Abstract: A composite having a stack of a repeating pattern of layers of: a layer of a nonconductive magnetic material, a first layer of a dielectric material; a layer of a semiconducting material; and a second layer of the dielectric material. The composite has a magnetic resonance frequency and a magnetic anti-resonance frequency and a plasma frequency at higher frequencies than the magnetic resonance frequency.

Abstract: 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.