Reconstructed coronal loops and the distribution of their physical parameters. Panels a–c: 3D structure of the magnetic field from a potential field model with the background of the 171 Å waveband on 2010 October 16, 2011 September 6, and 2012 March 7, respectively. Panels d–f: corresponding height (black filled dot), the distribution of the magnetic field strength (blue filled dot) along the loop length, and the average magnetic field strength (blue dashed line). Panels g–i: corresponding electron density (black solid line) and the fitting curve (red dashed line).