A recent homework problem had us derive the parallel plate
capacitor equation for electrostatics. This gives the
capacitance of a parallel plate structure in terms of the plate area,
distance between the plates and relative permittivity. The equation
for this situation is:
$
C = \epsilon_{R}\epsilon_{0}\frac{A}{d}
$
After solving this problem for the analytical solution, I was curious
to see how closely the result matched a 3D field solver. Using the
Capacitance Extraction mode in Cadence 3D Workbench, I designed a
parametric model of the parallel plate capacitor with variable edge
length, distance and
dielectric constant
(See image above for the
model).
Dk
was varied but the complex component (dissipation factor)
was set to zero to ignore any dielectric losses. The edges were swept
at lengths of 0.1 inch, 1 inch and 10 inch. The distance was swept
with values of 1mil, 10mil and 100mil. Finally, the
dielectric
constant
was swept with values of 1, 10 and 100. This resulted in 27
unique cases, and the analytical result was compared to the extracted
result in each case.
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Comments
Has anyone else ever thought about why so many engineers are also
active amateur radio operators? My theory is that there's just so much
passion for the science and practical use of these complex electronic
systems! We enjoy the problems, challenges and solutions so much that
we want to find other ways outside of work to find those same
experiences. In this case, I've got a story that starts with some
amateur radio equipment but comes full-circle to address an extremely
common design issue. Specifically, we'll look at the Arrow OSJ antenna
performance as well as the characteristics of a printed circuit board
antenna.
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