Updated July 6,
here to go to our page on circulators
here to go to our page on isolators
here to go to our page on ferrite switches
here to go to our page on ferroelectric phase shifters
here to go to our page on ferrite beads
This page attempts to tie together
our content on ferrite devices. Please help
us out with more material!
New for July 2013: This ferrite information came from Vishnu. Thanks!
Ferrite is a high resistance magnetic material and it consists of mainly ferrite oxide along with one or more other metals. Ferrite material is extremely useful at microwave frequencies. Electromagnetic waves pass through ferrites with negligible attenuation. Electromagnetic wave propagation undergoes phase shift due to ferrites, which can be influenced by the applied DC magnetic fields. The ferrites are popularly used in microwave isolators, circulators, and switches. They are used at RF frequencies in inductors as core material. Thy are also used in TV (cathode ray tube) deflection yokes. The specific resistivity of ferrites for use at microwave frequency is on the order of 10^12 ohm-cm. Typical relative permittivities of ferrites lie in the range of 5-20.
Magnetically soft versus magnetically
What do we mean by "magnetically
'soft'"? Alloys useful for magnetic shielding are said to be
magnetically "soft" because they can absorb magnetic energy
without retaining it. Magnetically "hard" materials, on
the other hand, make good magnets because they can retain a strong
magnetic field even after the source of the magnetic energy has
been removed. When a magnetic field is removed from a magnetic shield
alloy, there is no remaining (residual) magnetic field. The measure
of this property is called coercive force. For a magnetic shield,
the lower the coercive force, the better.
Oersted: A unit (symbol Oe) of
magnetic field strength. It is equal to a force of one dyne acting
upon a unit magnetic pole in a vacuum.