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{{projectinfo|Application|Simulating The Performance Of Installed Antennas On Vehicular Platforms Using EM.Tempo|ART_GOLF_Fig_title.png|In this project, large parabolic reflectors fed by pyramidal horn antennas mounted on a complex, real-sized, automobile platform are modeled and analyzed using EM.Illumina and EM.Tempo.|*[[Building Geometrical Constructions in CubeCAD | CubeCAD]]

*[[EM.Illumina]]CAD Model*Pyramidal HornPatch Wizard*Parabola*Object of RevolutionYee Mesh

The patch structure was simulated using [[EM.Tempo]]'s FDTD solver on a thick metal ground. The 3D far-field radiation pattern of the isolated finite-substrate patch antenna is shown in the figure below. The directivity of the patch is computed to be 7.09dB.

== Computational Environment Importing the Vehicle Model ==

For this project, we use an IGES CAD model of a Volkswagen Golf automobile. The Mirage III CAD model has an approximate length consists of 15m, 2019 different surface objects. They are originally grouped into a wingspan number of 8m, and an approximate height of 4.5m. Expressed different object sets as shown in free-space wavelengths at 850 MHz, the approximate figure below. The overall dimensions of the aircraft model car are 42.5 about 420cm &#955times;₀ x 22.66 200cm &#955times;₀ x 12.75 λ₀. 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 time142cm.

<table><tr><td>[https[Image://awsART GOLF Fig1.amazon.com/ Amazon Web Services] allows one to acquire highpng|thumb|left|720px| The four-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), port view of the [[EMimported CAD model of the vehicle before material assignments in CubeCAD.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.</td></tr><br clear="all"/table> =Patch on Roof=

Materials used in car The CAD model:is initially imported to CubeCAD. From there we transfer all the parts to [[EM.Tempo]], where the FDTD simulation is to take place. We also place a cement block underneath the automobile to model the road surface. A number of materials are defined and assigned to the various parts of the vehicle as listed in the table below.

| 0.005005S/m| Car windows

| 0.005005S/m| Tires

| 38000003.8&times;10⁶ S/m| Wheel rims

Simulation Information<table><tr><td>[[Image:Roof wheel mat.png|thumb|left|640px| Assigning material composition to various vehicle parts in EM.Tempo.]]</td></tr></table>

Farfield Resolution: 2First, we place the patch antenna on the roof of the Golf model as shown in the figure below.5 degrees

Simulation Time<table><tr><td>[[Image: 4 hours, 45 minutesRoof patch.png|thumb|left|420px| The location of the patch antenna on the vehicle's roof.]]</td></tr></table>

Typical Performance : 320 MCells/By default, [[EM.Tempo]]'smesh generator tries to place grid points at the corners of each graphic object's bounding box, and also at any internal boundaries any object may have. For models with a large number of complex geometric objects, this could drive the typical mesh cell size toward the "Absolute Minimum Grid Spacing", and would result in a much denser mesh than is required. Since the Golf model has more than 2000 distinct graphic objects, we will turn off some of these adaptive mesh options. A mesh density of 18 cells per effective wavelength is chosen for this structure with the absolute minimum grid spacing parameter set equal to 0.75mm. The figures below show the Yee mesh of the whole vehicle structure as well as the portion of the roof in the proximity of the installed patch antenna. The overall mesh involves <b><u>220 million</u></b> cells.

Power Threshold<table><tr><td>[[Image: -40 dBRoof mesh.png|thumb|left|640px| The mesh of the vehicle structure generated by EM.Tempo.]]</td></tr></table>

Thread Factor<table><tr><td>[[Image: 8Roof patch mesh.png|thumb|left|420px| A close-up of the mesh of the patch antenna and its neighboring region of the vehicle's roof.]]</td></tr></table>

The FDTD simulation of the vehicle structure was run on [https://aws.amazon.com/ Amazon Web Services]. For the purpose of this project, we logged into an Amazon instance via Remote Desktop Protocol (RDP) and used a c4.4xlarge instance running Windows Server 2012. This instance had 30 GB of RAM memory, and 16 virtual CPU cores. The CPU for this instance was an Intel Xeon E5-2666 v3 (Haswell) processor. The thread factor setting essentially tells the FDTD engine how many CPU threads to use during [[EM.Tempo]]'s time-marching loop. For a given system, some experimentation may be needed to determine the best number of threads to use. In many cases, using half of the available hardware concurrency works well. This comes from the fact that many modern processors often have two cores per memory port. In other words, Eight thread factors were used for many problemsthis simulation, the FDTD solver cannot load and store data from CPU memory quickly enough to use all the available threads or hardware concurrency. The extra threads remain idle waiting for the data, and a performance hit is incurred due to the increased thread context switching. [[EM.Cube]] will attempt use a version of the FDTD engine optimized for use with Intel's AVX instruction set, which provides a significant performance boost. If AVX is unavailable, a less optimal version total computation time of the engine will be used alternatively285 minutes.

[[Image:Roof The figure below shows the electric fielddistribution of the vehicle-antenna combination structure in the vertical ZX plane that passes through the center of the vehicle.png|thumb|left|400px|]]

<table><tr><td>[[Image:Roof meshfield.png|thumb|left|400px640px|The dB-scale electric field distribution of the vehicle-antenna combination structure in the vertical ZX plane.]]</td></tr></table>

[[Image:Roof mesh settingsThe figure below shows the 3D far-field radiation pattern of the installed patch antenna on the vehicle's roof.png|thumb|left|400px|]]For this simulation, the far-field angular resolution was set to 2.5&deg; along both azimuth and elevation directions.

<table><tr><td>[[Image:Roof mesh settings advancedpattern.png|thumb|left|400px640px|3D far-field radiation pattern of the vehicle-antenna combination structure, with the patch antenna installed on the vehicle's roof.]]</td></tr></table>

By default, [[EM.Tempo]]'s mesher tries to place grid points at The figures below show the corners 2D polar radiation patterns of each graphic object's bounding box, and also at any internal boundaries the object may haveroof-mounted patch antenna in the principal YZ and ZX planes. For models Comparing these graphs with a large number those of complex objects, this can drive the typical mesh cell size toward the Absolute Minimum Grid Spacing, and result isolated patch antenna in a much finer mesh than is required. Since the VW Golf model has around 2000 graphic objects, we will turn off these optionsprevious section reveals the impact of the mounting platform on the radiation characteristics of the installed antenna.

<table><tr><td>[[Image:Roof yz cut.png|thumb|left|480px| 2D linear-scale polar radiation pattern of the roof-mounted patchantenna in the YZ plane..]]</td></tr><tr><td>[[Image:Roof zx cut.png|thumb|left|400px480px|2D linear-scale polar radiation pattern of the roof-mounted patch antenna in the ZX plane..]]</td></tr></table>

[[Image:Roof patternNext, we move the patch antenna onto the front hood of the Golf model close to the front windshield as shown in the figure below.png|thumb|left|400px|]]

<table><tr><td>[[Image:Roof wheel matHood mount.png|thumb|left|400px480px|The location of the patch antenna on the vehicle's hood.]]</td></tr></table>

[[Image:Roof wheel mat selectThe figure below shows the details of the Yee mesh around the new location of the patch antenna.png|thumb|left|400px|]]Due to the curvature of the surface of most parts in this area, the generated mesh has denser grid lines. This increases the total number of mesh cells to more than <b><u>230 million</u></b>.

<table><tr><td>[[Image:Roof yz cutHood mount mesh detail.png|thumb|left|400px480px|The details of the Yee mesh of the vehicle structure generated by EM.Tempo around the location of the patch antenna on the hood.]]</td></tr></table>

[[Image:Roof zx cutThe FDTD simulation of the vehicle structure with its new antenna location is performed on the same computing platform using Amazon Web Services (AWS). The total computation time in this case increased to 325 minutes.png|thumb|left|400px|]]

=Patch on <table><tr><td>[[Image:Hood=nearfield.png|thumb|left|640px| The dB-scale electric field distribution of the vehicle-antenna combination structure in the vertical ZX plane.]]</td></tr></table>

Mesh size<table><tr><td>[[Image: 230 million cellsHood pattern.png|thumb|left|640px| 3D far-field radiation pattern of the vehicle-antenna combination structure, with the patch antenna installed on the vehicle's hood.]]</td></tr></table>

Farfield Resolution: 2The figures below show the 2D polar radiation patterns of the hood-mounted patch antenna in the principal YZ and ZX planes. Comparing these graphs with those of the two previous cases shows significant reflection and diffraction effects at the new location of the patch antenna.5 degrees

Simulation Time: 5 hours, 25 minutes<table><tr>Typical Performance : 320 MCells/s Power Threshold: -40 dB Thread Factor: 8 <td>[[Image:Hood mountyz cut.png|thumb|left|400px480px|2D linear-scale polar radiation pattern of the hood-mounted patch antenna in the YZ plane.]]</td></tr><tr><td>[[Image:Hood mount mesh detailzx cut.png|thumb|left|400px480px|2D linear-scale polar radiation pattern of the hood-mounted patch antenna in the ZX plane.]]</td></tr></table>

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