Configurable, reconfigurable, and run-time reconfigurable computing
Design and Analysis of Reconfigurable Frequency Selective...
Transcript of Design and Analysis of Reconfigurable Frequency Selective...
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The University of Mississippi Department of Electrical Engineering C
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Frequency Selective Surfaces using FDTD
Center of Applied Electromagnetic System Research (CAESR) , Department of
Electrical Engineering, University of Mississippi, USA
Khaled ElMahgoub, Fan Yang and Atef Z. Elsherbeni
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Outlines Introduction Analysis of Skewed Grid Periodic Structures
Motivation
The New Reconfigurable FSS
Numerical Results Conclusion
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Introduction
What is a reconfigurable FSS (RFSS)?
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It is an FSS which has a frequency response that can be shifted or altered altogether while in operation.
What is an FSS?
Periodic structure that exhibit total reflection or transmission for certain frequency range.
In what application such structures are used ?
Electromagnetic (EM) filters, radomes, absorbers, artificial electromagnetic band gap materials, and many other applications.
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Different Techniques for RFSS
How can the response of the FSS be alerted or shifted during operation?
This can be accomplished by mainly three techniques as follows: 1. By changing the electromagnetic properties of the FSS screen or
substrate. 2. By altering the geometry of the structure. 3. By introducing elements into the FSS screen that vary the current flow
between metallic patches.
ACES Conference 2011 © Khaled ElMahgoub 31 March 2011
(1) (2) (3) (1) G. Y. Li, Y. C. Chan, T. S. Mok, and J. C. Vardaxoglou, “Analysis of frequency selective surfaces on biased ferrite substrate,” in IEEE AP-S Dig., vol. 3, Jun.
1995, pp. 1636–1639. (2) J. M. Zendejas,, J. P. Gianvittorio,, Y. Rahmat-Samii, and J. W. Judy, “Magnetic MEMS Reconfigurable Frequency-Selective Surfaces,” J. of
Microelctromechanical Systems, Vol. 15, No. 3, Jun 2006, pp. 613-623. (3) S. M. Amjadi and M. Soleimani, “Design of Band-Pass Waveguide Filter Using Frequency Selective Surfaces Loaded with Surface Mount Capacitors Based On
Split-Field Update FDTD Method,” Progress In Electromagnetics Research B, Vol. 3, 271–281, 2008.
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Outlines Introduction Analysis of Skewed Grid Periodic Structures
Motivation
The New Reconfigurable FSS
Numerical Results Conclusion
ACES Conference 2011 © Khaled ElMahgoub 31 March 2011
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The University of Mississippi Department of Electrical Engineering C
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Various implementations of PBCs have been developed such that only one unit cell needs to be analyzed instead of the entire structure.
Floquet Theory:
With plane wave
Excitation
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Unit A
Extended in x- direction
Exte
nded
in y
- dire
ctio
n
( , 0, ) ( , , ) .y yjk PyE x y z E x y P z e= = = ×
ACES Conference 2011 © Khaled ElMahgoub 31 March 2011
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7 Analytical reflection coefficient of
infinite dielectric slab
PBC for FDTD
Field Transformation Method
Split Field Method
Multi-spatial Grid Method
Direct Field Method
Sine-Cosine Method
Constant Horizontal wavenumber Method
Field transformation methods are used to eliminate the need for time-advanced data.
Direct field methods, work directly with Maxwell’s equations and there is no need for any field transformation
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Electric field in frequency domain can be written as: ( 0, , ) ( , , ) .x xjk PxE x y z E x P y z e= = = ×
Fix kx in FDTD simulation instead of the angle θ. kx = k0 sinθ
( 0, , , ) ( , , , ) .x xjk PxE x y z t E x P y z t e= = = ×8
( 0, , , ) ( , , , sin )xxPE x y z t E x P y z tC
θ= = = +
Frequency domain to time domain
Frequency domain to time domain
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Using the same constant horizontal wavenumber method one can easily simulate periodic structure with skewed grid
(x = Px, y = Py)
(x = 0, y = 0)
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(x = Px, y = Py)
(x = 0, y = 0)
Constant Horizontal Wavenumber for Skewed Grid
So to update Ex at the boundary y = 0
For i + (Sx /∆x ) ≤ nx
1/ 2 1/ 2( ,0, ) ( , , ) .y yx x jk Pjk Sn nz z yxSxH i k H i n k e e+ +
∆= + × ×
For i + (Sx /∆x ) > nx
( )1/ 2 1/ 2( , 0, ) ( , , ) .y yx x x jk Pjk S Pn nz z x yxS
xH i k H i n n k e e−+ +
∆= + − × ×
To update Ex at the boundary y = Py
For i -(Sx /∆x ) ≤ 0 ( )1 1( , 1, ) ( ,1, ) .y yx x x jk Pjk S Pn nx y x x x
SxE i n k E i n k e e
−− −+ +
∆+ = + − × ×For i -(Sx /∆x ) > 0 1 1( , 1, ) ( ,1, ) .y yx x jk Pjk Sn nx y x x
SxE i n k E i k e e
−−+ +
∆+ = − × ×
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Outlines Introduction Analysis of Skewed Grid Periodic Structures
Motivation
The New Reconfigurable FSS
Numerical Results Conclusion
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Motivation
Reflection coefficient for dipole FSS normal incident TEz plane wave with skew angle of 90o and 63.43o.
Skew angle of 90o and 63.43o
0 2 4 6 8 10 12 14 160
0.2
0.4
0.6
0.8
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Frequency [GHz]
Ref
lect
ion
coef
ficie
nts
mag
nitu
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Skewed Method α = 90°Skewed Method α = 63.43° Axial Method α = 90°Axial Method α = 63.43°
Normal Incidence (kx = 0 m-1)
Skew angle of 90o
Skew angle
of 63.43o
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Outlines Introduction Analysis of Skewed Grid Periodic Structures
Motivation
The New Reconfigurable FSS
Numerical Results Conclusion
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The New Reconfigurable FSS
This RFSS has two control parameters which increase the degree of freedom of the reconfigurability.
The first control parameter is the diode which has two states, ON or OFF
The second control parameter is the movements of different rows of the FSS
( )0
/ 1 ,d dqV kTI I e = −
Diode Current Equation.
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Outlines Introduction Analysis of Skewed Grid Periodic Structures
Motivation
The New Reconfigurable FSS
Numerical Results Conclusion
ACES Conference 2011 © Khaled ElMahgoub 31 March 2011
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Numerical Results
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Normal incident (kx = ky = 0 m-1) with different skew angles
2 4 6 8 10 12 14 150
0.2
0.4
0.6
0.8
1
Frequency [GHz]
Ref
lect
ion
coef
ficie
nts
mag
nitu
des
α = 90°α = 75.06°α = 68.19°
Diode OFF 2 4 6 8 10 12 14 15
0
0.2
0.4
0.6
0.8
1
Frequency [GHz]
Ref
lect
ion
coef
ficie
nts
mag
nitu
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α = 90°α = 75.06°α = 68.19°
Diode ON
2 4 6 8 10 12 14 150
0.2
0.4
0.6
0.8
1
Frequency [GHz]R
efle
ctio
n co
effic
ient
s m
agni
tude
s
α =90°α =68.19°
2 4 6 8 10 12 14 150
0.2
0.4
0.6
0.8
1
Frequency [GHz]
Ref
lect
ion
coef
ficie
nts
mag
nitu
des
α =90°α =68.19°
Oblique incident (kx = 20 m-1, ky = 0 m-1) with different skew angles
Diode OFF Diode ON
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Numerical Data
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Case No. Diode State
Skew Angle Incident kx (m-1) Position of Reflection Coefficient Peak
1 OFF 90o Normal kx = 0 13.36 GHz 2 ON 90o Normal kx = 0 7.53 GHz 3 OFF 75. 06o Normal kx = 0 13.92 GHz 4 ON 75. 06o Normal kx = 0 7.69 GHz 5 OFF 68.19o Normal kx = 0 14.37 GHz 6 ON 68.19o Normal kx = 0 7.83 GHz 7 OFF 90o Oblique kx = 20 13.27 GHz 8 ON 90o Oblique kx = 20 7.54 GHz 9 OFF 68.19o Oblique kx = 20 14.32 GHz
10 ON 68.19o Oblique kx = 20 7.84 GHz
Different simulation cases
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Outlines Introduction Analysis of Skewed Grid Periodic Structures
Motivation
The New Reconfigurable FSS
Numerical Results Conclusion
ACES Conference 2011 © Khaled ElMahgoub 31 March 2011
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Conclusion
A new RFSS design was introduced.
The reconfigurability of the design is based on two techniques:
Controlling a diode state
Controlling a mechanical movement to change the skew angle of the FSS grid.
The design was simulated using FDTD/PBC algorithm (full-wave EM simulator), while taking into account the actual model of the diode and different skew angles.
The simulations were efficient in both memory usage and computational time.
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Design and Analysis of Reconfigurable Frequency Selective Surfaces using FDTD OutlinesIntroductionSlide Number 4OutlinesPeriodic Boundary Conditions (PBC)Previous PBC for FDTDConstant Horizontal Wave Number ApproachSkewed Grid ApproachConstant Horizontal Wavenumber for Skewed GridOutlinesMotivationOutlinesThe New Reconfigurable FSSOutlinesNumerical ResultsNumerical DataOutlinesConclusionThank you for Listening��Any Questions??