Assume $f(r)=\delta(r-R)$ where $\delta(\cdot)$ is a ring delta function. In other word, $f$ is a circular delta function on a circle with radius $R$. I want to do the convolution of $f$ with itself ($f*f$).
How can I do convolution in polar(spherical) coordinates. I read that I can use Hankel and inverse Fourier transforms to obtain the convolution, however I am not into the subject and I will appreciate if some could help me with this.