
37-6 Electromagnetic Variables
Capacitance and dissipation factor of the dielectric-loaded parallel-plate capacitor are used in the
me
dium
fr
equency
ra
nge
to de
termine
th
e
co
mplex
pe
rmittivity
of ma
terials
. A su
bstitution
me
thod
is
ge
nerally
e
mployed
i
n
a S
chering
b
ridge
c
ircuit
f
or
t
his
m
easurement
.
In th
e
Sc
hering
br
idge
sh
own
in Fi
gure
37.5, as
sume
th
at
th
e
ca
pacitor
C
v
is disconnected for the time
be
ing
an
d
th
e
ca
pacitor
C
s
contains the dielectric sample. In the case of a lossy dielectric sample, it can
be mo
deled
as an id
eal
ca
pacitor
C
x
in series with a resistor R
x
. e bridge is balanced by adjusting C
d
an
d
R
c
. An analysis of this circu ...