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ELEctromagnetic DIAgnostics Lab.
-Via Sommarive 14, I-38050 Trento Italia
E-mail: massmo.donelli disi.unitn.it
Stri lineStri lineStri line andandand Microstri lineMicrostri lineMicrostri line
MasterMaster DegreeDegree Electronic and TelecommunicationElectronic and TelecommunicationA.A.A.A. 20122012--20132013
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Stripline propagation structures
-
itself well to microwave integrated circuitry
.
Since stripline has 2 conductors and ahomogeneous dielectric, it can support a
wave.
The stripline can also support higher order
TM and TE modes but these are usuall
2avoided in practice.
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3Stripline transmission line. (a) Geometry. (b) Electric and magnetic fieldlines.
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quadrature hybrids
Photograph of a stripline circuit assembly, showing four
4quadrature hybrids, open-circuit tuning stubs, and coaxialtransitions.
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Formulas for Propagation Constant, Characteristic
Impedance and Attenuation
0 01/ /p r rv c = =
The phase velocity of a TEM mode:
0 0 0r r
p
kv
= = =
The propagation constant of the stripline is
0
p
ZC C v C
= = =
The characteristic impedance of a transmission line is
Laplaces equation can be solved by conformal mapping to find
5
the capacitance per unit length of the stripline. complicatedspecial function
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For practical computations simple empirical formulas have
.
30 bZ
=
.er +
e
0 for / 0.35e
W bW W >=
Given the characteristic impedance, the strip width is
2
(0.35 / ) for / 0.35W b W bb b =
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The loss are due to the dielectric loss and the conductor loss
-3
02.7 10 for 120s rR Z
A Z
>
r 0
30 ( )
0.16 for 120
c
s
b t
R B Z
=
