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Metamaterials - Concept and Applications. March 2006. Dr V esna Crnojevi ć -Bengin F aculty of Technical Sciences University of Novi Sad. Overview. Microwave passive circuits Metamateri als Definition Examples LH metamateri als Ide a Phenomena Realization LH microstrip structures

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metamaterials concept and applications

Metamaterials - Concept and Applications

March 2006

Dr Vesna Crnojević-Bengin

Faculty of Technical Sciences

University of Novi Sad

overview
Overview
  • Microwave passive circuits
  • Metamaterials
    • Definition
    • Examples
  • LHmetamaterials
    • Idea
    • Phenomena
    • Realization
  • LHmicrostrip structures
    • Resonant and non-resonant structures
    • Applications
problem
Problem
  • DimensionsPerformances
  • End-coupled ms resonator:
  • Antennas: narrow beam with only one source element?
    • Classical theory: large source
    • Metamaterials: ENZ substrate
metamaterial s

Metamaterials

Characteristics

Definition

Types

Examples

material characteristics
Material Characteristics
  • Rel. permitivityεr
  • Rel. permeabilityμr
  • Rel. index of refraction
  • Rel. characteristic impedance
extreme values of r and r
Extreme values ofεrandμr
  • Metamaterials:
    • EVL – Epsilon Very Large
    • ENZ – Epsilon Near Zero
    • MVL – Mu Very Large
    • MNZ – Mu Near Zero
    • MENZ – Mu and Epsilon Near Zero
    • HIMP – High Impedance
    • LIMP – Low Impedance
    • HIND – High Index
    • LIND – Low Index

μr

εr

definition
Definition

Metamaterials are artificial structures that exhibit extreme values of effectiveεr i μr.

metamaterial s do not exist
Metamaterials Do Not Exist
  • Artificial materials
  • Periodic structures
  • Period much smaller thenλ

 Homogenization of the structure

 Effective values of εrandμr

left handed mm

Left-Handed MM

First Ideas

Development

Realization

Applications

other quadrants
Other Quadrants?
  • Single-negative MM:εr<0 orμr<0

μr

evanescent

mode

(plasma,metals@THz)

propagation

mode

(isotropic dielectrics)

εr

evanescent

mode

(ferrites)

veselago s intuition
Veselago’s Intuition
  • Double-negative MM:εr<0 andμr<0 ?

μr

evanescent

mode

(plasma,metals@THz)

propagation

mode

(isotropic dielectrics)

εr

?

evanescent

mode

(ferrites)

conditions of existence
Conditions of Existence
  • No law of physics prevents the existence of DN MM
  • Generalized entropy conditions for dispersive media must be satisfied ()
veselago s conclusions
Veselago’s Conclusions
  • Propagation constant βis real &negative

Propagation mode exists

 Antiparalel group and phase velocities

Backward propagation (Left-hand rule)

 Negative index of refraction

synonyms
Synonyms
  • Double-Negative (DN)
  • Left-Handed (LH)
  • Negative Refraction Index (NRI)
  • (Metamaterials)
left handed m etamaterial s
Left-Handed Metamaterials
  • Double-negative MM: εr<0 andμr<0

μr

evanescent

mode

(plasma,metals@THz)

propagation

mode

(isotropic dielectrics)

εr

propagation

mode

(Left-Handed MM)

evanescent

mode

(ferrites)

consequences of lh mm
Consequences of LH MM
  • Phenomena of classical physics are reversed :
    • Doppler effect
    • Vavilov-Čerenkov radiation
    • Snell’s law
    • Lensing effect
    • Goss-Henchen’seffect
but alas
But Alas...

Everything so far was “what if”...

Can single- or double-negative materials really be made?

first sn mm j b pendry
First SN MM – J. B. Pendry

εr<0 - 1996. μr<0 - 1999.

why is r negative
Why is r negative?
  • Plasmons – phenomena ofexcitation in metals
    • Resonance of electron gas (plasma)
    • Plasmon produces a dielectric functionof the form:
  • Typically, fpis in the UV-range
  • Pendry: fp=8.2GHz
experimental validation
Experimental Validation
  • Smith, Shultz, et al. 2000.
lh ms structures

LH MS Structures

Resonant and non-resonant structures

Applications

r e sonant lh s tru c ture s
Resonant LH Structures
  • Split Ring Resonator (SRR)

Very narrow LH-range

Small attenuation

  • Many applications, papers, patents
    • Super-compact ultra-wideband (narrowband) band pass filters
    • Ferran Martin,Univ. Autonoma de Barcelona
wide stopband
Wide Stopband

Garcia-Garcia et al,IEEE Trans. MTT, juni 2005.

complementary srr
Complementary SRR
  • Application of Babinet principle - 2004.
  • CSRR givesε‹0
lh bpf csrr gap
LH BPF – CSRR/ Gap
  • November 2004.
  • Gaps contribute toμ‹0
  • Low attenuation in the right stopband
bpf csrr stub
BPF – CSRR/Stub
  • August 2005.
  • 90% BW
  • Not LH!!!
three elements
Three “Elements”
  • CSRR/Gap– steep left side
  • CSRR/Stub – steep right side
  • 2% BW
multiple srr s and s piral s
Multiple SRRsandSpirals

Crnojević-Bengin et al, 2006.

fra c tal srr s
Fractal SRRs

Crnojević-Bengin et al, 2006.

n on resonant lh structures
Non-Resonant LH Structures
  • June 2002.
    • Eleftheriades
    • Caloz & Itoh
    • Oliner
  • Transmission Line (TL) approach
  • Novel characteristics:
    • Wide LH-range
    • Decreased losses
lh tl
LH TL
  • Dual structure
a very simple proof
A Very Simple Proof
  • Analogy between solutions of the Maxwell’s equations for homogenous media and waves propagating on an LH TL

Materials:LH TL:

=

!!!

crlh tl
CRLH TL
  • Real case – RH contribution always exists
lh tl characteristics
LH TL Characteristics
  • Wide LH-range

Caloz, Itoh, IEEE AP-S i USNC/URSI Meeting, juni 2002.

applications of lh mm
Applications of LH MM
  • Guided wave applications
    • Filters
  • Radiated wave applications
    • Antennas
  • Refracted wave applications
    • Lenses
guided w ave applications
Guided Wave Applications
  • Dual-bandand enhanced-bandwidth components
    • Couplers, phaseshifters, power dividers, mixers)
  • Arbitrary coupling-levelimpedance/phase couplers
  • Multilayer super-compactstructures
  • Zeroth-order resonatorswith constant field distribution

Lai, Caloz, Itoh, IEEE Microwave Magazin, sept. 2004.

dual band crlh devices
Dual-Band CRLH Devices
  • Second operating frequency:
    • Odd-harmonic - conventional dual-band devices
    • Arbitrary - dual-band systems
  • Phase-response curve of the CRLHTL :
    • DC offset – additionaldegree of freedom

 Arbitrary pair of frequenciesfor dual-band operation

  • Applications:

Phaseshifters,

matching networks,

baluns, etc.

dual band b lc lin caloz itoh ims 03
Dual-Band BLC Lin, Caloz, Itoh, IMS’03.
  • Conventional BLC operates atfand3f
  • RH TL replaced by CRLH TL

 arbitrary second passband

c s crlh dc caloz itoh mwcl 2004
CµS/CRLH DCCaloz, Itoh, MWCL, 2004.
  • Conventional DC:

 broad bandwidth(>25%)

 loose coupling levels(<-10dB)

  • CRLH DC:

 53% bandwidth

 coupling level −0.7dB

zor sanada caloz itoh apmc 2003
ZOR Sanada, Caloz, Itoh, APMC 2003.
  • Operates atβ=0
  • Resonance independentof the length
  • Q-factor independent of the number of unit cells
sssr crnojevi bengin 2005
SSSRCrnojević-Bengin, 2005.
  • LZOR=λ/5
  • LSSSR=λ/16
  • Easier fabrication
  • More robust to small changes of dimensions
radiated w ave applications
Radiated Wave Applications
  • 1-D i 2-D LW antennas and reflectors
    • ZOR antenna, 2004. - reduced dimensions
    • Backfire-to-Endfire LW Antenna
    • Electronically controlled LW antenna
    • CRLH antenna feeding network
backfire to endfire l w antena
Backfire-to-Endfire LW Antena
  • Operates at its fundamental mode
    • Less complexand more-efficient feeding structure
  • Continuousscanning from backward (backfire)to forward (endfire) angles
  • Able to radiate broadside

Liu, Caloz, Itoh, Electron. Lett., 2000.

electronically controlled lw antenna
Electronically Controlled LW Antenna
  • Frequency-independent LWantenna
  • Capable of continuousscanning and beamwidth control
  • Unit cell:

CRLH with varactor diode

  • βdepends on diode voltage
antenna feeding network
Antenna Feeding Network

Itoh et al, EuMC 2005.

refracted w ave applications
Refracted Wave Applications
  • Most promising
  • Not much investigated - 2-D, 3-D
    • Negative focusing at an RH–LH interface
    • Anisotropic metasurfaces
    • Parabolic refractors...
current research
Current Research...
  • Subwavelengthfocusing:
    • Grbic, Eleftheriades, 2003, (Pendry 2000):
    • NRI lense with εr=−1 andµr=−1achieves focusing at an area smaller thenλ2
  • Anisotropic CRLH metamaterials:
    • Caloz, Itoh, 2003.
    • PRI in one direction, NRI in the orthogonal
    • Polarizationselective antennas/reflectors
future applications
Future Applications
  • Miniaturized devices basedZOR
  • MM beam-formingstructures
  • Nonlinear MM devices for generationof ultrashort pulses forUWBsystems
  • Active MM - dual-band matching networks for PA,high-gain bandwidth distributed PA, distributed mixers
  • Refracted-wave structures – compact flat lenses, near-field high-resolutionimaging, exotic waveguides
  • SN MM – ultrathin waveguides, flexible single-mode thick fibers, verythin cavity resonators
  • Terahertz MMs – medical applications
  • Natural LH MM – currentlynot known to exist
  • SF MM - chemists, physicists, biologists,and engineers tailor materials missing in nature
main challenges
Main Challenges
  • Wideband 3-D isotropic LH meta-structure
main challenges1
Main Challenges
  • Development of fabrication technologies(LTCC, MMIC, nanotechnologies)
  • Development of nonmetallic LH structures for applications at optical frequencies
  • Miniaturization of the unit cell
  • Development of efficient numerical tools
conclusion
Conclusion

“LH materials …one of the topten scientific breakthroughs of 2003.”

Science, vol.302, no.5653, 2004.

“MMs have a huge potential and may represent one of theleading edges of tomorrow’s technologyin high-frequencyelectronics.”

Proc. of the IEEE, vol.93, no.10, Oct.2005.