scholarly journals Partially Transparent Jaumann-Like Absorber Applied to a Curved Structure

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Alireza Motevasselian ◽  
B. L. G. Jonsson
Keyword(s):  
Sensitivity Analysis ◽  
Cross Section ◽  
Low Frequency ◽  
Radar Cross Section ◽  
Frequency Interval ◽  
Two Dimensional ◽  
Resistive Layer ◽  
Front End ◽  
Low Pass ◽  
Metal Backing

A Jaumann absorber with its metal backing replaced with a combined low-pass and polarizer FSS is investigated with respect to its absorption and its polarization-dependent low-frequency transparency properties. This structure is applied to an idealized curved wing-front end, and its monostatic radar cross-section is determined. The FSS-Jaumann structure preserves an absorption similar to the planar Jaumann absorber in the higher frequency interval and enables a partial transparency in the TEzpolarization at 1 GHz. In addition, once the structure is applied to the wing-front end, a significant reduction in two-dimensional radar cross-section for both the TMzand TEzpolarization over 2–16 GHz is observed. A sensitivity analysis shows that the resistivity of the inner resistive layer has a large impact on the 1 GHz transmission.

Energy Transmission by Barotropic Rossby Waves Revisited

2005 ◽  
Vol 35 (11) ◽  
pp. 2228-2236 ◽  
Author(s):  
R. P. Matano ◽  
E. D. Palma
Keyword(s):  
Cross Section ◽  
Rossby Waves ◽  
Bottom Topography ◽  
Low Frequency ◽  
Energy Transmission ◽  
Low Pass ◽  
Mid Atlantic Ridge ◽  
High Frequency Waves ◽  
The Individual ◽  
Matching Techniques

Abstract This article presents a semianalytic method to investigate the properties of energy transmission across bottom topography by barotropic Rossby waves. The method is first used to revisit the analytical estimates derived from wave-matching techniques and Wentzel–Kramers–Brillouin (WKB) approximations. The comparison between the semianalytic method and WKB indicates that the results of the latter are valid for waves with periods longer than a month and ridges taller than ∼1000 m and wider than ∼500 km. For these parameter values both methods predict the passage of low-frequency waves and the reflection of high-frequency waves. The semianalytic method is then used to discuss the energy transmission properties of a cross section of the Mid-Atlantic Ridge. It is shown that the filtering characteristics of realistic bottom topographies depend not only on the spatial scale set by the cross-section envelope, but also on the scales of the individual peaks. This dependence is related to the fact that topographies narrower than ∼400 km (e.g., peaks) are high-pass filters of incoming waves, while topographies wider than that (e.g., cross-section envelopes) are low-pass filters. In the particular case of the Mid-Atlantic Ridge the neglect of the contribution of individual peaks leads to an erroneous estimate of the filtering properties of the massif.

scholarly journals Signal Propagation in Soil Medium: A Two Dimensional Finite Element Procedure

2021 ◽  
Author(s):  
Frank Kataka Banaseka ◽  
Kofi Sarpong Adu-Manu ◽  
Godfred Yaw Koi-Akrofi ◽  
Selasie Aformaley Brown
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Scattered Field ◽  
Radar Cross Section ◽  
Transverse Magnetic ◽  
Arbitrary Cross Section ◽  
Observation Angle ◽  
Two Dimensional ◽  
Total Field ◽  
Dimensional Finite Element

A two-Dimensional Finite Element Method of electromagnetic (EM) wave propagation through the soil is presented in this chapter. The chapter employs a boundary value problem (BVP) to solve the Helmholtz time-harmonic electromagnetic model. An infinitely large dielectric object of an arbitrary cross-section is considered for scattering from a dielectric medium and illuminated by an incident wave. Since the domain extends to infinity, an artificial boundary, a perfectly matched layer (PML) is used to truncate the computational domain. The incident field, the scattered field, and the total field in terms of the z-component are expressed for the transverse magnetic (TM) and transverse electric (TE) modes. The radar cross-section (RCS), as a function of several other parameters, such as operating frequency, polarization, illumination angle, observation angle, geometry, and material properties of the medium, is computed to describe how a scatterer reflects an electromagnetic wave in a given direction. Simulation results obtained from MATLAB for the scattered field, the total field, and the radar cross-section are presented for three soil types – sand, loam, and clay.

scholarly journals A HYBRID METHOD TO ACCELERATE THE CALCULATION OF TWO-DIMENSIONAL MONOSTATIC RADAR CROSS SECTION ON PEC TARGETS

2016 ◽  
Vol 50 ◽  
pp. 47-54
Author(s):  
Chao Fei ◽  
Xinlei Chen ◽  
Yang Zhang ◽  
Zhuo Li ◽  
Chang Qing Gu
Keyword(s):  
Cross Section ◽  
Hybrid Method ◽  
Radar Cross Section ◽  
Two Dimensional
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