1. n. [Formation Evaluation]
The additional loss in amplitude of an electromagnetic wave emitted by an electromagnetic propagation or dielectric propagation measurement compared to that of a plane wave. The spreading loss depends on the geometry of the transmitter-receiver array and also on the dielectric properties of the formation. The same effect also causes a small correction to the propagation time.
See: attenuation, broadside array, dielectric propagation log, electromagnetic propagation, electromagnetic propagation measurement, endfire array, plane wave