Analysis of the measurement plane change in street illumination measurements

The article explores the holographic method of measuring the antenna pattern. A flat antenna array is used as the antenna under test, and a planar rectangular surface is used as the surface on which the amplitudephase distribution in the near field is measured. Using the example of a flat antenna array, we consider the influence of the size of the measurement surface of the amplitude-phase distribution of the field in a plane orthogonal to the reconstruction plane of the radiation pattern. Antenna emitters are excited with a combined amplitude distribution and linear phase distribution. The field in the longitudinal zone of the lattice is determined using the Kirchhoff integral. The reconstructed radiation patterns are estimated using the amplitude-phase distribution over the entire measurement plane in comparison with the array radiation pattern in the far zone. A numerical analysis of the influence on the errors in determining the parameters of the lattice radiation pattern using the holographic method is also carried out: the number of columns of the amplitude-phase distribution on the measurement plane, the position of this plane in three coordinates relative to the plane of the aperture of the lattice. It is shown that if the spacing of the points of measurement of the amplitude-phase distribution and the pitch of the lattice are equal, to restore the radiation pattern using the holographic method, it is sufficient to use one column of the amplitude-phase distribution on the measurement plane. This greatly simplifies and reduces the cost of the measurement process and the necessary equipment. Examples of determining errors in measuring the parameters of the antenna array when shifting the plane of measurement of the amplitude-phase distribution in three coordinates are given.

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3D Velocity Measurement by Orthogonal-Plane Micro-PIV for Electrokinetic Enhancement of Surface Reaction

ASME 2013 11th International Conference on Nanochannels, Microchannels, and Minichannels ◽

10.1115/icnmm2013-73214 ◽

2013 ◽

Author(s):

Akihiko Ishida ◽

Daisuke Ichimura ◽

Masahiro Motosuke

Keyword(s):

Velocity Field ◽

Flow Velocity ◽

Velocity Measurement ◽

Surface Reaction ◽

Bottom Wall ◽

3D Flow ◽

Reaction Efficiency ◽

Micro Piv ◽

Measurement Plane ◽

Orthogonal Plane

In microfluidic systems, surface reaction is diffusion-limited because the effect of convection on mass transport decreases due to low Peclet number. It is indicated that an externally induced flow toward the reactive interface is effective to enhance the efficiency of the surface reaction. However, it is difficult to evaluate the flow velocity normal to the substrate, which directly contributes to the enhancement of the surface reaction, due to the monolithic dimension of microfluidic device. This paper reports the development of a 3D flow velocity measurement method by orthogonal-plane micro-PIV to evaluate the contribution of flow distortion by alternating-current electrokinetic phenomena on the reaction enhancement. 3D velocity field is reconstructed from two orthogonal velocity fields measured by 2D micro-PIV with different measurement planes; one is based on normal observation with the measurement plane parallel to the bottom wall and the other is based on a lateral observation with the plane perpendicular to the bottom wall through a sidewall of a fluidic channel made of PDMS (100 × 50 μm). Complete 3D velocity field is determined by scanning the measurement plane in each observation scheme. Validity of orthogonal-plane micro-PIV for the 3D velocity measurement was confirmed by the measurement of three component velocities in a tilt rectangular microchannel. Then, we investigated AC-driven electrothermal (ACET) effect induced by the property gradient of fluid due to temperature nonuniformity under an electric field application. Effective flow structure of ACET for the enhancement of surface reaction, a circular stirring fluid motion which conveys bulk fluid to the surface region, was observed. This stirring motion of fluid could improve the binding opportunities between suspended and immobilized species and result in the promotion of reaction efficiency. It is clarified that 3D flow of ACET contributes to the localized enhancement of the surface reaction efficiency.

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