4. Calculate the series resistance due to the conductor losses at 400 MHz.
SOLUTION:
Equations (4.9)
,
(4.10)
, and
(4.11)
are used to calculate the surface resistivity
for the transmission line. Initially, the resistance for both the bottom and top portions of the
transmission line is calculated assuming the microstrip equations. Then
equation (4.10)
is
used to determine the stripline resistance. To determine the resistivity, the square root of the
frequency is divided out.
To determine how the resistance will vary with frequency, it is necessary to determine the
frequency at which the skin depth becomes smaller than the conductor thickness. To do so,
we examine
equation (4.2)
, substitute the conductor thickness in place of the skin depth, and
solve for the frequency.
Below 17 MHz, the resistance of this conductor is approximately equal to the dc resistance
[
equation (4.1)
]:
Above 17 MHz, the resistance will vary with the square root of frequency:
Therefore, the resistance at 400 MHz is
Summary :
Below 17 MHz, the resistance of this conductor is approximately equal to the dc resistance [ equation (4.1) ]: Above 17 MHz, the resistance will vary with the square root of frequency: Therefore, the resistance at 400 MHz is
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resistance,frequency,mhz,conductor,determine,equation,equations,line,410,skin,depth,calculate,resistiity