{ "cells": [ { "cell_type": "markdown", "metadata": {}, "source": [ "# Chapter 6: Antenna Arrays" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 6.10_1: Find_the_Directivity.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "//Example No. 6.10.1\n", "clc;\n", "clear;\n", "close;\n", "format('v',6);\n", "n=10;//no. of elements\n", "//d=lambda/4;(spacing)\n", "dBYlambda=1/4;///(Spacing/wavelength)\n", "//Broadside array\n", "D=2*n*dBYlambda;//unitless(Directivity)\n", "D=10*log10(D);//dB(Directivity)\n", "disp(D,'Directivity for broadside array in dB : ');\n", "//Endfire array\n", "D=4*n*dBYlambda;//unitless(Directivity)\n", "D=10*log10(D);//dB(Directivity)\n", "disp(D,'Directivity for Ordinary endfire array in dB : ');" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 6.10_2: Design_ordinary_endfire_array.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "//Example No. 6.10.2\n", "clc;\n", "clear;\n", "close;\n", "format('v',6);\n", "D=20;//dB(Directivity)\n", "//d=lambda/4;(spacing)\n", "dBYlambda=1/4;//(spacing/wavelength)\n", "D=10^(D/10);//unitless(Directivity)\n", "n=D/4/dBYlambda;//no. of elements\n", "disp(n,'(i) No. of elements : ');\n", "LBYlambda=(n-1)*dBYlambda;//(length/wavelength)\n", "disp('(ii) Length of the array is '+string(LBYlambda)+'*lambda');\n", "HPBW=2*acosd(1-1.391/%pi/n/dBYlambda);//degree(HPBW)\n", "disp(HPBW,'(iii) HPBW in degree : ');\n", "SLL=-13.46;//dB(Side lobe level)\n", "disp(SLL,'(iv) SLL in dB : ');\n", "Beta_into_lambda=2*%pi;//(temorary calculatuion)\n", "//alfa=-Beta*d;//for theta=0\n", "//alfa=Beta*d;//for theta=180\n", "alfa1=-Beta_into_lambda*dBYlambda;//radian////for theta=0\n", "alfa1=alfa1*180/%pi;//degree(angle)\n", "alfa2=Beta_into_lambda*dBYlambda;//radian////for theta=180\n", "alfa2=alfa2*180/%pi;//degree(angle)\n", "disp(alfa2,alfa1,'(v) Progressive phase shift, α for theta equals to 0° & 180° are : ');" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 6.14_1: Four_Element_broadside_array.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "//Example No. 6.14.1\n", "clc;\n", "clear;\n", "close;\n", "format('v',6);\n", "SLL=19.1;//dB(Side Lobe Level)\n", "//d=lambda/2;(spacing)\n", "dBYlambda=1/2;//(Spacing/wavelength)\n", "n=4;//(no. of elements)\n", "r=round(10^(SLL/20));//(ratio of main lobe to side lobe)\n", "m=n-1;//(degree )\n", "//T3(x0)=r=4*x0^3-3*x0;\n", "x0=roots([4 0 -3 -r]);//(Coefficient)\n", "x0=x0(1);//taking real value(Coefficient)\n", "//E4(z)=T3(x)=4*x^3-3*x=4*a1*z^3-3*a1*z+a0*z\n", "//4*a1*z^3=4*x^3 where z^3=(x/x0)^3\n", "a1=4*x0^3/4;//(Coefficient)\n", "//a0*z-3*z*a1=-3*x\n", "a0=(3/x0*a1-3)*x0;//(Coefficient)\n", "disp(a0,a1,'Coefficients of array polynomial a1 & a0 are : ');\n", "disp(a0/a1,a1/a1,'Relative current amplitudes are :');" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 6.2_1: Relative_field_patter.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "//Example No. 6.2.1\n", "clc;\n", "clear;\n", "close;\n", "format('v',5);\n", "n=2;//(No. of point source)\n", "//E=E0*{exp(%i*%pi/2)-exp(-%i*si/2)} where exp(-%i*si)=-1\n", "//si=Beta*d*cosd(fi)=2*%pi*cosd(fi)\n", "//E=2*%i*E0*sind(%pi*cosd(fi)); But 2*%i*E0=1\n", "fi=[0 30 60 90 120 150 180 210 240 270 300 330];//degree(angle)\n", "En=sin(%pi*cosd(fi));//Normalized field\n", "disp('Different values of fi : ');\n", "disp(string(fi));\n", "disp('Corresponding normalized field is : ');\n", "disp(string(abs(En)));" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 6.2_2: Radiation_patern.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "//Example No. 6.2.2\n", "clc;\n", "clear;\n", "close;\n", "format('v',5);\n", "n=2;//(No. of point source)\n", "//E=E0*{exp(%i*(%pi/4+si/2))-exp(-%i*(%pi/4+si/2))} as exp(%i*theta)+exp(-%i*theta)=2*cos(theta)\n", "//E=2*E0*cos(%pi/4+si/2);\n", "//si=Beta*d*cosd(fi)=2*%pi*cosd(fi)\n", "//En=cos(%pi/4+Beta*d*cosd(%pi/4)); But 2*E0=1\n", "fi=[0 30 60 90 120 150 180 210 240 270 300 330];//degree(angle)\n", "En=cos(%pi/4+%pi/4*cosd(fi));//Normalized field\n", "disp('Different values of fi : ');\n", "disp(string(fi));\n", "disp('Corresponding normalized field is : ');\n", "disp(string(abs(En)));" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 6.2_3: Field_patter.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "//Example No. 6.2.3\n", "clc;\n", "clear;\n", "close;\n", "format('v',5);\n", "//E=cos(fi)+sin(fi)