Narrator:???

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Metamaterials CH5

• Narrator???

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Index

• Part1Leaky-wave antenna are of much concern due
  to its
• highly
  directivity, fast-wave structure
• (dltltl) .
• Part2Dispersion of NRI-TL media, discussed with
  Sievenpipers mushroom structure.

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Part1Implementation of LWA(P.160)
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The dimensions are given for a printed structure
at 15 GHz on a 20 mil substrate of e , 3.
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Experiment results (P.161)
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5
Another similar structure23
Fig1
Fig2
Fig3
Satisfying the following relationship cos(bd)co
s(kd)Xsin(kd)/2Z bd phase delay of unit
cell. kd phase delay of TL segment. X1/wC
reactance due to series capa. Z characteristic
impe. qarcsin(b/k)
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Return loss24
Bidirectional
Unidirectional
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Conclusion

• Slot antenna is actually a bidirectional antenna,
  unwanted direction can be suppressed by ground
  plane.
• However, ground plane may produce parasitic TEM
  waves which would limit the VSWR(Voltage standing
  wave ratio) bandwidth. Recently, an approximately
  unidirectional antenna has been inspired by old
  bidirectional ones, harnessing phase cancelling
  technique.

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Part2 Dispersion NRI-TL media(P.165)
?This inherently quasitransverse electromagnetic
mode (quasi-TEM) analysis is used to quickly
and accurately calculate the dispersion of the
lowest pass-band and several of the upper
pass-bands.
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Implementation (P.165)
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Calculations31
31
Tmtl Transfer matrix of uniform MTL.
wgtgtg
Where C,L are per-unit-length matrix.
Periodic structure(Bloch)
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Result(P.166)
For simplicity, via and patch edges are loaded
with lumped inductor(L11.6nH) and
capacitor(C2pF)
By MTL, Im part of propagation const. gd ranges
from (0.125p)j to (0.066p)j.For consistency with
experiment result of super lens, taking the sign
that will induce exponential growth. Center of
stop band1.38GHz ,with leakage due to
mismatch(reflection) loss.
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Conclusion

• The cause of superlens can be analyzed by
  FEM(finite-element method). That is,devided the
  antenna into finite numbers of unit cells of
  mushroom structure,and calculating an unit
  cells voltage and current, the other oness
  voltage and current can be inferred from Blochs
  recursive relationship.

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Preview

• Anisotropic grid monopole antenna.
• Resonance cone refraction effects in a
  low-profile antenna.
• Thanks for comprehension.