how to assign dimention for radiation box for dipole in hfss /any relation with lambd

i had design the dipole at 2.4GhZ, now prob is at the end of the design need to draw radiation box . what are the rules for drawing the dimentions of radiation box? is there any rules/equations / any relation with respect to lambda?

Typically, you want the edges of the box to be at least lambda/4 away from the closest radiating surface.