What are the extra lines on this farfield plot?
Here's how I see it: -



I've extended the blue lines and they form an angle that is 75.8 degrees and coincide with the -3 dB points from a peak magnitude of 7.28 dBi.


  I'm having trouble understanding why the plot isn't single-valued (2nd
  red circle)


I have no idea which 2nd red circle you mean and why you expect something that is single valued.