An integral equation representation of wide‐band electromagnetic scattering by thin sheets

Geophysics ◽  
2002 ◽  
Vol 67 (3) ◽  
pp. 746-754 ◽  
Author(s):  
Yoonho Song ◽  
Hee Joon Kim ◽  
Ki Ha Lee
Keyword(s):  
Integral Equation ◽  
Frequency Band ◽  
Electromagnetic Scattering ◽  
High Frequency ◽  
Thin Sheet ◽  
Wide Band ◽  
Impedance Method ◽  
Thin Sheets ◽  
Wave Source ◽  
Band Frequency

An efficient, accurate numerical modeling scheme has been developed, based on the integral equation solution to compute electromagnetic (EM) responses of thin sheets over a wide frequency band. The thin‐sheet approach is useful for simulating the EM response of a fracture system in the earth. The focus of this development has been the accuracy of the numerical solution over a wide‐band frequency range of up to 100 MHz. The effect of displacement currents is included to correctly evaluate high‐frequency EM scattering. Currently, EM responses of two thin sheets with different geometrical and electrical properties embedded in a three‐layer earth can be modeled over a frequency band of 10−3 to 108 Hz. The layered earth and the sheets can be electrically dispersive, an important feature that allows analysis of frequency‐dependent characteristics of the model under investigation. The source field can be generated by a remote or local electric or magnetic dipole located on the surface or in a borehole. A plane‐wave source can also be used, and numerical analyses have been made for magnetotellurics and the high‐frequency impedance method.

scholarly journals Three Different Compact Elliptical Slot Ultra -Wide band Antennas for Wireless Communication Applications

2021 ◽  
pp. 52-59
Author(s):  
K. S Chakradhar ◽  
◽  
V. Malleswara Rao
Keyword(s):  
Frequency Band ◽  
Return Loss ◽  
Wide Band ◽  
Circular Ring ◽  
Ultra Wide Band ◽  
Impedance Bandwidth ◽  
Band Frequency ◽  
Uwb Antennas ◽  
Elliptical Ring ◽  
Pcb Design

From this current paper, 3 separate elliptical slotted ultra- wide band (UWB) antennas are being proposed. These antennas have been designed with a standard PCB design process to be capable of integrating with radiofrequency or microwave circuitry. Two designs were presented in which the initial design comprised a half circular ring radiator and the remaining one considers a half elliptical ring radiator. The third design of the radiator is in the shape of a crescent. The impedance bandwidth of all these presented antenna designs varies from 2.5GHz and reaches to 14GHz with a S11 less than -10GHz. Here, every proposed antenna design also has a consistent radiation pattern across its frequency band of interest. The performance of the antenna is impressive for lower band frequency in UWB system, which differs in a range of 3.1GHz to 5.1GHz. Across the whole frequency band the antenna shows a 10db return loss bandwidth. The antenna is fabricated on RT-duroid substrate and fed with 50 Ω coupled tappered transmission line.

Development and Evaluation of a High Frequency Response Signal Conditioning Amplifier for Miniature, Silicon Bridge-Type Pressure Transducers

2012 ◽  
Author(s):  
J. Ilott ◽  
W. D. E. Allan
Keyword(s):  
Frequency Response ◽  
High Frequency ◽  
Wide Band ◽  
Pass Band ◽  
Signal Conditioning ◽  
Band Frequency ◽  
Differential Signal ◽  
Pressure Transducers ◽  
High Frequency Response ◽  
Experimental Apparatus

In addition to their small size, miniature silicon pressure transducers offer wide-band frequency response. Taking advantage of the high-frequency response of these pressure transducers within an electrically noisy environment requires high bandwidth amplification and anti-alias filtering. This paper describes a signal conditioning amplifier that provides for linear phase filtering of a differential or single-ended input signal and outputs a differential signal. Differential signals are suitable for driving long cable runs that may be required when digital recording hardware cannot be located in close proximity to experimental apparatus. The design has also been shown to exhibit nearly constant group delay over the pass-band, reducing the need for substantial oversampling of the pressure transducer signals to avoid the nonlinear phase response typical of low-pass filters in the vicinity of their cut-off frequency. Testing has shown the module to provide a very flat pass-band response while achieving a high-order filter response at the cut-off frequency, along with excellent steady state DC accuracy.

AN AUTOMATIC METHOD OF DIRECT INTERPRETATION OF MAGNETIC PROFILES

Geophysics ◽  
1976 ◽  
Vol 41 (3) ◽  
pp. 531-541 ◽  
Author(s):  
Sudhir Jain
Keyword(s):  
Magnetic Field ◽  
High Frequency ◽  
Thin Sheet ◽  
Thin Sheets ◽  
Automatic Method ◽  
Field Profile ◽  
Total Magnetic Field ◽  
Magnetic Field Profile ◽  
Direct Interpretation ◽  
Susceptibility Contrast

The well‐known equations for the total magnetic field due to thin sheets and the edges of a thick body (Werner, 1953) can be programmed to compute automatically the depth to the top, susceptibility contrast, and the dip of these features from a given total magnetic field profile. The synthetic anomalies show that in ideal cases the depths can be determined to the accuracy of 10 percent or better, provided the source of the anomaly can be identified as a bounding edge or the thin sheet. It has also been found that the anomalies due to edges approximately one depth unit apart in horizontal direction can be resolved. Vertically, the interpretation of shallow bodies is not affected by the presence of deeper bodies. However, the deeper bodies can be located only when they cause anomalies much stronger than those associated with shallow bodies, or when the shallow bodies are displaced from the deep edges horizontally by a distance equal to or greater than the depth to the top of deep edges. The shallow high‐frequency anomalies tend to mask the interpretation of deeper anomalies rather than cause erroneous estimates. Susceptibility contrasts can be estimated reasonably accurately only when the dips are about 40 degrees or greater. The dip estimates are accurate to within 10 percent.

Wide Frequency Band DC Corona Current Measurement and Analysis of Bundle Conductor Based on UHV Corona Cage

2013 ◽  
Vol 718-720 ◽  
pp. 600-604
Author(s):  
Fang Cheng Lü ◽  
Lei Zhu ◽  
Yun Peng Liu ◽  
Qing Zhong Geng ◽  
Jun Zhu ◽  
...  
Keyword(s):  
Frequency Band ◽  
High Frequency ◽  
Rain Rate ◽  
Wide Band ◽  
Current Measurement ◽  
Current Signal ◽  
Current Waveform ◽  
Wide Frequency Band ◽  
Corona Current ◽  
Measurement And Analysis

A wide frequency band DC corona current measurement system is introduced in this paper. GPS technology is applied to make sure that the voltage and current signal are collected synchronously. The wide band corona current signal is transmitted to the lower computer by the wireless network of 300M/s. The wide frequency band DC corona current waveform was gained in the Ultra High Voltage (UHV) Test Base in Wuhan, which can reflect the high frequency pulses of the corona current, and corona currents of 6 bundle conductor LGJ630-45 in dry and rain (rain rate 20mm/h) conditions are gained. The corona current in the rain condition is much larger than that in the dry condition.

scholarly journals Wideband Metamaterial Absorber Based on Combination of Unit Cells

2020 ◽  
Vol 4 (2) ◽  
Author(s):  
Puji Handayani ◽  
Gamantyo Hendrantoro ◽  
Eko Setijadi ◽  
Ahmad Mauludiyanto ◽  
Muhammad Rendy Anggara
Keyword(s):  
Frequency Band ◽  
Wide Band ◽  
Split Ring Resonator ◽  
Metamaterial Absorber ◽  
Simulation Software ◽  
Resonant Frequencies ◽  
Band Frequency ◽  
Wide Frequency Band ◽  
Unit Cells ◽  
Multiple Unit

Metamaterial absorber is an electromagnetic wave absorber made from metamaterial. It basically works in narrow band frequency as it is designed in a particular shape that related to its resonance frequency. However, some applications, e.g., anechoic chamber, require metamaterial absorber that can work in a wide frequency band. This paper discussed the design of wide band metamaterial absorber using the combination of multiple unit cells. The unit cells type was split ring resonator (SRR). SRR had advantages in terms of its simple shape, it could have more than one resonant frequencies depending on the number of its ring, and its shape could be modified easily to obtain the desired resonant frequencies. We designed metamaterial absorber having good absorbtion rate in 2-10 GHz frequency band. To cover this wide frequency band, we used five unit cells which were arranged on a flat plane. Each unit cell had several resonant frequencies. The design was carried out using simulation software of CST (Computer Simulation System). The fabricated design was measured and the results shown that it had an absorbtion rate of 99% in the measured frequency band.

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