Hi Md Siam Talukder ,

I know nothing about significance but one clarification comes to mind:

If you are drawing an 8 with a crossing line at the center: This shape is certainly not possible as electric field or, more generally, as a vector field.

If your 8 consists of two circles, touching each other at the center: This is a very common shape. Take a toroidal coil as example: In an arbitrary plane cross-section, containing the central axis of the toroid, the E field looks like that when the magnetic flux in the coil changes.

You can get a figure 8 radiation pattern when the antenna radiates equal beams in the forward and backward directions. I think two dipoles 180 degrees out of phase and 180 degrees apart would come close to this. A cut through the radiation pattern of a dipole looks like a figure 8, but it is actually a cut through a doughnut or car-tyre shape.