Orientation of Loop Antenna (receiving mode)
Since the EM waves are radial to line of sight and never longitudinal, it is the viewed  effective aperture geometry of the antenna  relative to \$\lambda /2\$ that permits matching the impedance or transferring RF power to a load. 

Thus when you see no aperture rotated by 90 deg now inline with line of sight, you can expect a null in the aperture and signal and thus only get fringe signals from reflections or nothing.  

This also applies to a dipole.  Staggered dipoles in parallel are called a Yagi antenna. 

The geometric ratio of conductor, l and gap, g of the return current determines the cable impedance. e.g. 200 vs 75 vs 50 Ohm as well as the Dk between them.

If signals are broadside to the antenna then the radial EM fields can induce a longitudinal current.