High-frequency radiating line

A high frequency radiating line intended to radiate electromagnetic energy over a defined frequency band, said defined frequency band extending in increasing frequency from a minimum frequency at which the line radiates electromagnetic energy in a radial direction, which line comprises a tubular outer conductor including apertures configured to form a periodic pattern (M) repeated along said outer conductor with a predetermined pitch (p), said pitch being a fraction of a maximium wavelength, said maximum wavelength corresponding to said minimum frequency, said fraction being equal to 1/((.epsilon..sub.r).sup.1/2 +1) where .epsilon..sub.r is the relative dielectric constant of the line, wherein the periodic pattern (M) has a length (L) equal to p/2.+-..DELTA., along a direction parallel to the axial direction of the line.