scholarly journals THE MULTILEVEL FAST PHYSICAL OPTICS METHOD FOR CALCULATING HIGH FREQUENCY SCATTERED FIELDS

2020 ◽  
Vol 169 ◽  
pp. 1-15
Author(s):  
Zhiyang Xue ◽  
Yu Mao Wu ◽  
Weng Cho Chew ◽  
Ya-Qiu Jin ◽  
Amir Boag
Keyword(s):  
High Frequency ◽  
Physical Optics ◽  
Scattered Fields

scholarly journals The Efficient Method for Calculating the Physical Optics Scattered Fields from the Concave Surfaces

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Yu Mao Wu ◽  
Hanzhang Zhou ◽  
Ya-Qiu Jin ◽  
Jun Hu ◽  
Haijing Zhou ◽  
...  
Keyword(s):  
High Frequency ◽  
Physical Optics ◽  
Brute Force ◽  
Numerical Examples ◽  
Type Integral ◽  
Frequency Independent ◽  
Highly Oscillatory ◽  
Scattered Fields ◽  
Steepest Descent Path ◽  
Quadratic Variations

In this work, the numerical steepest descent path (NSDP) method is proposed to compute the highly oscillatory physical optics (PO) scattered fields from the concave surfaces, including both the monostatic and the bistatic cases. Quadratic variations are adopted to approximate the integrands of the PO type integral into the canonical form. Then, on involving the NSDP method, we deform the integration paths of the integrals into several NSDPs on the complex plain, through which the highly oscillatory integrands are converted to exponentially decay integrands. The RCS results of the PO scattered field are calculated and are compared with the high frequency asymptotic (HFA) method and the brute force (BF) method. The results demonstrate that the proposed NSDP method for calculating PO scattered fields from concave surfaces is frequency-independent and error-controllable. Numerical examples are provided to verify the efficiencies of the NSDP method.

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 Reflexionseigenschaften von Windenergieanlagen im Funkfeld von Funknavigations- und Radarsystemen

2015 ◽  
Vol 13 ◽  
pp. 9-18 ◽  
Author(s):  
S. Sandmann ◽  
S. Divanbeigi ◽  
H. Garbe
Keyword(s):  
High Frequency ◽  
Physical Optics ◽  
Very High Frequency ◽  
Radio Range ◽  
Multi Level ◽  
Very High

Abstract. Die hier behandelte Untersuchung befasst sich mit den Störungen des elektrischen Feldes einer Doppler Very High Frequency Omnidirectional Radio Range Navigationsanlage (DVOR) in der Gegenwart von Windenergieanlagen (WEA). Hierfür wird die Feldstärke auf 25 konzentrischen Kreisbahnen, sog. Orbit Flights verschiedener Höhen und mit verschiedenen Radien rund um die DVOR-Anlage numerisch simuliert. Insbesondere werden die Einflüsse diverser Parameter der WEA wie deren Anzahl, Position, Rotorwinkel, Turmhöhe und Rotordurchmesser auf die Feldverteilung herausgestellt, sowie die Anwendbarkeit der Simulationsmethode Physical Optics (PO) durch Vergleich der Simulationsergebnisse mit denen der Multi Level Fast Multipol Method (MLFMM) untersucht.

Shadow Radiation Iterative Physical Optics Method for High-Frequency Scattering

2018 ◽  
Vol 66 (2) ◽  
pp. 871-883 ◽  
Author(s):  
Igor Gershenzon ◽  
Yaniv Brick ◽  
Amir Boag
Keyword(s):  
High Frequency ◽  
Physical Optics

Null field approach to scalar diffraction II. Approximate methods

1977 ◽  
Vol 287 (1339) ◽  
pp. 79-95 ◽  
Keyword(s):  
Computational Procedure ◽  
Diffraction Theory ◽  
Field Method ◽  
Physical Optics ◽  
Surface Source ◽  
Approximate Methods ◽  
Null Field ◽  
Physical Optics Approximation ◽  
Definition Of ◽  
Scattered Fields

We develop from our generalized null field method a generalization of the Kirchhoff, or physical optics, approach to diffraction theory. Corresponding to each particular null field method there is a corresponding physical optics approximation, which becomes exact when one of the coordinates being used is constant over the surface of the scattering body. We show how to improve these approximations by a computational procedure which is more efficient than those introduced in the previous paper. The reradiations from our physical optics surface sources more nearly satisfy the extinction theorem the deeper they penetrate the interiors of scattering bodies. We find that we have to introduce a new definition of the parts of a body’s surface that are directly illuminated and shadowed, and we suggest that this may be more apposite in general than the usual definition. The computational examples presented herein indicate that useful approximations to surface source densities are obtained in the umbra and penumbra of bodies. These examples also show that our scattered fields are in several particulars superior to those obtained from the conventional Kirchhoff approach. It is important to choose that physical optics approximation most appropriate for the scattering body in question.

Time-Domain Line-Integral Representations of Physical-Optics Scattered Fields

2017 ◽  
Vol 65 (1) ◽  
pp. 309-318 ◽  
Author(s):  
Tian Tian Fan ◽  
Xiao Zhou ◽  
Wen Ming Yu ◽  
Xiao Yang Zhou ◽  
Tie Jun Cui
Keyword(s):  
Time Domain ◽  
Integral Representations ◽  
Physical Optics ◽  
Line Integral ◽  
Scattered Fields
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