Axial Ratio

Axial ratio is defined as the ratio of the major to the minor axis of the polarization ellipse.

  1. Exand Ey are orthogonal complex-valued field components. If either is zero, HFSS treats the field as linearly polarized. However, if neither Exand Ey is zero:
  2. Compute circular components E- and E+ from:

     

    E- = Ex - jEy

    (1)

     

    E+ = Ex + jEy

    (2)

  1. If E+ = 0 or E- = 0 HFSS understands the field as perfectly circular, the axial ratio is 1. Otherwise, for the elliptical polarization case, HFSS determines the tilt angle t from:

     

    phase(E-/E+) = 2t

    (3)

  2. Rotate the original data to coincide with the axes of the polarization ellipse.

     

    (4)

     

    (5)

  1. The Axial Ratio AR is given by:

     

    (6)

Because the above definition does not discriminate between major and minor ellipse axes, to enforce the convention that AR< 1, it is necessary to check this condition and if necessary invert the value obtained.