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CST MICROWAVE STUDIO® • www.cst.com • Mar-051

•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)

Recent research results by using CST microwave studio at Antenna Lab., POSTECH


Electromagnetic Electromagnetic BandgapBandgap (EBG) (EBG) SuperstratesSuperstrates for for DualDual--band Directivity Enhancementband 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.


Electromagnetic Electromagnetic BandgapBandgap (EBG) (EBG) SuperstratesSuperstrates for for DualDual--band Directivity Enhancementband Directivity Enhancement

20dB directivity enhancement at the desired dual band can be achieved by using a dielectric rod superstrate with two defects.

Directivity results of the EBG composite


A compact EBG superstrate for wideband directivity

Compact 6x3 cross rod EBG composite

Directivity results of the EBG composite

Field distribution of EBG superstratedepending on their size


Dual-band and dual-polarization 11x11strip-mesh FSS composite

Z

X

Y

Dual-band dual-polarization patch antenna

x

y6.2mm

5.6mm

Periodic Boundary Condition (PBC)

Substrate of the patch

PML

PBC

Mirrored by image theory

Unit cell of the FSS

gap

Plane wave incidence

Dual band dual polarized 11x11 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

S21 results of strip-mesh unit cell Directivity results of strip-mesh FSS composite



The radiation pattern of the FSS composite at 11.9 GHz

The radiation pattern of the FSS composite at 12.75 GHz


An unit of a pair of UTP line

A Unit cell of UTP

UTP line

Crosstalk of UTP(unshielded Twisted Pairs) line


Obtain [S] ofunit lengthUsing MWS

[T] of unit length

[T] ofoverall length

[S] ofoverall length

Transforming [S] to [T]

Transforming [T] to [S]

Cascading

Crosstalk of UTP(unshielded Twisted Pairs) line


Compact aperture coupled antenna by using shorting wall


< E-field >

< E-field >

< Surface current >

< Surface current > < Partial shorting wall >

Typical patch antenna

Proposed compact antenna

Compact aperture coupled antenna by using shorting wall


Ω

<Top view>

<Bottom view>

Printed Monopole for 2.4/5.2/5.8GHz WLAN operation

Geometry of printed monopole antenna


< Surface current at 2.4GHz > < Surface current at 5.5 GHz >

0 1 2 3 4 5 6 7Frequency(GHz)

-40

-35

-30

-25

-20

-15

-10

-5

0

Ret

urn

Loss

(dB

)

WT3=12mmWT3=13mmWT3=14mmWT3=15mmWT3=16mm

0 1 2 3 4 5 6 7Frequency(GHz)

-40

-35

-30

-25

-20

-15

-10

-5

0

Ret

urn

Loss

(dB

)simulatedmeasured

Printed Monopole for 2.4/5.2/5.8GHz WLAN operation


RHM(Right Handed Material)

LHM(Left Handed Material)

Positive Permeability and Permittivity

Negative Permeability and Permittivity

Negative Refractive Index(NRI)

• Double negative index material (Metamaterial)

- Property of double negative index material

Positive Refractive Index(PRI)

- RHM : support propagating forward wave ⇒ positive refractive angle

- LHM : support propagating backward wave ⇒ negative refractive angle


x

z

ysource

backward

forward

broadside

θ

longitudinalpolarization

Antenna Configuration

• Backward-wave Antenna Based on NRI L-C Networks

Backward-wave Antenna Structure

β

ω0cβω −=

ILH

GUIDANCE

IVRH

GUIDANCE

IILH

RAD.

IIIRH

RAD.

0cβω +=

0ω

CRLH dispersion diagram

- Antenna operated in both LH and RH RAD. regions

- Possible to scan beam for operating frequencies

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