Modeling Printed Antennas Using The Matlab Antenna Toolbox

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# Modeling Printed Antennas Using The Matlab Antenna Toolbox - PowerPoint PPT Presentation

Modeling Printed Antennas Using The Matlab Antenna Toolbox. Wajih Iqbal Clemson University Advisor: Dr. Martin. Outline. Background Integral equations and method of moments overview Formulating the antenna model LP patch antenna Future work . Background.

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## Modeling Printed Antennas Using The Matlab Antenna Toolbox

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### Modeling Printed Antennas Using The Matlab Antenna Toolbox

Wajih Iqbal

Clemson University

Outline
• Background
• Integral equations and method of moments overview
• Formulating the antenna model
• LP patch antenna
• Future work
Background
• Graduate students usually use Ansoft HFSS for antenna modeling
• Too complicated and expensive for undergrads
• A much easier and user-friendly code has been developed by Makarov (Worcester Polytechnic Institute) called the Matlab Antenna Toolbox (MAT)
Background (cont’d)
• The code is based on method of moments and is limited to about 7000 unknowns
• The code is reasonably precise for simple printed antennas
• I have modeled and studied 15 different antenna structures
Integral Equations and Method of Moments Overview
• Statement of an Electromagnetic Boundary Condition
• Consider an incident wave (with no z variation i.e. 2D problem)

5

The Electric Field Integral Equation

The current on the strip is the unknown to be determined. The unknownquantity is under the integral sign.

Solution of Integral Equations (MoM)

Three Major Steps

• Step 1: Approximate unknown (surface current) by means of a finite sum of N known functions each with an unknown coefficient.
Solution of Integral Equations (MoM)
• Step 2: Substitute the approximation (Step 1) into the IE and establish a well-conditioned system of linear equations by enforcing the resulting equations over N subintervals which are within the interval where a solution is desired

(substitute and apply testing function)

Solution of Integral Equations (MoM)
• Step 3: Solve the N by N linear system of equations from step 2 and thereby obtain values for the coefficients.

Once we have found J(r) we can find all the radiation properties of the antenna

Why Printed Antennas?
• Printed antennas are low-profile planar structures that utilize printed circuit board (PCB) technology
• They are compact, low cost, easy to manufacture and suitable for integration with electronic systems
• Multi-band operation can also be achieved by integrating several coupled printed antenna elements of different lengths and geometries on the same PCB
• Dimension can be smaller with higher dielectric
• GPS, Radar, Satellite communication, Military, cell phones, and wireless laptops

Create 2Dgeometry

Feeding Probe

Create 3D geometry

and feed

MoM Calculations

Patch

Ground Plane

Input impedance/

Return loss

Near field and far

field properties

Execution Flow Chart
Formulating the Antenna Model

Feeding Probe

Design:

• Linearly polarized patch antenna
• Patch is 30x40mm
• Ground plane is 50x60mm
• Substrate has εr = 2.55

Patch

Ground Plane

View without Dielectric

Dielectric

Patch

Feeding Probe

Ground Plane

Side View

View with Dielectric

2-D Mesh Projection

Patch

Feed point

Ground plane

Layer(s) properties

Substrate structure

Volume Mesh Generation

Ground plane

Vertical metal faces

Feeding points

Patch

Properties of the Patch Antenna

Input Impedance

4800 unknowns took 1.5 hours for 50 frequency points (65sec for each point)

Solid line – Matlab

Dotted line – Ansoft HFSS

Resonance

Properties of the Patch Antenna

Return Loss

2.99 GHz

2.93 GHz

2.96 GHz

Far Field Properties

Directivity (xz-plane)

Co-polar dominates

At 2.96GHz

Front to back ratio is about 10dB

Far Field Properties

Total Directivity (dB)

3D Directivity

The maximum directivity is approximately 7.4 dB at zenith

Near Field Properties

z-Directed Electric Field

y-Directed Electric Field

x-Directed Electric Field

x

y

Near Field Properties

Surface Current Distribution (x-directed)

Surface Current Distribution (y-directed)

Surface Current Distribution (z-directed)

Future Work
• Simulate more multiband antennas accordingly with future wireless communication needs
• Incorporate the genetic algorithm with the code for antenna optimization
• After convergence studies construct and test a multiband antenna in the spherical near field chamber
Acknowledgements
• Dr. Anthony Martin
• Dr. Daniel Noneaker
• Dr. Xiao-Bang Xu
• Michael Frye
Questions
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