The effect of coupling current and equivalent electrical length in terahertz modulator

In this paper, a point has been proposed that coupling current exist in terahertz devices, especially some typical structures, such as split ring resonators. Gaps are no longer treated as capacitances are not exact. By varying the width of gap, a kind of relationship between coupling ratio and gap´s width has been made. And it has been testified to be approximately suitable in some other structures. Equivalent electrical length has been brought in to explain how the currents with the same orient cause resonance, of which fabricate a frequency band, via S parameter. Our work may open another method to explain electromagnetic wave resonating in metal structure.