Small ball probabilities for certain gaussian fields

We study the behavior of the tail probabilities $P(V^2<r)$ as $r\to 0$, where $V^2$ is defined by the following double sum $$V^2 =\pi^{-4}\,\sum\limits_{i,j\ge 1} \Big((i+b)\,(j + \delta)\Big)^{-2}\,\xi_{ij}^2,$$ where $\{\xi_{ij}\}$ are independent standard normal random variables, and $b$ and $\delta$ are constants: $b>-1,\ \delta>-1$.