transmit_line.m

用数值算法这里用的是矩量法计算地面上方单导体传输线的电容

function y1=transmit_line( )
format long;
syms t;
e0=8.854187818e-12;
d=0.01;%直径
H=0.1; %距地面的距离
D=2*H;
N=10;
r=d/2;
l=pi*d;
deltl=l/N;
c1=deltl^2;
c2=deltl^2;
for m=1:N
    for n=1:N
        sita=pi/N+(n-1)*2*pi/N;
        xm=r*cos(pi/N+(m-1)*2*pi/N);  %每段中点的坐标
        ym=r*sin(pi/N+(m-1)*2*pi/N)+H;
        xn=r*cos(pi/N+(n-1)*2*pi/N);
        yn=r*sin(pi/N+(n-1)*2*pi/N)+H;
        dxn=deltl*cos(pi/2-sita);
        dyn=deltl*sin(pi/2-sita);
        a1=(xm-xn)^2+(ym+yn)^2;
        b1=-2*(xm-xn)*dxn+2*(ym+yn)*dyn;
        a2=(xm-xn)^2+(ym-yn)^2;
        b2=-2*(xm-xn)*dxn-2*(ym-yn)*dyn;
s(m,n)=deltl*(interg(a1,b1,c1,0.5)-interg(a1,b1,c1,-0.5)-interg(a2,b2,c2,0.5)+interg(a2,b2,c2,-0.5)) 
    end
end
A=s\ones(N,1);
C1=deltl*sum(A)*(4*pi*e0);
C2=pi*e0/log((D+sqrt(D^2-d^2))/d);
C1/C2;