Electric Dipole Antenna Research Articles

Radio frequency electric field-enhanced sensing based on the Rydberg atom-based superheterodyne receiver.

We present enhanced sensing of a radio frequency (RF) electric field (E-field) by the combined polarizability of Rydberg atoms and the optimized local oscillator (LO) field of a superheterodyne receiver. Our modified theoretical model reveals the dependencies of the sensitivity of E-field amplitude measurement on the polarizability of Rydberg states and the strength of the LO field. The enhanced sensitivities of the megahertz (MHz) E-field are demonstrated at the optimal LO field for three different Rydberg states ${\rm 43D}_{5/2}$, ${\rm 60S}_{1/2}$, and ${\rm 90S}_{1/2}$. The sensitivity of 63 MHz for the ${\rm 90S}_{1/2}$ state reaches 9.6 $\times 10^{-5}\rm \,V/m/\sqrt {Hz}$, which is approximately an order of magnitude higher than those already published. This result closely approaches the sensitivity limit of a 1 cm passive dipole antenna without using an impedance matching network. This atomic sensor based on the Rydberg Stark effect with heterodyne technique is expected to boost an alternative solution to electric dipole antennas.

Wideband low‐profile magneto–electric dipole antenna stacked with patch and metasurface

AbstractHere, a novel low‐profile wideband and high‐gain magnetoelectric dipole antenna with metasurface superstrate is proposed. The magnetoelectric dipole antenna printed on single layer consists of a probe fed patch with four shorted patches arranged symmetrically. Gain enhancement is achieved by placing two side walls and metasurface superstrate with an air gap. Additional rectangular patch connected to the same probe is placed above the magnetoelectric dipole antenna within an air gap. This improves impedance bandwidth, gain and efficiency significantly. Overall profile of antenna is 0.15 λ0, which is lower compared to conventional magnetoelectric dipole antennas with a profile of 0.25λ0. The proposed antenna fabricated on FR4 substrate shows 57% of wide impedance bandwidth from 3.63 to 6.57 GHz with overall size of 1λ0 × 1λ0 × 0.15λ0. The maximum gain in the operating band is 10.2 dBi.

Research on Channel Characteristics and Electrode Electrical Performance of Earth Current Field Information Transmission Technology.

Starting from the need for emergency rescue information transmission in tunnel engineering accidents, this article focuses on researching and solving the technical problems of information transmission between rescue personnel and trapped personnel after tunnel engineering collapse accidents, before and during the rescue process. The research objects are the information transmission channel and grounding electrode in the earth current field information transmission technology, and the electromagnetic characteristics of the earth medium and the electrical performance of the grounding electrode are studied and analyzed using the electromagnetic simulation software Maxwell based on finite element algorithm, establish a three-dimensional model based on the transmission of current field information of the ground electrode, analyze the effects of the electrode array, electrode depth, and radius on impedance. Research has shown that the impedance of the earth is related to the resistivity of the medium and is not a human-controllable factor. To reduce the contact impedance of an electric dipole antenna, one should start with the contact impedance of the earth electrode. The impedance of the transmitting end is an important factor affecting the efficiency of information transmission; parallel connection of multiple grounding electrodes, increasing the depth of grounding electrode penetration into the soil layer, and increasing the radius between grounding electrode pairs are all effective methods to reduce the contact impedance of electric dipole antennas, thereby improving information transmission capacity. To achieve wireless information transmission through the stratum, by appropriately selecting the operating frequency of electromagnetic waves, a certain distance of signal transmission can be achieved.

MICS-Band Helical Dipole Antenna for Biomedical Implants

This letter presents the design, analysis, and measurement of a miniaturized ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\text{7}\!\times\!\text{7.5}$</tex-math></inline-formula> mm) electrically small helical dipole antenna with the introduction of a flexible magnetic sheet of high permittivity and permeability for biomedical implants. The proposed helical dipole, operating at 402–405 MHz Medical Implant Communication Services (MICS) band, supports wider bandwidths (10 dB bandwidth: simulated 33 MHz; measured 49.5 MHz) compared to the state-of-the-art designs. In addition, as a hybrid between a magnetic loop antenna and an electric dipole antenna and operating in the normal mode with small radian (ka < 0.36), enhanced radiation efficiency has been achieved as a result of the magnetic sheet. Measured in-body to on-body transmission verifies the antenna performance.

Simulation of electric field response of horizontal circular electric half wave dipole antenna for seabed logging

Seabed logging (SBL) is a direct and remote application of controlled source electromagnetic (CSEM) method to detect hydrocarbon resources beneath the seafloor in offshore conditions. In this method, electromagnetic waves are used to detect the resistivity contrast between various sediment layers. The current source of electromagnetic waves is a horizontal electric dipole (HED) antenna. The antenna design represents a challenge in shallow waters (less than500 m seawater depth) due to the presence of airwaves that lead to a low signal-to-noise ratio, hence hindering the detection of a hydrocarbon reservoir. A horizontal circular electric half-wave dipole will be used in this work as the source of electromagnetic waves. The numerical solution for the electric field response will be developed based on solving the Maxwell equations in two modes: the poloidal and toroidal modes. Simulation results have shown that the new antenna is able to detect the presence of deep hydrocarbon reservoirs (up to 5000 m) in shallow-water environment. Comparison of the average percentage difference in delineation between the circular and the HED was carried out. The new antenna results in 61 % delineation compared to 15 % for the HED at 5000 m hydrocarbon depth and 200 m seawater depth, indicating the ability of the antenna to disperse the airwaves. The results also show that the airwaves are significantly reduced from nearly 15000 m (for the HED) to 10000 m offset for the proposed antenna, hence increasing the signal-to-noise ratio. These results seem to indicate the potential for the new antenna to be used as an EM source for SBL in shallow-water environment.

Design of Low-RCS Broadband High-Gain Antennas Based on Transmission Array Metasurface.

In this paper, a low-RCS broadband high-gain antenna based on metasurface transmission array is proposed, consisting of two parts: a metasurface transmission array and a feed antenna. When designing the metasurface transmission array, the phase compensation method is used to achieve the beam convergence effect of metasurface in the broadband. By designing the elements and using the checkerboard arrangement, the RCS of the incident wave with fixed polarization can be reduced more than 10 dB at X band or Ku band. The feed antenna is designed as a microstrip magnetic and electric dipole antenna, which has the characteristics of small structure and wide impedance bandwidth. An antenna that can reduce RCS by more than 10 dB in Ku band is simulated and measured. The measurement and simulation results show that the −10 dB operating bandwidth of the high-gain antenna designed in this paper is 6.7~13.5 GHz, and the relative bandwidth is 67%. The designed metasurface can effectively improve the gain of the antenna in the operating frequency band. In this way, the design of high-gain antenna is realized, and the antenna has an obvious RCS reduction effect on the vertically incident y-polarized wave in the whole Ku band. The method to design an antenna in this paper realizes the regulation of radiation and scattering at the same time, which has important reference significance for expanding the function of transmission array antennae and has great application value.

Electrically Small Piezocomposite Strain Antennas

Recent literature has explored the use of single-material piezoelectrics for impedance matching in electrically small strain antennas. Efficiency calculations have assumed that radiation resistance is the same as that of a small wire dipole. In this work, piezoelectric composites, or piezocomposites, are used for impedance matching electrically small antennas to increase the degrees of freedom in the design process. A methodology is proposed for impedance matching a piezocomposite strain antenna at the desired center frequency over the desired bandwidth via optimal choice of materials, volume fraction, and shape without the need for an external matching network. Furthermore, the radiation resistance for piezoelectric strain antennas is derived from Wheeler’s power factor and is shown to be much smaller than that of the similarly sized electric dipole antenna that was assumed in much of the literature. The radiated power and efficiency are expressed directly in terms of piezocomposite material properties and the dimensions of the antenna. The results from this investigation provide a model of the impedance matching capabilities and efficiency limits for the piezoelectric strain antenna, demonstrating fundamental limitations for VLF applications.

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.

The Micro‐Broadband Receiver (μBBR) on the Very‐Low‐Frequency Propagation Mapper CubeSat

AbstractThe very low frequency (VLF) propagation mapper (VPM) is a 6U CubeSat designed to measure VLF radio waves in Low‐Earth Orbit. The science goals of the VPM mission are to measure VLF signals broadcast by the DSX mission, and to study natural and anthropogenic signals (from lightning and VLF transmitters) in the near‐Earth space environment. The primary payload consists of an electric field dipole antenna deployed to 2 meters in length, and a magnetic search coil deployed 50 cm from the spacecraft. Signals from these two sensors are conditioned by analog electronics, sampled, and then processed digitally into downloadable data products. The VPM mission was launched in January 2020; science operations began in March 2020 and continued through September, when contact with the spacecraft was lost. This paper describes the mission goals and instrument designs in detail, as well as some examples of the VPM data set.

Origin of the Weak Plasma Emission Line Detected by Voyager 1 in the Interstellar Medium: Evidence for Suprathermal Electrons

Abstract Recently, a very weak, nearly continuous plasma wave emission line has been discovered in the nearby interstellar medium at the electron plasma frequency. The new observations were made by the plasma wave instrument on the Voyager 1 spacecraft, which crossed into the interstellar medium in 2012 August. Several questions remained unanswered after the initial discovery. Why was the emission line not observed until several years after Voyager 1 entered the interstellar medium, what is the wavelength of the plasma oscillations responsible for the emission line, and what is the origin of the oscillations? Here, we provide answers to these questions. On the most important question, namely the origin of the oscillations, the evidence strongly suggest that the emission is driven by suprathermal electrons that excite plasma oscillations comparable to the quasi-thermal noise (QTN) that is commonly observed by space plasma wave instruments with long, thin electric dipole antennas. These results imply the existence of a relatively dense population of suprathermal electrons that could contribute significantly to the overall pressure in the interstellar medium. Although the similarities to the previous QTN observations are impressive, there is no certainty that the emissions are driven by thermal excitation, and other sources should be explored, such as the possibility that they are driven by pressure fluctuations associated with the short-wavelength cascade of interstellar turbulence.

A Study of a Probe-Based Millimeter-Wave Far-Field Antenna Measurement Setup [Measurements Corner

This article presents a finite difference time domain (FDTD) analysis of a probe-based millimeter-wave (mm-wave) far-field antenna measurement setup. First, it is found that a full-wave simulation of the entire setup requires formidable computational resources, and thus a reasonable simplification of the setup model is made. Then, an electric dipole antenna operating at 28 GHz is placed in the setup, and the reflected/scattered/refracted/absorbed/diffracted/obstructed field distribution and distortion on radiation patterns by equipment are simulated. Finally, a quiet zone assessment is conducted.

Electric and magnetic dipole antennas of a directional resistivity logging-while-drilling tool for “look-around” boundary detection

Directional resistivity logging-while-drilling tools play an important role in geosteering. In contrast to the widely used tool with magnetic dipole transmitters and receivers, tools are investigated with electric and magnetic dipoles as transmitters and/or receivers for “look-around” boundary detection. Measurement schemes are selected based on their look-around boundary detection abilities. Those measurement schemes are studied regarding the sensitivity and depths of boundary detection, the optimal transmitter-receiver distance and frequency, and the effects of a drill collar using the coefficient propagator method and the finite-difference method. Higher sensitivity to a boundary often implies a shallower depth of investigation. More specifically, the measurement schemes using an electric dipole transmitter and receiver are the least sensitive to the boundary; however, such schemes have the maximum depth of detection and the strongest signal strength. The schemes using electric and magnetic dipole transmitters and receivers have a moderate depth of detection and signal strength. The measurement schemes with a magnetic dipole transmitter and receiver have the highest sensitivity to the boundary and the weakest signal strength. The drill collar affects the response of all of the measurement schemes. However, this effect cannot be corrected with a simple coefficient for the schemes using an axial electric dipole transmitter, but it can be corrected for others. The optimal frequencies and optimal transmitter-receiver distances of those schemes have two types: the changing one that changes with the distance to boundaries and the fixed one that usually has the lowest frequency or the shortest transmitter-receiver distance. The characteristics of each measurement scheme will guide the tool designs and determine its role in the application and method of interpretation.

Progress and technical framework of the BAW mediated magnetoelectric antenna

Traditional electric dipole antennas have been suffering from size scaling-down limitation, difficult impedance matching, low radiation efficiency and other inherent limitations. Therefore, the bulk acoustic wave (BAW) mediated magnetoelectric (ME) coupling antenna is accurately defined on base of its physical essence, which can also be named a magnetic dipole antenna, or a novel mechanical antenna. Its working mechanism is quite different from that of electric dipole antennas, which is conducive to solving their problems through disruptive innovation. Based on further understanding the physical essence of mechanical antenna, its theoretical origin and classification are reviewed. Taking BAW ME antenna as a typical implementation case, the research progress and key scientific issues of BAW ME antenna are summarized, furthermore, the framework of the technical solution for BAW ME antenna is also presented.

Anapole Meta-Atoms: Nonradiating Electric and Magnetic Sources.

The existence of classical nonradiating electromagnetic sources is one of the puzzling questions to date. Here, we investigate radiation properties of physical systems composed of a single ultrahigh permittivity dielectric hollow disk excited by electric or magnetic pointlike dipole antennas, placed inside the inner bore. Using analytical and numerical methods, we demonstrate that such systems can support anapole states with total suppression of far-field radiation and thereby exhibit the properties of electric or magnetic nonradiating sources. It is shown that the suppression of the far-field radiated power is a result of the destructive interference between radiative contributions of the pointlike dipole antennas and the corresponding induced dipole moments of the hollow disk. The experimental investigation of the nonradiating electric source has been performed to confirm our theoretical predictions. Our results pave the way to create and realize compact nonradiative sources for applications in modern wireless power transfer systems, sensors, RFID tags, and medical technologies.

Proximity coupled fed wideband printed magneto–electric dipole antenna

Results are presented fora wideband printed magneto-electric dipole antenna. The printed electric dipole and reflector are separated by an air-gap and is fed with a coaxial transmission line and a printed proximity coupled T-shaped feeding strip. The slot between the electric dipole halves forms the magnetic dipole radiating aperture. This feeding mechanism allows for good impedance matching at adjacent resonances of the electric and magnetic dipoles to achieve wideband operation. The two printed electric dipole halves are DC shorted to the reflector. The results show that this antenna can operate over a wide bandwidth with good gain, stable unidirectional radiation patterns and low cross polarization. The effect of the air-gap height and the relative permittivity of the substrate on which the dipole is printed are investigated. Results show that an optimum air-gap height for a specific substrate permittivity can be determined that will result in a gain with a small variation over the entire impedance bandwidth of the antenna. Simulated as well as measured results are presented for a prototype antenna with a small gain variation and overall dimensions of 1.33λ0 × 1.33λ0 × 0.19λ0. A measured impedance bandwidth of 54% with an average gain of 9.2 dBi is achieved.

Inferring Jovian Electron Densities Using Plasma Wave Spectra Obtained by the Juno/Waves Instrument

AbstractThe Waves instrument onboard the Juno spacecraft has plasma wave‐measuring capabilities using a single electric dipole antenna and a uniaxial magnetic search coil. Together, these simultaneously measure electric and magnetic field spectral densities in the frequency range 50 Hz–20 kHz, above which only electric field spectral densities are measured up to 41 MHz. A major objective of the Juno mission is to explore Jupiter's high‐latitude magnetosphere and ionosphere. One of the key contributions of the Waves instrument is the determination of electron densities from plasma wave spectra. Given the very high magnetic field strengths near Juno's perijove passes, established techniques cannot be utilized to infer electron densities since such highly magnetized space plasma conditions have not previously been met in planetary missions. By revisiting theoretical treatments of plasma waves, we describe a novel method to determine electron densities from plasma wave spectra that is unique to the near‐Jupiter region. In the absence of the commonly observed upper hybrid resonance frequency in high‐density space plasmas (e.g., the vicinities of Io, Ganymede, Enceladus, and the near‐Earth environment), we achieve this by identifying emission cutoffs at the lower hybrid frequency and electron plasma frequency. Further, we discuss the development of the process and tools for identifying and digitizing appropriate resonance and cutoff frequencies.

The Influence of DNA Solution on Dipole Antenna Purcell Factor Spectra

In this study, deoxyribonucleic acid (DNA) solution effect on the Purcell factor of an electric dipole antenna was analyzed. Any antenna tuned to a resonance can be described as a radiator, and the effect of the environment on its radiation can be defined as Purcell factor. It is possible to determine the Purcell factor in terms of the real part of the antenna input impedance. Therefore, the Purcell factor of an antenna in the presence of pure water and DNA solution was calculated through measuring the input impedance of a dipole antenna with resonance frequency of 9.6-11.6 GHz. The Purcell factor of the antenna was measured and analyzed in the frequency range 5-16 GHz for the samples placed at 5 mm to 20 mm from the antenna. The frequency bands where the maximum DNA sensitivity of Purcell factor occurs were determined.

Wide-angle scanning linear phased arrays based on wide-beam magneto electric dipole antenna

Microstrip phased array has aroused interest of many researchers because of its beam agility. However, a big problem for typical microstrip array is that its main beam can only scan from about –50° to 50°, with a gain loss of 4-5 dB. Meanwhile, the relatively narrow operating bandwidth of microstrip antenna is also a problem in application. These flaws have dramatically limited its applications and spawned many studies on phased array with wide-angle scanning capability. Several methods have been proposed to broaden the scanning coverage of phased array, such as utilizing pattern-reconfigurable antenna as an element of array, taking wide-beam antenna as the element of array, and adopt metasurface as the top cladding of array. However, most of existing researches mainly focus on achieving wide-angle scanning performance within a relatively narrow bandwidth. A phased array that possesses wide-angle scanning capability at both main planes within a relatively wide bandwidth is highly desirable. In this paper, a wide-beam magnetoelectric (ME) dipole antenna is proposed. It consists of an ME dipole antenna in the form of microstrip patch and a pair of magnetic dipoles. Metallic through holes integrated with patches and ground are utilized to form magnetic currents. Extra magnetic dipoles are added to broaden the 3-dB beam-width. The simulated results reveal that the 3-dB beam-width of the proposed antenna is greater than 107° in the E-plane (9 GHz–12 GHz) and 178° in the H-plane (7 GHz–12 GHz) respectively. The impedance bandwidth of the proposed antenna is 53.26% from 7.3 GHz to 12.6 GHz (VWSR &lt; 2). Based on the proposed antenna element, two linear phased arrays are fabricated and measured. To test the wide-angle scanning capability of the arrays, each antenna element is simply fed with alternating currents with identical amplitude and linearly increasing phases. The measured results reveal that the wide-angle scanning capability of H-plane array and E-plane array can be obtained from 9 GHz to 12 GHz. The scanning beam of the H-plane array can cover the range from -90° to 90°. The scanning beam of the E-plane array can cover the range from –70° to 70°. The impedance bandwidth of the central antenna is 27.03% for the H-plane array from 9.6 GHz to 12.6 GHz (active VWSR &lt; 2.5) and 36.36% for the E-plane array from 9 GHz to 13 GHz (active VWSR &lt; 2) respectively. Hence, the proposed method can be used as a reference for designing a wide-beam antenna and wide-angle scanning phased array and the designed phased arrays can be applied to X-band radar systems.

Bandwidth-Enhanced Low-Profile Magneto-Electric Dipole Antenna With Shorting Parasitic Elements

This paper presents a low-profile magneto-electric (ME) dipole antenna with an enhanced impedance bandwidth realized by the loading of shorting parasitic elements. The antenna contains a horizontal planar electric dipole antenna, a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Gamma $ </tex-math></inline-formula> -shaped shorted patch antenna, a pair of parasitic L-shaped shorted patches, and a direct feed. By loading of the parasitic L-shaped patches such that they are shorted to the ground, the proposed antenna attains a significant bandwidth enhancement while maintaining excellent broadside radiation characteristics. An antenna prototype with a low profile of only <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.11\lambda _{0}$ </tex-math></inline-formula> was fabricated and tested ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{0}$ </tex-math></inline-formula> is the free-space wavelength referring to the center frequency). The antenna achieves a measured impedance bandwidth of 75.64% (1.34–2.97 GHz) for a voltage standing wave ratio (VSWR) of less than 2. Within the operating band, the measured gain ranges from 6.23 to 8.49 dBi. Additionally, stable radiation patterns on both E- and H-planes with a high front-to-back ratio of more than 20.5 dB are achieved.

Взаємодія хвиль і частинок при інжекції модульованого електронного пучка в іоносферну плазму. Теорія та експеримент

We present the results of the active space experiment with charged particle beam's injection (electrons and xenon ions) carried out onboard Intercosmos-25 station and daughter Magion-3 subsatellite. The ones are obtained under conditions when the particle beams were injected in opposite directions relative to the magnetic field B0 in such a way that the electron injection was directed towards the Earth. Mechanisms of beam-plasma instabilities relative to the excitation of electrostatic and electromagnetic waves are considered during the electron beam injection (~10 keV, 0.1 A) from the Intercosmos-25 station. Development of transverse instability on the first cyclotron resonance leads to the excitation of whistler mode waves backward-propagating relative to the injected electrons (from the Earth). The investigation object was the beam-excited differential fluxes of ionospheric electrons in a wide energetic range of 27 eV — 412 keV registered by the charged particle spectrometers onboard the Magion-3 subsatellite. Thereby, the interaction of whistler waves with ionospheric electron fluxes is stimulated by the energy transfer mechanisms such as 'particle-wave-particle'. Numerical results of beam-plasma instabilities are compared also with thermal plasma parameters registered at different space points on the station and subsatellite. Excitation of longitudinal and transverse beam-plasma instabilities will inevitably lead to their competition, which will affect the results of the experiment. The data of stimulated fluxes of ionospheric electrons allow us to investigate the various effects of the wave-particle interaction, taking into account the influence of the growth rate of longitudinal instability on the excitation angle of whistlers and their structure. This approach is based on the results of laboratory experiments to determine the pattern of excited whistlers for an electric dipole antenna and the analogy of the beam-plasma channel with the radiating system. The results of the active space experiment confirm the dependence of the growth rate of whistler mode waves on the development of longitudinal beam instability.