1 files changed, 79 insertions, 0 deletions
diff --git a/3773/CH15/EX15.3/Ex15_3.sce b/3773/CH15/EX15.3/Ex15_3.sce
new file mode 100644
index 000000000..9cf97010a
--- /dev/null
+++ b/3773/CH15/EX15.3/Ex15_3.sce
@@ -0,0 +1,79 @@
+//Chapter 15: Antennas for Special Applications
+//Example 15-12.1
+clc;
+
+//Variable Initialization
+f = 60e6    //Frequency(Hz)
+dep = 20    //Depth of antenna location (m)
+sigma = 1.33e-2    //Conductivity (mho per m)
+eps0 = 8.85e-12    //Air Permittivity (F/m)
+epr1 = 80    //Real part of relative permittivity (unitless)
+alphat = 10    //Elevation angle (degrees)
+cl = 1    //Circumference (lambda)
+%pitch = 12.5    //%pitch angle (degrees)
+c = 3e8    //Speed of light (m/s)
+
+dir_gb = 3    //Directivity of George Brown turnstile (unitless)
+Aer_gb = 6    //Effective aperture of George Brown turnstile (unitless)
+r = 1e3    //Distance between transmitter and receiver (m)
+Pt = 100    //Transmitted power (W)
+
+//Calculations
+epr11 = sigma/(eps0*2*%pi*f)    //Loss term of relative permittivity (unitless)
+epr = epr1 + %i*epr11    //Relative permittivity (unitless)
+alphac = acos(sqrt(1/epr1))    //Critical angle (degrees)
+alpha = acos(cos((alphat)*%pi/180)/sqrt(epr1))    //Angle of incidence (degrees)
+
+n1=12    //Number of turns
+rad = cl/(2*%pi)    //Radius of loop (lambda)
+sl = tan((12.5)*%pi/180)
+hpbw1 = 52/(cl*sqrt(n1*sl))    //Half power beamwidth for 12 turns(degrees)
+dir1 = 12*(cl**2)*n1*sl    //Directivity for 12 turns (unitless)
+n2 = n1*2    //Number of turns
+hpbw2 = 52/(cl*sqrt(n2*sl))    //Half power beamwidth for 24 turns(degrees)
+dir2 = 12*(cl**2)*n2*sl    //Directivity for 24 turns (unitless)
+num = 20    //Number of turns chosen
+
+p_perpt=[]
+p_pallt=[]
+for i=0:%pi/180:%pi
+p_perp = [(sin(i)-sqrt(epr - cos(i)**2))/(sin(i)+sqrt(epr - cos(i)**2))]
+p_pall = [(epr*sin(i)-sqrt(epr - cos(i)**2))/(epr*sin(i)+sqrt(epr - cos(i)**2))]
+p_perpt($+1)=p_perp
+p_pallt($+1)=p_pall
+end
+
+Sr = 0.5*((p_perpt)**2 + (p_pallt)**2)    //Relative power density reflected (unitless)
+St = 1 - Sr     //Relative power density transmitted (unitless)
+
+theta = 0:%pi/180:%pi
+
+subplot(1,2,1)
+plot(theta,St)
+title("Relative Power Vs Elevation Angle")
+
+subplot(1,2,2)
+polarplot(theta,real(St))
+title("Pattern of Transmission")
+
+wave_lt = c/f    //Wavelength (m)
+diam = wave_lt/(sqrt(epr1)*%pi)    //Submerged helix diameter (m)
+att_cons = (%pi*epr11)/(wave_lt*sqrt(epr1))    //Attenuation constant for water (Np/m)
+att_d = 20*log10(exp(-att_cons*dep))    //Attenuation in the water path (dB)
+Dir = 12*(cl**2)*num*sl    //Directivity for 20 turn helix (unitless)
+Ae = Dir*(wave_lt**2)/(4*%pi)    //Effective aperture (m^2)
+
+Pr = Pt*Ae*dir_gb/((r**2)*(wave_lt**2))    //Received power(W)
+
+loss_inter = 10*log10(St(10))    //Loss at the interface for alpha = 83.68 (dB)
+tot_loss = abs(att_d + loss_inter)    //Total loss (dB)
+Pr_act = Pr/(10**(ceil(tot_loss)/10))    //Net Actual received power (W)
+
+
+//Results
+mprintf("Half power beamwidth for 12 turns is %.0f degrees",hpbw1)
+mprintf("\nDirectivity for 12 turns is %.1f", dir1)
+mprintf("\nHalf power beamwidth for 24 turns is %.0f degrees",hpbw2)
+mprintf("\nDirectivity for 24 turns is %.1f", dir2)
+mprintf("\nA helix of %d turns is chosen for reasonable compromise",num)
+mprintf("\nThe signal level at the distance of 1km is %.2e W",Pr_act)