MATLAB规范化评估一

%***********************************************************************
% LOOP.m
%**********************************************************************
% This is a MATLAB based program computes the:
% I. Maximum directivity (dimensionless and in dB)
% II. Radiation resistance
% III. Directivity pattern (in dB) in polar form
% IV. Normalized elevation far-field pattern (E-phi, in dB)
%
% and also plots the:
% I. Directivity polar pattern (in dB)
% II. Normalized far-field polar amplitude pattern (E-phi, in dB)
%
% for a circular loop (with constant current). The loop is radiating
% into free space.
%
% The directivity and radiation resistance are calculated using
% the trailing edge method in increments of 1 degree in theta.
%
% **Input parameters:
% 1. A: Loop radius (in wavelengths)
%
% **Note:
% The far-zone electric field component E-phi exists for
% 0 < theta < 180 and 0 < phi < 360.
%-----------------------------------------------------------------
% Converted from Fortran to Matlab 3/2002 by Kelly O’Dell.
% Modified by Marios Gkatzianas
%-----------------------------------------------------------------
%
clear all;
close all;
format long;

warning off;

%—Choice of output—

fprintf(‘Output device option \n\tOption (1): Screen\n\tOption (2): File \n’);
ERR = 1;
while(ERR ~= 0)
DEVICE = input(’\nOutput device = ',‘s’);
DEVICE = str2num(DEVICE);
if(DEVICE == 1)
ERR = 0;
elseif(DEVICE == 2)
FILNAM = input('Input the desired output filename: ',‘s’);
ERR = 0;
else
error(‘Outputting device number should be either 1 or 2\n’);
end
end

%—Definition of constants and initialization—

PI = 4.0atan(1.0);
E = 120.0PI;
THETA = PI/180.0;
UMAX = 0.0;
PRAD = 0.0;
TOL = 1.0E-5;

%—Input the radius of the loop—

A = input(’\nRadius of loop in wavelengths = ',‘s’);
A = str2num(A);
%Insert input data error loop**

%—Main program------------------------------------

I = 1;
while(I <= 180)
XI = IPI/180.0;
X = 2.0PIAsin(XI);
if(abs(X) < TOL)
F = 0.0;
else
F = besselj(1,X);
end
U = A^2*(2.0*PI)2/8.0EF^2;
if(U > UMAX)
UMAX = U;
end
UA = Usin(XI)THETA2PI;
PRAD = PRAD+UA;
I = I+1;
end
D = (4.0PIUMAX)/PRAD;
DDB = 10.0log10(D);
RR = 2.0PRAD;

%—Calculation of elevation far-field patterns in 1 degree increments—
fid = fopen(‘ElevPat.dat’,‘w’);
fprintf(fid,’\tLoop\n\n\tTheta\t\tH (dB)\n’);
fprintf(fid,’\t-----\t\t------\n’);
T = zeros(180,1);
HT = zeros(180,1);
HdB = zeros(180,1);

x = 1;
while(x<=180)
T(x) = x-0.99;
Y = 2PIA*sin(T(x)THETA);
HT(x) = besselj(1,Y);
x = x+1;
end
HT = abs(HT);
HTmax = max(HT);
HdB = 20log10(abs(HT)/HTmax);

x = 1;
while(x<=180)
fprintf(fid,’\n %5.0f %12.4f’,T(x),HdB(x));
x = x+1;
end

fclose(fid);

%—Create output------------
if(DEVICE == 2)
fid = fopen(FILNAM,‘w’);
else
fid = DEVICE;
end

x=linspace(0,4piA,500);
dx=x(2)-x(1);
den=sum(besselj(2,x)*dx);
theta=linspace(0,pi,300);

Dth=4piA/den*(besselj(1,2piAsin(theta))).^2;
Dth(1)=0;
Dth_db=10log10(Dth);

%—Echo input parameters and output computed parameters—
fprintf(fid,’\nLOOP:\n-----’);
fprintf(fid,’\n\nInput parameters:\n-----------------’);
fprintf(fid,’\nRadius of loop in wavelengths = %6.4f’,A);
fprintf(fid,’\n\nOutput parameters:\n------------------’);
fprintf(fid,’\nDirectivity (dimensionless) = %6.4f’,D);
fprintf(fid,’\nDirectivity (dB) \t= %6.4f’,DDB);
fprintf(fid,’\nRadiation resistance (Ohms) = %9.4f’,RR);
fprintf(fid,’\n\n***NOTE:\nThe normalized elevation pattern is stored\n’);
fprintf(fid,‘in an output file called …ElevPat.dat\n\n’);

if(DEVICE == 2)
fclose(fid);
end

%—Plot elevation far field pattern------
% plot(T,-abs(HdB),‘b’);
% axis([0 180 -60 0]);
% grid on;
% xlabel(‘Theta (degrees)’);
% ylabel(‘Amplitude (dB)’);
% legend([‘a = ‘,num2str(A),’ \lambda’],0);
% title(‘Loop Far-Field Elevation Pattern’);

T=T’; HdB=HdB’;

T=[T T+180];
Hdb=[HdB fliplr(HdB)];

% Figure 1
% ********
polar_dB(T,-abs(Hdb),-60,max(Hdb),4);
title(‘Elevation plane normalized amplitude pattern (dB)’,‘fontsize’,16);

% Figure 2
% ********
figure(2);
polar_dB([theta theta+pi]*180/pi,[Dth_db fliplr(Dth_db)],-60,max(Dth_db),4);
title(‘Elevation plane directivity pattern (dB)’,‘fontsize’,16);

%—End of program-----------------------------------------