I am trying to simulate OAM(orbital angular momentum) in CST using UCA (uniform circular array). The literature shows they are setting observation distance to a particular value and plotting the phase of E-field which is spiral pattern. However, I am unable to verify the plots presented in literature.

1. I have created the structure with 8 patch antennas with 8 discrete ports.
2. I have excited these antennas simultaneously with the desired phase shift.
3. I am simulating using time domain solver and observing E-field and farfield at desired frequency.

I need help with following points.

1.  I am unable to plot phase of farfield.
2. How to set farfiled observation point to a particular distance 
3. What do the left phase, right phase signify?

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