A quadrifilar helix antenna (1) comprising a first and a second set of helical antenna elements (2a 5a, 2b 5b) symmetrically arranged around a longitudinal axis extending through the axial center of the antenna (1). The antenna (1) is excited from feeding points (2c 5c) in a local ground plane at the bottom (6) of the antenna. The helical antenna elements (2a 5a) of the first set are interconnected in respective top ends of the elements at the top (7) of the antenna. The bottom ends of the first set are in galvanic contact with the respective feeding points (2c 5c). The antenna is characterized in that the top ends of helical antenna elements (2b 5b) of the second set are arranged in an open circuit and remain unconnected. The bottom ends of the helical antenna elements (2b 5b) of the second set each includes a connection (2d 5d) to the local ground plane.