EM Theory Research Articles

Electromagnetics theory-based new equation to improve harmonically tuned power amplifier theory and design

ABSTRACT Power amplifiers (PA) are used to boost the power of signals. Recently, harmonically tuned power amplifiers (HTPA) offer high efficiency and wider bandwidth than conventional PA. HTPA achieves by shaping waveforms using varying drain terminal impedance conditions (open and short-circuited etc.), but this impedance creates reflected waves at the drain. Existing HTPA methods lack a foundation in Electromagnetic Theory (EM), leading them to miss reflected waves. As a result, the existing equations show problems Type I: generate unwanted and non-required higher-order harmonics (n > 3); and Type II: they cannot link with simulated/measured results properly. This paper proposes an alternative approach by applying EM theory to develop a general HTPA equation. This equation works for any HTPA class and overcomes problems (Type I & II). To validate the proposed theory and equation, continuous mode Class F PA is designed and fabricated. Theoretical, simulation and experimental results all showed good agreement.

Physics-based models for communications in random complex propagation media, including keyhole effects in MIMO

Extensive research has been reported on MIMO systems for complex environments. It is noted that many communications studies make use of the channel matrix of transmitters and receivers, signal vectors, SNR, and eigenvalues. However, the channel matrix is often expressed in terms of channel modeling, and the detailed statistical characteristics of the channel in terms of physical characteristics of atmospheric turbulence, particulate matter, and rough surfaces and terrain are often not explicitly shown. This paper discusses the inclusion of expressions of physical characteristics of the random medium in the channel matrix. Therefore, the key point of this paper is that the channel matrix is explicitly given in terms of the actual physical parameters of the random environment using the mutual coherence function and stochastic Green’s functions; we call this a ‘physics-based’ communications model. This paper presents a formulation of physics-based communications models in the presence of a random medium based on analytical statistical EM theory. We use the keyhole MIMO as an example to show the key points of this approach. It is hoped that this study may help extend channel modeling to include analytical statistical EM theory for atmospheric turbulence, ocean turbulence, and rough terrain.

INCONSISTENCIES IN EM THEORY - THE KELVIN POLARIZATION FORCE DENSITY CONTRADICTION

Calculations of resultant electrostatic force on a charged spherical or cylindrical capacitor with two sectors of different dielectrics, based on the classical formulas of electrostatic pressure, Kelvin polarization force density, and Maxwell stress tensor predict a reactionless force that violates Newton’s 3rd law. Measurements didn’t confirm the existence of such a reactionless thrust, thus there is an apparent inconsistency in the classical EM theory that leads to wrong results.

Ecological Modernization Theory (EMT): Antecedents and Successors

This study consolidates the state of academic research on the Ecological Modernization Theory (EMT). The EMT starts from a sociological perspective and enters into a series of political and economic factors that are considered crucial under the aegis of processes and practices. EM predicts that under political, economic, and technological conditions, competition among capitalists can be redirected to achieve eco-efficiency of pollution prevention. Based on a literature review from across 26 years, the study presents an overview of the evolution of the theme, background, and future perspectives. Using the databases Scopus, Web of Science, and Science Direct, a sample of 291 studies was mapped, which were read in full. Content analysis was conducted to abstract the current panorama of the theory of ecological modernization and to infer trends of the progress of the subject. The originality/value of this study is that we integrate diverse research perspectives into a comprehensive multidimensional structure of EM, with the purpose of analyzing the antecedents, artifacts associated with theory, method, types of studies developed, constructs explored together with the theory of EM and subcategories context, relevant stakeholders, technological innovations, and public policies. As future perspectives for studies, we suggest aligning EMT with circular economy, industry 4.0, and management information systems based on big data.

Trends and Future Research in Electronic Marketing: A Bibliometric Analysis of Twenty Years

Electronic marketing (eM) is a flourishing phenomenon that is gaining intense concern because of a significant impact on organizational performance. Over the past few decades, the relevance of eM has been observed in numerous fields (e.g., consumers, organizational strategy, advertisement, and overall philosophy of management to understand the insights globally). To effectively maneuver the field, all stakeholders, particularly academicians and practitioners, must comprehend the current position of the eM theory and practices for dynamic utilization. A systematic bibliometric analysis can serve this issue by providing a holistic view of the publication trend and its trajectory in terms of various themes, including citations and publication metrics. This study analyzes the bibliometric data from 2000 to 2019 to reveal the most productive countries, universities, authors, journals, and prolific publications in electronic marketing. To this end, VOS viewer software was used to visualize the mapping based on co-citation, bibliographic coupling (BC), and co-occurrence (CC). The primary addition of this research is to provide an overview of eM tendencies and paths that may help researchers know the tendencies and future research directions worldwide.

In-turn capacitive effect resultant from a high dielectric constant found in a ferromagnetic ferrite

Getting negative permeability in ferromagnetic materials as observed in dimensional resonance effect (DRE) raises several questions about the existence of negative permeability in natural materials like ferrite, its dependence on core size, and the way of solving the contradiction with EM theory. This paper shows that negative permeability can't be achieved in ferromagnetic materials without biasing and DRE is a matter of using low frequency inductor’s equivalent model for extracting the permeability at high frequencies. The real effect of dielectric constant on inductor’s behaviour is disclosed, its responsibility on the appearance of unusual capacitive phenomenon between parts of the turn is checked practically and by simulation. The study shows that the parameters which enhance this phenomenon are shape and copper-covered area of the core.Measuring the input impedance of an inductor consisting of six Ni-Zn toroidal cores, and provided by a single turn and connector, shows the appearance of two resonances, and that, the frequencies at which these resonances occur depend on connector’s location, this results are interpreted by in-turn capacitive effect phenomenon while DRE can’t interpret it. This study can be used to improve ferromagnetic devices, like probes, at high frequencies.

Double Helix Structure of Photon

Does photon have structure, what structure? A useful clue is: The EM theory predicts that the helical distribution of vector EH plus speed makes the angular momentum of the circular polarized light. Photon possesses speed and spin , weather its spin and other basic properties are also owing to the similar EH structure plus ? We are going to find out the answer. Starting from an ordinary symmetrical EM-wave beam, we do not presuppose it having any relation with the photon and quantization. We will prove the symmetrical wave beam is circular polarized; it is composed of an -energy packet and a conical (EM) wave with much smaller energy. The energy packet is a small and thin slice of circular polarized EH field wrapped by a cylindrical side membrane with helically distributed . Mechanical equilibrium between and stresses in the side membrane and the EH field inside construct a very steady structure to keep its integrity and energy. The energy-packet will be proved having almost all the basic properties we used to know for the photon(s). It floats on the front of the conical (EM) wave. They move with the same phase until meeting an obstacle. The energy packet and accompanying wave satisfy the same circular polarized wave function and play a role together in the processes of emission, absorption and interference. They show wave particle properties all the time. It seems such EM train can be reasonably treated as a photon and vice versa.

Realistic Expectations for Deep Ground Penetrating Radar Performance

Ground penetrating radar (GPR) is unique amongst geophysical tools in terms of its imaging resolution and the diversity of its applications. Since its commercialisation four decades ago, GPR has also been distinguished because of the prevalence of some of its purveyors to oversell the method’s capabilities, relying largely on the end users’ lack of understanding of the underlying physics. Early adopters in the 1980s and 90s were dismayed to find that environments suitable for its purported ubiquitous deep penetration capabilities were rare and that it required resistivities well into the 1000s of Ohm m. Regardless of the advances made in electronics and antenna design in the intervening decades, the fundamental limitations have not changed.Misconceptions, “specsmanship” and hype have continued to abound in the GPR marketplace, particularly in recent years. Systems purporting to penetrate hundreds of metres using “megawatt” transmitters from the former Eastern Bloc have been promoted for mineral exploration, particularly in Australia and Africa. Other pseudo-radar concepts, such as the use of beam forming to achieve kilometres of penetration with centimetre accuracy, or THz laser scanners which can detect individual diamonds deep underground, have generally targeted junior exploration groups who lack in-house geophysical guidance.This work provides an overview of the fundamentals of non-dispersive EM wave propagation in the ground and an examination of the recent published performance claims of some GPR and pseudo-GPR systems within the context of accepted EM theory. The accepted methods for potentially increasing GPR performance, given the emerging technologies such as novel transmitter and receiver designs and new GPR antennas, are also discussed.

Metallic nanolayers: a sub-visible wonderland of optical properties [Invited

It was predicted long ago that ultra-thin metallic films must exhibit unusual optical properties for radiation frequencies from rf to infrared domain. A film would remain highly reflective even when it is orders of magnitude thinner than a skin depth at any frequency. Only when it is a few nanometers thick (depending on material but not on the frequency), its reflectivity and transmittivity get equal, while its absorption peaks at 50%. It has been confirmed experimentally and new directions and applications were proposed. We review the EM theory of the phenomenon and recent developments in the field, and present some new results.

Correction to "direction of arrival estimation for monostatic MIMO radar using reduced-dimension RISR algorithm"

Presents corrections to the paper, “Direction of Arrival Estimation for Monostatic MIMO Radar Using Reduced- Dimension RISR Algorithm,” (Xiaofang, D., et al), 11th International Symposium on Antennas, Propagation and EM Theory (ISAPE), Guilin, China, October 18-21, 2016.

Basic Laws of EM Theory

Instead of electric charge, as the basic substance of EM theory, its static potential, as some energetic fluid, in the dielectric, non-resistive and reactive medium, is here taken as the starting quantity. All the remaining EM quantities are thus defined in the succession, by the standard differential equations, with algebraic relations and central laws derived as their formal consequences. Not only that majority of the former results are confirmed, but some of them are completed, rationally interpreted and mutually related. On the other hand, a few formal concepts appear as inadequate or excessive at least.

Announcement and Call for Papers: ISAPE2012 The 10th International Symposium on Antennas, Propagation, and EM Theory October 22–26, 2012, Xi'an, CHINA

Announcement and Call for Papers: ISAPE2012 The 10th International Symposium on Antennas, Propagation, and EM Theory October 22–26, 2012, Xi'an, CHINA

Announcement and call for papers: ISAPE2012 - The 10th International Symposium on Antennas, Propagation, and EM Theory

Announcement and call for papers: ISAPE2012 - The 10th International Symposium on Antennas, Propagation, and EM Theory

Integration of numerical and field-theoretical techniques in the design of single- and multi-band rectennas for micro-power generation

We introduce an integrated design methodology for the optimization of RF-to-DC conversion efficiency of multi-band rectennas (rectifying antennas), with the aim of harvesting the RF energy available in humanized environments. Existing RF sources can either operate at known frequencies, power budgets, and locations, or can be ubiquitously available at different frequency bands, and with unknown directions of incidence and polarizations. In all cases, the RF link power budget may be extremely low. In order to harvest a significant quantity of energy, it is thus mandatory to place a very special care in the design of each part of the receiving/storing system. For this purpose, the receiving antenna must be optimized together with the rectifying circuit and the load. In our work, this is accomplished by a rigorous design tool based on the concurrent use of nonlinear/electromagnetic (EM) CAD tools and EM theory. The effectiveness of the method is demonstrated by comparing the computed and measured performance of single- and multi-band rectennas, both linearly and circularly polarized. Such antennas are designed to harvest RF energy from a variety of cellular and WiFi systems that are normally present in civil environments.

Announcement and Call for Papers: ISAPE2010 The 9th International Symposium on Antennas, Propagation, and EM Theory

Announcement and Call for Papers: ISAPE2010 The 9th International Symposium on Antennas, Propagation, and EM Theory

Announcement and Call for Papers: ISAPE2010 The 9th International Symposium on Antennas, Propagation, and EM Theory

Announcement and Call for Papers: ISAPE2010 The 9th International Symposium on Antennas, Propagation, and EM Theory

Announcement and Call for Papers: ISAPE2010 The 9th International Symposium on Antennas, Propagation, and EM Theory

Announcement and Call for Papers: ISAPE2010 The 9th International Symposium on Antennas, Propagation, and EM Theory

The SUMMA Graduate Fellowships in Advanced Electromagnetics

These fellowships are intended to promote exceptionally creative contributions to the advancement of electromagnetic theory and applications. They promote EM theory (conceptual, new ideas, new approaches), but with apparent potential applications (antennas, scattering, propagation, other EM devices). They will be awarded to graduate students studying electromagnetics for pursuit of the PhD. Such students may be currently MS or PhD candidates. It is expected that these fellowships will be of primary interest to students in electrical engineering specializing in electromagnetics, but in some universities such students may be in other departments (e.g., mathematics and physics). Eligibility for these fellowships is international, except where legal regulations or restrictions may apply. The award of this fellowship is nondiscriminatory and is not based on race, color, religion, sex, national origin, handicap, or family status. Immediate family members or close associates of any members of the evaluation committee or SUMMA officers/board members are ineligible.

Ground-penetrating-radar response to fracture-fluid salinity: Why lower frequencies are favorable for resolving salinity changes

Time-lapse ground-penetrating-radar (GPR) surveys exploit signal-amplitude changes to monitor saline tracers in fractures and to identify groundwater flow paths. However, the relationships between GPR signal amplitude, phase, and frequency with fracture aperture and fluid electrical conductivity are not well understood. We used analytical modeling, numerical simulations, and field experiments of multifrequency GPR to investigate these relationships for a millimeter-scale-aperture fracture saturated with water of varying salinity. We found that the response of lower-frequency radar signals detects changes in fluid salinity better than the response of higher-frequency signals. Increasing fluid electrical conductivity decreases low-frequency GPR signal wavelength, which improves its thin-layer resolution capability. We concluded that lower signal frequencies, such as [Formula: see text], and saline tracers of up to [Formula: see text] conductivity are preferable when using GPR to monitor flow in fractured rock. Furthermore, we found that GPR amplitude and phase responses are detectable in the field and predictable by EM theory and modeling; therefore, they can be related to fracture aperture and fluid salinity for hydrologic investigations of fractured-rock flow and transport properties.

The SUMMA Graduate Fellowships in Advanced Electromagnetics

These fellowships are intended to promote exceptionally creative contributions to the advancement of electromagnetic theory and applications. They promote EM theory (conceptual, new ideas, new approaches), but with apparent potential applications (antennas, scattering, propagation, other EM devices). They will be awarded to graduate students studying electromagnetics for pursuit of the PhD. Such students may be currently MS or PhD candidates. It is expected that these fellowships will be of primary interest to students in electrical engineering specializing in electromagnetics, but in some universities such students may be in other departments (e.g., mathematics and physics). Eligibility for these fellowships is international, except where legal regulations or restrictions may apply. The award of this fellowship is nondiscriminatory and is not based on race, color, religion, sex, national origin, handicap, or family status. Immediate family members or close associates of any members of the evaluation committee or SUMMA officers/board members are ineligible.