Wavelength Dependent Microwave Devices Based on Metamaterial Technology by Professor Bal Virdee BSc(Eng) PhD CEng FIET
EM response of materials are determined by the spatial distribution of its atoms and molecules. Conventional material Meta material Polarizable atoms Artificial atoms Magnetic polarizability Form effective medium
Metamaterials (eft-handed Materials ) Artificially structured materials in sub-wavelength scale Electromagnetic (EM) properties derive from shape and distribution of constituent units (usually metallic & dielectric components) EM properties not encountered in natural materials EM properties Electrical permittivity Magnetic permeability Enables the engineering of electromagnetic properties
Metamaterials Negative electrical permittivity () Negative magnetic permeability () n n v 1 v 1 Z Negative ε, μ, n Novel and unique propagation characteristics in those materials!
If both ε and µ are negative, how does n = -1? 1 e 1 e e e e e n Metamaterials 1 e
E-field EM wave propagation in a real materials k E vg v p S > 0, > 0 (ight-handed) H propagation H-field
E-field Novel phenomena in left-handed materials E vg v p k S k S H H > 0, > 0 < 0, < 0 (ight-handed) (eft-handed) E vg v p S E H E-field propagation propagation H-field H-field Backwards propagation (opposite phase & energy velocity)
H propagation phenomena
Negative efraction H material n > 0 n > 0 n < 0 Snell s aw n1 sin n sin i 1 n 1 t sin sin i n t ight bends in the wrong way for n 1 > 0 and n < 0
Applications Miniaturization High-speed circuits High resolution imaging systems Highly sensitive biomedical sensors Superlens Cloaking
Historical background Victor Veselago Sir John Pendry David Smith V G Veselago, The electrodynamics of substances with simultaneously negative values of eps and mu, Usp. Fiz. Nauk 9, 517-56 (1967) J B Pendry, Negative refraction makes a perfect lens, PHYSICA EVIEW ETTES 85, 3966-3969 (1999) D Smith, et al., Determination of effective permittivity and permeability of metamaterials from reflection and transmission coefficients, Phys. ev. B, 65, 1-5, (000)
How to create arbitrary? z p (a) Thin-wire structure ε < 0, μ > 0 if E z pe pe pe r ( ) 1 1 ( ) r 0, for pe
How to create arbitrary and? (a) Thin-wire structure ε < 0, μ > 0 if E z (b) Split-ring resonator (S) structure ε > 0, μ < 0 if H y 0 0 ) ( ) ( 1 ) ( ) ( 1 1 ) ( m m r pe pe pe r F F pm m m r pe r F 1 for 0, for 0, 0 0 y p z p
esonance interpretation in terms of equivalent circuits DS C: capacitance per unit length : inductance per unit length S l l g / l g /: half-wavelength split-ring resonator
S medium will have a magnetic dipole moment per unit volume: Calculation Pendry et al, 99
S medium will have a magnetic dipole moment per unit volume: Around resonance, large induced currents lead to strong magnetic dipole response. Calculation Pendry et al, 99
Copper S, 0.7 cm size 1 cm pitch lattice, l=.5 cm S medium will have a magnetic dipole moment per unit volume: Around resonance, large induced currents lead to strong magnetic dipole response. r F 1 o Q o Calculation Pendry et al, 99
Experimental Verification Detector Microwave absorber ε < 0, μ < 0 Microwave beam Sample Microwave absorber H material (Prism) Unit cell: 5 mm Operating wavelength: 3 cm (8-1 GHz) adius of circular plates: 15 cm Detector was rotated around the circumference of circle in 1.5 degree steps UCSD, Science 9, 77 001
Experimental Verification. A. Shelby, D.. Smith and S. Schultz, Experimental verification of a negative refractive index of refraction, Science, vol. 9, pp. 77-79, Apr. 001.
Experimental Verification. A. Shelby, D.. Smith and S. Schultz, Experimental verification of a negative refractive index of refraction, Science, vol. 9, pp. 77-79, Apr. 001.
Cloaking at microwaves. A. Shelby, D.. Smith and S. Schultz, Experimental verification of a negative refractive index of refraction, Science, vol. 9, pp. 77-79, Apr. 001.
Cloaking at microwaves A A: Naked metal cyllinder exposed to microwave
Cloaking at microwaves A B A: Naked metal cyllinder exposed to microwave B: Metal cyllinder wrapped with metamaterial structure
Cloaking at optical wavelengths Invisible man become a reality?
C Z C Y 0 1 0 1 0 1 g p c C v C v C Y Z Z C C Z Y (H T series /shunt C) unit-cell
C C Z 1 Y 1 C Z C Y 0 0 0 1 1 1 1 g p c C v C v C Y Z Z C C C Z Y 0 1 0 1 0 1 g p c C v C v C Y Z Z C C Z Y Anti-parallel (H T series /shunt C) (H T series C/shunt ) unit-cell unit-cell
Composite ight/eft-handed Metamaterial C (Fm) C (Hm) se C < / unit-cell sh < / ight-hand gap C (Fm) c (Hm) < / purely H se CH c eft-hand gap l g
Composite ight/eft-handed Metamaterial C (Fm) C (Hm) se C < / unit-cell sh < / ight-hand gap c C (Fm) < / (Hm) CH purely H sh purely H CH c se (Hm) < / C (Fm) eft-hand gap l g
Composite ight/eft-handed Metamaterial C (Fm) C (Hm) se C < / unit-cell sh < / ight-hand gap C (Fm) c purely H l g Balanced CH guide wavelength 1 C 1 C < / purely H (Hm) sh CH c o se CH (Hm) < / C (Fm) eft-hand gap l g
CH Transmission-line Implementation unit-cell d microstrip line T-unction series shunt interdigital spiral capacitor inductor unit-cell via to ground interdigital capacitors CH line shorted stub inductors lg/
CH Transmission-line ight-hand gap c CH interdigital capacitors CH line sh purely H CH o se purely H shorted stub inductors lg/ c eft-hand gap l g H 0 H
Metamaterial Phase Shifter and B Coupler Compact phase shifters 0.1 mm Compact branch-line coupler 7 % size reduction MM branch-line coupler MM phase shifter Plated via to ground 43 % size reduction 8.70 mm Inter-digital capacitor
Metamaterial Couplers High coupling edge-coupled coupler (3dB Power splitter implementation) High directivity (over 40 db) and high isolation (over 70 db) coupler 3dB coupler prototype
Metamaterial Dual-Band at ace Coupler
Metamaterial Filter 5 db/div 1-pole filter Metamaterial design (mm) Conventional design (mm) 1 I = -1.75 db 1 = -13.8 db 0. 4 Start 1.50000 GHz 1.3515 GHz Stop 3.0000 GHz Transmission and reflection coefficient response of the 1-pole H microstrip filter
Metamaterial Filter 5 db/div 3-pole filter Metamaterial design (mm) Conventional design (mm) 67. 110.5 1 I = -3.7 db 1 = -14.10 db Start.00000 GHz 1.3900 GHz Stop.80000 GHz Transmission and reflection coefficient response of the 3-pole H microstrip filter
Metamaterial Energy Harvester 5-cell MM antenna array Converts ambient F/microwave energy from 3G, 4G, WiFi hub, HDTV etc. into about 7 V of electricity with an efficiency of 36.8% - comparable to a solar cell.
Metamaterial eflector A conventional reflector (curved PEC) in the virtual space A flat reflector (flat PEC) in the manipulated physical space
Metamaterial eflector Conventional reflector Flat reflector ϕ =0
Metamaterial Patch Antenna
Metamaterial Electronically Scanned Antenna series varactor shunt varactor asin k 0 DC block bias wires Preliminary esults Z 0 C C C 1 C 0-1 10 30 o 90 0 o 60-30 o 0 V0 0 V 5 V5 5 V 15 V 15 V 7 V 7 V - -3 150 60 o 30-60 o -4-5 180 90 o H H 0-90 o -4 @ 3.49 GHz -3 @ 3.49 GHz; scanning range is +35 o @0V to -9 o @ 7V