Net flux (F_I, upper) and circularly polarized fraction (F_V, lower) simulated for the reference circumstellar disk model (113.144 GHz CN line emission). In the lower images, the derivative of F_I is shown and fitted to F_V to estimate the LOS magnetic field strength (red dashed line). The profiles on the left are simulated with the reference disk model with an inclination of 30°. The simulated profiles on the right side use the reference disk model with an inclination of 30° and a dead zone close to the star. The extent of this dead zone ranges from the inner disk edge to a radial distance of ~5 AU and from the midplane to a vertical distance of ~0.5 AU in both directions.