YOu have to initialize your t and y as cells.....the output of the line which throws error is a vector, and you are storing it as a scalar...so error popping out.
q=10e8:(20e9-10e8)/1000:20e9;
q=q';
s=length(q);
epso = 8.8 *10.^-12;
epsr=5.7;
ro=3.63*(10.^-3);
epsl = 2.5;
ri=1.13*(10.^-3);
copen = (epso/sqrt(epsr)*log(ro/ri));
cload= (epsl/sqrt(epsr)*log(ro/ri));
t = zeros(1,s);
y = cell(length(q),1) ;
t = cell(length(q),1) ;
for f = 1:length(q)
fun = @(x)((((((besselj(0,(2*pi*q(f))/(3e8))*x*ro)-besselj(0,(2*pi*q(f))/(3e8))*x*ri)).^2)./x)*freload(x,q));
y{f} = copen*abs(integral(fun,0,Inf,'Arrayvalued',true));
t{f}=(1-y{f})./(1+y{f});
end
Now y and t are cells...you can do what you want with them.
