A secondary radar equipped with an electronic-scanning antenna with active or semi-active emission regime, covering space azimuthally over 360°, characterized in that said radar: - is mechanically and functionally independent of the primary radar; - applies the principles of separation ∘ of emission pattern for each interrogation of any mode; ∘ of reception pattern for each reply of any mode; ∘ of assignment of the tasks which are specific thereto to distinct units; - has one or more SSR / IFF interrogators dedicated at one and the same time to SSR or IFF surveillance and to gathering new mode S targets; - further contains one or more other SSR / IFF interrogators for selective surveillance (92, 93) dedicated to mode S surveillance and to directed interrogations of IFF identification; - ensures the simultaneous emission (61, 63) of the interrogations of said SSR / IFF interrogators (91, 92, 93) in different azimuths (71, 72, 73), said simultaneous emission being enabled when the azimuthal spacing of the beams formed in emission ensures a decoupled level of jamming at the level of the transponders of the aircraft between the interrogations received by the respective sidelobes of the beams formed in emission; - ensures simultaneous reception (62, 64) of the replies to said interrogators (91, 92, 93) in different azimuths (71, 72, 73), said simultaneous reception being enabled when the azimuthal spacing of the beams formed in reception ensures a decoupled level of jamming at the level of the radar between the replies expected by the respective sidelobes of the beams formed in reception; - instructs the interrogators to ensure amongst themselves the temporal separation of either the emission or reception periods when the spacing of the beams in azimuth is insufficient to guarantee detection. - is mechanically and functionally independent of the primary radar; - applies the principles of separation ∘ of emission pattern for each interrogation of any mode; ∘ of reception pattern for each reply of any mode; ∘ of assignment of the tasks which are specific thereto to distinct units; ∘ of emission pattern for each interrogation of any mode; ∘ of reception pattern for each reply of any mode; ∘ of assignment of the tasks which are specific thereto to distinct units; - has one or more SSR / IFF interrogators dedicated at one and the same time to SSR or IFF surveillance and to gathering new mode S targets; - further contains one or more other SSR / IFF interrogators for selective surveillance (92, 93) dedicated to mode S surveillance and to directed interrogations of IFF identification; - ensures the simultaneous emission (61, 63) of the interrogations of said SSR / IFF interrogators (91, 92, 93) in different azimuths (71, 72, 73), said simultaneous emission being enabled when the azimuthal spacing of the beams formed in emission ensures a decoupled level of jamming at the level of the transponders of the aircraft between the interrogations received by the respective sidelobes of the beams formed in emission; - ensures simultaneous reception (62, 64) of the replies to said interrogators (91, 92, 93) in different azimuths (71, 72, 73), said simultaneous reception being enabled when the azimuthal spacing of the beams formed in reception ensures a decoupled level of jamming at the level of the radar between the replies expected by the respective sidelobes of the beams formed in reception; - instructs the interrogators to ensure amongst themselves the temporal separation of either the emission or reception periods when the spacing of the beams in azimuth is insufficient to guarantee detection.