This paper presents an optimum design technique of an asymmetric V-dipole antenna and it’s a three-element Yagi-Uda array using Genetic Algorithm (GA). The optimization parameter for the V-dipole is the directivity and that for the Yagi-Uda array are the input impedance and directivity. The theoretical analysis has been done using a Moment-Method technique in a very simple step-by-step way, and...

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Microphone turbulence screens are used to suppress turbulent pressure fluctuations when measuring the acoustic pressure inside a duct with flow. They consist of a long tube with a slit covered with porous material, and thus are also called sampling tubes. Because they are not omnidirectional, it is necessary to calculate corrections when higher order modes are propagating in the duct. In order ...

2845 Sound directivity control is made possible by a compact array of independently driven loudspeakers. Recently, a control system for such a multi-channel source based on its acoustic radiation modes has been proposed. These modes form an orthogonal set of velocity patterns on the source surface, and emerge from the eigendecomposition of a free-field radiation operator that depends on frequen...

The optical antennas have the potential in various applications because of their field enhancement and directivity control. The directivity of a dipole antenna can be improved by directivity-enhanced Raman scattering structure, which is a combination of a dipole antenna and a ring reflector layer on a ground plane. The concentric rings can collect the light into the center hole. Depending upon ...

In this paper, we develop a new adaptive scheme in which an optimal distance-based update threshold is selected not only as a function of the call-to-mobility ratio, but also as a transitional directivity index ω; a new parameter introduced to give some measures of the mobile’s traveling patterns. It is assumed that when ω > 1, the mobile has a greater tendency of roaming “outwards” and hence a...