A circularly polarized MSA can be realized by exciting two orthogonal modes
with equal magnitudes, which are in phase quadrature.
The sign of the relative phase determines the sense of polarization (LHCP or RHCP)
[1, 3].
The simplest way to obtain CP is to use two feeds at orthogonal
positions that are fed by 1Ð0° and 1Ð90° as shown in Figure 8.2