twopath.m

这是一个超短波地面反射双线信道模型的matlab程序。

%地面反射双线模型
clear all;
R0=6370000;
K=4/3;
R=R0*K;
h=5;
H=1;
c=300000000;
f=100000000;
v=50000/3600;
d=0:1:18431;
Rd=(R+h)*sqrt(2*(1-cos(d/R)));
Rf=2*sqrt(R^2+(R+h)^2-2*R*(R+h)*cos(d/(2*R)));
t_cha=(Rf-Rd)./c;%只与d有关
theta_d=d./(2*R);
theta_r=pi/2-acos(((Rf./2).^2+(R+h)^2-R^2)./(Rf*(R+h)));
fai=theta_r-theta_d;
D=(1+(d.^2)./(2*R*d.*sin(fai))).^(-1/2);%扩散因子
D(1)=1;
for k=1:5
   if k==1%海水，最下面一条
       er=70;%相对介电常数
       es=5;%电导率
   else if k==2%湿土
           er(k)=30;
           es(k)=0.017;%电导率
       else if k==3%淡水
               er(k)=80;
               es(k)=0.005;
           else if k==4%中等干土
                   er(k)=15;
                   es(k)=0.002;
               else    %很干土
                   er(k)=3;
                   es(k)=0.0001;
               end
           end
       end
   end
    ec(k)=er(k)-60*i*es(k)*c/f;%反射媒质的等效复介电常数
    pv(k,:)=(ec(k)*sin(fai)-sqrt(ec(k)-cos(fai).^2))./(ec(k)*sin(fai)+sqrt(ec(k)-cos(fai).^2));%垂直极化反射系数
    ph(k,:)=(sin(fai)-sqrt(ec(k)-cos(fai).^2))./(sin(fai)+sqrt(ec(k)-cos(fai).^2));%水平极化反射系数
    r(k,:)=exp(-2*(2*pi*H*sin(fai)*f/c).^2);
    a_ping(k,:)=Rd.*abs(pv(k,:)).*D./Rf;%平坦地形,与d\ec\f有关
    a_banzhe(k,:)=Rd.*abs(pv(k,:)).*r(k,:).*D./Rf;%半遮挡地形,与d\ec\H\f有关
    fd=v*f/c;%与v和f有关
    fai_cha(k,:)=mod(angle(pv(k,:))+2*pi*(f+fd)*t_cha,2*pi)*180/pi;%与d\ec\f\v有关
    figure(2)
    plot(d/1000,a_ping(k,:)),grid,hold on
    figure(3)
    plot(d/1000,a_banzhe(k,:)),grid,hold on
    figure(4)
    plot(d/1000,fai_cha(k,:)),grid,hold on
end
figure(1)
plot(d/1000,t_cha*10^9),grid