scholarly journals Input Admittance, Directivity and Quality Factor of Biconical Antenna of Arbitrary Cone Angle

2021 ◽  
Author(s):  
Ramakrishna Janaswamy
Keyword(s):  
Quality Factor ◽  
Cone Angle ◽  
Analytical Formula ◽  
Wide Angle ◽  
Slowly Varying Function ◽  
Input Admittance ◽  
Arbitrary Length ◽  
Biconical Antenna ◽  
Arbitrary Cone ◽  
Analytical Expressions

New analytical expressions and numerical results for the quality factor and directivity as well as computationally convenient expressions for the input admittance of a symmetrical biconical antenna of arbitrary length $L$ and cone angle $\theta_0$ are presented. The quality factor for a wide-angle biconical antenna is shown to very closely approach the Chu's limit of $Q = (kL)^{-1}\{1+(kL)^{-2}\}$. Numerical calculations based on the analytical formula for antenna admittance confirm the conjecture that Foster's reactance theorem remains invalid even for perfectly conducting antennas. Furthermore, the variation of directivity of a wide-angle biconical antenna is a slowly varying function of its electrical length and is shown to depart significantly from that of a thin cylindrical dipole. <br>

scholarly journals Input Admittance, Directivity and Quality Factor of Biconical Antenna of Arbitrary Cone Angle

2021 ◽  
Author(s):  
Ramakrishna Janaswamy
Keyword(s):  
Quality Factor ◽  
Cone Angle ◽  
Analytical Formula ◽  
Wide Angle ◽  
Slowly Varying Function ◽  
Input Admittance ◽  
Arbitrary Length ◽  
Biconical Antenna ◽  
Arbitrary Cone ◽  
Analytical Expressions

New analytical expressions and numerical results for the quality factor and directivity as well as computationally convenient expressions for the input admittance of a symmetrical biconical antenna of arbitrary length $L$ and cone angle $\theta_0$ are presented. The quality factor for a wide-angle biconical antenna is shown to very closely approach the Chu's limit of $Q = (kL)^{-1}\{1+(kL)^{-2}\}$. Numerical calculations based on the analytical formula for antenna admittance confirm the conjecture that Foster's reactance theorem remains invalid even for perfectly conducting antennas. Furthermore, the variation of directivity of a wide-angle biconical antenna is a slowly varying function of its electrical length and is shown to depart significantly from that of a thin cylindrical dipole. <br>

scholarly journals Interaction of Bessel Light Beams with Epsilon-near-zero Metamaterials

2014 ◽  
Vol 3 (1) ◽  
pp. 44
Author(s):  
S. Kurilkina ◽  
M. Binhussain ◽  
V. Belyi ◽  
N. Kazak
Keyword(s):  
Magnetic Fields ◽  
Cone Angle ◽  
Dielectric Media ◽  
Electric And Magnetic Fields ◽  
New Type ◽  
Light Beams ◽  
Analytical Expressions ◽  
Plasmon Polaritons ◽  
Bessel Light Beams ◽  
Epsilon Near Zero

The article explores possibilities and conditions of generation of a new type of diffraction-free needle-like field Bessel plasmon polaritons (BPPs) with super narrow cone angle in an epsilon-near-zero metamaterial, surrounded by semi-infinite dielectric media. Correct analytical expressions are obtained and analyzed in detail for the electric and magnetic fields of BPPs formed inside and outside the metamateral slab.

scholarly journals DESIGN OF A WIDE-ANGLE BICONICAL ANTENNA FOR WIDEBAND COMMUNICATIONS

2009 ◽  
Vol 16 ◽  
pp. 229-245 ◽  
Author(s):  
Debalina Ghosh ◽  
Tapan Kumar Sarkar ◽  
Eric L. Mokole
Keyword(s):  
Wide Angle ◽  
Biconical Antenna ◽  
Wideband Communications

scholarly journals Improved Determination of Q Quality Factor and Resonance Frequency in Sensors Based on the Magnetoelastic Resonance Through the Fitting to Analytical Expressions

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4708
Author(s):  
Beatriz Sisniega ◽  
Jon Gutiérrez ◽  
Virginia Muto ◽  
Alfredo García-Arribas
Keyword(s):  
Quality Factor ◽  
Resonance Curve ◽  
Peak Position ◽  
Precipitation Reaction ◽  
Magnetoelastic Sensors ◽  
Resonance Curves ◽  
Quality Factor Q ◽  
Magnetoelastic Resonance ◽  
Analytical Expressions

The resonance quality factor Q is a key parameter that describes the performance of magnetoelastic sensors. Its value can be easily quantified from the width and the peak position of the resonance curve but, when the resonance signals are small, for instance when a lot of damping is present (low quality factor), this and other simple methods to determine this parameter are highly inaccurate. In these cases, numerical fittings of the resonance curves allow to accurately obtain the value of the quality factor. We present a study of the use of different expressions to numerically fit the resonance curves of a magnetoelastic sensor that is designed to monitor the precipitation reaction of calcium oxalate. The study compares the performance of both fittings and the equivalence of the parameters obtained in each of them. Through these numerical fittings, the evolution of the different parameters that define the resonance curve of these sensors is studied, and their accuracy in determining the quality factor is compared.

scholarly journals Experimental investigations of flow through wide angle conical diffusers with uniform flow and swirl type velocity distortions at inlet

2018 ◽  
Vol 22 (6 Part A) ◽  
pp. 2571-2581
Author(s):  
Arumugam Hemalatha ◽  
Nainarkuppam Mahalakshmi
Keyword(s):  
Cone Angle ◽  
Tangential Velocity ◽  
Boundary Layer Separation ◽  
Open Circuit ◽  
Area Ratio ◽  
Experimental Investigations ◽  
Wide Angle ◽  
Flow Parameters ◽  
Conical Diffuser ◽  
Flow Through

Swirl is a tangential velocity component of the fluid flow and is often present in the conical diffuser as a result of rotating machinery in the upstream section. The present experimental work is dedicated to study the effect of moderate swirl on wide angle conical diffuser performance and flow development. The experiments were performed in a low-speed open circuit wind tunnel. There are two different diffusers having a cone angle of 14? (with an area ratio 3.0) and 20? (with an area ratio 4.2) were selected for this investigation. The flow parameters have been measured using DANTEC DYNAMICS make constant temperature hot-wire anemometer (CTA). The results showed that the moderate swirl can significantly improve the stalled diffuser (20? cone angle) performance; however, it has a little effect on the diffuser (14? cone angle) having incipient turbulent boundary layer separation. It was confirmed that the introduction of moderate swirl reduces the chances of flow separation in wide angle conical diffusers.

Analysis of Wire Drawing and Extrusion Through Conical Dies of Small Cone Angle

1963 ◽  
Vol 85 (1) ◽  
pp. 89-95 ◽  
Author(s):  
Betzalel Avitzur
Keyword(s):  
Cone Angle ◽  
Wire Drawing ◽  
Power Balance ◽  
Wire Radius ◽  
Process Variables ◽  
Power Losses ◽  
Uniaxial Load ◽  
The Wire ◽  
Analytical Expressions ◽  
Entrance Velocity

Analytical expressions are derived for the required front pull for wire drawing, as well as the back push for extrusion. The effect of each of the process variables on these forces is presented graphically. The process variables are: the cone’s semiangle (α) initial (Ri) and final (Rf) wire radius, material yield limit (σ0) at uniaxial load, back pull (σxb) and front pull (σxf), coefficient of friction (μ) or shear factor (m), die land (L), exit velocity (vf), and entrance velocity (vi). The power balance is set for these powers: (1) Internal power of deformation of the wire, (2) power involved with the back force on the wire, (3) power involved with the front force on the wire, (4) power losses due to friction between the wire and the die.

Refined theory of tearing growth rates. Part 1. Plasma model without stability threshold

1994 ◽  
Vol 51 (1) ◽  
pp. 29-41 ◽  
Author(s):  
W. Barbulla ◽  
E. Rebhan
Keyword(s):  
Growth Rates ◽  
Analytical Formula ◽  
Refined Theory ◽  
Tearing Modes ◽  
Stability Threshold ◽  
Large Growth ◽  
Small Growth ◽  
Asymptotic Perturbation ◽  
Analytical Expressions

In the theory of tearing modes analytical expressions for the growth rate y are only known for large y > 1/TR. However, since resistive instabilities cannot be externally stabilized, they will rather be observed at small growth rates, which are also the ones that matter in a bifurcation analysis. In this paper the described gap in the tearing theory is closed for the model of a convected resistivity in a sheet pinch. The analytical expressions obtained from an asymptotic perturbation analysis for small growth rates are as simple as those for large growth rates. However, they differ from them appreciably, and also show a marked difference between symmetric and asymmetric perturbations. Specifically, for asymmetric modes in contrast to the symmetric ones, no stability threshold exists, i.e. all asymmetric modes are at least weakly unstable. In addition to the results for small growth rates, an implicit analytical formula is presented that bridges the regime between small and large growth rates. The high quality of the analytical results is confirmed by numerical solution of the full tearing equations

Vector Potential and Magnetic Field of Current-carrying Finite Elliptic Arc Segment in Analytical Form

1985 ◽  
Vol 40 (11) ◽  
pp. 1069-1074 ◽  
Author(s):  
L. Urankar
Keyword(s):  
Magnetic Field ◽  
Vector Potential ◽  
Elliptic Functions ◽  
Analytical Form ◽  
Efficient Computation ◽  
Jacobian Elliptic Functions ◽  
Arbitrary Length ◽  
Computation Algorithm ◽  
Incomplete Elliptic Integrals ◽  
Analytical Expressions

Analytical expressions for the components of the vector potential and magnetic field of a current-carrying elliptic arc filament of arbitrary length are derived. All the expressions developed consist of only known functions such as Jacobian elliptic functions, complete and incomplete elliptic integrals of the first, second and third kind, and thus permit a compact timesaving efficient computation algorithm.

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