Modeling the Installed

Performance of Antennas in a

Ship Topside Environment

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

Enow Tanjong

Electromagnetic SystemsComplete Technology in Action

Antenna

Filter Shielding

RCS

Installed Performance

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

Electron Tube

FSS

Array

Connectors PCB

Package

Cabling

System Level DesignAll-Encompassing EM-Simulation

EM Interaction

System analysisCoupling analysisRadiation analysis

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

Installed PerformanceEMC/ EMI/ E3

Challenges: Electromagnetic size, Complexity, Aspect ratio

Electrical Size

Frequency Application

1 MHz Lightning

10 MHz HF communications

100 MHz EMP

1 GHz L-Band

Communications

10 GHz Radar

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

El. Length

0.5λ

5λ

50λ

500λ

5000λ

FEM TD MLFMM AsymptoticMoM

Aspect Ratio

300 MHz

18 m

18 λ

1.575 GHz

160 m

840 λ

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

4 mm notches

0.9 mm radius feed pin3 mm wire radii

Approach 1: Brute force!

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

� Small detail � small time step

� longer simulation.

� HPC options: CPU, GPU, MPI.

� Mesh quality important

� Increased meshing in small

detail leads to high memory

requirement

� HPC options: CPU, MPI.

MLFMMTime Domain

Approach 2: Field Decomposition

FIT, TLM, FEM, MoM, MLFMM

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

Near-field source

Far-field source

FIT, TLM

MoM ,MLFMM, Asymptotic

Advantages of Field Sources

Near-field Source Far-field Source

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

� Small simulation volume � fine features can be simulated

accurately.

� Simulate source with appropriate mesh and solver.

� Can import external (measured) fields.

� No knowledge of antenna structure necessary (Intellectual Property).

Real World Navy FrigateComplete Technology in Action

1 GHz JTIDS antenna(FEM + MLFMM)

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

10 MHz HF whips (TD, MoM)

TD (FIT) Solution

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

FIT Solver

40 minutes, 1.3 GB RAM10 Million mesh cells

Far-Field Results at 10 MHz

Single antenna excited

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

Surface Current due to HF Antenna

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

MoM Solution

MoM Solver

60 minutes, 12 GB RAM

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

Low frequency stabilization available

Anisotropic mesh

refinement

JTIDS for L Band TDMA Network Radio

JTIDS antenna (1.0875 GHz)

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

Installed performance of antenna required

JTIDS Antenna Array Design

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

Rapid, automatic design of validated antenna elements

Convenient building block for larger, more complex designs

Synthesis, Optimization

Element Level Simulation

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

Snap nodes to boundaryReferences true geometry

Sensitivity Analysis

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

Sensitivity AnalysisParametric tolerance analysis with only a single simulation run

2nd Order 325000 Tetrahedrons

Mixed Order Elements

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

3rd Order Mixed 98000 Tetrahedrons

JTIDS Antenna Pattern in Isolation

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

Automatic phase center calculation

Arbitrary slant polarization

JTIDS Far Field Source on Ship

JTIDS antenna pattern imported and positioned on ship mast

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

Ship is 500 wavelengths long @ 1.0875 GHz

Characterization of Water Surface

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

At higher frequencies characterization of sea water as a

surface impedance material significantly reduces the amount of required computational resources

Surface Mesh at 1.0875 GHz

1,400,000 surfaces

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

1,400,000 surfaces

MLFMM Solver => 12 hours and ~84 GB RAM

JTIDS + Ship Results at 1.0875 GHz

Surface current

Far field pattern

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

Far field pattern

Complex Ship Model

USS Winston S. Churchill (DDG-81)

Provided by

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

Tactical Air Navigation (TACAN) Antenna

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

1.087 GHz TACAN antenna

Gain cut

3D Far-field

Antenna Gain not optimized

TACAN AntennaGain

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

TACAN Far Field Source on Ship

TACAN antenna pattern imported and positioned

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

TACAN Far Field + Ship meshed at 1.087 GHz

1,950,098 surfaces (including sea water) => Solvable with MLFMM but would require a large amount of RAM. MPI would be an option

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

Asymptotic SolutionShooting Bouncing Ray (SBR) method� Multiple bounces taken into account� Plane wave source for RCS analysis Incident Rays

Scattered Rays

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

Robust meshing enables discretization of complex models and Asymptotic solution requires far less computational resources making it ideal for this problem

TACAN + Ship Results at 1.087 GHz

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

Asymptotic solver => 3 hours, 600 MB RAM

Model size is approximately 783 wavelengths at 1.087 GHz

S-Band Radar Antenna

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

Radar Unit Element Patch Antenna

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

Right-hand Circular Polarized pin-fed Square Truncated Patch Antenna

designed for 3 GHz

Array Construction and Excitation

Array wizard constructs the array and applies

excitation

25 X 25 Array

Transient Solver

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

All 625 Ports created automatically by wizard

3 GHz S-Band Radar Array Results

Far-field

Surface Current

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

Simultaneous port excitation requiring 35 GB of RAM and 6 hours to run

S-band Radar Antenna Field source on Ship

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

Radar Antenna Array Pattern imported and Positioned

Single Radar + Ship Results at 3 GHz

Far-field

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

Model size is approximately 2160 wavelengths at 3 GHz

Multiple Far-Field Sources

Possible to import multiple FF sources and excite all at once

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

Antenna Analysis/Placement Features

• All standard antenna performance results (Gain, Surface Current, . . )

• Sensitivity analysis

• Up to 3rd order TET elements

• Frequency tabulated surface impedance

• Parameterization/ optimization

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

• Parameterization/ optimization

• Far-field and Near-field Source imports

• Array Wizard

• High Performance Computing Options

Summary

• CST MWS has the capability of solving electromagnetic problems both

at the component level and at the system level

• The complete technology available means the best tool can be used for

a particular analysis

• At the system level field decomposition techniques can be used for

CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Nov-10

• At the system level field decomposition techniques can be used for

more efficient analysis.

• The asymptotic method implemented in CST MWS can be used for very

complex electrically large simulations reduce the amount of resources

required