Learning Forum

[Guilin Sun]

I guess "shift" simply means that you move the reference point.

Phase is a little tough: it is relative. It should have a reference. For broadband source like yours, the phase reference point is usually the angle(E) at the shortest frequency. All other phases are based on this reference value. using unwrap(angle(E)) will lead to phases as a function with frequency without pi change.

If you use angle(E) it will remove the extra Pi phase,like the last graph in your post. 

If you change the shortest frequency the phase curve will be changed.

You shuld be ablge to get the phase like the green figure using unwrap(angle(Etheta)) or Ephi.

You can also use a reference point at the center frequency, by deducting its phase from all other phases.

Please try and let me know if you have questions further.