From 7f60ea012dd2524dae921a2a35adbf7ef21f2bb6 Mon Sep 17 00:00:00 2001
From: prashantsinalkar
Date: Tue, 10 Oct 2017 12:27:19 +0530
Subject: initial commit / add all books

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+// Example no 4.7
+// To compute diffraction loss and identify Fresnel zone within which tip of obstruction lies for a)h=25m b)h=0 c)h=-25m
+// Page no. 132
+
+clc;
+clear;
+
+// Given data
+lambda=1/3;                                         // Wavelength in meter
+d1=1*10^3;                                          // Distance between transmitter and obstructing screen in m
+d2=1*10^3;                                          // Distance between receiver and obstructing screen in m
+
+// a) For h=25m
+h=25;                                               // Effective heigth of obstruction screen in m
+v=h*sqrt((2*(d1+d2))/(lambda*d1*d2));               // Fresnel diffraction parameter
+printf('\n a) For h=25m Fresnel diffraction parameter v = %0.2f',v);
+printf('\n From the plot of Knife-edge diffraction gain as a function of Fresnel diffraction parameter, diffraction loss is 22dB.');
+Gd=-20*log10(0.225/v);                               // Diffraction loss for v>2.4 in dB
+printf('\n Using numerical approximation, diffraction loss for v > 2.4  = %0.1f dB',Gd);
+delta=(h^2/2)*((d1+d2)/(d1*d2));                    // Path length difference between direct and diffracted rays
+n=(2*delta)/lambda;                                 // Number of Fresnel zones in which the obstruction lies
+printf('\n Fresnel zone within which tip of obstruction lies = %0.2f',n);
+printf('\n Therefore, the tip of obstruction completely blocks the first three Fresnel zones.');
+
+// b) For h=0
+h=0;                                                // Effective heigth of obstruction screen in m
+v=h*sqrt((2*(d1+d2))/(lambda*d1*d2));               // Fresnel diffraction parameter
+printf('\n \n b) For h=0 Fresnel diffraction parameter v = %0.0f',v);
+printf('\n From the plot of Knife-edge diffraction gain as a function of Fresnel diffraction parameter, diffraction loss is 6dB.');
+Gd=-20*log10(0.5-0.62*v);                           // Diffraction loss for v=0 in dB
+printf('\n Using numerical approximation, diffraction loss for v=0 = %0.0f dB',Gd);
+delta=(h^2/2)*((d1+d2)/(d1*d2));                    // Path length difference between direct and diffracted rays
+n=(2*delta)/lambda;                                 // Number of Fresnel zones in which the obstruction lies
+printf('\n Fresnel zone within which tip of obstruction lies = %0.0f',n);
+printf('\n Therefore, the tip of obstruction lies in middle of first Fresnel zone.');
+
+// c) For h=-25m
+h=-25;                                                // Effective heigth of obstruction screen in m
+v=h*sqrt((2*(d1+d2))/(lambda*d1*d2));                 // Fresnel diffraction parameter
+printf('\n \n c) For h=-25m Fresnel diffraction parameter v = %0.2f',v);
+printf('\n From the plot of Knife-edge diffraction gain as a function of Fresnel diffraction parameter, diffraction loss is approximately 1dB.');
+Gd=0;                                                // Diffraction loss for v<-1 in dB
+printf('\n Using numerical approximation, diffraction loss for v < -1 = %0.0f in dB',Gd);
+delta=(h^2/2)*((d1+d2)/(d1*d2));                    // Path length difference between direct and diffracted rays
+n=(2*delta)/lambda;                                 // Number of Fresnel zones in which the obstruction lies
+printf('\n Fresnel zone within which tip of obstruction lies = %0.2f',n);
+printf('\n Therefore, the tip of obstruction completely blocks the first three Fresnel zones but diffraction loss is negligible.');
+
-- 
cgit