An antenna system , comprising: a first quadrifilar radiating element, QRE, comprising a plurality of first bifilar helical loops, BHLs, oriented in a mutual orthogonal relationship on a common axis (Z), each first BHL comprising a pair of elongated conductive legs which define a plurality of turns about said common axis (Z) at a first pitch angle (φ1) and having a first turn radius (r); a second QRE sharing a common feed structure with the first QRE, the second QRE comprising a plurality of second BHLs oriented in a mutual orthogonal relationship on the common axis (Z), each second BHL comprising a pair of elongated conductive legs which define a plurality of turns about the common axis (Z) at a second pitch angle (φ2) and having a second turn radius (r'); wherein the first QRE is tuned for operation in a first frequency band, the second QRE is tuned for operation in a second frequency band different from the first frequency band, and the first radius (r) is substantially the same as the second radius (r'), the pair of elongated conductive legs comprising each of the first BHLs , and the pair of elongated conductive legs comprising each of the second BHLs all occupy the same surface circumference around said common axis (Z), wherein the surface circumference is defined by a cylindrical dielectric form axially aligned with the common axis (Z), characterized in that a first helical length (d1) of each elongated conductive leg comprising each of the first BHLs is longer than a second helical length (d2) of each elongated conductive leg comprising each of the second BHLs , and the first pitch angle (φ1) is different from the second pitch angle (cp2). a first quadrifilar radiating element, QRE, comprising a plurality of first bifilar helical loops, BHLs, oriented in a mutual orthogonal relationship on a common axis (Z), each first BHL comprising a pair of elongated conductive legs which define a plurality of turns about said common axis (Z) at a first pitch angle (φ1) and having a first turn radius (r); a second QRE sharing a common feed structure with the first QRE, the second QRE comprising a plurality of second BHLs oriented in a mutual orthogonal relationship on the common axis (Z), each second BHL comprising a pair of elongated conductive legs which define a plurality of turns about the common axis (Z) at a second pitch angle (φ2) and having a second turn radius (r'); wherein the first QRE is tuned for operation in a first frequency band, the second QRE is tuned for operation in a second frequency band different from the first frequency band, and the first radius (r) is substantially the same as the second radius (r'), the pair of elongated conductive legs comprising each of the first BHLs , and the pair of elongated conductive legs comprising each of the second BHLs all occupy the same surface circumference around said common axis (Z), wherein the surface circumference is defined by a cylindrical dielectric form axially aligned with the common axis (Z), characterized in that a first helical length (d1) of each elongated conductive leg comprising each of the first BHLs is longer than a second helical length (d2) of each elongated conductive leg comprising each of the second BHLs , and the first pitch angle (φ1) is different from the second pitch angle (cp2). <EOS>