Minkowski QU loops in the vertical magnetic field. The top six panels were computed for ι = 10 ° < ι₀, where ι₀ is defined in Eq. (39) and defines the highest angle for which there should be two QU loops. The bottom six panels were computed for ι = 10 ° > ι₀. The six panels represent the following quantities. Top-left: summed images of the hot spot in normalized intensity. We note that the color coding has been inverted to improve readability (i.e., a darker color means more intense emission). Top-middle: astrometric track on sky. In this panel and the next ones, the color codes (from violet to red) are for time, clockwise motion on sky. Top-right: total flux (colored dots), linearly polarized flux (, red curve), and linear polarization fraction (LP, in percent, blue curve) evolution. The flux ratio F_ratio (maximum over minimum fluxes) is provided in the bottom-right corner of the panel together with the linearly polarized flux ratio (written in red) and the flux ratio F_ratio(avg) obtained after averaging over the angular dependence of the radiative transfer coefficients (the sin θ_B dependence). We note that the density and temperature of the hot spot have been chosen such that the low-inclination, vertical magnetic field near infrared flux peaks at around 10 mJy. Bottom-left: Q/I, U/I plane. Bottom-middle: Q, U plane (which we refer to when discussing the QU loops). Bottom-right: observed EVPA evolution. The red profile shows the emission EVPA evolution as predicted by the analytic model derived in Eq. (30). As predicted, the upper case shows two QU loops, while the bottom one shows only one loop.