Newnes Radio and RF Engineering Pocket Book, 3rd Edition

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be trapped between them. Under these conditions a signal can be

carried an abnormal distance before it can return to Earth resulting in

loss of signal at the intended receiver and possibly interference at a

distant one on the same frequency.

11.3 K factor

The degree and sense of refraction of wave is related to a factor known

as K. Refraction normally bends the wave downwards, extending the

range, but the refractive index of the atmosphere varies from place

to place and with time and height. At times, during an atmospheric

inversion for instance, and in some places on the earth the effect is

reversed:

When no bending occurs, K = 1.

When K>1, the bending is downwards, effectively increasing

the Earth’s radius.

When K<1, the bending is upwards, effectively ...