radiation Pattern of a Dipole Antenna %******************************************************************** ****** % Name: % Author: % Date: % Description: % Reference: % Design , 3rd Edition, page 173, eq. 4-64 3D_Radiation_Pattern Bruce Lei September 12, 2011 3-D Radiation Pattern of Dipole Antenna Constantine A.Balanis, Antenna Theory Analysis And %******************************************************************** ****** %Usage: %This program plots 3-D radiation Pattern of a Dipole Antenna %All the parameters are entered in the M-File clear all %Defining variables in spherical coordinates theta=[0:0.12:2*pi];%theta vector phi=[0:0.12:2*pi];%phi vector 

l_lamda1=1/100;% length of antenna in terms of wavelengths I0=1;% max current in antenna structure n=120*pi; %eta % evaluating radiation intensity(U) U1=( n*( I0^2 )*( ( cos(l_lamda1*cos(theta-(pi/2))/2) - cos(l_lamda1/2) )./ sin(theta-(pi/2)) ).^2 )/(8*(pi)^2); %converting to dB scale U1_1=10*log10(U1); %normalizing in order to make U vector positive min1=min(U1_1); U=U1_1-min1; % expanding theta to span entire space U(1,1)=0; for n=1:length(theta) theta(n,:)=theta(1,:); % 注意 theta(h,:)是通过扩展行向量 theta(1,:)得到的，类 似于 meshgrid(x,y)中的 x 的扩展方式。theta(1,:) = theta end phi(:,m)=phi(:,1); % 注意 phi(:,m)是通过扩展列向量 phi(:,1)得到的，类似于 % expanding phi to span entire space phi=phi'; %phi 现在是列向量 for m=1:length(phi) meshgrid(x,y)中的 y 的扩展方式。 end % expanding U to span entire space for k=1:length(U) U(k,:)=U(1,:); % U 仅仅与 theta 有关，故采用与 theta 相同的扩展方式! end % converting to spherical coordinates [x,y,z]=sph2cart(phi,theta,U); %plotting routine surf(x,y,z) colormap(copper) title('Radition Pattern for Dipole Antenna (length=1.5lamda)') xlabel('x-axis--->') ylabel('y-axis--->') zlabel('z-axis--->')