Concentric Hypnotic Circles

Hello,

I’d like to create a material in UE4 with concentric rings that constantly shrink towards the centre. Just like in this video HERE.

I imagine I would use a sine wave for this maybe but I’m not sure how to begin.

Any ideas on technique for this goal would be much appreciated. Bonus if you know how to achieve the same effect in Niagra.

Cheers.