Hmmm. I'm not 100% sure because I'm not familiar with Hankel transformations. But I read that in the documents `HankelTransform`

implicitly assumes that the input function is supported in $]0, infty[$[$[$[$, So if `ring delta`

is not zero, `r0`

must be positive As I said, this is implicitly accepted; for the return value of `InverseHankelTransform`

this is explicitly stated by multiplication `HeavisideTheta[r0]`

, Also note that

`1 / (2πr) DiracDelta[r - r0]`

equal `1 / (2πr0) DiracDelta[r - r0]`

,

We can check the result `InverseHankelTransform`

equal `ring delta`

in the sense of distribution by integration against a symbolic test function:

```
Integrate[(ringDelta - InverseHankelTransform[fRingDelta, ρ, r]) φ[r],
{r, 0, ∞},
Assumptions -> r0> 0
]
```

0