\documentclass{standalone}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{fourier}
\usepackage{pgfplots}
\pgfplotsset{compat=1.18}
\usepgfplotslibrary{polar}

\begin{document}

\begin{tikzpicture}
\begin{polaraxis}
\addplot[domain=0:360, thick, samples=200, smooth] {2*cos(4*x)};
\end{polaraxis}
\end{tikzpicture}

\end{document}