High-Frequency Diffraction by an Elliptic Cylinder With a Strongly Elongated Cross-Section

2015 ◽  
Vol 101 (5) ◽  
pp. 908-914
Author(s):  
I. V. Andronov ◽  
V. V. Monakhov
Keyword(s):  
Cross Section ◽  
High Frequency ◽  
Elliptic Cylinder

High-Frequency Diffraction of a Point Source Field by a Strongly Elongated Elliptic Cylinder

2019 ◽  
Vol 105 (6) ◽  
pp. 912-917
Author(s):  
Ivan V. Andronov
Keyword(s):  
Point Source ◽  
Cross Section ◽  
Acoustic Field ◽  
High Frequency ◽  
Elliptic Cylinder ◽  
Linear Source ◽  
Source Field ◽  
Major Semiaxis

The problem of diffraction of a high-frequency point source acoustic field by an infinite elliptic cylinder with a strongly elongated cross-section is studied. At every direction of propagation, the solution is shown to be similar to those of a linear source field diffraction by a cylinder with correspondingly enlarged major semiaxis.

The scaled RCS measurement method for lossy targets via dynamically matching the reflection coefficients in the THz band

2021 ◽  
Author(s):  
Shuang Pang ◽  
Yang Zeng ◽  
Qi Yang ◽  
Bin Deng ◽  
Hong-Qiang Wang
Keyword(s):  
Cross Section ◽  
High Frequency ◽  
Measurement Method ◽  
Dielectric Material ◽  
Frequency Estimation ◽  
Estimation Method ◽  
Physical Optics ◽  
Reflection Coefficients ◽  
Effective Solution ◽  
Terahertz Band

Abstract In the terahertz band, the dispersive characteristic of dielectric material is one of the major problems in the scaled radar cross section (RCS) measurement, which is inconsistent with the electrodynamics similitude deducted according to the Maxwell’s equations. Based on the high-frequency estimation method of physical optics (PO), a scaled RCS measurement method for lossy objects is proposed through dynamically matching the reflection coefficients according to the distribution of the object’s facets. Simulations on the model of SLICY were conducted, the inversed RCS of the lossy prototype was obtained using the proposed method. Via comparing the inversed RCS with the calculated results, the validity of the proposed method is demonstrated. The proposed method provides an effective solution to the scaled RCS measurement for lossy objects in the THz band.

scholarly journals Influence of Microstructure on the High-Frequency Ultrasound Measurement of Peak Density

2018 ◽  
Vol 1 (4) ◽  
Author(s):  
Jeremy Stromer ◽  
Leila Ladani
Keyword(s):  
Cross Section ◽  
High Frequency ◽  
Scattering Cross Section ◽  
Ultrasound Measurement ◽  
Sphere Diameter ◽  
High Frequency Ultrasound ◽  
Total Scattering ◽  
Peak Density ◽  
Scattering Cross ◽  
Frequency Ultrasound

Peak density is an ultrasound measurement, which has been found to vary according to microstructure, and is defined as the number of local extrema within the resulting power spectrum of an ultrasound measurement. However, the physical factors which influence peak density are not fully understood. This work studies the microstructural characteristics which affect peak density through experimental, computationa,l and analytical means for high-frequency ultrasound of 22–41 MHz. Experiments are conducted using gelatin-based phantoms with glass microsphere scatterers with diameters of 5, 9, 34, and 69 μm and number densities of 1, 25, 50, 75, and 100 mm−3. The experiments show the peak density to vary according to the configuration. For example, for phantoms with a number density of 50 mm−3, the peak density has values of 3, 5, 9, and 12 for each sphere diameter. Finite element simulations are developed and analytical methods are discussed to investigate the underlying physics. Simulated results showed similar trends in the response to microstructure as the experiment. When comparing scattering cross section, peak density was found to vary similarly, implying a correlation between the total scattering and the peak density. Peak density and total scattering increased predominately with increased particle size but increased with scatterer number as well. Simulations comparing glass and polystyrene scatterers showed dependence on the material properties. Twenty-four of the 56 test cases showed peak density to be statistically different between the materials. These values behaved analogously to the scattering cross section.

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