Electric Field Strength

Yagi-Uda Antenna is a widely used roof top DVB-T2 receiver antenna due to its high forward gain capability, low cost and ease in construction. In Tanzania, there have been some complaints which were logged to Tanzania Communications Regulatory Authority (TCRA) by the customers on the poor reception of DVB-T2 signals which may be caused by signal degradation. In this paper we propose enhancement of the gain of the Yagi antenna so as to improve the reception signals of the DVB-T2. This will help solve those complaints. It is well known that the increase in radiation pattern causes the increase in directivity and hence gain which will have an impact on good quality of reception for DVB-T2 signals coming from the transmitter. After carefully design and simulation in FEKO simulating software by adding the number of director elements and making some adjustments on the length and spacing between the elements, we managed to increase the gain of the antenna by 4.7dB. This is significant impr...

Surface localized defects represent a special class of microstructure in dielectric films. Whereas inhomogeneous media are often classified by volume fractions of their constituents, determinations of the local electric field require both microstructural definition and specific electric interaction among defect sites. Herein, we have used a finite element method to determine the local electric field for surface defects in dielectric films. The local electric field is both enhanced and focused in regions about the surface localized defect site. The resulting surface intensities exhibit a much broader range of magnitudes than accommodated by effective medium approximation and random resistor methods. 0009-2614/95/$09.50 © 1995 Elsevier Science B.V. All rights reserved SSDI 0009-2614(95)00075-5

The plate-type electrostatic precipitators are often used in industry, especially at dedusting of high gas flows. An important application is in case of thermo-electrical power plants. The electrostatic charging of dust particles depends on more electric parameters, and its experimental determination is difficult. The electrostatic charging depends on the electric field's strength, on the dust particles' diameter and on the particles' relative electric permittivity. For a real channel from the field on an ESP and for the discharge wires from industry, to which the discharge peaks are not identical, it was made a digital on-scale analysis, by the finite element method, for the field lines of the electric potential and electric fields' strength. The analysis was achieved for the cross-section and longitudinal section of a channel, when the gas has dust and when the dust is missing. The digital analysis is an important tool to determine and study the electric parameters, which are hard to be experimentally determined.

The authors analyze the T junction with an inductive post taking its diameter into account for the case where the current distribution is assumed on the surface of the post. A single cylindrical post placed in a T junction improves the impedance matching and compensates the junction discontinuity in a wide frequency band. The analysis 'clarifies the effects of the design parameters such as the diameter of the post and its location. It accurately predicts the measured return loss. On the basis of this analysis, an effective design procedure of the T junction is proposed and the reflection below-30 dB is realized over 4% bandwidth.

Extensive investigations of the absorption and desorption currents are carried out over the temperature range of 50 to 200 o C and electric fields up to 12 MV/m in 25.5 μm polyimide film base with 12.7 μm coating of Teflon ® FEP on one side. It is believed that this is the first time that studies on this film are reported in the literature.

One of the places where it is critical to prevent equipment malfunction due to electromagnetic interference is in the hospital operating room. Unfortunately, the electromagnetic environment in hospital operating rooms can be quite harsh. The electromagnetic fields present in this environment are created by distant sources such as AM and FM broadcast transmitting antennas as well as local sources such as electrosurgical units. In this paper, measured values are reported of electric and magnetic field strengths created by typical electrosurgical units. Measurements were taken in operating rooms at the Department of Veterans Affairs Medical Center in Fargo, ND, and were made for three electrosurgical units (ESU) operating modes. All three components of the electric and magnetic fields were determined as a function of frequency. Field strengths as large as 153 dB V/m and 76 dB A/m were measured 1 m from the electrosurgical unit.

Recently, a snow crab by-products hydrolysate has demonstrated antibacterial properties due to a peptide with a molecular weight of about 800 Da, but only at high concentration. Consequently, peptide hydrolysate has been fractionated to obtain peptides in a more purified form. The aim of this work was to separate a snow crab by-products hydrolysate by electrodialysis with ultrafiltration membranes (EDUF). EDUF, which allows separation of molecules according to their charges and molecular weights, was used to recover and concentrate the active antibacterial fraction. Two different ultrafiltration membranes (20 and 50 kDa) and two electrical field strengths (2 and 14 V/cm) were used as separation parameters. After EDUF separation, the 300-600 Da peptide molecular weight range was the most recovered with an abundance of 94%. Moreover, fractionation at 14 V/cm with ultrafiltration membranes of 50 kDa allowed the recovery of an anionic fraction which showed antibacterial properties on Escherichia coli ATCC 25922 and Listeria innocua HPB 13.

Abstra. c.t. Measurements of large apparent D.C. Volt/meter (V/m) vertical fields in a number of electric fields (-V/m) in the middle atmosphere experiments [Bragin et al., 1974], as have the made by two sounding rockets are carefully group at Pennsylvania State University (e.g. analyzed and shown to be spurious. This may shed [Hale et al., 1981]). These results are quite some doubt on recent measurements of large D.C. remarkable, but they do not fit with a model of a electric fields by other experimenters. Evidence passive middle atmosphere. is presented, for one rocket, indicating that the The above results have spurred interest in measured electric fields are aligned with the the possible existence of a middle atmosphere velocity vector of the rocket. This suggests the electric generator. As a result other teams have possibility that the measured electric fields are developed instruments capable of measurements in due to a negatively charged wake. A comparison the altitude range 30-90 km. The Houston group of measurements made by different electric field developed a parachute-borne detector using booms is also .presented. We see that in one symmetric double probes and indeed also detected Large Midgle Atmospheric Electric Fields displayed an assymmetric pattern as the spheres Simultaneous measurements of VLF transmissions moved into and out of the wake, returning nearly in the mesosphere and stratosphere, Trans-. Am. to the nominal D.C. level between excursions. GeoDhvs. Union, 17, April 28, 1981.

The behavior of wire antennas loaded at the driving point with varistor-composite materials is analyzed in the time domain via a numerical formulation. Varistor-composite materials are nonlinear transient arresters with a subnanosecond response time. Connecting these nonlinear elements in parallel with the feeding transmission line and adjusting the characteristic curves of varistor materials (i.e., current density and dielectric constant versus electric-field strength), the nonlinear load drains off currents of excessive potential levels. At operating voltages the material presents a higher impedance path and the arrester interference with the normal operation of the antenna under protection is minimal.

Modifying the standard constant-voltage poling procedure significantly enhances the inbuilt electric field strength (and consequently χ (2)) and leads to control of the nonlinear region evolution, both crucial parameters to integrate nonlinearity in waveguiding regions.

Bu çalışmada, karasal yayıncılıkta kapsama alanı hesabında kullanılmak üzere ışın izleme tekniğine dayanan yayılım modellerine yönelik iyileştirme çalışmaları sunulmaktadır. Bu amaçla, kapsama alanı hesabında alıcı noktasındaki elektrik alan şiddetini kestirmek veya yayılım yol kaybını hesaplamak için geniş bir şekilde kullanılan Geometrik Kırınım Teorisine (GKT) dayalı kırınım modelleri irdelenerek, iyileştirilmiş bir model sunulmaktadır. Önerilen model, GKT'nin türevsel bileşenlerini içeren Eğim Kırınımı ile dış bükey zarf yöntemlerinin birleştirilmesine dayanmaktadır. Benzetim sonuçları ile farklı modellerin hesaplama süresi ve kestirim hatası bakımından karşılaştırma sonuçları verilmektedir.

This paper presents the field trial results of the terrestrial digital multimedia broadcasting (T-DMB) service in Korea. The T-DMB system, based on the Eureka-147 digital audio broadcasting (DAB) system, provides streaming video, CD-quality audio and data services at speeds of up to 300 km/h using H.264 video codec along with additional channel coding and interleaving schemes. In order to provide seamless high-quality services on various radio channels, we measured the bit error rate (BER), electric field strength (EFS), and subjective video quality using specially-designed mobile test equipment. From the field tests we obtained the required effective EFS (EEFS) for error-free reception and also derived the minimum EFS from the link budget analysis. Furthermore, we present the optimal transmit and receive parameters for constructing the T-DMB networks and also developing T-DMB broadcasting equipment and mobile receivers.

Extensive investigations of the absorption and desorption currents are carried out over the temperature range of 50 to 200 o C and electric fields up to 12 MV/m in 25.5 μm polyimide film base with 12.7 μm coating of Teflon ® FEP on one side. It is believed that this is the first time that studies on this film are reported in the literature.

Radio refractivity N exerts considerable influence on radio signals at Very High Frequency (VHF) and higher frequency bands. In particular, surface refractivity correlates positively with radio field strength, and knowledge of its temporal and/or spatial variability is important in predicting performance of terrestrial radio networks, especially at VHF frequencies. In this work, measurement of electric field strength of Frequency Modulated (FM) radio signals in Niger State, Nigeria was carried out at the onset and peak of the wet season; variation of surface radio refractivity was obtained in Minna, Niger State based on concurrent measurement of surface air temperature, pressure and relative humidity. Variation of electric field strength of FM radio signals in the wet season is found to agree in general with the observed variation of surface radio refractivity, Ns, in Niger State, Nigeria.

The vertical electric field component was measured by a group of the Ukrainian Institute of Radio Astronomy on board the Professor Zubov scientific vessel during April 1989 at latitudes from 30"s to 50"N. Results of the amplitude measurements in the Atlantic of natural ELF radio signals and those from the VLF navigation system "Omega" at its lowest frequency of 10.2 kHz are given. Characteristics were obtained of the moving ship as the field-site for the ELF observations. Variations in the ELF radio noise amplitu'de recorded at tropical latitudes agree with the computed data for the model of three continental centres of lightning activity. The VLF results were obtained by the "beat" technique providing the simplest narrow-band amplitude registration. Range dependencies of the field amplitudes from A (Norway), B ((Liberia) and F (Argentina) stations have been analysed. The VLF attenuation factor was estimated for ,the ambient day conditions along the four cardinal directions. This allowed the detection of a statistically significant attenuation difference between the east-west and west-east propagation paths. The VLF radio signal was also used as a probe to evaluate the effective height of the vertical electric antenna and to calibrate the ELF noise amplitudes.

Modifying the standard constant-voltage poling procedure significantly enhances the in-built electric field strength (and consequently χ (2)) and leads to control of the nonlinear region evolution, both crucial parameters to integrate nonlinearity in waveguiding regions.

Modifying the standard constant-voltage poling procedure significantly enhances the inbuilt electric field strength (and consequently χ (2)) and leads to control of the nonlinear region evolution, both crucial parameters to integrate nonlinearity in waveguiding regions.

Dielectrophoresis (DEP) has been proven as a method of manipulating and analyzing the electrophysiological properties of bioparticles by applying non-uniform electric fields generated through special electrodes. Various electrode geometries have been developed to address different applications. Simulation of the electric field strength over electrodes is essential in order to optimize the generated DEP force for enhancing cell manipulation. This paper describes the study of electric field distribution over planar multiple microarray dot electrode using numerical modeling of Comsol Multiphysics 4.2a®. Results show that the electric field strength is axisymmetrical around the centre of the dot aperture and that is higher at the dot edges than the dot centers. Further studies will be conducted to investigate the effect of applying different frequencies, varying dots size and adding ground plane in between the electrode dots. © 2012 IEEE.

http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6498060