Panel a: as in Fig. 1, but with three values of Ψ, Ψ₁ = 90°, Ψ₂ = 75° and Ψ₃ = 60°. Panel b: vectors on the Stokes (Q, U) plane. The jet vector is stationary. The 3 burst vectors rotate CCW around the tip of the jet vector, starting at t = −10 and ending at t = +10. The sum vector rotates around the origin. The arrow at bottom right shows the direction of time. The vectors for Ψ₃ are shown at t = +6. Loops 1 and 2 enclose the origin but loop 3 does not. Panel c: polarized flux density, PF, and EVPA, for the 3 cases in (b). Note that cases 1 and 2, which enclose the origin in (b), have EVPA rotations of 180°, while case 3 has a mild swing of 42.0° CW followed by a return to the starting level. Note also in (c) that case 2 has a deep PF minimum with a rapid EVPA swing, when the loop in (b) gets close to the origin.