In which direction or directions does an electrically small loop (less than 1/10 wavelength in circumference) have nulls in its radiation pattern?
Why A small loop acts as a magnetic dipole: current is essentially uniform around the loop, and it responds to the magnetic field component that threads through the loop. Radiation and reception are strongest in the plane of the loop (a figure-8 pattern edge-on), and drop to sharp nulls along the axis perpendicular to the loop, which is the broadside direction. Those deep nulls are why small shielded loops are prized for direction finding and for nulling out a local noise source.
Watch out The choice naming the plane of the loop describes where the small loop's signal peaks, not its nulls; that answer would be right for a large full-wave loop, which does radiate broadside.
Look through the hole of a small loop and you hear nothing: nulls along the axis, peaks edge-on.