5 impedancematching 120211105230 phpapp02
TRANSCRIPT
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Impedance
Matching
AntennaAntenna
EngineeringEngineering
CHO, Yong HeuiCHO, Yong Heui
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1. Impedance Matching
Basic Concept
Voltage or Current → atio is a !e" #actor
$oad
%a&e
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Ma'imum po(er trans#er
1. Impedance matching
Condition for maximum power transfer -
Matching network
- Usually source and load are fixed.
Reflection
- Conjugate matching doesn’t mean no
reflection.
No reflection-
*0 )( L Z Z =
L Z Z =
0
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출처 ) *AI+
1. Impedance Matching
Varia-le hase +hi#ter
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Matching (ith lumped elements
Compact sie !ifficulties in finding the proper "alue of # or C #-network$ %-network$ and -network
Π
1. Impedance matching
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rocedure) $/net(or!
!efine
!raw
&ind to intersect the
circle
!raw
&ind to cancel out
0/ Z Z z L L =
L L z y /1=
jx z L +=1
11 =++= jX jx z in
jB
L z
jX jx
1. Impedance matching
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E'ample
!esign the # section matching network to
match the transmission line$
where
[ ] [ ] MHz f Z j Z L 500,100,100200 0 =Ω=Ω−=
+mith chart
1. Impedance matching
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+ingle/stu- matching
'pen stu( and short stu(
+hort stu- 0$
Open stu- 0C
1. Impedance matching
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+ingle/stu- matching
)imple matching network
+mith chart
1. Impedance matching
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rocedure) shunt stu-
!efine
!raw
Mo"e to the direction of
generator
&ind the intersection of the
circle
*djust the length of a shunt
stu(
0/ Z Z z L L =
L L z y /1=
jb y L +=1
jb yS −=11 =−+=
+=
jb jb
y y y S Lin
1. Impedance matching
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2ou-le/stu- matching
&ixed length (etween the load and stu(
+mith chart
1. Impedance matching
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3uarter/(a&e trans#ormer
+asy calculation of the matching network Narrow (andwidth characteristics
4/,01 λ == l Z Z Z L
1. Impedance matching
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ransitions
Complicated design procedure ,road (andwidth characteristics %he theory of small reflections
,inomial multisection line Che(yshe" multisection line %apered line
1. Impedance matching