drawaltitude.m

计算电波传播的一个MATLAB程序,用抛物线法求解的..还是初始阶段,共享一下.

%The program is used to illustrate the loss of wavefront propagating forward 
%t-height of the source in meter
%frequency-frequency of source in MHz
function drawHeight(hs,frequency)
epsilon0=1e-9/(36*pi);
mu0=4*pi*1e-7;
const=3e8;
k0=2*pi*frequency*1e6/const;
deltax=180;
deltah=0.5;

x=eps:deltax:200e3;
height=eps:deltah:500;
for k=1:length(x)
    tantheta(:,k)=(height' - hs)./x(k);
    dist(:,k) = sqrt((height' - hs).^2 + x(k)^2);
end
theta=atan(tantheta);

% direct=sqrt(4*pi)/(pi/12);
% freep = sqrt(60*direct) ./ dist;
% 
% p=k0*sin(theta);

y=exp(-(height').^2*log(2)/(2*(k0)^2*sin(pi/12))).*exp(-i*height'*hs)-conj(exp(-(height').^2*log(2)/(2*(k0)^2*sin(pi/12)))).*exp(i*height'*hs);
ans=y;   %   %  %
figure;
plot(height,-20*log10(abs(ans)),'r');
y=ifft(y);
q=y;   
for m=2:length(x)
    q=exp(i*(k0).*deltax.*height'/6400000).*ifft(exp(-i*deltax.*k0.*(sin(theta(:,m))).^2 /2).*fft(q));
    y=[y q];
end

figure;
h1=10;
plot(x,-20*log10(abs(y(h1,:))),'r');
xlabel('range in meter');
ylabel('power in dB');
titletext = strcat('场强随距离的变化，高度为(m)： ');
title(texlabel(titletext));
hold on;
h2=25;
plot(x,-20*log10(abs(y(h2,:))),'g');
h3=40;
plot(x,-20*log10(abs(y(h3,:))),'b');
legend(num2str(deltah*h1),num2str(deltah*h2),num2str(deltah*h3));
hold off;

figure;
x1=100;
plot(height,-20*log10(abs(fft(y(:,x1)))),'r');
xlabel('height in meter');
ylabel('power in dB');
titletext = strcat('场强随高度的变化，在距离为(km)： ');
title(texlabel(titletext));
hold on;
x2=250;
plot(height,-20*log10(abs(fft(y(:,x2)))),'g');
x3=400;
plot(height,-20*log10(abs(fft(y(:,x3)))),'b');
legend(num2str(deltax*x1/1e3),num2str(deltax*x2/1e3),num2str(deltax*x3/1e3));
hold off;

% figure;
% meshc(x,height,-20*log10(abs(y)));
% figure;
% meshc(x,height,-20*log10(abs(fp)));
% figure;
% meshc(x,height,-20*log10(abs(y./fp)));
figure;
image(-20*log10(abs(y)));
keyboard;