NDB Loop Antenna RNAV

The signal received by the ADFADF —Automatic Direction Finder loop aerial will depend upon what part of the incoming wave hits each of the two vertical components of the loop aerial.

Imagine you are in the sea and there are waves coming directly towards you. If you stand facing the incoming waves with your hands by your side, the wave will be at the same height on each of your two arms. There is no difference between the heights. On the other hand, if you turn so you are side on to the waves, then the water height on each of your arms will be different. In the loop aerial, this difference in “height” of the waves generates an electric signal as the different “heights” cause a difference in voltages. Thus, the signal will be strongest when the plane of the loop in in the same direction as the incoming signal.