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MURI Teleconference 5/28/04

MURI Teleconference 5/28/04. Professor Tatsuo Itoh. Electrical Engineering Department University of California, Los Angeles. Agenda. Voltage scanned Leaky Wave Antenna Near Field Focusing using Non-uniform Leaky Wave Antenna 2D Mushroom Structure Planar Lens Surface Plasmon

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MURI Teleconference 5/28/04

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  1. MURI Teleconference 5/28/04 Professor Tatsuo Itoh Electrical Engineering Department University of California, Los Angeles

  2. Agenda • Voltage scanned Leaky Wave Antenna • Near Field Focusing using Non-uniform Leaky Wave Antenna • 2D Mushroom Structure • Planar Lens • Surface Plasmon • Leaky Wave Antenna • Generalized Transmission Matrix Method

  3. Composite Right / Left-Handed (CRLH) TL Infinitesimal Circuit Model Transmission Line Representation Propagation Constant Balanced Case

  4. Motivation of Electronically-Scanned LW Antenna • Conventional LWA • Frequency dependent scanning • Conventional Electrically-Scanned LWA • Frequency independent scanning • Only two discrete states are possible • Waveguide configuration with PIN diode • Conventional Magnetically-Scanned LWA • Frequency independent scanning • Biasing DC magnetic field  NOT practical • Waveguide configuration • Novel Electronically Scanned LWA • Frequency independent scanning  Efficient Channelization • Continuous scanning capability • Microstrip technology  Low profile R. E. Horn, et. al, “Electronic modulated beam steerable silicon waveguide array antenna,” IEEE Tran. Microwave Theory Tech. H. Maheri, et. al, “Experimental studies of magnetically scannable leaky-wave antennas having a corrugated ferrite slab/dielectric layer structure,” IEEE Trans. AP. L. Huang, et. al, “An electronically switchable leaky wave antenna,” IEEE Trans. AP.

  5. The Principle of the Proposed Idea : Radiation Angle Control • Scanning angle is dependent on inductances and capacitances  Introducing varactor diodes • Capacitive parameters are controlled by voltages  Dispersion curves are shifted vertically as bias voltages are varied  Radiating angle becomes a function of the varactor diode’s voltages

  6. Modified Layout of a Microstirp CRLH TL Unit cells • Series and Shunt Varactors  Fairly constant characteristic impedance  Additional degree of freedom for wider scanning range • Reverse biasing to Varactors  Anodes of varactors : GND  Cathodes of varactors: Biasing

  7. Dispersion diagram

  8. + - - + + Prototype of 30 Cell Proposed TL Bias Configuration • The cathodes of three varactors in the same direction  Efficient biasing: Only one bias circuitry in unit cell • Back to back configuration of two series varactors  Fundamental signals : in phase and add up  Harmonic signals: out of phase and cancel • Port 1 : Excitation Port 2: Terminated with 50 ohms  Suppress undesired spurious beams

  9. Continuous Scanning Capability at 3.33 GHz V = 18 V LH ( β < 0) V = 3.5 V Broadside ( β = 0 ) V = 1.5 V RH ( β > 0) • Scanning Range Δθ = 99º (-49º to +50º)  Backward, forward, and broadside • Biasing Range ΔV = 21 V ( 0 to 21 V) • Fixed operating frequency : 3.33 GHz • Good agreement with theoretical and experimental results

  10. Performance as a LW Antenna • High directivity : One of attractive characteristic of LW antennas Achieved by increasing the number of cells  Large radiation aperture • Antenna dimension :  Maximum Gain : 18 dBi at broadside ( V = 3.5 V )

  11. fi=-Ezi(RiF)+Ez(rF) ~ k0|RiF|+constant ~ Focusing by a Planar Non-Uniform LW Interface Principle Dipole array model for the TX antenna d0 = l0/2 F = 6l0. E-Field of a Dipole E-Field Maximization

  12. Effects of Different Array Length. 0 0 -2 -2 -4 -4 -6 -6 -8 -8 -10 -10 -12 -12 -14 -14 -16 -16 -18 -18 L=12l0 L=12l0 4 0 -2 2 4 0 6 8 2 10 4 12 L=30l0 L=30l0 Normalized Electric Field (dB) Normalized Electric Field (dB) x(l0)(z=0) z(l0)(z=0) F = 6l0 L = 12l0 L = 30l0 z(l0) z(l0) dB

  13. Piece-Wise Linear Approximation fi~ k0|RiF|+constant ~ F = 6l0 L = 30l0 dB

  14. Effects of Leakage Factor Willkinson power divider Non-uniform LW antenna F = 6l0 L = 30l0 Prototype

  15. Passive, planar and non-uniform LW focusing interface • Simplified phased-array model of the non-uniform LW structure • Optimized phase distribution for focusing • Focusing by a thin planar passive interface instead of a bulk of LH material or active components

  16. Realization of 2D Metamaterials 2D Lumped Element Structure: Meta-Circuit (“closed”) LH 2D interconnection Chip Implementation RH 2.5D Textured Structure: Meta-Surface (“open”) Enhanced Mushroom Structure Uniplanar Interdigital Structure top patch via sub-patches ground plane

  17. Analysis of the Periodic 2D TL Ingredients: Unit cell representation and parameters Transmission or [ABCD] Matrixes: relate In/out I/V Kirchoff’s Voltage/Currents Laws: Linear Homogeneous System in Bloch-Floquet Theorem: relates in/out phases, Brillouin zone resolution → dispersion diagram: NB: can be solved numerically (fast) or analytically (insight)

  18. Negative Refractive Index of Mushroom Structure Positive / negative refractive index 10 Open top caps 5 0 Frequency (GHz) ground plane n= c0 b /w Absolute refractive index –5 vias G – M –10 dispersion diagram G – X TM0TEM if h/<<1 dielectric line –15 air line –1.0 –0.5 0 0.5 1.0 quasi-TE Electric field distribution, | E | source quasi-TEM focus strong C (MIM)  mixed RH / LH refocus

  19. RH CRLH LH HIGH-PASS GAP Parameter Extraction Method • How to determine: LR, CR, LL, CL • - Full-wave analysis: ωΓ1, ωX1, ωM1 • Compute ωse, ωL, ωR, ωsh,ωLωR = ωsh ωse • - Compute Bloch impedance ZB= fct(ωX1) • Insert ZB(ωX1) to determine • Finally, using ,

  20. Plane Wave to Cylindrical Wave Effective Medium Full-Wave Demonstration Paraboloidal “Refractor” Principle nI > nII: Hyperbola nI < nII: Ellipse nI = -nII: Parabola Mushroom Implementation

  21. Full-Wave Demonstration of Microwave Surface Plasmon ATR-Type Setup (PPWG) 2D CRLH Metamaterial Constitutive Parameters and Dispersion Effective Medium Demonstration

  22. 2D Mushroom-Structure Leaky-Wave a Dispersion Diagram RH M X Γ fΓ2 fΓ1 LH Γ M Γ X Equivalent CRLH circuit Unit cell

  23. 2D Mushroom-Structure Leaky-Wave cont’d 2D Dispersion Diagram Isotropy RH LH Γ Γ β = 0.1π/a RH M X Γ fΓ2 fΓ1 LH Γ X M Γ

  24. Conical Beam Operation Prototype (top view) Measured Radiation Patterns RH LH center excitation Radiation Principle β β RH Radiation Angle vs Frequency vp vp θ θ β β LH vp vp θ θ

  25. Full-Scanning Edge-Excited 2D-LW Antenna E.g. Hexagonal 3-ports antenna surface each port scans from backfire-to-endfire  N-ports = N-edges/2

  26. Array Factor Approach of LW Structures Phased Array Leaky-Wave Structure DISCRETE EFFECTIVELY HOMOGENEOUS • linear phase : uniform structure • exponentially decaying magnitude: • excitation: induced by propagation • array factor: • linear phase: • constant magnitude: • excitation: feed at each element • array factor: directivity  N

  27. 2D network  decomposed into N columns of M unit cells • each column  column transmission matrix [T]; [T]tot = [T]N • unit cell parameters known from extraction [T] [T]tot CRLH Generalized Transmission Matrix Method (GTMM)

  28. 12  12 network  GTMM – Global S-Parameters: Examples CRLH unit cell Test parameters

  29. GTMM – Global S-Parameters: Example cont’d

  30. Dispersion Diagram Frequency (GHz) Currents distributions 21  21 network GTMM – Fields Distributions, Example, 2D, g

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