\documentclass{scrartcl}
\usepackage{color}
\usepackage{multicol}
\usepackage[final]{graphicx}
\usepackage{pst-plot,pstricks}
\begin{document}
	\psset{xunit=1cm,yunit=1cm}
	\begin{pspicture}(-2.5,-2.5)(2.5,2.5)
		\psaxes[Dx=3,Dy=3]{->}(0,0)(-2.5,-2.5)(2.5,2.5)
		\psdot[dotstyle=x,dotsize=0.2](-1.5,-1.5)
		\psdot[dotstyle=x,dotsize=0.2](-1.5,1.5)
		\psdot[dotstyle=o,dotsize=0.2](1.5,-1.5)
		\psdot[dotstyle=o,dotsize=0.2](1.5,1.5)
		\rput[l](2.2,0.3){$\sigma$}
		\rput[r](-0.1,2){$j\omega$}
	\end{pspicture}
	\begin{pspicture}(-0.5,-0.5)(10.5,4.5)
		\psaxes[Dx=20,Dy=20]{->}(0,0)(-0.5,-0.5)(10.5,4.5)
		\psline(0,4)(10,4)
		\rput[l](10.5,0){$\omega$}
		\rput[r](-0.1,4.5){$\left|\underline{H}\right|$}
	\end{pspicture}
\end{document}
