A magnetic ferrite microwave resonator frequency tunable filter and method
for tuning a filter having both a resonator portion and a tuning portion.
The resonator portion has an input for receiving an electromagnetic signal
and an output for emitting an electromagnetic signal. A tuning portion
includes a magnetic ferrite element disposed in first and second magnetic
fields generated by a fixed magnet and an electromagnet. The magnetic
ferrite element has a magnetic permeability determined by the first and
second magnetic fields. The first magnetic field places a ferromagnetic
resonance frequency of the ferrite element near a frequency of the
electromagnetic signal transmitted by the resonator portion. The second
magnetic field is variable in response to a varying current supplied to
the electromagnet to change the permeability of the ferrite element, to
thereby alter the center frequency of the resonator, thereby facilitating
tuning of the electromagnetic signal.