Recent research results by using CST
microwave studio at Antenna Lab., POSTECH
•Electromagnetic Bandgap (EBG) and Frequency Selective
Surface (FSS) type superstrate for directivity enhancement
-12x3 EBG superstrate for dual band directivity enhancement
-Compact EBG superstrate for wideband directivity enhancement
-11x11 strip-mesh FSS superstrate for dual band dual polarization
• Crosstalk of UTP(Unshielded Twisted Pairs) line
• Compact and dual band antenna for mobile application
-Compact aperture coupled antenna by using shorting wall
-Printed Monopole Antenna for 2.4/5.2/5.8GHz WLAN Operation
- Double negative index material (Metamaterial)
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CST MICROWAVE STUDIO® • www.cst.com • Mar-05
Electromagnetic Bandgap (EBG) Superstrates for
Dual-band Directivity Enhancement
We can estimate the center frequency of the directivity enhancement from the
simulation results of the unit cell, without simulating the entire structure.
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CST MICROWAVE STUDIO® • www.cst.com • Mar-05
Electromagnetic Bandgap (EBG) Superstrates for
Dual-band Directivity Enhancement
Directivity results of the EBG composite
20dB directivity enhancement at the desired dual band can be achieved by using a
dielectric rod superstrate with two defects.
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CST MICROWAVE STUDIO® • www.cst.com • Mar-05
A compact EBG superstrate for wideband directivity
Directivity results of the EBG composite
Compact 6x3 cross rod EBG composite
Field distribution of EBG superstrate
depending on their size
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CST MICROWAVE STUDIO® • www.cst.com • Mar-05
Dual band dual polarized 11x11 strip-mesh FSS composite
y
Dual-band dualpolarization patch
antenna
6.2mm
Z
X
PML
x
Y
Unit cell of the FSS
5.6mm
gap
Substrate of
the patch
Mirrored
by image
theory
Periodic
Boundary
Condition
(PBC)
PBC
Dual-band and dual-polarization
11x11strip-mesh FSS composite
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Plane wave
incidence
CST MICROWAVE STUDIO® • www.cst.com • Mar-05
Dual band dual polarized 11x11 strip-mesh FSS composite
S21 results of strip-mesh unit cell
Directivity results of strip-mesh FSS
composite
• From the results of the unit cell, we can design the FSS composite
• Dual band dual polarized directivity enhancement can be obtained from
the strip mesh FSS composite
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CST MICROWAVE STUDIO® • www.cst.com • Mar-05
Dual band dual polarized 11x11 strip-mesh FSS composite
The radiation pattern of the FSS
composite at 11.9 GHz
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The radiation pattern of the FSS
composite at 12.75 GHz
CST MICROWAVE STUDIO® • www.cst.com • Mar-05
Crosstalk of UTP(unshielded Twisted Pairs) line
UTP line
A Unit cell of UTP
An unit of a pair of UTP line
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CST MICROWAVE STUDIO® • www.cst.com • Mar-05
Crosstalk of UTP(unshielded Twisted Pairs) line
Obtain [S] of
unit length
Using MWS
Transforming
[S] to [T]
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[T] of
unit length
[T] of
overall length
Cascading
[S] of
overall length
Transforming
[T] to [S]
CST MICROWAVE STUDIO® • www.cst.com • Mar-05
Compact aperture coupled antenna by using
shorting wall
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CST MICROWAVE STUDIO® • www.cst.com • Mar-05
Compact aperture coupled antenna by using
shorting wall
< E-field >
< Surface current >
Typical patch antenna
< E-field >
< Surface current >
< Partial shorting wall >
Proposed compact antenna
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CST MICROWAVE STUDIO® • www.cst.com • Mar-05
Printed Monopole for 2.4/5.2/5.8GHz
WLAN operation
<Top view>
Ω
<Bottom view>
Geometry of printed monopole antenna
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CST MICROWAVE STUDIO® • www.cst.com • Mar-05
Printed Monopole for 2.4/5.2/5.8GHz
WLAN operation
< Surface current at 2.4GHz >
< Surface current at 5.5 GHz >
-5
-5
-10
-10
-15
-15
-20
-20
-25
WT3=12mm
WT3=13mm
WT3=14mm
WT3=15mm
WT3=16mm
-30
-35
-40
0
1
2
3
4
Frequency(GHz)
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Return Loss(dB)
0
Return Loss(dB)
0
5
6
7
-25
-30
simulated
measured
-35
-40
0
1
2
3
4
5
6
Frequency(GHz)
CST MICROWAVE STUDIO® • www.cst.com • Mar-05
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• Double negative index material (Metamaterial)
- Property of double negative index material
RHM(Right Handed Material)
Positive Permeability
and Permittivity
Positive Refractive
Index(PRI)
LHM(Left Handed Material)
Negative Permeability
and Permittivity
Negative Refractive
Index(NRI)
- RHM : support propagating forward wave ⇒ positive refractive angle
- LHM : support propagating backward wave ⇒ negative refractive angle
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CST MICROWAVE STUDIO® • www.cst.com • Mar-05
• Backward-wave Antenna Based on NRI L-C Networks
Antenna Configuration
backward
broadside
Backward-wave Antenna
Structure
y
source
θ
x
forward
longitudinal
polarization
z
CRLH dispersion diagram
ω = − β c0
ω
ω = + β c0
II
III
LH
RH
RAD. RAD.
I
LH
GUIDANCE
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- Antenna operated in both LH and RH RAD. regions
- Possible to scan beam for operating frequencies
IV
RH
GUIDANCE
ω0
β
CST MICROWAVE STUDIO® • www.cst.com • Mar-05