\tikzset{block/.default={0.8cm}{0.6cm}}
\tikzset{addb/.append style={scale=0.7}}
\tikzset{node distance=0.6}
\def\cdist{0.7}

\definecolor{T}{rgb}{0.230, 0.299, 0.754}%
\definecolor{S}{rgb}{0.706, 0.016, 0.150}%
\setlength\fwidth{7cm}
\setlength\fheight{4cm}

\begin{tikzpicture}
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    name=axis,
    width=\fwidth,
    height=\fheight,
    at={(0, 0)},
    xmode=log,
    xmin=0.1,
    xmax=1000,
    xminorticks=true,
    xlabel={Frequency [Hz]},
    ymode=log,
    ymin=0.001,
    ymax=10,
    yminorticks=true,
    ylabel={Magnitude},
    axis background/.style={fill=white},
    xminorgrids,
    yminorgrids
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  \begin{customlegend}[legend cell align=left, %<= to align cells
    legend entries={ % <= in the following there are the entries
      ${w_L}^{-1}$,
      ${w_H}^{-1}$,
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    \addlegendimage{dashed, T}
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