如何用matlab畫天線的三維方向圖？

01-07

貼兩個畫著玩的：

線天線在不同電長度下的方向圖

全長4.4個波長的線天線方向圖

下面給出振子天線三維方向圖的MATLAB代碼，以供參考。我計算了定向性，並取點源作為基準，繪製的是線性圖，程序還具有類似 Balanis 教材中切去部分方向圖的功能，以便查看。

close all; clear; clc;


Llambda = 0.5;

Lr = 2*pi*Llambda;

F = @(theta, phi) ((cos(Lr/2.*cos(theta)) - cos(Lr/2))./sin(theta)).^2;
Ntheta = 36; Nphi = 72;

theta = linspace(0,pi,Ntheta);  phi = linspace(0,2*pi,Nphi);

dtheta = pi/Ntheta; dphi = 2*pi/Nphi;

theta([1 end]) = [eps pi-eps];

[THETA, PHI] = meshgrid(theta, phi);
R = F(THETA, PHI);

Ravg = sum(sum(R.*sin(THETA)*dtheta*dphi/(4*pi)));

R = R/Ravg;

D = max(R(:));
% for visual purposes, specify the segment of the pattern to be cut

phiI1 = 56; phiI2 = 72;

R(phiI1+1:phiI2-1,  = NaN;
figure(1), hold on

% isotropic antenna pattern as reference

[x,y,z] = sphere;

p0 = surf(x,y,z,0);

set(p0, "facecolor",[.8 .8 .8],"facealpha",0.2,"edgealpha",0.4)

% antenna pattern

[x,y,z] = sph2cart(PHI, pi/2-THETA, R);

p1 = surf(x,y,z,R/D*2-1);

colormap jet;

set(p1, "facealpha",0.8,"edgealpha",0.5);

% additional cross section

[x,y,z] = sph2cart(PHI([phiI1 phiI2],:), pi/2-THETA([phiI1 phiI2],:), R([phiI1 phiI2],:));

p2 = patch(x",y",z","w");

set(p2, "facealpha",0.6,"edgealpha",0.2)

set(gcf, "render","painter","color","w") view(45,8), axis image off set(gca, "position", [-0.0 0.0 1 1])

樓上的畫圖太高端，我Matlab學得不好，只會一些簡單用法。

之前的答案有問題，經過樓上大神的提醒，現在修改一下。

%電基本振子的方向圖 clear; clc; theta=meshgrid(eps:pi/180:pi); phi=meshgrid(eps:2*pi/180:2*pi)"; F=abs(sin(theta)); [x,y,z]=sph2cart(phi,pi/2-theta,F);%之前第二個變數直接寫的是theta，對照說明以後已改正 figure(1); mesh(x,y,z); title("電基本振子的立體方向圖"); xlabel("x"),ylabel("y"),zlabel("F( heta,phi)"); theta=linspace(eps,2*pi,100); F_E=abs(sin(theta)); figure(2); polar(theta,F_E); title("E面方向圖");

這裡貼上立體方向圖和E面方向圖：

我還做了一個動態的，但我不知道怎麼弄GIF(尷尬……)，就只貼代碼好了。

clear; clc; for i=1:30 theta=meshgrid(eps:pi/180:pi); phi=meshgrid(eps:2*pi/180:2*pi)"; l=i*0.1; f=abs(cos(2*pi*l*cos(theta))-cos(2*pi*l))./abs(sin(theta)+eps); fmax=max(max(f)); [x,y,z]=sph2cart(phi,pi/2-theta,f/fmax);%之前第二個變數直接寫的是theta，對照說明以後已改正 mesh(x,y,z); axis([-1 1 -1 1 0 1]); title("對稱陣子方向圖隨著振子電長度的變化") m(:,i)=getframe; end movie(m,1,1);