non planar Electromagnetic wave

the em wave that we study generally in books are uniform plane waves.
can you please elaborate non planar waves with some examples.

Hello,

I think in free space it will be impossible to current state of knowledge. In case of bounded propagation it can be non-planar (think of various transmission lines and wave guides (metallic or dielectric) ). It all follows from the Maxwell Equations.

As a simple example, the near field of an antenna, e.g. a Hertz dipole is neither uniform nor plane.

but how will we determine that wave is planar or non-planar ?

If you can find a plane (within your volume of interest) where all E-field contributions are in phase, you can consider it a plane wave. For antenna applications a deviation of 22.5degr is mostly accepted and therefore still considered a plane wave.

A certain field can be considered plane when it hits a small antenna (say a 2*2 element array), however it may not be plane (enough) for a 8*8 element array (as that is physically larger).

Plane versus non-plane is of importance for antenna measurement.

didnt' get a full picture of that.
can you provide any tutorial on this.