# E Vs. H Waves RNAV

An electromagnetic wave is formed of two components, the electric (E) and magnetic (H) waves. These oscillate perpendicular to each other as they travel outwards in the same direction.

A useful way to imagine this is to imagine a line going from your eye to a distant object. This represents the way the wave is travelling away from you, the “aerial”. In this case, the E wave would be moving up and down along this line towards the object (for example, like waves in the sea) but the H wave will be going side to side (for example, like a snake slithering along the ground).

This distinction is not purely academic, as when the wave is received it is more efficient if the wave is in the same plane as the receiving antenna. In the case above, the antenna would be pointing vertically upwards, to generate the “up and down” wave. This is important because the receiving antenna will receive the signal best if it is also in the same plane as the electric signal. Hence, waves generated by vertical aerials are best received by other vertical aerials, and so on.