Provided is a tunable magnetic field amplifying device capable of easily
adjusting resonance frequencies and tuning usable bands by using discrete
elements to vary electric properties of elements that are used for
amplifying a magnetic field of a specific microwave band. The tunable
magnetic field amplifying device includes a Swiss roll formed by winding
a metal sheet coated with a dielectric in a spiral cylinder shape once or
several times; and a tunable capacitor connected between an inner sheet
of and an outer sheet of the metal sheet for tuning a resonance
frequency.