Directions of the radio waves in the observer’s frame. The two smaller tangent grey disks in the middle of the plot correspond to the waves that are beamed at ≤90° from the Alfvén wing axis in the source frame in the approximation of very high γ values (see text for the precise meaning of “very high”). The two large circles (black lines) are the radio-beaming patterns associated with the CMI. They are defined by x = δ_± + θ_ocosϕ_o and y = θ_osinϕ_o, with θ_o and ϕ_o the cylindrical angular coordinates of the wave vector in the observer’s reference frame of each Alfvén wing. θ_o and ϕ_o are related via Eq. (10) (or Eq. (13)) to the wave vector coordinates in the source frame θ_s and ϕ_s given by Eq. (12). The most intense emissions correspond to the innermost intersection of each large circle with the horizontal axis. Here γ = 10, r = 0.1 AU and α_s = 85°. With these parameters, x = 78. The stars mark the directions of the most intense radio emissions.