\begin{tikzpicture}
\begin{axis}[
	name=plot1,
	axis lines*=middle,
	enlargelimits = true, clip=true,
	scale only axis,
	width=\textwidth,
	height=0.2\textwidth,
	ymin=0, ymax=2,
	xmin=-4, xmax=4,
	axis line style={->,>=stealth},
	xlabel={ \tikz[baseline]{\node[fill=blue!20,anchor=base] (t1) {$\Omega$};}},
	ylabel={ $X_c(j\Omega)$},
	every axis x label/.style={
		at={(ticklabel* cs:1)},
		anchor=north,
	},
	every axis y label/.style={
		at={(ticklabel* cs:0.8)},
		anchor=south,
		xshift=0.7cm,
	},	
	ytick=1,
	yticklabels={ $A$},
	xtick={-2, 0, 2},
	xticklabels={ $-\Omega_b$,  0, $\Omega_b$}, 
	every outer y axis line/.append style={white!15!black},
	every y tick label/.append style={font=\color{white!15!black}},
	legend style={draw=white!15!black,fill=white,legend cell align=left}]
	\addplot[solid, line width=1pt] coordinates {(0, 0) (2, 1) (2, 0) (7, 0)};
    \addplot[solid, fill=blue!40, line width=1pt] coordinates {(-7, 0) (-2, 0) (-2, 1) (0, 0)};
\end{axis}

\begin{axis}[
	name=plot2,
    at=(plot1.below south east), anchor=above north east, yshift=-0.75cm,
	axis lines*=middle,
	enlargelimits = true,	clip=true,
	scale only axis,
	width=\textwidth,
	height=0.2\textwidth,
	ymin=0, ymax=2,
	xmin=-4, xmax=4,
	axis line style={->,>=stealth},
	xlabel={ \tikz[baseline]{\node[fill=blue!20,anchor=base] (t1) {$\omega = \Omega T$};}},
	ylabel={ $X(e^{j\omega})$},
	every axis x label/.style={
		at={(ticklabel* cs:1)},
		anchor=north,
	},
	every axis y label/.style={
		at={(ticklabel* cs:0.8)},
		anchor=south,
		xshift=0.7cm,
	},	
	ytick=1,
	yticklabels={ },
	xtick={-4, ..., 4},
	xticklabels={$-2\pi$, $-\frac{3\pi}{2}$, $-\pi$, $-\frac{\pi}{2}$, 0, $\frac{\pi}{2}$, $\pi$, $\frac{3\pi}{2}$, $2\pi$}, 
	every outer y axis line/.append style={white!15!black},
	every y tick label/.append style={font=\color{white!15!black}},
	legend style={draw=white!15!black,fill=white,legend cell align=left}]
	
	\if\SOLUTIONS1
		\node at (axis cs: 0.5, 1) {$A/T$};
		\foreach \df in {-8, -4, 0, 4, 8}
		{
			\edef\temp{\noexpand\addplot[solid, line width=1pt] coordinates {(0+\df, 0) (2+\df, 1) (2+\df, 0) (7+\df, 0)};}
			\temp
			\edef\temp{\noexpand\addplot[solid, fill=blue!40, line width=1pt] coordinates {(-7+\df, 0) (-2+\df, 0) (-2+\df, 1) (0+\df, 0)};}
			\temp
		}
 	\fi
\end{axis}

\begin{axis}[
name=plot3,
at=(plot2.below south east), anchor=above north east, yshift=-0.75cm,
axis lines*=middle,
enlargelimits = true, clip=true,
scale only axis,
width=\textwidth,
height=0.2\textwidth,
ymin=0, ymax=2,
xmin=-4, xmax=4,
axis line style={->,>=stealth},
xlabel={ \tikz[baseline]{\node[fill=blue!20,anchor=base] (t1) {$\omega = \Omega T$};}},
ylabel={ $X_d(e^{j\omega})$},
every axis x label/.style={
	at={(ticklabel* cs:1)},
	anchor=north,
},
every axis y label/.style={
	at={(ticklabel* cs:0.8)},
	anchor=south,
	xshift=0.7cm,
},	
ytick=1,
yticklabels={ },
xtick={-4, ..., 4},
xticklabels={$-2\pi$, $-\frac{3\pi}{2}$, $-\pi$, $-\frac{\pi}{2}$, 0, $\frac{\pi}{2}$, $\pi$, $\frac{3\pi}{2}$, $2\pi$},  
every outer y axis line/.append style={white!15!black},
every y tick label/.append style={font=\color{white!15!black}},
legend style={draw=white!15!black,fill=white,legend cell align=left}]

\if\SOLUTIONS1
\node at (axis cs: 0.5, 1) {$A/T$};
\foreach \df in {-10, -6, -2, 2, 6, 10}
{
	\edef\temp{\noexpand\addplot[solid, line width=1pt] coordinates {(0+\df, 0) (2+\df, 1) (2+\df, 0) (7+\df, 0)};}
	\temp
	\edef\temp{\noexpand\addplot[solid, fill=blue!40, line width=1pt] coordinates {(-7+\df, 0) (-2+\df, 0) (-2+\df, 1) (0+\df, 0)};}
	\temp
}
\fi
\end{axis}

\begin{axis}[
name=plot4,
at=(plot3.below south east), anchor=above north east, yshift=-0.75cm,
axis lines*=middle,
enlargelimits = true, clip=true,
scale only axis,
width=\textwidth,
height=0.2\textwidth,
ymin=0, ymax=2,
xmin=-4, xmax=4,
axis line style={->,>=stealth},
xlabel={ \tikz[baseline]{\node[fill=blue!20,anchor=base] (t1) {$\omega = \frac{\Omega T}{2}$};}},
ylabel={ $X_e(e^{j\omega})$},
every axis x label/.style={
	at={(ticklabel* cs:1)},
	anchor=north,
},
every axis y label/.style={
	at={(ticklabel* cs:0.8)},
	anchor=south,
	xshift=0.7cm,
},	
ytick=1,
yticklabels={ },
xtick={-4, ..., 4},
xticklabels={$-2\pi$, $-\frac{3\pi}{2}$, $-\pi$, $-\frac{\pi}{2}$, 0, $\frac{\pi}{2}$, $\pi$, $\frac{3\pi}{2}$, $2\pi$}, 
every outer y axis line/.append style={white!15!black},
every y tick label/.append style={font=\color{white!15!black}},
legend style={draw=white!15!black,fill=white,legend cell align=left}]

\if\SOLUTIONS1
\node at (axis cs: 0.5, 1) {$A/T$};
\foreach \df in {-8,-6,..., 8}
{
	\edef\temp{\noexpand\addplot[solid, line width=1pt] coordinates {(-1+\df, 0) (0+\df, 1) (0+\df, 0) (\df, 0)};}
	\temp
	\edef\temp{\noexpand\addplot[solid, fill=blue!40, line width=1pt] coordinates {(\df, 0) (\df, 1) (1+\df, 0) (\df, 0)};}
	\temp
}
\fi
\end{axis}

\begin{axis}[
name=plot5,
at=(plot4.below south east), anchor=above north east, yshift=-0.75cm,
axis lines*=middle,
enlargelimits = true, clip=true,
scale only axis,
width=\textwidth,
height=0.2\textwidth,
ymin=0, ymax=2,
xmin=-4, xmax=4,
axis line style={->,>=stealth},
xlabel={ \tikz[baseline]{\node[fill=blue!20,anchor=base] (t1) {$\omega = \frac{\Omega T}{2}$};}},
ylabel={ $X_f(e^{j\omega})$},
every axis x label/.style={
	at={(ticklabel* cs:1)},
	anchor=north,
},
every axis y label/.style={
	at={(ticklabel* cs:0.8)},
	anchor=south,
	xshift=0.7cm,
},	
ytick=1,
yticklabels={},
xtick={-4, ..., 4},
xticklabels={$-2\pi$, $-\frac{3\pi}{2}$, $-\pi$, $-\frac{\pi}{2}$, 0, $\frac{\pi}{2}$, $\pi$, $\frac{3\pi}{2}$, $2\pi$}, 
every outer y axis line/.append style={white!15!black},
every y tick label/.append style={font=\color{white!15!black}},
legend style={draw=white!15!black,fill=white,legend cell align=left}]

\if\SOLUTIONS1
\node at (axis cs: 0.5, 1) {$A/T$};
\foreach \df in {-8,-4,..., 8}
{
	\edef\temp{\noexpand\addplot[solid, line width=1pt] coordinates {(-4+\df, 0) (-0.5+\df, 0) (-0.5+\df, 0.5) (\df, 1) (\df, 0) (-0.5+\df, 0)};}
	\temp
	\edef\temp{\noexpand\addplot[solid, fill=blue!40, line width=1pt] coordinates {(\df, 0) (\df, 1) (0.5+\df, 0.5) (0.5+\df, 0) (\df, 0)};}
	\temp
}
\fi
\end{axis}

\node[below, inner sep=0.25cm] at (plot1.south) {(a)};
\node[below, inner sep=0.25cm] at (plot2.south) {(b)};
\node[below, inner sep=0.25cm] at (plot3.south) {(c)};
\node[below, inner sep=0.25cm] at (plot4.south) {(d)};
\node[below, inner sep=0.25cm] at (plot5.south) {(e)};


\end{tikzpicture}
