Bandwidth enhancement using nonlinear inductors

It is shown that a radiating element can potentially have a bandwidth wider that the maximum bandwidth defined by Chu´s fundamental limit if the linear time invariant (LTI) assumption does not hold. A nonlinear inductor is employed to study the behavior of a non-LTI resonator as a narrow-band antenna equivalent. A ferrite core is used to construct a nonlinear inductor with current-dependent inductance. We use a cubic function to model the i-φ profile, which results in Duffing equation. Numerical results show that nonlinearity can increase the resonator´s bandwidth compared to the linear case.