wire2mom.m

用矩量法计算线天线的电磁场（MATLAB编程）

global h k a zhf 
c=3e8;
f=300e6;
wave_length=c/f;
h=0.5*wave_length;
k=2*pi/wave_length;
a=7.022e-3*wave_length;
%----------------------
V=1;
number_match=4;
zh=[0 h/3 h*2/3 h];
aita0=120*pi;
%----------------------
for n=1:number_match
    zhf=zh(n);   
    zmn(n,1)=quad8('wire21',-h,h);
    zmn(n,2)=quad8('wire22',-h,h);
    zmn(n,3)=quad8('wire23',-h,h);
end   
for n=1:number_match
    zmn(n,4)=cos(k*zh(n));
    Vi(n)=-j/aita0*V/2*sin(k*abs(zh(n)));
end
c1=zmn\Vi.';
%----------------------
zp=[-h:h/150:h];
for m=1:length(zp)
    I(m)=c1(1)*sin(k*(h-abs(zp(m))))+c1(2)*(cos(k*zp(m))-cos(k*h))+c1(3)*(cos(k*zp(m)/2)-cos(k*h/2));
end
figure(1);
plot(real(I(151:length(zp))),zp(151:length(zp))/wave_length,'r');hold on;
plot(imag(I(151:length(zp))),zp(151:length(zp))/wave_length,'b');
plot(abs(I(151:length(zp))),zp(151:length(zp))/wave_length,'-.');
figure(2);
plot(real(I),zp/wave_length,'r');hold on;
plot(imag(I),zp/wave_length,'b');

%--------------------------------------------------
global SITA h C1 C2 C3
sita=[0:pi/1800:2*pi];
C1=c1(1);C2=c1(2);C3=c1(3);
for m=1:length(sita)
    SITA=sita(m);
    f_sita(m)=sin(sita(m))*quad8('current1',-h,h);
end
F_sita=abs(f_sita)/max(abs(f_sita));
figure(3);
polar(sita,F_sita);     % E-plane

fai=[0:pi/1800:2*pi];
sita_V=pi/2;
for m=1:length(sita)
   SITA=sita_V;
   f_fai(m)=sin(SITA)*quad8('current1',-h,h);
end
figure(4);
polar(fai,abs(f_fai)/max(abs(f_fai)),'r');        % H-plane

%-------------------------------
F_sum=0;
D_sita=pi/1800;
for m=1:(length(sita)-1)/2
    F_sum=F_sum+sin(sita(m))*D_sita*F_sita(m)^2;
end
D=4*pi/F_sum/(2*pi);        % D 
I_in=I(151);
f_sita_un=max(abs(f_sita/I_in));
Rr=120*f_sita_un^2/D;          % Rr