An active electronically scanned array antenna comprising: • an active array configured to radiate/receive radiofrequency signals through first radiating openings lying on a ground plane; • a dielectric cover designed to act both as wide-angle impedance matcher and as protection for the active electronically scanned array antenna, whereby the dielectric cover is parallel to the ground plane and spaced apart from the latter by a given distance so as to result in an air gap present between said dielectric cover and said ground plane; and • a plurality of calibration devices operable to calibrate said active electronically scanned array antenna; said active electronically scanned array antenna being characterized in that each calibration device comprises a respective radiating portion, a respective transition portion, and a respective middle portion; wherein for each calibration device: • the respective radiating portion is arranged between the dielectric cover and the ground plane, is oriented parallelly to the ground plane, and comprises a respective first waveguide ending, at a first end, with a respective second radiating opening which - gives out onto the air gap towards corresponding first radiating openings, - is perperidicular to the ground plane, and - is configured to receive radiofrequency signals radiated through said corresponding first radiating openings and to radiate radiofrequency signals in the air gap towards said corresponding first radiating openings; • the respective transition portion is oriented perpendicularly to the respective radiating portion and includes a respective second waveguide and a respective third waveguide cascaded thereto; • the respective middle portion is curved at 90° and includes a respective fourth waveguide coupled, at one end, to the respective third waveguide and, at the other end, to a second end of the respective first waveguide; • the respective first waveguide, the respective third waveguide and the respective fourth waveguide have - one and the same given width depending on an operating frequency of the calibration device, and - one and the same given height such that to enable the respective radiating portion to be arranged between the dielectric cover and the ground plane; and • the respective second waveguide is coupled through a respective SMA connector with a signal source to receive therefrom the radiofrequency signals to be radiated, and has - said given width, and - a height greater than said given height. • an active array configured to radiate/receive radiofrequency signals through first radiating openings lying on a ground plane; • a dielectric cover designed to act both as wide-angle impedance matcher and as protection for the active electronically scanned array antenna, whereby the dielectric cover is parallel to the ground plane and spaced apart from the latter by a given distance so as to result in an air gap present between said dielectric cover and said ground plane; and • a plurality of calibration devices operable to calibrate said active electronically scanned array antenna; said active electronically scanned array antenna being characterized in that each calibration device comprises a respective radiating portion, a respective transition portion, and a respective middle portion; wherein for each calibration device: • the respective radiating portion is arranged between the dielectric cover and the ground plane, is oriented parallelly to the ground plane, and comprises a respective first waveguide ending, at a first end, with a respective second radiating opening which - gives out onto the air gap towards corresponding first radiating openings, - is perperidicular to the ground plane, and - is configured to receive radiofrequency signals radiated through said corresponding first radiating openings and to radiate radiofrequency signals in the air gap towards said corresponding first radiating openings; - gives out onto the air gap towards corresponding first radiating openings, - is perperidicular to the ground plane, and - is configured to receive radiofrequency signals radiated through said corresponding first radiating openings and to radiate radiofrequency signals in the air gap towards said corresponding first radiating openings; • the respective transition portion is oriented perpendicularly to the respective radiating portion and includes a respective second waveguide and a respective third waveguide cascaded thereto; • the respective middle portion is curved at 90° and includes a respective fourth waveguide coupled, at one end, to the respective third waveguide and, at the other end, to a second end of the respective first waveguide; • the respective first waveguide, the respective third waveguide and the respective fourth waveguide have - one and the same given width depending on an operating frequency of the calibration device, and - one and the same given height such that to enable the respective radiating portion to be arranged between the dielectric cover and the ground plane; and - one and the same given width depending on an operating frequency of the calibration device, and - one and the same given height such that to enable the respective radiating portion to be arranged between the dielectric cover and the ground plane; and • the respective second waveguide is coupled through a respective SMA connector with a signal source to receive therefrom the radiofrequency signals to be radiated, and has - said given width, and - a height greater than said given height. - said given width, and - a height greater than said given height.