1. Multifunctional Materials Antenna Array Team Rachel Anderson, JD Barrera, Amy Bolon, Stephen Davis, Jamie Edelen, Justin Marshall, Cameron Peters, David Umana Frank Drummond, Sean Goldberger Dr. Gregory H. Huff Dr. Patrick Fink, Tim Kennedy, Phong Ngo Space Engineering Institute Texas A&M University College Station, TX 77843-3118 Email: ghuff@tamu.edu

2. Team Breakdown Materials Team –Amy Bolon, Senior Mechanical Engineering –Stephen Davis, Sophomore Aerospace Engineering –Cameron Peters, Freshman Aerospace Engineering Antenna Team –Rachel Anderson, Senior Electrical Engineering –JD Barrera, Senior Electrical Engineering –Jamie Edelen, Freshman Computer Engineering –Justin Marshall, Senior Electrical Engineering –David Umana, Freshman Electrical Engineering Graduate Mentors – Frank Drummond, Aerospace Engineering – Sean Goldberger, Electrical Engineering

3. Outline  Motivation  Project Goals  Methodology  Materials  Antennas  Integrated System  Results  Future Work  Questions

4. Motivation NASA JSC Needs  Advanced airborne and space-based platforms  Antennas that utilize the electromagnetic spectrum more effectively  Operating at multiple frequencies  Communication on multiple channels

5. Project Goals  Investigate multidisciplinary concepts, materials, and measurements needed to simultaneously reconfigure the antenna array  Design and fabricate a 1x2 array of reconfigurable microstrip patch antennas using electromagnetically functionalized colloidal dispersions (EFCDs)  Determine the limits of reconfiguration and electromagnetic visibility of colloidal dispersions with different material systems (dielectric, magnetic, etc.) System Diagram

6. Reconfigurable Antennas Other Systems:  Uses PIN diode switches or Microelectromechanical systems (MEMS) actuator  Thermal issues Our System:  Pressure Driven Vascular Network  No Bias/Control Wires  Continuous Tuning  Integrated into Substrate Reconfigurable Microstrip Parasitic Array [10] PIN diode-based reconfigurable antenna [8]

7. Methodology Materials Team -Obtain effective properties of microfluidic system -Examine effects of frequency on the electrical force -Prepare EFCDs Antenna Team -Develop analytical model for antenna -Study materials and hardware -Design reconfigurable antenna array Examined concepts for colloidal material with electrical double layer Perform experiments on microfluidically reconfigurable antenna array

8.  Electromagnetically Functionalized Colloidal Dispersions (EFCDs)  Barium Strontium Titanate (BSTO) –High dielectric constant –Low losses –Availability  Oil –Low losses –Easily varied viscosity –Availability  Surfactant –Prevents material aggregation Materials Oil BSTO Surfactant

9. Materials  Permittivity – describes how an electric field affects and is affected by a dielectric material –High permittivity reduces electric field present  Colloids – system involving small particles of one substance suspended in another –ex: milk, Styrofoam, mist  Surfactant creates the electrical double layer around the BSTO particles, which deters aggregation [2][3]

10. Electrostatics  Gauss’s Law –Assuming linear dielectric, no magnetic field –Governing equation used for modeling  Electric Fields produced by particles [5]

11.  Calculate the effective material properties for a colloidal mixture (permittivity, permeability)  For non-ideal systems, have to consider: –Shape (spheres, discs or needles) –Heterogeneous inclusions (layered sphere) –Polydispersity (various shapes, sizes and masses) Maxwell Garnett Mixing Rule Maxwell Garnett Mixing Rule Equation [9] ε e = 5 ε i = 80

12.  Studied the relationship between permittivity and the electric field  Greater permittivities reduces the effect of the electric field  Problem set up: –Single particle within a fluid, voltages on either end –Particle and fluid have different permittivities Permittivity Example εfεf εpεp 1V-1V L=1, r=0.1

13. Permittivity Example Results  Case 2: ε f =100ε 0, ε p =10ε 0  Case 1: ε f =100ε 0, ε p =1000ε 0

14.  Model the fluid and particle flow for the antenna –Find effective properties of fluid flowing around particles Materials Team Goal εpεp εpεp εpεp εfεf ε eff

15. Effective Properties Calculation  Using periodic boundary conditions to solve for the effective permittivity of the colloidal fluid  Vary direction of voltage flow to solve for the electric field (E) and electric displacement (D) in the x and y directions –Solve the following equation:  Permittivity matrix is in the form of the identity matrix 0 0

16. 2D COMSOL Results Voltage varying in X-direction Voltage varying in Y-direction 50%

17. 3D COMSOL Results 10%

18. Frequency Effects on Particle  A particle between two electrodes with AC voltage will receive a force dependent upon frequency V V=0

19. Patch Antenna Background  Substrate clad with two conductive layers  Resonant frequency based on dimensions and substrate properties  Coaxial probe used as transmission line  Lowest order mode (TE 10 )  Electric Distribution  Radiation as a result of fringe fields Single Patch Antenna [7]Transmission Line and Electric Field [7]

20. Calculations: Matlab  Equations used for very 1 st order approximations  Implemented equations in Matlab Length of Patch28.29mm Width of Patch36.96mm Matlab Calculation ResultsGraph – Antenna Length vs. Frequency Antenna Equations [6]

21. HFSS Modeling  HFSS – Electromagnetic simulator and CAD software  Simulated single patch antenna  Obtain better approximations for length and probe positioning HFSS Single Patch Antenna Model HFSS Simulated Results Length of Patch27.9mm Width of Patch37mm a (Distance from Edge) 5.7mm

22. HFSS Modeling Results  VSWR plot: 1 corresponds to 100% power transmitted  Water wave hitting a wall  Smith Chart: 1 corresponds to all min on VSWR  Bulls eye

23. Current Research Integration of Vascular Reconfiguration Mechanisms in a Microstrip Patch Antenna, G. H. Huff and S. Goldberger, in review IEEE Antennas and Wireless Propagation Letters, submitted Nov. 2007

24. Patch Array

25. Antenna Fabrication Construct Substrate MoldMix and Bake SubstrateSolder Probes to Ground Plane Complete Antenna Structure Solder Probe and Overlapping Copper Tape Cut Copper Tape and Attach to Substrate

26. Material Preparation Gather Materials Weigh EFCD, Surfactant and Oil Input material into syringe Mix Material with Vortex Machine Place Material in Sonicator Place syringe in system syringe pump

27. Reconfigurable Antenna System Entire Reconfigurable Antenna Setup  System connected by tubing, valves and Y-splitters  Inner capillary of antenna filled with oil  EFCD material flows through outer capillaries of antenna

28. Results Microstrip Patch Array: Experimental Model (3 GHz Design)

29. Results Smith ChartVSWR Plot (GHz) Resonant frequency decreased 150MHz as EFCD introduced into antenna system Small Array Behavior of Frequency Reconfigurable Antennas Enabled by Functionalized Dispersions of Colloidal Materials, Sean Goldberger and G. H. Huff, in proc. 2009 URSI North American Radio Science Meeting, Boulder, CO, Jan. 2009

30. Future Work  Poly-dispersal systems  Different EFCD particle shapes  Different antenna designs  Materials  Feasibility testing of system in dynamic environment  Closed loop system  Zero gravity testing NASA KC-135 [3]

31. Acknowledgements  Dr. Gregory H. Huff  Dr. Patrick Fink  Tim Kennedy  Phong Ngo  Dr. James G. Boyd  Mrs. Magda Lagoudas  Stephen A. Long  Jacob McDonald  Bolutife P. Ajayi  Frank Drummond  Sean Goldberger

32. References  [1] Ansoft, HFSS© v11.1.2, Pittsburgh, PA 15219  [2] "Capacitor." Chemistry Daily. 4 Jan. 2007. Oct. 2008.  [3] Cowing, Keith. "Weightless Over Cleveland - Part 1: Floating Teachers." SpaceRef.com. 1 Oct. 2006. 20 Nov. 2008.  [4] Davis, Doug. "Gauss's Law." General Physics II. 2002. 20 Nov. 2008.  [5] "Electrostatic Charge and Bacterial Adhesion." Bite-Sized Tutorials. 7 Nov. 2008.  [6] Goldberger, Sean. “Microstrip Patch Antenna Design using a Hybrid Transmission Line and Cavity Model,” Class report, Dept. of Elec. and Comp. Engineering, Texas A&M Univ., College Station, Texas, 2008.  [7] Long, S. A. “A Cognitive Compensation Mechanism for Deformable Antennas,” M.S. thesis, Dept. of Elec. and Comp. Engineering, Texas A&M Univ., College Station, Texas, 2008.  [8] Piazza, Daniele, Nicholas J. Kirsch, Antonio Forenza, Robert W. Heath, Jr., and Kapil R. Dandekar. “Design and Evaluation of Reconfigurable Antenna Array for MIMO Systems." IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION 56 (2008): 869-881.  [9] Sihvola, A. Electromagnetic Mixing Formulas and Applications. Washington, D.C.: Institution of Engineering and Technology (IET), 1999. 40-78.  [10] Zhang, S., G. H. Huff, J. Feng, and J. T. Bernhard. "A Pattern Reconfigurable Microstrip Parasitic Array." IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION 52 (2004): 2773-2776.

33. Project Team Back Center: Joel Barrera Third Row: Justin Marshall and Cameron Peters Second Row: Rachel Anderson, Amy Bolon, and Stephen Davis Front Row: Sean Goldberger, David Umana, Jamie Edelen, and Frank Drummond