How can I create this figure?

Hi everybody I want to write codes that create Concentric Circles like this figure(first.png),please help me. Actually these circles are path for a sensor node which is equipped with GPS(which is called beacon node), this sensor node traverses the network on these paths in order to help normal nodes to assume their position(coordinates). First I want to create this path and then move this beacon node on these paths(The red stars are beacon points).I have attached the figures. Thanks in advance.

Answer 1

[KSSV]

r0 = 0 ; dr = 0.2 ; r1 = 1. ;
r = r0:dr:r1;
th = linspace(0,2*pi) ;
figure
hold on
axis equal
for i = 1:length(r)
    x = r(i)*cos(th) ;
    y = r(i)*sin(th) ;
    plot(x,y) ;
end

[Zeinab Ahmadi93]

Thanks dear KSSV... :) I have seen the codes like this but the problem is that I don't know how to change the ranges to match my desirable figure and as you can see there is a line which connect the three circles... I don't know how to create them:(