Relative Pemittivity Study of Materials Used in Biological Electromagnetic Absorption Tests by Using the Reflection Coefficient Method in the Frequency Range from 200 MHz to 8.5 GHz

2006 ◽  
Author(s):  
A. Valentino ◽  
A. Vera ◽  
C.J. Trujillo ◽  
A. Baez ◽  
H. Zepeda ◽  
...  
Keyword(s):  
Reflection Coefficient ◽  
Frequency Range ◽  
Electromagnetic Absorption ◽  
Materials Used ◽  
Coefficient Method

scholarly journals Design and Development of a Wideband Planar Yagi Antenna Using Tightly Coupled Directive Element

Micromachines ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 975
Author(s):  
Muhammad A. Ashraf ◽  
Khalid Jamil ◽  
Ahmed Telba ◽  
Mohammed A. Alzabidi ◽  
Abdel Razik Sebak
Keyword(s):  
Reflection Coefficient ◽  
Wireless Communication ◽  
Radiation Pattern ◽  
Excellent Agreement ◽  
Frequency Range ◽  
Fractional Bandwidth ◽  
Yagi Antenna ◽  
Tightly Coupled ◽  
Simulation Results ◽  
Novel Concept

In this paper, a novel concept on the design of a broadband printed Yagi antenna for S-band wireless communication applications is presented. The proposed antenna exhibits a wide bandwidth (more than 48% fractional bandwidth) operating in the frequency range 2.6 GHz–4.3 GHz. This is achieved by employing an elliptically shaped coupled-directive element, which is wider compared with other elements. Compared with the conventional printed Yagi design, the tightly coupled directive element is placed very close (0.019λ to 0.0299λ) to the microstrip-fed dipole arms. The gain performance is enhanced by placing four additional elliptically shaped directive elements towards the electromagnetic field’s direction of propagation. The overall size of the proposed antenna is 60 mm × 140 mm × 1.6 mm. The proposed antenna is fabricated and its characteristics, such as reflection coefficient, radiation pattern, and gain, are compared with simulation results. Excellent agreement between measured and simulation results is observed.

scholarly journals Conductivity tomography at two frequencies

Geophysics ◽  
2003 ◽  
Vol 68 (2) ◽  
pp. 516-522 ◽  
Author(s):  
Junxing Cao ◽  
Zhenhua He ◽  
Jieshou Zhu ◽  
Peter K. Fullagar
Keyword(s):  
Single Frequency ◽  
Dual Frequency ◽  
Frequency Range ◽  
Frequency Method ◽  
New Approach ◽  
Electromagnetic Absorption ◽  
Universal Approach ◽  
Approximate Frequency ◽  
Transmitting Antenna

We present a new approach for crosshole radio tomography. Conductivity images of the investigated area are reconstructed from the ratio of the electric field intensities measured at two similar frequencies. The method largely avoids assumptions about the radiation pattern and in‐situ intensity of the transmitting antenna, which introduce errors in conventional single‐frequency crosshole electromagnetic‐absorption tomography. Application of the method to field data achieved an improvement in resolution of anomalies over traditional single‐frequency absorption tomography. The dual‐frequency method is not a universal approach; it is suitable for moderately conductive media (<0.01 S/m) over the approximate frequency range 1–100 MHz.

scholarly journals Influence of water content of expanded clay on the reflection coefficient of electromagnetic shild

2021 ◽  
Vol 66 (1) ◽  
pp. 93-100
Author(s):  
T. V. Borbot’ko ◽  
S. E. Savanovich
Keyword(s):  
Reflection Coefficient ◽  
Moisture Content ◽  
Electromagnetic Radiation ◽  
Pore Size ◽  
Operating Frequency ◽  
Reflection Coefficients ◽  
Frequency Range ◽  
Operating Frequency Range ◽  
Influence Of Water ◽  
The Relationship

The regularities of the influence of the moisture content of expanded clay on the values of the reflection coefficient of electromagnetic radiation (EMR) of this material in the frequency range of 1–17 GHz have been established. The relationship between the size of fractions (pore size) of expanded clay and the operating frequency range of the EMR screen samples has been determined. It is shown that a twofold increase in the moisture content of expanded clay with fractions of 1…4 and 10…20 mm provides an extension of the operating frequency range of the EMR shield samples made on the basis of this material, with a decrease in the reflection coefficient of the test samples by 1.7 and 3 times, respectively. It was found that an increase in the moisture content of expanded clay from 19 to 40 % with a decrease in the size of its fractions from 10…20 to 1…4 mm and a pore size from 0.1…0.2 to 0.01…0.06 mm provides a decrease in the values of the reflection coefficient of EMR screen samples at frequencies of 7.7–17.0 GHz, and an increase in the size of expanded clay fractions from 1…4 to 10…20 mm with an increase in the size of its pores from 0.01…0.06 to 0.1…0.2 mm provides a decrease in the values of the reflection coefficient of EMR screen samples at frequencies of 1.0–7.7 GHz. It is shown that the practical use of these regularities makes it possible to form EMR screen samples with reflection coefficients from –2.8 to –22.0 dB in the frequency range 1–17 GHz, which makes it possible to recommend them for use when creating shielded rooms.

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