Simple circuit schematics symbols

An example of how to create simple schematic symbols using paths and macros. The example also shows how the symbols can be combined with the signalflow library by Karlheinz Ochs. For a general circuit library this should be done by creating custom node shapes. However, that would require a lot more work.

Edit and compile if you like:

% Simple circuit schematics symbols
% Author: Shengshan Cui
\documentclass{article}
\usepackage{tikz}
\usepackage{subfig}


\usepackage{signalflowdiagram}

% Define two simple circuit schematics symbols
\def\antenna{%
    -- +(0mm,4.0mm) -- +(2.625mm,7.5mm) -- +(-2.625mm,7.5mm) -- +(0mm,4.0mm)
}

\def\ground{%
    -- +(0mm,-4.0mm) {
        [yshift=-4mm]
        +(-2mm,0mm) -- +(2mm,0mm)
                +(-1mm,-1mm) -- +(1mm,-1mm)
                +(-0.3mm,-2mm) -- +(0.3mm,-2mm)
        }
}

\begin{document}

\begin{figure}
    \centering
    \subfloat[Stand alone symbols]{
        \begin{tikzpicture}
            \draw[step=.5cm,black!25,very thin] (-1.4,-1.4) grid (1.4,1.4);
            \draw[color=red,thick] (0,0) \antenna;
            \draw[color=blue,thick] (0,0) \ground;
        \end{tikzpicture}
    }\qquad
    \subfloat[Combining symbols with the signalflow library]{
        \begin{tikzpicture}
            \node[input]  (in)                   {$x(t)$};
            \node[delay]  (del) [right from=in]  {$T$};
            \node[coordinate] (out) [right from=del] {};
            % signal paths
            \path[r>] (in)  -- (del);
            \path[r] (del) -- (out) \antenna \ground;
        \end{tikzpicture}
    }
\end{figure}

\end{document}