Abstract: The invention relates to a plane periodic antenna, wherein it comprises a conductive plate having radiating elements formed from two lines of flat teeth, whereof the dimensions are deduced from one another on the basis of a homothetic transformation of ratio .tau. and expansion pole O, the teeth of one of the two lines being inserted between the teeth of the other line and the end of one given tooth being separated from the edge of the plate located between two teeth of the other line by a predetermined gap, a supply line place in a plane close to that of the plate making it possible to supply the teeth, from the predetermined gap, a ground plane located at a distance from each tooth varies as a function of the wavelength of each tooth.

Abstract: The invention relates to wide-band, plane, spiral antennas. A conductive arm is arranged spirally in a plane close to a reflector. A resonator member positioned at the centre and in front of the spiral assists the area opposite which it is situated to radiate at high frequencies, to the detriment of the peripheral areas. An absorbent member whose thickness increases from the centre to the periphery increases this effect even further.