.



Looks can be deceiving. The NVIS loop and DRRR are both
constructed of large diameter conductors because of the
lower radiation resistance they share. But other than that,
they have little in common. The DRRR requires a ground plane,
and is vertically polarized, the exact opposite requisite for NVIS.

Although a vehicle top is usually made of metal, a loop antenna,
by its nature, does not not require a ground plane.