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## Main Question or Discussion Point

Is it true that we can consider a spherical wave in the far field (i.e. away from antenna, at a large distance) as a plane wave ? For a plane wave the electric field at a distance s is usually given as:

E(s) = E(0) * exp(-jks) ----- (1)

where k is the wave vector, s is the distance travelled and E(0) is the electric field at a reference point.

But if I'm not wrong then in case of a spherical wave, there is a 1/s decay so for spherical wave:

E(s) = E(0) * 1/s * exp(-jks) --------(2)

Now my question is: If I am trying to simulate a plane wave with a spherical wave in far field, then should I use formula (1) or (2).

E(s) = E(0) * exp(-jks) ----- (1)

where k is the wave vector, s is the distance travelled and E(0) is the electric field at a reference point.

But if I'm not wrong then in case of a spherical wave, there is a 1/s decay so for spherical wave:

E(s) = E(0) * 1/s * exp(-jks) --------(2)

Now my question is: If I am trying to simulate a plane wave with a spherical wave in far field, then should I use formula (1) or (2).