#!/usr/bin/gnuplot -persist

m_to_in = 39.3700787

set title "Parabolic reflector gain"
set xlabel "Projected apeture (inches)"
set xrange [0.00000:1 * m_to_in]
set ylabel "Gain dBi"
set yrange [0:*]

set key top left
set grid xtics ytics

wl(freq) = (3*10**8)/(freq) * m_to_in
gain(freq, apeture) = 10 * log( 0.65 * ((4 * pi * apeture)/(wl(freq) ** 2)) )

plot 10*log( 0.65 * ((4 * pi * x)/(wl(0.915 * 10**9) ** 2)) ) title "915 MHz" ,\
     10*log( 0.65 * ((4 * pi * x)/(wl(2.400 * 10**9) ** 2)) ) title "2.4 GHz" ,\
     10*log( 0.65 * ((4 * pi * x)/(wl(5.800 * 10**9) ** 2)) ) title "5.8 GHz"

#exit

plot gain(2412 * 10**6, x) title "802.11g channel  1" ,\
     gain(2417 * 10**6, x) title "802.11g channel  2" ,\
     gain(2422 * 10**6, x) title "802.11g channel  3" ,\
     gain(2427 * 10**6, x) title "802.11g channel  4" ,\
     gain(2432 * 10**6, x) title "802.11g channel  5" ,\
     gain(2437 * 10**6, x) title "802.11g channel  6" ,\
     gain(2442 * 10**6, x) title "802.11g channel  7" ,\
     gain(2447 * 10**6, x) title "802.11g channel  8" ,\
     gain(2452 * 10**6, x) title "802.11g channel  9" ,\
     gain(2457 * 10**6, x) title "802.11g channel 10" ,\
     gain(2462 * 10**6, x) title "802.11g channel 11" ,\
     gain(2467 * 10**6, x) title "802.11g channel 12" ,\
     gain(2472 * 10**6, x) title "802.11g channel 13" ,\
     gain(2484 * 10**6, x) title "802.11g channel 14"