\documentclass{scrartcl}
\usepackage{color}
\usepackage{multicol}
\usepackage[final]{graphicx}
\usepackage{pst-plot,pstricks}
	\input{pstplot-logarithmic-axes}
\begin{document}
	\psset{xunit=3cm,yunit=0.1cm}
	\begin{pspicture}(-3,-50)(3,20)
		\psgrid[xunit=0.5,yunit=10,subgriddiv=0,griddots=5,gridlabels=0](-4,-4)(4,1)
		\psaxes[log=x,Dy=10]{->}(-2,0)(-2,-40)(2.2,11)
		\psplot[plotstyle=curve,linecolor=green]{-2}{0.5}{20 x mul}
		\psplot[plotstyle=curve,linecolor=red]{-2}{-0.4}{0}
		\psplot[plotstyle=curve,linecolor=red]{-0.4}{2}{-20 x mul 8 sub}
		\psplot[plotstyle=curve,linecolor=blue]{-2}{0.475}{0}
		\psplot[plotstyle=curve,linecolor=blue]{0.475}{2}{x 0.475 sub -20 mul}
		\psplot[plotstyle=curve]{-2}{-0.4}{20 x mul}
		\psplot[plotstyle=curve]{-0.4}{0.475}{-8}
		\psplot[plotstyle=curve]{0.475}{2}{x 0.475 sub -20 mul 8 sub}
		\rput(2,3){$\Omega=\frac{\omega}{\omega_0}$}
		\rput(-2,14){$\frac{\left|\underline{H}\left(j\omega\right)\right|}{dB}$}
		\rput[l](0.5,10){\green{$j\Omega$}}
		\rput[l](1.7,-40){\red{$\frac{1}{1+aj\Omega}$}}
		\rput[l](2,-30){\blue{$\frac{1}{1+bj\Omega}$}}
	\end{pspicture}
\end{document}