SLIDE 1 1 1
Design of Microwave Absorbing Structure and Microwave Shielding Structure By using Composite Materials, Nanomaterials and evolutionary computation
“Sapienza” Universitá di Roma Scuola di Ingegneria Aerospaziale
DOTTORATO DI RICERCA XXIII CICLO
Dottorando
Ing.Davide Micheli
Tutor
Gradoni
Supervisor
Marchetti Tesi di Dottorato
Roma 01/02/2011
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Target: Modeling microwave Absorbing Material using carbon nano-materials end Evolutionary computation
Topics Topics
Carbon Nano-materials and dielectric characterization
3
Absorber design Evolutionary computation modeling
4
1 2 3 4 5
1 2 3 4 5
5
Experimental validation
Electromagnetic absorbing model
2
EMI: shielding and absorbing
1
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Target: Modeling microwave Absorbing Material using carbon nano-materials end Evolutionary computation
Topics Topics
Carbon Nano-materials and dielectric characterization
3
Absorber design Evolutionary computation modeling
4
1 2 3 4 5
1 2 3 4 5
5
Experimental validation
Electromagnetic absorbing model
2
EMI: shielding and absorbing
1
SLIDE 4 Why EMI Shielding and Absorbing ? Why EMI Shielding and Absorbing ?
EMI de finitio n
Electromagnetic Interference (EMI), defined by NATO as an electromagnetic disturbance which interrupts, obstructs, or otherwise degrades the effective performance of electronic or electrical equipment.( www.glenair.com/html/emi.htm). SISTEMS AFFECTED AND GENERATING EM DISTURBNCES
PC EM shield Cellular Phone Lightning War scenario TLC system Satellites Anechoic Chamber Radar Stealthness Electronic war
SLIDE 5 Why EMI Shielding and Absorbing ? Why EMI Shielding and Absorbing ?
NASA Contractor Report 4784 Design Guidelines for Shielding Effectiveness, Current Carrying Capability, and the Enhancement
- f Conductivity of Composite Materials
- Electromagentic compatibility (EMC) occurs when all equipment in a
system operates properly without electronic interference from equipment within or outside the system.
- Electromagentic interference (EMI) occurs when there is a source of
emission and a unit that is susceptible and a mtehod of tranmsission between the two.
- Such interference can be controlled reducing unnecessary emission,
susceptibility, and/or interrupting the transmission path.
SLIDE 6
Why EMI Shielding and Absorbing ? Why EMI Shielding and Absorbing ?
NASA Reference Publication 1374. In time period up to 1993 N° 17 Case histories of spacecraft, and N° 120 Case histories military and civil apparatus failure or anomalies attributed to EMI Some NASA cases histories: A low level signal not always present and not due spurious of radio station or mobile transmitters, interfere with on board Saturn V vehicle sub-system. Investigation revealed that Carbon-arch- lamps surrounding the vehicle, were producing broadband frequency disturbances. During checkout of Skylab Apollo Telescope, an EMC test illuminated the entire Skylab with various transmitter frequencies. This revealed failure in the Telemetry system.
SLIDE 7 Why EMI Shielding and Absorbing ? Why EMI Shielding and Absorbing ?
Some Non NASA cases histories Disasters caused by EMI problems In 1967 in Vietnam, a Neavy jet landing experienced an uncommanded release of munitions that struck a fully armed and fueled fighter on deck. The results were explosion, the dead of 134
- sailors. This accident was caused by the Radar illuminating the
landing aircraft. The resulting EMI sent an unwanted signal to the weapons system. During the early years of ABS’s, Mercedes automobiles equipped with ABS had severe braking problems along a certain stretch of German autobahn. The brakes where affected by a near-by radio transmitter as drivers applied them on the curved section of
- highway. The nearterm solution was to erect a mesh screen along
the roadway to attenuate the EMI.
SLIDE 8
Why EMI Shielding and Absorbing ? Why EMI Shielding and Absorbing ?
Stealthness Military applications
SLIDE 9 9 9
Target: Modeling microwave Absorbing Material using carbon nano-materials end Evolutionary computation
Topics Topics
Carbon Nano-materials and dielectric characterization
3
Absorber design Evolutionary computation modeling
4
1 2 3 4 5
1 2 3 4 5
5
Experimental validation
Electromagnetic absorbing model
2
EMI: shielding and absorbing
1
SLIDE 10
Electromagnetic absorbing theory Electromagnetic absorbing theory
PRINC IPL ES O F ABSO RBER O PERAT IO N
When a certain interface separating different material is encountered, incoming electromagnetic waves are in part reflected and in part transmitted through material.
EM Interference wave Transmitted Interference wave Lossy material
EM Transmission attenuation (dB), determines the EM Shielding properties of Materials or Structure EM Reflected components determines the amounts in interference presence
SLIDE 11 Electromagnetic absorbing theory Electromagnetic absorbing theory
PRINC IPL ES O F ABSO RBER O PERAT IO N
From Maxwell equation such system can be well studied using the equivalent transmission line equations and schemes
η1 η2 η3 l2 Incoming wave Reflected wave Transmitted wave Lossy material
η1 η2 η3
- Since the material wave impedance η is
different from free space impedance η there will be impedance mismatch and this will create the reflected wave.
- Since the material will always have
some losses, there will be attenuation
2 1 2 1
η η η η + − = Γ
SLIDE 12 Absorbing Structure Absorbing Structure
k rk rk TE k k rk rk TM k
ϑ ε µ ε µ η ϑ ε µ ε µ η cos 1 cos = =
⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ =
+ + 1 1 sin
arcsin
k k r k r k
ϑ ε ε ϑ Layers are characterized by different values of εk giving the kth-layer transverse characteristic impedances TM and TE upon electromagnetic wave incidence angle θk
where for Snel’s law
SLIDE 13 Absorbing Structure Absorbing Structure
In Absorbing applications, RC at the air-absorber interface can be evaluated by the following equation relating the free space impedance to the input impedance seen at the air-multilayer structure interface
where Z0 ≅ 377 Ω is the free space impedance and Zi is the input impedance at the first air-absorber
- interface. The input wave impedance of
the multilayer, backed by PEC, can be expressed iterating the following equation for each layer k
TE TM TE TM i TE TM TE TM i TE TM
Z Z Z Z RC
/ / / / /
+ − =
( ) ( ) ( ) ( )
k k TE TM ik k k TE TM k k k TE TM k k k TE TM ik TE TM k TE TM ik
t jZ t t j t Z Z β β η β η β η sin cos sin cos
/ 1 / / / 1 / / − −
+ + =
tk is the layer k thickness in m, whereas the wave number is βk
( )
k rk rk rk ik rk rk k
j f f ϑ ε ε µ ε µ π ϑ ε µ ε µ π β cos " ' 2 cos 2 − = =
1 2 3
SLIDE 14 Microwave Shielding Material Microwave Shielding Material
In calculating Transmission Coefficient (TC) at the last interface of the multilayer – i.e., at the absorber-air interface – a more general formalism, based
- n the application of boundary conditions for tangential fields, has been used in
place of the transmission lines approach. For an arbitrary layer k of the configuration depicted in Fig. below, it is possible to write:
k k k k k k k k k k k k k k k k
z j k z j k z j k k k z j k k k z j k z j k z j k z j k
e E e E e E e E e E e E e E e E
1 1 1 1
1 1 1 1 1 1
+ + + +
− + − + + − + − + + − + − + + − − +
− = − + = +
κ κ κ κ κ κ κ κ
η η η η
η ηk
k
is the TM/TE is the TM/TE characteristic wave characteristic wave impedance of each impedance of each layer layer
k rk rk TE k k rk rk TM k
ϑ ε µ ε µ η ϑ ε µ ε µ η cos 1 cos = =
E H
SLIDE 15 15 15
Target: Modeling microwave Absorbing Material using carbon nano-materials end Evolutionary computation
Topics Topics
Carbon Nano-materials and dielectric characterization
3
Absorber design Evolutionary computation modeling
4
1 2 3 4 5
1 2 3 4 5
5
Experimental validation
Electromagnetic absorbing model
2
EMI: shielding and absorbing
1
SLIDE 16 Why composite materials ? Why composite materials ?
- A composite is any combination of two or more materials
designed to achieve some characteristic not offered by any of the materials alone.
- Reinforcing materials consists in fillers like graphite or even
better carbon nanotubes.
- In recent years composite materials have been used for
spacecraft structure because of their light weight, high strength and ease of fabrication even though they are not as electrically conductive as metal structure
SLIDE 17 CARBONs and Epoxy-resin adopted
- CNFs (Carbon NanoFibers), bought at SigmaAldrich
(diameter around 75 nm, length 50-100 µm);
- MWCNTs (Multi-Wall Carbon Nanotubes type NANOCYLTM
NC7000), bought at NANOCYL (diameter around 9.5 nm, length 1.5 µm, purity 90%)
- Epoxy-resin is: PrimeTM 20LV (density 1.123 g/cm3),
Hardner (density 0.936 g/cm3);
SLIDE 18 CARBON
iso NA half-life DM
a) diamond; b) graphite; c) lonsdaleite; d-f) fullerenes (C60, C540, C70); g) amorphous carbon; h) carbon nanotube.
98.9% stable with 6 neutrons
13C
stable 1.1% with 7 neutrons
14C
trace y beta- 5730
DIAMOND GRAPHITE
CARBON NANOSTRUCTURES
SLIDE 19 CNTs PROPERTIES
PARAMETER CARBON NANOTUBE REFERENCE Density 0.6 ÷100 nm 50 nm-large and some nanometers-thick ribbons through E.B. Lithography Length Some thousands nanometers
1,33 ÷ 1.40 gr/cm3 Aluminium alloys : 2.7 gr/ cm3 Carbon fibers: 1.74 ÷ 1.94 gr/cm3 Tensile strength 45 GPa High Strength steels : 2 GPa Carbon fibers: 3.5 GPa Young modulus ≈ 1÷ 4 TPa Carbon fibers : 0.23÷ 0.52 TPa Elasticity Pliability up to very high angle without fracture Metals and carbon fibers break over lower pliability angles Electrical properties Metal/semiconductor It depends on the nanotube structure Density current 1*109 A/ cm2 (estimated) Copper wire melting point at 1*106 A/ cm2 Field emission Activation of phosphorus compounds at ≈ 1÷3 V with 1 µm spacing electrodes 50÷100 V/µm for molibdenum Thermal conductivity 6000 W/m°K Very pure diamond : 3320 W/m°K Thermal Stability Stable up to 2800 °C in vacuum and 750 °C in atmosphere Microchip joints melt within 600÷1000 °C Chemical properties Functionalisation according with carbon chemistry Cost 1500 $/gr Aurum cost : 10 $/gr
≈ 1÷ 4 TPa 1*109 A/ cm2 (estimated) 1500 $/gr
SLIDE 20 Carbon micro and Nano Carbon micro and Nano-
materials
CNFs GRAPHITE CF MWCNTs SWCNTs CF Human hair MWCNTs
SLIDE 21
Nano Structured composite material Nano Structured composite material
1
Nanocomposite manufacturing: Mix: Epoxy-Resin and Carbon Nanopowders Mix: before and after Ultrasonication 20kHz
2 3
Sample holder filling for subsequent EM characterization
SLIDE 22
Nano Structured composite material Nano Structured composite material
Composite manufacturing: Use of in-house press Composite manufacturing: To much early polymerization !!!!! (BAD situation to avoid)
SLIDE 23 Some samples of the composites is inserted in the λ/4 adapter of the wave guide calibration kit.
EM characterization of Carbon EM characterization of Carbon Composite Nano Structured material Composite Nano Structured material
Sample holder
Measurements of Scattering parameters Snm
Vector Network Analyzer
1 2
SLIDE 24 EM characterization of Carbon EM characterization of Carbon Composite Nano Structured material Composite Nano Structured material
Vector Network Analyzer
WG14/WR137 WAVEGUIDE CAL KIT FREQ. RANGE 5.38-8.18GHZ (FLANN) WG16/ WR90 WAVEGUIDE CAL KIT FREQ. RANGE 8.2-12.4 GHZ (AGiLENT) WG18/WR62 WAVEGUIDE CAL KIT FREQ. RANGE 12.4 – 18 GHZ (AGILENT)
Wave guide section & sample holder
SLIDE 25 EM characterization of Carbon EM characterization of Carbon Composite Composite Nano Nano Structured material Structured material
Reflection and Transmission Reflection and Transmission (Scattering Parameters): (Scattering Parameters):
The meanings of the Scattering parameters Snm are:
S11
Reflected power Incident power
S12
Incident power Transmitted power
S22
Incident power Reflected power
S21
Incident power Transmitted power
SLIDE 26 EM characterization of Carbon EM characterization of Carbon Composite Composite Nano Nano Structured material Structured material
Meaning of the permittivity and permeability Meaning of the permittivity and permeability
- The real part of permittivity (er‘) is a measure of how much energy from an
external electric field is stored in a material.
- The imaginary part of permittivity (er’’ ) is called the loss factor and is a
measure of how dissipative or lossy a material is to an external electric field.
µr µr
“
εr εr
“
Extraction Algorithm
Intrinsic material Permittivity and Permeability tan δµ tan δε Loss tangents Intrinsic wave impedance
S11 S12 S21 S22
Physical Observable
Scattering Parameters η
SLIDE 27 EM characterization of Carbon EM characterization of Carbon Composite Composite Nano Nano Structured material Structured material
Permittivity of MWCNTs composite materials
Real part of permittivity Imaginary part of permittivity
6 8 10 12 14 16 18 2 4 6 8 10 12 14 16 18 20
Frequency (GHz) Real component of Permittivity
Resin Epoxy MWCNTs 0.5% MWCNTs 1% MWCNTs 2% MWCNTs 2.5% MWCNTs 3% 6 8 10 12 14 16 18 5 10 15
Frequency (GHz) Imag component of Permittivity
Resin Epoxy MWCNTs 0.5% MWCNTs 1% MWCNTs 2% MWCNTs 2.5% MWCNTs 3%
SLIDE 28 EM characterization of Carbon EM characterization of Carbon Composite Composite Nano Nano Structured material Structured material
Characteristic intrinsic microwave impedance of carbon materials For a TEM (Transversal Electromagnetic Wave) propagating in a dielectric layer denoted with k-index, the wave impedance is expressed by the equation below
ty permittivi complex " ' impedance wave stic characteri space free 377 1 " ' 1 377 " ' = − = ≅ − ≅ − = = = ε ε µ ε ε ε ε µ ε µ ε ε µ µ ε µ η j j j
r r r r k k k
Since dielectric permittivity ε is a function of frequency f(Hz) then, the microwave intrinsic impedance of the composite material is a function of frequency too.
SLIDE 29 EM characterization of Carbon EM characterization of Carbon Composite Nano Structured material Composite Nano Structured material
WAVE IMPEDANCE DATA BASE OF AVAILABLE MATERIALS
6 8 10 12 14 16 18 60 80 100 120 140 160 180 200 220 240
Frequency (GHz) Module of intrinsic wave impedance
Resin Epoxy MWCNTs 0.5% MWCNTs 1% MWCNTs 2% MWCNTs 2.5% MWCNTs 3%
" ' ε ε µ η j
r
− =
SLIDE 30 EM characterization of Carbon EM characterization of Carbon Composite Composite Nano Nano Structured material Structured material
- Supposing “conductive cylinders” in place of nanotube until a percolating
cluster was formed.
- Percolation was defined as the concentration at which there is “microwave
connection” of continuous cluster of cylinders.
Several complex mechanisms of electric conduction are possible:
- Network of electric conductive path
- Nanocapacitances
- Jumping of electrons between
adjacent nanomaterials
- Atomic and electronic polarization
SLIDE 31 EM characterization of Carbon EM characterization of Carbon Composite Nano Structured material Composite Nano Structured material
In the X-band, Electrical conductivity of CNF are higher then other carbon materials In the X-band, Loss Factor of CNF are higher then other carbon materials
8 9 10 11 12 13 10 20 30 40 50 60 70 80
Frequency (GHz) Loss Factor (%)
Graphite 10%wt SW CNT 1wt% CNF 1wt%
' ' ' '
2 2 ε ε π σ ε π σ ωε σ ε f f = ⇒ = =
[ ]
2 2
21 11 1 100 (%) S S LossFactor − − × =
improving of conventional absorber based on graphite using nanomaterial
SLIDE 32 32 32
Target: Modeling microwave Absorbing Material using carbon nano-materials end Evolutionary computation
Topics Topics
Carbon Nano-materials and dielectric characterization
3
Absorber design Evolutionary computation modeling
4
1 2 3 4 5
1 2 3 4 5
5
Experimental validation
Electromagnetic absorbing model
2
EMI: shielding and absorbing
1
SLIDE 33 Absorbing Structure Absorbing Structure Design and Optimization Design and Optimization
Optimization: consists in minimizing reflection coefficient and overall multilayer thickness and transmission coefficient Questions:
How many layers we need ? Which is the best layers materials
type ?
Which is the best layer thickness ?
Each layer need to be optimized in terms of material type and thickness
E H
Propagation Direction
PEC or Free Space
Incident Electromagnetic Field
Free Space
θinc
SLIDE 34 Design and Optimization: Design and Optimization: Stochastic methods Stochastic methods Search Search algorithm: algorithm:
Non Intelligent method (WPO) Non Intelligent method (WPO) Intelligent method (PSO) Intelligent method (PSO) Evolutionary method (GA) Evolutionary method (GA)
SLIDE 35
Design and Optimization: Design and Optimization: Stochastic methods Stochastic methods Search algorithm: Search algorithm: Non Intelligent method Non Intelligent method: : Winning Particle Winning Particle Optmization Optmization
1 1 2 2 3 3 3 3 1 1 Step 1 Step 1 Step 2 Step 2
SLIDE 36 Winning Particle Optimization Winning Particle Optimization
Winning particle optimization (WPO), is a very simple algorithm where at each time epoch of evolution, particle which best fit the
- bjective function (OF), is deputed to pilot the trajectory of the
remaining nonintelligent particles within the multidimensional space of solutions.
( ) ( ) ( ) ( )
Parameter e Convergenc 1]
interval the in number random Dimensions Space to 1 and Number Particle to 1 Number Particle to 1 if 1 if 1 where = = = = ≠ = = > − = < + = δ
m k m k m k m k m
R n n m q k q k i PB i P g i PB i P g
( ) ( ) ( )
i PB g i P R i P
q m k m m k m
⋅ + ⋅ ⋅ = + δ 1
amplitude jump 5 5 velocity e convergenc 2 1 number interation WPO iteration current WPO where . 1 1 ≤ < ≤ < = = ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ + − = σ . P . IN i IN i
P
σ δ
SLIDE 37
Minimization of thickness to zero using WPO and 4 particles
Winning Particle Optimization in action Winning Particle Optimization in action
SLIDE 38 Winning Particle Optimization in action Winning Particle Optimization in action
5 10 15 20 25 30 0.5 1 1.5 2 2.5 3 3.5 4 4.5x 10
4
Iterations Objective Function
Sphere Function Minimization
SLIDE 39
Minimization of some standard Objective Functions using WPO.
Griewank Function Rastrigin Function Sphere Function Rosenbrock Function
Winning Particle Optimization Winning Particle Optimization
SLIDE 40 RUN
Sphere σ =0.5 Rastrigin σ =1 Griewank σ =0.5 Rosenbrock σ =1 Ackley σ =1 Run 1
1.94E-17 0.00E+00 0.00E+00 56.8406 1.14E-14
Run 2
2.73E-41 0.00E+00 0.00E+00 5.84E+01 1.15E-14
Run 3
0.00E+00 0.00E+00 1.22E-15 5.86E+01 1.15E-14
Run 4
0.00E+00 0.00E+00 0.00E+00 5.85E+01 2.93E-14
Run 5
4.22E-25 0.00E+00 0.00E+00 5.86E+01 8.97E-14
Run 6
7.36E-48 0.00E+00 0.00E+00 5.85E+01 4.71E-14
Run 7
5.66E-47 4.17E-09 0.00E+00 5.85E+01 3.64E-14
Run 8
4.55E-24 0.00E+00 0.00E+00 5.86E+01 6.41E-12
Run 9
5.81E-48 0.00E+00 0.00E+00 56.8569 3.64E-14
Run 10
0.00E+00 9.85E-08 0.00E+00 5.84E+01 4.71E-14
WPO Mean Value 58.17 WPO Stand. Dev. 0.70
WPO WPO
Minimization of some standard Objective Functions using WPO.
SLIDE 41 Absorbing Structure Absorbing Structure Design and Optimization Design and Optimization
The Elementary Objective Function (EOF) for TM and TE modes are named as CostRCTM, CostRCTE, for reflection coefficient, CostT, for thickness. The formal definition of the EOFs for TM and TE modes in Eq. below are shown. We can observe that for each Particle (Pa), the corresponding EOF is evaluated over the entire frequency band and over the entire angular incident range. where Ch is the current chromosome (Particle in WPO e PSO), freq is the frequency step, fmin and fmax are the start and stop of frequency band, θ is the current angular step, θmin and θmax represent the angular range bounds. The definition of the EOF for thickness is
( ) ( ) ( ) ( ) ⎥
⎦ ⎤ ⎢ ⎣ ⎡ ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ = ⎥ ⎦ ⎤ ⎢ ⎣ ⎡ ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ =
∑ ∑ ∑ ∑
= = = = = = = = max min max min max min max min
, , , ,
f freq f freq TE TE f freq f freq TM TM
freq Pa RC Pa CostRC freq Pa RC Pa CostRC
ϑ ϑ ϑ ϑ ϑ ϑ ϑ ϑ
ϑ ϑ
( ) [
]
) ( .... ) ( ) (
1 9 10
Pa thick Pa thick Pa thick Pa CostT + + + =
where thickk is the thickness of he k-th layer.
SLIDE 42 Two different weighting factors are introduced, one called α weighting CostT w.r.t. CostRC and CostTC, one called γ, weighting CostRC w.r.t. CostTC. Such weighting factors are chosen by the user and their meaning has to be intended as the capability of the tool to design the multilayer structure making privilege to the electromagnetic performances w.r.t. the thickness when α tend to 1, or making privilege in lowering the transmission coefficient (shielding applications) rather than lowering the reflection coefficient (RAM applications) when g tend to 0. Global Objective Function (GOF) is a linear combination of the described EOF:
Absorbing Structure Absorbing Structure Design and Optimization Design and Optimization
( ) ( ) ( ) ( )
[ ]
( )
Pa OF Pa OF Pa OF Pa GOF 3 ) 1 ( 2 1 1 ⋅ − + ⋅ − + ⋅ ⋅ = α γ γ α
α and γ are weighting coefficient (0<α<1), (0<γ<1), A is defined as ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( )
⎥ ⎦ ⎤ ⎢ ⎣ ⎡ = ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ + = ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ + = C Pa CostT Pa OF A Pa CostTC A Pa CostTC Pa OF A Pa CostRC A Pa CostRC Pa OF
TE TM TE TM
3 2 1
( ) ( )
umber AngleStepN mber FreqStepNu ×
C is defined as .
( ) ( )
ness LayerThick rs LayerNumbe max max ×
SLIDE 43 Absorbing structure obtained using WPO
Absorbing Structure Absorbing Structure Design and Optimization Design and Optimization
∼12.26 mm = 3.27 mm = 2,66 mm = 3.00 mm = 0.32 mm Incidence Wave Reflected Wave Infinite length Infinite length θ° Resin-epoxy = 3.00 mm MWCNTs 3wt% MWCNTs 1wt% MWCNTs 3wt% Resin-epoxy
Transmitted Wave
SLIDE 44 Absorbing structure obtained using WPO Reflection Coefficient dB
Absorbing Structure Absorbing Structure Design and Optimization Design and Optimization
6 8 10 12 14 16 18
Frequency (GHz) Module of Reflection Coefficient TE (dB)
theta=0° theta=10° theta=20° theta=30° theta=40° theta=50° theta=60° theta=70° theta=80° 6 8 10 12 14 16 18
Frequency (GHz) Module of Reflection Coefficient TM (dB)
theta=0° theta=10° theta=20° theta=30° theta=40° theta=50° theta=60° theta=70° theta=80°
SLIDE 45 Absorbing structure obtained using WPO Transmission Coefficient dB
Absorbing Structure Absorbing Structure Design and Optimization Design and Optimization
6 8 10 12 14 16 18
- 50
- 45
- 40
- 35
- 30
- 25
- 20
- 15
- 10
Frequency (GHz) Module of Transmission Coefficient TE (dB)
theta=0° theta=10° theta=20° theta=30° theta=40° theta=50° theta=60° theta=70° theta=80° 6 8 10 12 14 16 18
- 50
- 45
- 40
- 35
- 30
- 25
- 20
- 15
- 10
Frequency (GHz) Module of Transmission Coefficient TM (dB)
theta=0° theta=10° theta=20° theta=30° theta=40° theta=50° theta=60° theta=70° theta=80°
SLIDE 46 46 46
Target: Modeling microwave Absorbing Material using carbon nano-materials end Evolutionary computation
Topics Topics
Carbon Nano-materials and dielectric characterization
3
Absorber design Evolutionary computation modeling
4
1 2 3 4 5
1 2 3 4 5
5
Experimental validation
Electromagnetic absorbing model
2
EMI: shielding and absorbing
1
SLIDE 47 Absorber model: experimental validation Absorber model: experimental validation
Sphere Min. Function
Tx Ant. Rx Ant. Tile NRL ARCH.
AGILENT PNA
Composite material multilayer Tile Metal plate Satimo antenna
NRL arch NRL arch NRL arch NRL arch Multilayer Tile Multilayer Tile
∼0.40 ± 0.5mm ∼3,00 ± 0.5mm Epoxyresin MWCNTs 0.5wt% Aluminum plate ∼1,60 ± 0.5mm ∼0.60 ± 0.5mm Inicidence Wave Reflected Wave 200 mm 200 mm MWCNTs 3wt% α ∼2.6 mm
Multilayer Tile Multilayer Tile
SLIDE 48 Absorber model: experimental validation Absorber model: experimental validation
Sphere Min. Function
5.38 5.87 6.37 6.86 7.35 7.85 8.34 8.83 9.33 9.82 10.3 10.8 11.3 11.8 12.3 12.8 13.3 13.8 14.3 14.8 15.2 15.7 16.2 16.7 17.2 17.7
Frequency (GHz) Reflection Loss (dB)
RC(dB)_TE_Resyn_MWCNT_0.5_3%_5deg RC(dB)_TM Resyn_MWCNT_0.5_3%_5deg RC(dB)_TE Resyn_MWCNT_0.5_3%_5deg_Simulated RC(dB)_TM Resyn_MWCNT_0.5_3%_5deg_Simulated
Incidence angle 5 Incidence angle 5
SLIDE 49 Absorber model: experimental validation Absorber model: experimental validation
Sphere Min. Function
5.38 5.87 6.37 6.86 7.35 7.85 8.34 8.83 9.33 9.82 10.3 10.8 11.3 11.8 12.3 12.8 13.3 13.8 14.3 14.8 15.2 15.7 16.2 16.7 17.2 17.7
Frequency (GHz) Reflection Loss (dB)
RC(dB)_TE Resyn_MWCNT_0.5_3%_20deg RC(dB)_TM Resyn_MWCNT_0.5_3%_20deg RC(dB)_TE Resyn_MWCNT_0.5_3%_20deg_Simulated RC(dB)_TM Resyn_MWCNT_0.5_3%_20deg_Simulated
Incidence angle 20 Incidence angle 20
SLIDE 50 Shielding effectiveness measurement Shielding effectiveness measurement
Tx Antenna Rx Antenna and sample h ld
Scattering parameters Scattering parameters Sij Sij measurements and SE computation measurements and SE computation
⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎣ ⎡ = ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎣ ⎡ =
2 Short 21 2 Open 21 Reference 2 Material 21 2 Open 21 Material
10 ) ( 10 ) ( S S LOG dB SE S S LOG dB SE
SLIDE 51 Shielding effectiveness measurement Shielding effectiveness measurement
Sample Holder enclosure Rx horn antenna Materials under test Sample Holder Microwave hermetic enclosure Blocking horn antenna system
Sample Holder Enclosure Microwave secure Enclosure Composite materials
SLIDE 52 Epoxyresin MWCNT 2% ∼1 ± 0.1mm Inicidence Wave 40 mm 20 mm ∼3 ± 0.1mm MWCNT 3% ∼5 ± 0.1mm Transmitted Wave ∼1 ± 0.1mm MWCNT 1%
Epoxy-resin MWCNT 3% ∼1 ± 0.1mm Inicidence Transmitted Wave 40 mm 20 mm ∼4 ± 0.1mm
Shielding effectiveness measurement Shielding effectiveness measurement
SLIDE 53
Shielding effectiveness of CC Shielding effectiveness of CC
SLIDE 54 20 40 60 80 100 120 8.20 8.36 8.53 8.69 8.86 9.02 9.19 9.35 9.52 9.68 9.84 10.01 10.17 10.34 10.50 10.67 10.83 10.99 11.16 11.32 11.49 11.65 11.82 11.98 12.15 12.31 Frequency (GHz) Shielding Effectiveness (dB)
Shielding effectiveness measurement Shielding effectiveness measurement
10 mm Resin+MWCNTs 1,2,3wt% 6.5mm MWCNTs 6wt% 4mm Carbon-Carbon Metal plate covering antenna 6.5mm MWCNTs 10wt%
SLIDE 55
Conclusion Conclusion
1.Composite nanostructured composite materials have been electromagneticlly characterized in terms of dielectric properties. 2.Mathematical model of absorber has been applied using evolutionary computation called Winnning Particle Optimization 3.Validation of absorber design method has been experimentally performed obtaining interesting results in terms of shielding and absorption capability of multilayer materials.
SLIDE 56
Thanks ! Thanks ! Davide Davide Micheli Micheli
