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Modeling Printed Antennas Using The Matlab Antenna Toolbox

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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  1. Modeling Printed Antennas Using The Matlab Antenna Toolbox Wajih Iqbal Clemson University Advisor: Dr. Martin

  2. Outline • Background • Integral equations and method of moments overview • Formulating the antenna model • LP patch antenna • Future work

  3. 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)

  4. 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

  5. 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

  6. Formulation of an Integral Equation

  7. The Electric Field Integral Equation The current on the strip is the unknown to be determined. The unknownquantity is under the integral sign.

  8. 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.

  9. 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)

  10. 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

  11. 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

  12. 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

  13. 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

  14. 2-D Mesh Projection Patch Feed point Ground plane

  15. Layer(s) properties Substrate structure Volume Mesh Generation Ground plane Vertical metal faces Feeding points Patch 3D model ready!

  16. 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

  17. Properties of the Patch Antenna Return Loss 2.99 GHz 2.93 GHz 2.96 GHz

  18. Far Field Properties Directivity (xz-plane) Co-polar dominates At 2.96GHz Front to back ratio is about 10dB

  19. Far Field Properties Total Directivity (dB) 3D Directivity The maximum directivity is approximately 7.4 dB at zenith

  20. Near Field Properties z-Directed Electric Field y-Directed Electric Field x-Directed Electric Field x y

  21. Near Field Properties Surface Current Distribution (x-directed) Surface Current Distribution (y-directed) Surface Current Distribution (z-directed)

  22. 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

  23. Acknowledgements • Dr. Anthony Martin • Dr. Daniel Noneaker • Dr. Xiao-Bang Xu • Michael Frye

  24. Questions • ? • ? • ? • ? • ? • ? • ? • ?

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