nanospot with accuracy better than 40 nm. It confined the fluorescence emission into a 16-degree wide beam and enhanced the signal by 11.8 times. Moreover, the position of the antenna, and consequently the beam direction, can be controlled by simply adjusting the direction of the magnetic fields. Theoretical analyses show that this magnetic alignment technique is stable and accurate, providing a new strategy for building high-performance tunable nanophotonic devices.

Magnetic strong coupling between rectangular hole metamaterials and Fabry–Pérot microcavity in THz region

Various studies have so far been conducted on the strong coupling interaction between light and matter in microcavities. Although most of them report on the coupling between the electric field and the electric dipole, the coupling between the magnetic field and the magnetic dipole is rarely reported. In this study, we investigated the strong coupling interaction between a magnetic field and a magnetic dipole using a Fabry–Pérot microcavity structure in the THz region consisting of wire grid (WG) mirrors and rectangular hole (RH) metamaterials. Here, the RH is well known as a magnetic current type slot antenna, which can be regarded as a magnetic dipole. To verify this concept, we analyzed the transmission properties of WG, RH, and a microcavity consisting of WG and RH (WGRH) using the transmission line theory. Consequently, we found that in this WGRH, normal mode splitting occurs, and anti-crossing behavior is observed in the dispersion relation. The samples were designed using the finite difference time-domain method and were fabricated via photolithography. We measured the transmission spectrum of the fabricated samples using THz time-domain spectroscopy. Finally, we observed a splitting of the transmission peak owing to mode coupling between the magnetic field and the magnetic dipole in WGRH.