scholarly journals Flexible Hilbert-Curve Loop Antenna Having a Triple-Band and Omnidirectional Pattern for WLAN/WiMAX Applications

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Dang-Oh Kim ◽  
Che-Young Kim ◽  
Dae-Geun Yang
Keyword(s):  
Circular Polarization ◽  
Radiation Pattern ◽  
Loop Antenna ◽  
Hilbert Curve ◽  
Third Order ◽  
The Third ◽  
Flexible Loop ◽  
Loop Antennas ◽  
Antenna Factor ◽  
Triple Band

A triple-band flexible loop antenna is proposed for WLAN/WiMAX applications in this paper. The proposed antenna is formed by the third-order Hilbert-curve and bending type structure which provides flexible characteristics. Even though the radius of the curvature for bending antennas is changed, a triple-band feature still remains in the proposed antenna. Moreover, the antenna exhibits the characteristics of omnidirectional radiation pattern and circular polarization. To verify the receiving performance of antenna, a simulation on the antenna factor was conducted by an EM simulator. Based on these results, the suggested antenna makes a noteworthy performance over typical loop antennas.

Rigorous solution of multiply fed dipole antenna

1986 ◽  
Vol 64 (3) ◽  
pp. 303-310 ◽  
Author(s):  
H. A. Ragheb ◽  
M. Hamid
Keyword(s):  
Radiation Pattern ◽  
Current Distribution ◽  
Close Agreement ◽  
Dipole Antenna ◽  
Linear Antenna ◽  
Rigorous Solution ◽  
Third Order ◽  
Input Admittance ◽  
First Order ◽  
The Third

This paper presents an extension of Hurd's solution for the input admittance of a long linear antenna to the general case of an arbitrarily and multiply fed dipole antenna. Accurate expressions for the radiation pattern, current distribution, and input admittance of the arbitrarily fed dipole antenna are derived by the Wiener–Hopf technique. The results are compared with Harrington's solution for the case of an arbitrarily fed dipole and very close agreement is observed. For a multiply fed dipole, a comparison with Strait and Hirasawa indicates that our expression for the radiation pattern is highly accurate, even when it only corresponds to the first-order expression of the current distribution. The current distribution and the input admittance are calculated up to the third order and include terms of O(1/h2), where h is half the tip-to-tip length of the antenna.

scholarly journals A novel bandwidth enhanced triple band antenna for satellite and airborne applications

2020 ◽  
Vol 19 (2) ◽  
pp. 659
Author(s):  
Mohammed Ismail Mohammed
Keyword(s):  
Antenna Array ◽  
Third Order ◽  
Large Space ◽  
Mobile Wireless ◽  
Bandwidth Enhancement ◽  
The Third ◽  
Array Performance ◽  
Satellite Service ◽  
Fixed Wireless ◽  
Triple Band

<p align="justify"><span>This paper presents a novel bandwidth enhancement technique in which a passive stack of third order Sierpinski carpet fractal antenna is parasitically coupled to the driven element that is also a Sierpinski fractal of third order. Edge feeding technique is used. The passive stack placed symmetric to the driven elements provide the combined benefits of horizontal and vertical parasitic coupling, with added advantage of miniaturization contributed by fractal technology. Result of the study indicate that the antenna array provide triple band with a large inter-band separation that mitigates the effects of inter-band interference. The first band at 6.1Ghz with bandwidth of 250Mhz supports mobile wireless and fixed satellite service, the second band at 7.1Ghz with 350Mhz bandwidth supports mobile wireless, fixed wireless and fixed satellite service. The third band is at 11.6Ghz with bandwidth of 1.4Ghz and supports fixed wireless and fixed satellite services. The number of elements in the parasitic stack influence array performance in terms of bandwidth, gain and directivity. The bandwidth in the third band increased from 1.5Ghz for two-element stack to 1.7Ghz for three-element. This has an advantage over conventional antenna array, that use more active antenna elements that have the limitations of more power consumption and large space occupancy. </span></p>

Probe size and 5th-order aberration

1987 ◽  
Vol 45 ◽  
pp. 134-135 ◽  
Author(s):  
Zhifeng Shao
Keyword(s):  
Electron Probe ◽  
Spherical Aberration ◽  
Wave Length ◽  
Cylindrical Symmetry ◽  
Electron Wave ◽  
Third Order ◽  
The Third ◽  
Probe Radius ◽  
Small Probe ◽  
Probe Size

A small electron probe has many applications in many fields and in the case of the STEM, the probe size essentially determines the ultimate resolution. However, there are many difficulties in obtaining a very small probe.Spherical aberration is one of them and all existing probe forming systems have non-zero spherical aberration. The ultimate probe radius is given byδ = 0.43Csl/4ƛ3/4where ƛ is the electron wave length and it is apparent that δ decreases only slowly with decreasing Cs. Scherzer pointed out that the third order aberration coefficient always has the same sign regardless of the field distribution, provided only that the fields have cylindrical symmetry, are independent of time and no space charge is present. To overcome this problem, he proposed a corrector consisting of octupoles and quadrupoles.

Children’s Recall of Approximations to English

1973 ◽  
Vol 16 (2) ◽  
pp. 201-212 ◽  
Author(s):  
Elizabeth Carrow ◽  
Michael Mauldin
Keyword(s):  
Language Development ◽  
Fourth Order ◽  
Third Order ◽  
Memory Processes ◽  
The Third ◽  
General Index ◽  
General Linguistic

As a general index of language development, the recall of first through fourth order approximations to English was examined in four, five, six, and seven year olds and adults. Data suggested that recall improved with age, and increases in approximation to English were accompanied by increases in recall for six and seven year olds and adults. Recall improved for four and five year olds through the third order but declined at the fourth. The latter finding was attributed to deficits in semantic structures and memory processes in four and five year olds. The former finding was interpreted as an index of the development of general linguistic processes.

scholarly journals Ultrafast Third-Order Nonlinear Optical Response Excited by fs Laser Pulses at 1550 nm in GaN Crystals

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3194
Author(s):  
Adrian Petris ◽  
Petronela Gheorghe ◽  
Tudor Braniste ◽  
Ion Tiginyanu
Keyword(s):  
Harmonic Generation ◽  
Nonlinear Optical ◽  
Laser Pulses ◽  
Third Harmonic Generation ◽  
High Repetition Rate ◽  
Third Order ◽  
Third Harmonic ◽  
The Third ◽  
High Repetition ◽  
Gan Crystal

The ultrafast third-order optical nonlinearity of c-plane GaN crystal, excited by ultrashort (fs) high-repetition-rate laser pulses at 1550 nm, wavelength important for optical communications, is investigated for the first time by optical third-harmonic generation in non-phase-matching conditions. As the thermo-optic effect that can arise in the sample by cumulative thermal effects induced by high-repetition-rate laser pulses cannot be responsible for the third-harmonic generation, the ultrafast nonlinear optical effect of solely electronic origin is the only one involved in this process. The third-order nonlinear optical susceptibility of GaN crystal responsible for the third-harmonic generation process, an important indicative parameter for the potential use of this material in ultrafast photonic functionalities, is determined.

Boundary-Value Problems for Third-Order Lipschitz Ordinary Differential Equations

2014 ◽  
Vol 58 (1) ◽  
pp. 183-197 ◽  
Author(s):  
John R. Graef ◽  
Johnny Henderson ◽  
Rodrica Luca ◽  
Yu Tian
Keyword(s):  
Differential Equation ◽  
Differential Equations ◽  
Ordinary Differential Equations ◽  
Boundary Value Problems ◽  
Order Differential Equation ◽  
Boundary Value ◽  
Point Boundary ◽  
Third Order ◽  
Optimal Length ◽  
The Third

AbstractFor the third-order differential equationy′″ = ƒ(t, y, y′, y″), where, questions involving ‘uniqueness implies uniqueness’, ‘uniqueness implies existence’ and ‘optimal length subintervals of (a, b) on which solutions are unique’ are studied for a class of two-point boundary-value problems.

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