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

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

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

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.

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

 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

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

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

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

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 )

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 ~

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

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

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

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

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

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:

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

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,

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

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

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

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

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

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

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

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

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

GTMM – Global S-Parameters: Example cont’d

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