[Tex/LaTex] How to change the distance between abstract and section 1

Question

My LaTeX format is as follows:

Abstract: Abstract goes here.

Section 1:

It should be noted that my abstract is one column and sections are two-column.
Abstract and Section 1 are very close together. I want some space between abstract and
Section 1. I tried \hfill but it only affects on one column but at the beginning of
the second column the Abstract and Section 1 are close together. How can I fix it?

\documentclass[a4paper,twocolumn]{article}
\usepackage{graphicx}
\usepackage[cmex10]{amsmath}
\usepackage{mathtools}
\usepackage[usenames]{color}
\usepackage[table]{xcolor}
\usepackage{lipsum}
\usepackage{multicol}

\renewenvironment{abstract}{%
  \noindent\bfseries\abstractname:\normalfont}{}
\begin{document}
\title{
\textbf{Title}
}

\setlength{\columnsep}{0.8cm}

\begin{abstract}
Abstract is here 
\end{abstract}

\section{Introduction}
\section{circuit}
Circuit is here
\subsection{Noise analysis}
Noise analysis is here
\section{Circuit Design}
Circuit Design is here
\section{Simulation Results}
Simulation Results is here
\section{Conclusion}
Conclusion is here.
\begin{thebibliography}{1}
\bibitem{}Friis, H. T.: 
\end{thebibliography}
\end{document}

This is my first experience with Latex and it's a real pain…

Answer 1

You could just insert a \bigskip between the abstract and your first section. If this is not enough, add some more \bigskips. One \bigskip is "worth" 12pt by default (plus/minus some stretch/shrink). If you want less space, issuing a \medskip is 1/2 a \bigskip at 6pt by default (plus/minus some stretch/shrink). And then there's \smallskip which is 1/2 a \medskip at 3pt by default (plus/minus some stretch/shrink).

Alternatively, issuing a \vspace{<len>} (with an optional *) should also do the trick, where <len> is some TeX length (like 1cm, say). More information on the \vspace command is available on TeXBlog.

The above additions to your code is manual, and therefore viable as a one-time use. However, it is also possible to (say) patch the abstract environment to automatically append a larger skip once it's done.

---

Edit: I assume your twocolumn document configuration stems from: How can I place a one-column-abstract in a two-column document? In this case the use of \vspace does not provide any effective solution (nor does \...skip which is defined in terms of \vspace). I would suggest using the multicols environment provided by the multicol package, and use in your document in the following way:

\documentclass{article}
\usepackage[margin=2cm]{geometry}% http://ctan.org/pkg/geometry
\usepackage{lipsum}% http://ctan.org/pkg/lipsum
\usepackage{multicol}% http://ctan.org/pkg/multicol
\begin{document}

\begin{abstract}
\lipsum[1]
\end{abstract}

\vspace{2cm}% Additional space between abstract & rest of document

\begin{multicols}{2}
\section{First section}
\lipsum[2-4]
\section{Second section}
\lipsum[5-7]
\section{Last section}
\lipsum[8-10]
\end{multicols}
\end{document}

If you need more than two columns, modify the mandatory { } argument of \multicols. In the above example, the geometry package provides a means to modify the page layout/dimensions (I set the text margins to be 2cm from the page border using margin=2cm), while the lipsum package provides dummy text.