Difference between revisions of "Application Note 5: Simulating The Performance Of Installed Antennas On Vehicular Platforms Using EM.Tempo"

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== Examining the Radiation Pattern of an Isolated Patch Antenna in the Free Space ==
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== Examining the Radiation Pattern of an Isolated Patch Antenna ==
  
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[[Image:ART PARAB Fig1.png|thumb|left|250px| Geometry of a parabola curve and its parameters in accordance with the conventions used by Ref. [1].]]
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Revision as of 20:55, 18 October 2016

Application Project: Simulating The Performance Of Installed Antennas On Vehicular Platforms Using EM.Tempo
ART GOLF Fig title.png

Objective: In this project, large parabolic reflectors fed by pyramidal horn antennas are modeled and analyzed using EM.Illumina and EM.Tempo.

Concepts/Features:

  • EM.Tempo
  • EM.Illumina
  • Pyramidal Horn
  • Parabola
  • Object of Revolution
  • Field Distribution
  • Radiation Pattern

Minimum Version Required: All versions

'Download2x.png Download Link: None

Introduction

In this application note, we demonstrate how to use EM.Tempo to compute and analyze the radiation pattern of a patch antenna installed on a vehicular platform. Specifically, the CAD model of a Volkswagen Golf automobile is first imported to EM.Cube. Then, a microstrip patch antenna with a finite-sized substrate is placed at different locations of the car's body.


To import the CAD model of a commercial aircraft platform to EM.Cube and analyze the performance of a monopole antenna mounted on its top using EM.Cube's FDTD simulator.

In this tutorial you will continue exploring how to solve large computational problems involving millions of mesh cells.


Examining the Radiation Pattern of an Isolated Patch Antenna

Geometry of a parabola curve and its parameters in accordance with the conventions used by Ref. [1].


Patch wizard raw.png
Default parameterization for the probe-fed patch wizard.
Patch s11.png
Patch rad pattern.png
Patch zx cut.png
Patch yz cut.png

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 dimensions of the aircraft model are 42.5 λ0 x 22.66 λ0 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 time.

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.



Patch on Roof

Materials used in car model:

Material Relevant Components

of Golf Model

εr σ
PEC car body 1
Glass car windows 6.5 0.005
Plastic head-light covers, brake-light covers,

license plate mounts

2.2 0.0
Rubber tires 2.9 0.005
Aluminum wheel-rims 1 3800000
Cement road 1.9 0.0

Simulation Information:

Mesh size: 220 million cells

Farfield Resolution: 2.5 degrees

Simulation Time: 4 hours, 45 minutes

Typical Performance : 320 MCells/s

Power Threshold: -40 dB

Thread Factor: 8

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, for many problems, 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 of the engine will be used alternatively.

Roof field.png
Roof mesh.png
Roof mesh settings.png
Roof mesh settings advanced.png

By default, EM.Tempo's mesher tries to place grid points at the corners of each graphic object's bounding box, and also at any internal boundaries the object may have. For models with a large number of complex objects, this can drive the typical mesh cell size toward the Absolute Minimum Grid Spacing, and result in a much finer mesh than is required. Since the VW Golf model has around 2000 graphic objects, we will turn off these options.

Roof patch.png
Roof patch mesh.png
Roof pattern.png
Roof wheel mat.png
Roof wheel mat select.png
Roof yz cut.png
Roof zx cut.png


Patch on Hood

Simulation Information:

Mesh size: 230 million cells

Farfield Resolution: 2.5 degrees

Simulation Time: 5 hours, 25 minutes

Typical Performance : 320 MCells/s

Power Threshold: -40 dB

Thread Factor: 8

Hood mount.png
Hood mount mesh detail.png
Hood nearfield.png
Hood pattern.png
Hood yz cut.png
Hood zx cut.png