电磁数值计算作业

1、第 14 题双位法求解八木天线Consider a three-element Yagi-Uda dipole antennaThe length of reflector is 0.500l , the length of diver is 0.460l , and the1.0.419l .length of director is2.The spacing between reflector and driver is equal to the spacing between driver and director, both are equal to 0.2l .The charact

2、eristic impedance of transmission line feeding the antenna isequal to Zc = 50W .3.The objective is to calculate the following parameters:The input impedance. ( Zin = 33 - j7.5W )1.um power gain. ( G = 7.6dBi )2.3.4.TheThe front-to-back ratio. ( FBR = 18.6dB ) The standing wave ratio. ( SWR = 1.57 )G

3、= Zin - Zcand SWR =Zin + Zc（1）示意图图 11+ G 1- G 图 2（2）电流分布图图 3（3）E 面方向图图 4(4)H 面方向图图 5（5）三维图图 6（6）运行结果Zin=36.515 -5.1745i W G=7.9953dB FBR=18.62dBSWR=1.4(7) 程序clear; clc;clf;global k lr l ld a N m n LR L LD S lambda=1;c=3*108; f=c/lambda; w=2*pi*f;ep=(10(-9)/(36*pi);k=2*pi/lambda;mu=4*pi*10(-7); LR=0.

4、5*lambda; L=0.46*lambda; LD=0.419*lambda; S=0.2*lambda; N=51;a=0.002; lr=LR/(N-1);l=L/(N-1);ld=LD/(N-1); v0=1; Zc=50;z=zeros(N-2)*3,(N-2)*3);%N 为奇数ll1=ones(1,(N-2)*lr,ones(1,(N-2)*l,ones(1,(N-2)*ld;for m=1:(N-2)*3for n=1:(N-2)*3z(m,n)=j*w*mu*ll1(m)*ll1(n)*psi1(m,n)+(psi1(m+0.5,n+0.5)-psi1(m+0.5,n-0.

5、5)-psi1(m-0.5,n+0. 5)+psi1(m-0.5,n-0.5)/(j*w*ep);endendv=zeros(N-2)*3,1);v(N-2)*3+1)/2,1)=v0;i=inv(z)*v; i1=zeros(1,N); for n=1:(N-2)i1(1,n+1)=i(n,1);end i2=zeros(1,N);for n=(N-1):2*(N-2) i2(1,n+2-(N-1)=i(n,1);end i3=zeros(1,N);for n=2*(N-2)+1:3*(N-2)i3(1,n+2-(2*(N-2)+1)=i(n,1);endfigure(1)z1=-LR/2:

6、LR/(N-1):LR/2;plot(z1,abs(i1),'b'); hold on;z2=-L/2:L/(N-1):L/2;plot(z2,abs(i2),'g'); hold on;z3=-LD/2:LD/(N-1):LD/2;plot(z3,abs(i3),'r'); xlabel('分段的坐标'); ylabel('Magnitude/A'); title('电流分布');legend('反射器','有源阵子','引向器')Zin=v0/i(

7、N-2)*3+1)/2);%输入阻抗figure(2) ll2=ones(1,N)*lr,ones(1,N)*l,ones(1,N)*ld; y1=zeros(1,N);y2=S*ones(1,N); y3=2*S*ones(1,N); y=y1 y2 y3; z=z1 z2 z3; i4=i1 i2 i3; phi=pi/2; thita=0:0.01:2*pi;for m=1:length(thita)u=i4*sin(thita(1,m).*exp(j*k*(y*sin(thita(1,m)*sin(phi)+z*cos(thita(1,m).*ll2; f(m)=sum(u);endp

8、olar(thita,abs(f)./max(abs(f); title('E 面方向图');G=10*log10(30*k2*max(abs(f)2/(real(Zin)*abs(i(N-2)*3+1)/2)2);%功率增益FBR=20*log10(max(abs(f)/abs(f(fix(3*pi/(0.01*2)+1);%前后功率比gamma=(Zin-Zc)/(Zin+Zc);SWR=(1+abs(gamma)/(1-abs(gamma);%驻波比figure(3) thita=pi/2; phi=0:0.01:2*pi; for m=1:length(phi)u=i4

9、*sin(thita).*exp(j*k*(y*sin(thita)*sin(phi(1,m)+z*cos(thita).*ll2; g(m)=sum(u);endpolar(phi,abs(g)./max(abs(g); title('H 面方向图');figure(4)syms thita phi F=abs(sum(i1*sin(thita).*exp(j*k*(y1*sin(thita)*sin(phi)+z1*cos(thita)*lr+sum(i2*sin(thita).*exp(j*k*(y2*sin(thita)*sin(phi)+z2*cos(thita)*l+sum(i3*sin(thita).*exp(j*k*(y3*sin(thita)*sin (phi)+z3*cos(thita)*ld