ADF Errors

Question 1

Vertical or antenna effect

Answer 1

When two halves of the loop is unbalanced, the current induced in the E field does not sum up to zero, this affects the null signal. So the direction of arrival of the null is not perpendicular to the plane of the loop.

Question 2

Quadrantal error

Answer 2

When waves arrive at the aircraft striking the whole aircraft, some of the waves will be reflected and the antenna will receive the reflections together with the direct waves, this will affect the null signal. Hence causing the indication to suffer considerable errors.

Question 3

Night effect

Answer 3

This is the polarisation error. This effect is most noticeable during sunrise or sunset when the ionosphere is changing the most rapidly.

Question 4

Static interference

Answer 4

Static build up on the airframe and consequent discharges will reduce the effective range and accuracy of the ADF. Thunderstorms is also a source of static interference, this will give huge bearing errors.

Question 5

Coastal refractions

Answer 5

When a wave is over land it has a different speed than when it is over sea. At the coastline, the speed change will cause the wave to bend towards the land as attenuation is greater.

When the wave is at 90 degrees to the coastline, there will not be any effect. When the wave is at 30 degrees to the coastline, it will have considerable effect. High flying aircrafts will also experience this effect less compared to low flying ones.