deletions | additions       diff --git a/It_is_obvious_that_both__.tex b/It_is_obvious_that_both__.tex  index b7ebaf2..afa4d9a 100644  --- a/It_is_obvious_that_both__.tex  +++ b/It_is_obvious_that_both__.tex 
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It is obvious that both AC and DC conductivity are highly non-linear. non-linear and dispersive.  When applied voltage with certain frequency, other frequencies might appear, contributing to background noise. The nonlinear conductivity also implies the current will oscillate about $113 MHz$ and its higher harmonics\cite{Thorne_1986}. When applied a random signal, be it AC, DC or AD/DC mixed signal, with adequate noise, the current will respond according to the Fig.6. The discrete Fourier transform should give the amplitude and the resonant frequency and its higher harmonics. The DFT plot is shown in Fig.7 with the input as a mixed signal with frequency $160 MHz$. There are two major peaks one at about $175 MHz$ and the other at $290 MHz$ with amplitude ratio $\approx 0.25$. However, the plot disagrees with the experimental results, where the harmonics are the integer times of the fundamental with amplitude ratio of $0.63$. Moreover, the result stated that at least three harmonics could be observed.