Abstract: A quadrifilar helix antenna includes a cylindrical support extending along an antenna axis; a plurality of spiral conductors wrapped helically on the cylindrical support and along the antenna axis from a feed end to a remote end; a circular ground plane perpendicular to the antenna axis; and each of the spiral conductors including a plurality of gaps, with the gaps having capacitors between conducting portions of the spiral conductors. The capacitors are positioned higher than 60 mm above the ground plane, and capacitance value varies inversely with height. The antenna exhibits a DU(10°)=?20 dB or better at an operating frequency f0=1575 MHz. The diameter of the cylindrical support is 30+/?5 mm. A total height of the cylindrical support is 300+/?50 mm. A winding angle of the helix is variable.

Abstract: A quadrifilar helix antenna includes a cylindrical support extending along an antenna axis; a plurality of spiral conductors wrapped helically on the cylindrical support and along the antenna axis from a feed end to a remote end; a circular ground plane perpendicular to the antenna axis; and each of the spiral conductors including a plurality of gaps, with the gaps having capacitors between conducting portions of the spiral conductors. The capacitors are positioned higher than 60 mm above the ground plane, and capacitance value varies inversely with height. The antenna exhibits a DU(10°=?20 dB or better at an operating frequency f0=1575 MHz. The diameter of the cylindrical support is 30 +/?5 mm. A total height of the cylindrical support is 300 +/?50 mm. A winding angle of the helix is variable.

Abstract: A quadrifilar helix antenna includes a cylindrical support extending along an antenna axis; a plurality of spiral antenna elements wrapped helically on the cylindrical support and along the antenna axis from a feed end to a remote end; a ground plane having a diameter of about 300 mm and perpendicular to the antenna axis; and each of the antenna elements including a plurality of breaks, with the breaks having capacitors between conducting portions of the antenna elements. All capacitors a positioned higher than 60 mm above the ground plane, and capacitance value varies inversely with height. The antenna exhibits a DU(10°)=?20 dB or better at an operating frequency f0=1575 MHz. The diameter of the cylindrical support is 30 +/?5 mm. A total height of the cylindrical support is 300 +/?50 mm. A winding angle of the helix is variable.

Abstract: A quadrifilar helix antenna includes a cylindrical support extending along an antenna axis; a plurality of antenna elements wrapped helically on the cylindrical support and along the antenna axis from a feed end to a remote end; a ground plane having a diameter of about 300 mm and perpendicular to the antenna axis; and each of the antenna elements including a plurality of breaks, with the breaks having capacitors between conducting portions of the antenna elements. All capacitors are positioned higher than a height H1=90+/?30 mm mm above the ground plane. The antenna exhibits a DU(10°-90°)[dB]=?20 dB or better at an operating frequency f0=1575 MHz. The diameter of the cylindrical support is 30+/?5 mm. A total height of the cylindrical support is 300 +/?50 mm. A winding angle of the helix is variable.