Illustration of the spinor 𝒫_v in the complex plane (Q, U) for a sum of two almost anti aligned power laws, with a close-up view around v = v₀ (upper panel). Black crosses mark the steps of 10 GHz on the signal. The values of frequencies are indicated above the crosses in GHz. The corresponding polarized intensity P_v (central panel) and polarization angle γ_v (lower panel). We choose logarithmic representations to emphasize the focus on the v ~ v₀ point.