Input impedance and reflection coefficient in fractal-like models of asymmetrically branching compliant tubes

1996 ◽  
Vol 43 (7) ◽  
pp. 715-722 ◽  
Author(s):  
D.J. Brown
Keyword(s):  
Reflection Coefficient ◽  
Input Impedance

scholarly journals Broadband Dipole-Loop Combined Nanoantenna Fed by Two-Wire Optical Transmission Line

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Janilson L. de Souza ◽  
Karlo Q. da Costa ◽  
Victor Dmitriev ◽  
Felipe Bamberg
Keyword(s):  
Reflection Coefficient ◽  
Transmission Line ◽  
Radiation Pattern ◽  
Method Of Moments ◽  
Input Impedance ◽  
Optical Transmission ◽  
Near Field ◽  
Impedance Matching ◽  
Linear Method ◽  
Geometrical Parameters

This paper presents a broadband nanoantenna fed by a two-wire optical transmission line (OTL). The antenna is defined by a combination of a dipole and a loop, where only the dipole element is connected to the OTL. The analysis is fulfilled by the linear method of moments with equivalent surface impedance to model the conductors. Firstly, the nanoantenna alone is investigated, where the input impedance, current distribution, reflection coefficient, fractional bandwidth, radiation efficiency, and radiation pattern are analyzed. Then, the input impedance matching of this antenna with the OTL is considered. In this case the current, near field distribution, radiation pattern, and reflection coefficient are calculated for different geometrical parameters. The results show that the loop inserted in the circuit can increase the bandwidth up to 42% and decreases the reflection coefficient in the OTL to −25 dB.

scholarly journals A super wideband circular-shaped fractal antenna loaded with concentric hexagonal slots

2018 ◽  
Vol 7 (3.29) ◽  
pp. 211 ◽  
Author(s):  
Srinivasarao Alluri ◽  
Nakkeeran Rangaswamy
Keyword(s):  
Wireless Communications ◽  
Reflection Coefficient ◽  
Input Impedance ◽  
Ground Plane ◽  
Fractal Antenna ◽  
Total Size ◽  
Compact Size ◽  
Peak Gain ◽  
Good Agreement ◽  
Microstrip Feed

This article presents a super wideband (SWB) circular-shaped fourth iterative fractal antenna loaded with concentric hexagonal slots. A tapered microstrip feed and a partial ground plane is used. It has a total size of 40 × 27 × 1.6 mm3. Numerical results of the antenna show that it provides a bandwidth from 1.43 GHz to more than 40 GHz (percentage bandwidth greater than 186%) with a bandwidth ratio of approximately greater than 28:1 for S11 < -10 dB. A prototype of the proposed antenna has been fabricated and its performances are measured up to 15 GHz. A good agreement is achieved between the numerical and experimental reflection coefficient, VSWR and input impedance. Measured radiation patterns at different frequencies and simulated peak gain are presented and discussed. It has the advantages of super wide bandwidth and compact size. The developed antenna is suitable for various wireless communications such as GPS, GSM, UMTS, ISM and UWB.  

The method of determining the metrological performance of unit reference standards of reflection coefficient in waveguides at millimeter waves

2020 ◽  
pp. 59-63
Author(s):  
A.S. Bondarenko ◽  
A.S. Borovkov ◽  
I.M. Malay ◽  
V.A. Semyonov
Keyword(s):  
Reflection Coefficient ◽  
Millimeter Waves ◽  
Primary Standard ◽  
Reference Standards ◽  
Measurement Scale ◽  
Current State ◽  
Coefficient Measurement ◽  
Mathematical Equations ◽  
Electrodynamic Modeling ◽  
Metrological Performance

The analysis of the current state of the reflection coefficient measurements in waveguides at millimeter waves is carried out. An approach for solving the problem of reproducing the reflection coefficient measurement scale is proposed. Mathematical equations, which are the basis of the reflection coefficient measurement equation are obtained. The method of determining the metrological performance of reflection coefficient unit’s reference standards is developed. The results of electrodynamic modeling and analytical calculations by the developed method are compared. It is shown that this method can be used for reproducing the reflection coefficient unit in the development of the State primary standard.

REFLECTION COEFFICIENT OF AN ELECTROMAGNETIC WAVE IN CONDUCTIVE MEDIA

2018 ◽  
pp. 100-106
Author(s):  
M. S. Sudakova ◽  
M. L. Vladov ◽  
M. R. Sadurtdinov
Keyword(s):  
Reflection Coefficient ◽  
Ground Penetrating Radar ◽  
Electromagnetic Waves ◽  
Water Contamination ◽  
Survey Design ◽  
Direct And Inverse Problems ◽  
The Difference ◽  
Ground Penetrating ◽  
Ideal Dielectric

Within the ground penetrating radar bandwidth the medium is considered to be an ideal dielectric, which is not always true. Electromagnetic waves reflection coefficient conductivity dependence showed a significant role of the difference in conductivity in reflection strength. It was confirmed by physical modeling. Conductivity of geological media should be taken into account when solving direct and inverse problems, survey design planning, etc. Ground penetrating radar can be used to solve the problem of mapping of halocline or determine water contamination.

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