Abstract: The present invention relates to a planar antenna (1) for excitation of the TE01-mode of an electromagnetic wave and adapted to be arranged in a waveguide tube (2). The planar antenna comprises a substrate (6) of dielectric material having a first surface (7) intended to face towards a filling good surface and a second surface (8) facing in an opposite direction. A first group (9) of a plurality of dipole arms (10) is arranged on the first surface (7) or the second surface (8) on a perimeter of a circle with a predetermined radius. A second group (11) of a plurality of dipole arms (12) is arranged on the first surface (7) or the second surface (8) on the perimeter of the circle with the predetermined radius. The dipole arms (10) of the first group (9) extend in a first direction and the dipole arms (12) of the second group (11) extend in a direction opposite the first direction.

Abstract: The present invention relates to a planar antenna (1) for excitation of the TE01-mode of an electromagnetic wave and adapted to be arranged in a waveguide tube (2). The planar antenna comprises a substrate (6) of dielectric material having a first surface (7) intended to face towards a filling good surface and a second surface (8) facing in an opposite direction. A first group (9) of a plurality of dipole arms (10) is arranged on the first surface (7) or the second surface (8) on a perimeter of a circle with a predetermined radius. A second group (11) of a plurality of dipole arms (12) is arranged on the first surface (7) or the second surface (8) on the perimeter of the circle with the predetermined radius. The dipole arms (10) of the first group (9) extend in a first direction and the dipole arms (12) of the second group (11) extend in a direction opposite the first direction.