An automatic target tracking system and method employ an image capturing system for acquiring a series of images in real time of a distant area containing a remote target, and a processing system for processing the acquired images to identify the target and follow its position across the series of images. The ring comprises a first surface running perpendicular to the center axis, a second surface which is parallel to the first surface, and a plurality of spaced apart through openings running parallel to the center axis and extending through the fixation plate. One or more of these filter cells is associated with a damped series resonance circuit comprising a capacitor series coupled with an RL circuit between two winding of a symmetrical coil of the associated filter cell.