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5
Microwave Ferrite Devices
5.1 Introduction
Matter is composed of atoms and molecules. Atoms in themselves are com-
posed of tiny particles, including electrons. As illustrated in Figure 5.1, these
electrons not only revolve around a nucleus but also spin about their own
axis. The orbiting and spinning electrons are considered to be tiny cur-
rent loops. The two loops with I
orb
and I
spin
currents encompassing inni-
tesimal surface areas S
orb
and S
spin
result in two magnetic dipole moments
m
orb
(= I
orb
S
orb
) and m
spin
(= I
spin
S
spin
). As is evident from Table 5.1, in all major
magnetic materials, the contribution of spinning elect ...