Idealised directional spectrum

Idealised representation of directional spectrum (energy units omitted) for a typical north-westerly swell, mixed with presence wind sea .

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% Idealised directional spectrum
% Author: Marco Miani
\documentclass{article}
% Set target color model to RGB
\usepackage[rgb]{xcolor}
\usepackage{tikz}
\usepackage[active,tightpage, floats]{preview}
%\PreviewEnvironment{tikzpicture}
\setlength\PreviewBorder{5pt}%
\begin{document}
\begin{figure}[t]
    
    \begin{tikzpicture}[scale=.95]  
        \draw (0, 0) circle (3.8cm);
        \foreach \x  in {0, 30, ..., 330}
        \draw (-\x+90:3.8) -- (-\x+90:4.0) (-\x+90:4.4) node {$\x^\circ$};
        \foreach \x  in {0,1, ..., 3}
        \draw[dashed,ultra thin,gray] (0,0)circle(\x);
        \draw[->,dashed,gray](0,0) to[] (3.5,0);
        %Add labels with names of the primary and secondary colors.
        \foreach \x/\text in {1/f$_{S}$, 3/f$_{W}$}
        \draw (\x,0) node [below]{\text};
        \foreach \x/\text in {.5,.6,...,1.5}
        \draw [-,thin,red] (90:\x) arc(90:135:\x);
        \draw[-,ultra thin,red,dashed] (0,0) to[] (0,7);
        \draw[-,ultra thin,red,dashed] (0,0) to[] (-5.4,5);
        \foreach \x/\text in {2.5,2.6,...,3.5}
        \draw [-,thin,blue] (60:\x) arc(60:165:\x); 
        \draw[-,ultra thin,blue,dashed] (0,0) to[] (3.5,6);
        \draw[-,ultra thin,blue,dashed] (0,0) to[] (-7,1.9);
            
        \draw [<->,ultra thin,blue!20] (65:5) arc(65:160:5);
        \draw [<->,ultra thin,red!20] (95:7) arc(95:130:7);
        \path[font=\footnotesize]
        (-3.5,6.5) node[above right] {$Swell\ Sea$}
        (-5,2.5) node[left] {$Wind\ Sea$};
        %(.5,0) node[above right] {$0.1\ Hz$}
        %   (3.8,.2) node[left] {$0.3\ Hz$};
        %   
 
 
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