I understand that you want to extract phase angles from channel matrix (which is 'csi' in the data file). However, using the script you provided, I am not able to get the same plot you had.
The difference is that using the "unwrap" function leads to phase angles within a range of [-5 5). This behavior is expected with regards to the documentation page in the following help link.
As described in the above page, the default tolerance of the "unwrap" function is 'pi'. Most of the phase angle jumps (in absolute values) are less than 'pi' in the original phase angle matrix. As a result, the result of using the "unwrap" function includes three sawtooth-shape curves within a range of [-5 5).
The difference you saw might be caused by the tolerance used in the "phase" function. You can inspect the code of this function by executing the following command in the MATLAB Command Window:
The tolerance used by the "phase" function is '3.5' at line 26. This value is larger than the default tolerance used by the "unwrap" function. If you modify the tolerance in the "phase" function and use it to process the data in 'csi', the result is similar to the curves in the middle plot you had.