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

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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

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Composite Right / Left-Handed (CRLH) TL Infinitesimal Circuit ModelTransmission Line Representation Balanced CasePropagation Constant

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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 Novel Electronically Scanned LWA Frequency independent scanning Efficient Channelization Continuous scanning capability Microstrip technology Low profile Conventional Magnetically-Scanned LWA Frequency independent scanning Biasing DC magnetic field NOT practical Waveguide configuration 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.

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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 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

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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 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 Modified Layout of a Microstirp CRLH TL Unit cells

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Dispersion diagram Voltages Parameters 0 V5 V10 V L R,var [nH] C R, var (=C L,var ) [pF] L L1 [nH] C R1 [pF] L L2 [nH]4.597 C L1 [pF]0.485 L R1 [nH]2.027

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Prototype of 30 Cell Proposed TL 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 Bias Configuration

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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 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

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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 ) 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 )

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Focusing by a Planar Non-Uniform LW Interface Principle Dipole array model for the TX antenna E-Field Maximization d 0 = 0 /2F = 6 E-Field of a Dipole zi (R iF +E z (r F ) ~ k 0 |R iF |+constant ~

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x( z Normalized Electric Field (dB) Effects of Different Array Length. z( z( z z( Normalized Electric Field (dB) L=12 L=30 L=12 L=30 F = 6 0 dB L = 30 0 L = 12 0

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Piece-Wise Linear Approximation F = 6 0 ~ k 0 |R iF |+constant ~ dB L = 30 0

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Effects of Leakage Factor Willkinson power divider Non-uniform LW antenna Prototype F = 6 0 L = 30 0

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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

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

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

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

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Parameter Extraction Method RH LH CRLH HIGH-PASS GAP How to determine: L R, C R, L L, C L - Full-wave analysis: ω Γ1, ω X1, ω M1 - Compute ω se, ω L, ω R, ω sh, ω L ω R = ω sh ω se - Compute Bloch impedance Z B = fct(ω X1 ) - Insert Z B (ω X1 ) to determine - Finally, using,

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Paraboloidal “Refractor” Plane Wave to Cylindrical WavePrinciple Mushroom ImplementationEffective Medium Full-Wave Demonstration n I > n II : Hyperbola n I < n II : Ellipse n I = -n II : Parabola

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

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2D Mushroom-Structure Leaky-Wave Unit cell a Equivalent CRLH circuit Dispersion Diagram ΓΓ X M LH RH fΓ1fΓ1 Γ X M fΓ2fΓ2

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2D Mushroom-Structure Leaky-Wave cont’d ΓΓXM LHLH RH fΓ1fΓ1 Γ X M β = 0.1π/a fΓ2fΓ2 2D Dispersion Diagram Γ LH Γ RH Isotropy

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Conical Beam Operation Prototype (top view) ββ vpvp vpvp vpvp vpvp LH RH θθ θ ββ θ Radiation Principle center excitation RH LH Measured Radiation Patterns Radiation Angle vs Frequency

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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

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Array Factor Approach of LW Structures Phased ArrayLeaky-Wave Structure linear phase: constant magnitude: excitation: feed at each element array factor: DISCRETEEFFECTIVELY HOMOGENEOUS linear phase : uniform structure exponentially decaying magnitude: excitation: induced by propagation array factor: directivity N

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Generalized Transmission Matrix Method (GTMM) 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 CRLH [T] [T] tot

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GTMM – Global S-Parameters: Examples CRLH unit cell Test parameters 12 12 network

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GTMM – Global S-Parameters: Example cont’d

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

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