Ferrite aerials for reception in cars

[G8HQP Dave]

It is often said that local interference is vertically polarised. I suspect that it is not as simple as that. There can also be a longitudinal component. A simple whip or 'long wire' antenna would be sensitive to this whatever its orientation. MF/HF dipoles (which are less sensitive to longitudinal components because of balance) are more often arranged horizontally.

People put up a typical vertical monopole and find it noisy. They put up a typical horizontal dipole and find it quieter - but also poorer at picking up broadcast ground wave signals. They conclude that local noise is vertical, but they are not comparing like with like because it is not realised that local interfering signals are not quite the same as radiated transverse signals.