{{projectinfo|Application|Modeling Radar Signature of Of Real-Sized Aircraft Using EM.Tempo|ART AIR title.png|In this article, we explore computing RCS the radar cross section of electrically large structures, like real-sized aircraft.|*[[Building Geometrical Constructions in CubeCAD | CubeCAD]]
*[[EM.Tempo]]
*Radar Cross Section
*Large ProjectsHigh Performance Computing*CAD Model Import
*Plane Wave Source
*Cloud-Based Resources
== Computational Environment ==
The Mirage III CAD model has an approximate length of 15m, a wingspan of 8m, and an approximate height of 4.5m. Expressed in free-space wavelengths at 850 MHz, the approximate dimensios dimensions of the aircraf aircraft model are 42.5 λ<sub>0</sub> x 22.66 λ<sub>0</sub> x 12.75 λ<sub>0</sub>. Thus, for the purposes of [[EM.Tempo]], we need to solve a region of about 12,279 cubic wavelengths. For problems of this size, a very large CPU memory is needed, and a high-performance, multi-core CPU is desirable to reduce the simulation time.
[https://aws.amazon.com/ Amazon Web Services] allows one to acquire high-performance compute instances on demand, and pay on a per-use basis. To be able to log into an Amazon instance via Remote Desktop Protocol (RDP), the [[EM.Cube]] license must allow terminal services. For the purpose of this project, we used a c4.4xlarge instance running Windows Server 2012. This instance has 30 GB of RAM memory, and 16 virtual CPU cores. The CPU for this instance is an Intel Xeon E5-2666 v3 (Haswell) processor.
== Mesh Generation & Setting the FDTD Solver Parameters ==
To generate the FDTD Yee mesh of this structure, we use the "Fast Run/Low Memory Settings" preset. This will set the minimum mesh density at 15 cells per λ<sub>eff</sub>, and permits grid adaptation only where necessary. This preset provides slightly less accuracy than the "High Precision Mesh Settings" preset, but it results in a smaller mesh size, and therefore a shorter run time. At 850 MHz, the resulting FDTD mesh contains about '''<b><u>270 million </u></b> cells'''.
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After the simulation is complete, the 3D simulation data associated with the project observables can be visualized from [[EM.Tempo]]'s navigation tree. The near-field distribution maps are shown in the figures below. The standing wave field patterns are visibly seen around the aircraft.
<divtable><tr><td>[[Image:Large struct article ScreenCapture1.png|thumb|left|500px|Electric field distribution in the horizontal sensor plane underneath the aircraft.]]</divtd></tr><divtr><td>[[Image:Large struct article ScreenCapture2.png|thumb|left|500px|Electric field distribution in the vertical sensor plane passing through the center line of the aircraft.]]</divtd></tr></table>
The figure below shows the total 3D bistatic RCS pattern of the aircraft:
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[[Image:Large struct article ScreenCapture3.png|thumb|left|500px|The 3D total RCS pattern of the Mirage model at 850 MHz in dBsm. The aircraft structure is shown in the freeze state.]]
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<div>[[Image:Large struct article ScreenCapture3.png|thumb|left|500px|The 3D total figures below show the Cartesian graphs of the bistatic RCS pattern of the Mirage model at 850 MHz aircraft in dBsm.]]</div>the three principal coordinate planes:
<divtable><tr><td>[[Image:RCS XY.png|thumb|left|500px|The Cartesian graph of the XY-cut RCS of the aircraftin m<sup>2</sup>.]]</divtd><div/tr><tr><td>[[Image:Large struct article RCS YZ.png|thumb|left|500px|The Cartesian graph of the YZ-cut RCS of the aircraftin m<sup>2</sup>.]]</divtd><div/tr><tr><td>[[Image:RCS ZX.png|thumb|left|500px|The Cartesian graph of the ZX-cut RCS of the aircraftin m<sup>2</sup>.]]</divtd></tr></table>
The figures below show the polar graphs of the bistatic RCS pattern of the aircraft in the three principal coordinate planes: <divtable><tr><td>
[[Image:RCS XY Polar.png|thumb|left|500px|The polar graph of the XY-cut RCS of the aircraft in dBsm.]]
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[[Image:RCS YZ Polar.png|thumb|left|500px|The polar graph of the YZ-cut RCS of the aircraft in dBsm.]]
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[[Image:RCS ZX Polar.png|thumb|left|500px|The polar graph of the ZX-cut RCS of the aircraft in dBsm.]]
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