introduction to metamaterials - jcee · applications: tunable filters. μ
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Introduction to Metamaterials:Application to Communications
Systems Design
Ignacio Gil Departament d’Enginyeria Electrònica
Universitat Politècnica de Catalunya, Spain
I.Gil
Outline
Motivation
Metamaterials Introduction
Applications
Filtering
Couplers, Diplexers, Dividers
Design Example: RF-MEMS Metamaterials
Conclusions
I.Gil
Outline
Motivation
Metamaterials Introduction
Applications
Filtering
Couplers, Diplexers, Dividers
Design Example: RF-MEMS Metamaterials
Conclusions
I.Gil
Motivation
RF Front-EndIF stages and
signal processing
I.Gil
Motivation
TechnologiesMicromachining
RF MEMSMCM-D
New Design Strategies
Electromagnetic BandGaps METAMATERIALS
Devices isolation
Filtering
Espurious supression
Miniaturization
Radiation leakage inhibition
Tunability
Efficiency
Low-losses
High-Q
Si Technology
Reconfigurable devices
Multi-metal structures
I.Gil
Motivation
Metamaterials Introduction
Applications
Filtering
Couplers, Diplexers, Dividers
Design Example: RF-MEMS Metamaterials
Conclusions
Outline
I.Gil
MetamaterialsArtificially fabricated material, based on periodic (or quasi-periodic)structures, with singular and controllable electromagnetic properties, notpresent sometimes in natural media.
Types • Electromagnetic and Photonic Cristals (EBG, PBG)• Effective media with negative index (LHM, ENG, MNG)
EBG LHM
Period ∼ λg
Bragg Effect
Bragg Condition
pπβ =
Woodpile structureε, μ simultaneiusly negativePeriod << λg (miniaturization)
I.Gil
MetamaterialsEffective media metamaterialsArtificial structures with controllable magnetic permeability and/or dielectricpermittivity.
ε
μRHM
n, β >0, n∈ℜ(dielectric materials)
LHMn, β <0, n∈ℜ(no existing in nature)
MNGn, β ∈ℑ
(Ferrimagnetic materials)
ENGn, β ∈ℑ
(Plasmas, metals at optical frequencies)
Medios opacos
• Transparent medium• Backward waves• Negative refraction index !!!!!!!• Left Handed Media (LHM)
I.Gil
Metamaterials
Maxwell EquationstB
cxE
∂∂
−=∇1
tD
cxH
∂∂
=∇1
HB μ=
ED ε=
Monocrhomatic plane wave Hc
xE μωβ =
Ec
xH εωβ −=
ExHcSπ4
=
Poynting Vector
E
H
β
β
E
H
RHM LHM
S S
Left Handed Materials– LHM (properties)
vg
vp
vg
vp
I.Gil
Metamaterials
Doppler effect
Cherenkov radiation
Negative refraction
Curved lenses Flat lenses
V. Veselago, Sov. Phys. Usp, 1968
Left Handed Materials– LHM (properties)
I.Gil
MetamaterialsSynthesis of LHM (superposition of two artificial media)
E
βH
SRR - Pendryε < 0 μ < 0
d << λg
2
2
1ωω
ε p−= 22
2
1o
Fωωωμ−
−=
F: Fractional area.
ωo: resonance frequency
μ < 0 ⇔ ωo < ω < ωo/(1-F)1/2
Plasma
frequency
First synthesis of a LHM – Smith, 2000
I.Gil
Excited by an axial magnetic field
Current loops between the rings
LC tank behaviour
pulo CrC ⋅⋅= πspul
o LCr ⋅⋅=π
ω 2
SRR
22
2
1o
Fωωωμ−
−=F: fractional area
μ<0 ⇔ ωo < ω < ωo/(1-F)1/2
Metamaterials
Medium with μ < 0
I.Gil
Metamaterials
COMPLEMENTARY
CSRR
SRR
Medium with ε < 0
Excited by an axial electric field
CSRRs can be placed in the ground plane of amicrostrip line.
fSRR ≈ fCSRR
Complementary Split Rings Resonator (CSRR)
First resonant particle with negative permittivity
I.Gil
Metamaterials
I.Gil
Metamaterials
f
S(2,1)
fp
fo
SRRs
wires
BACKWARD WAVE PROPAGATION
Ek S
H
SRRs μ < 0
INDUCTORS ε < 0
SUPERPOSITION
LHM MEDIUM
I.Gil
-50
-40
-30
-20
-10
0
0 2 4 6 8 10 12
Frequency (GHz)
S(1,
1), S
(2,1
) (dB
)
S(1,1)
S(2,1)
• Good frequency selectivity
• Small dimensions
• Out of band rejection > 25dB
IL ≈ 3.5dBsBW ≈ 0.6GHz
Arlon εr=2.43 ; h=0.49mm
1st LHM planar structure based on SRRs
F. Martin et al., APL, 2004
Metamaterials
I.Gil
Metamaterials
S(2,1)
fp
fo
CSRRs
gaps
CSRRs ε < 0
GAPS μ < 0
f
BACKWARD WAVE PROPAGATION
Ek S
H
SUPERPOSITION
LHM MEDIUM
I.Gil
Metamaterials
-40
-30
-20
-10
0
0 1 2 3 4 5 6
Frequency (GHz)
S(1,
1), S
(2,1
) (dB
)
IL ≈ 4dBsBW ≈ 0.4GHz
2Cg 2Cg
F. Falcone et al., PRL, 2004
I.Gil
Outline
Motivation
Metamaterials Introduction
ApplicationsFiltering
Couplers, Diplexers, Dividers
Design Example: RF-MEMS Metamaterials
Conclusions
I.Gil
Applications: Narrow Band Pass Filters
Bonache et al., Micr. & Opt. Tech. Lett., 2005
Falcone et al., Phys. Rev. Lett., 2004
Bonache. et al., IEEE Trans. Micr. Theo.Tech., 2006
I.Gil
Applications: Ultra Wide Band Pass Filters
Bonache et al., Micr. & Opt. Tech. Lett., 2005
I.Gil
Applications: Improved Stop Band Filter
García-García. et al., IEEE Micr.Trans. Theo. Tech., 2005
I.Gil
Applications: Tunable Filters
μ<0
I. Gil et al., Electronics Letters, 2004
VLSRR
Tunable BW
Infineon BB833
9pF-0.75pF (0V-28V)
I.Gil
Applications: Tunable Filters(a)
(b)
(a)
(b)Measurement
Electric simulations(with losses) Tuning
range>30%
I. Gil et al., IEEE-Micr. Trans.Theo. Tech., June 2006
I.Gil
0,5 1,0 1,5 2,0
-50
-40
-30
-20
-10
0
S11
S21
S P
aram
eter
s (d
B)
Frequency (GHz)
S51 S41 S21 S31 S11 S21 Simulation S11 Simulation
Jarauta et al., Micr. & Opt. Tech. Lett., 2006
M. Gil et al., PIERS, 2006
(2,1)S
(3,1)S(1,1)S
(3,2)S
J. Bonache et al., Elec. Lett., 2006
Applications: Couplers, Diplexers, Dividers
I.Gil
Outline
Motivation
Metamaterials Introduction
Applications
Filtering
Couplers, Diplexers, Dividers
Design Example: RF-MEMS Metamaterials
Conclusions
I.Gil
Tunable Metamaterials
1-D tunable metamaterials structures implemented inmicrostrip technology by using VLSRR
Significant losses due to varactor-metal junction resistance
Low quality factor, Q~10-30
RF-MEMS Metamaterials
I.Gil
CSRR+RF-MEMS CPW Unit Cell
CSRR
c=d=10μm
l=480μm ; w=130 μm
CPW
W=150μm ; G=30μm
RF-MEMS bridge
B=80μm ; b=100μm
H=290μm ; h=40μm
RF-MEMS modifies the electrical characteristics of CSRR (fo)
I.Gil
CSRR+RF-MEMS CPW Simulation
4-stage periodic device
50Ω CPW structure
Agilent Momentum
Coplanar mode
Mesh frequency=100GHz
Mesh density=20cells/λ
Device lenght: 2780μm
Distance between CSRR: 220μm
No mechanical effects
Up-state: MEMS_h=2μm
Down-state: MEMS_h=0.5μm
I.Gil
CSRR+RF-MEMS CPW Simulation
fo at Q-band: 39.2-49.2GHz
Tuning Range: ~20%
Rejection Level: IL<-50dB
No losses simulation
Down-state
Up-state
Up-state
Down-state
I.Gil
CSRR+RF-MEMS CPW Technology
Stripped-down RF-MEMS technology
3 lithographic steps
Al layer sputter-deposited and patterned on AF45 glass substrate(CPW structure)
Sacrificial photoresist layer (anchoring regions of the MEMS)
Al layer deposited (sacrifial layer removal)
Electrically floating bridge anchored directly on the substratein holes of the CPW ground planes
I.Gil
CSRR+RF-MEMS CPW Technology
Down-state: bridge only contacts the centre of CPW strip
Native Al oxide as interposer to prevent DC shorts
Al layer thickness: tAl=1μm
AF45 substrate: εr=5.9; h=650μm
Photoresist Layer: tPh=3μm
I.Gil
(a)
(b)
Actuation Voltage: 0-17V
fo at Q-band: 39-48GHz
Tuning Range: ~20%
Rejection Level: IL<-40dB
Good losses level (<-3dB)
CSRR+RF-MEMS CPW Experimental
I.Gil
Simulation vs Experimental
(a) (b)
Good agreement
Approximation validated
I. Gil et al., Electronics Letters, 2008
I.Gil
Motivation
Metamaterials Introduction
Applications
Filtering
Couplers, Diplexers, Dividers
Design Example: RF-MEMS Metamaterials
Conclusions
Outline
I.Gil
Conclusions
Metamaterials: Microwave engineering solution in order toachieve compact and miniaturized devices with asignificant performance improvement
Applications: Filtering, couplers, diplexers, dividers, etc
Performance:
Filtering: BPF:high selectivity ; UWBPF ; RPF: high rejection
Tunable devices: Tuning range~20%, IL<-40dB, high-Q (low losses)
Future work: RF-MEMS Band pass frequency response(ε,μ<0) , electrical modelling
Thanks for your attention!
Questions??
Introduction to Metamaterials:Application to Communications
Systems Design
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