Quadrifilar helix feed network

A radio antenna system comprising:

• a quadrifilar antenna having four helical arms having electrically connected first ends and separated second ends located on different quadrants of a circle;
• a first balun having two feed points located on opposite quadrants of the circle for feeding two of the helical arms, and
• a second balun having two feed points located on different opposite quadrants of the circle for feeding the other two of the helical arms, wherein the first balun comprises:
• a first dielectric substrate having a first side and an opposing second side;
• two electrically conductive sections located on the first side of the first dielectric substrate for separately providing the two feed points of the first balun;
• and
• a first feed line located on the second side of the first dielectric substrate for electromagnetically coupling the electrically conductive planes of the first balun for providing a 180° phase differential between the two feed points of the first balun, and wherein the second balun comprises:
• a second dielectric substrate having a first side and an opposing second side;
• two electrically conductive planes located on the first side of the second dielectric substrate for separately providing the feed points of the second balun;
• and
• a second feed line located on the second side of the second dielectric substrate for electromagnetically coupling the electrically conductive planes of the second balun or providing a 180° phase differential between the two feed points of the second balun, wherein the first substrate has a first slot and the second substrate has a second slot complimentary to the first slot for orthogonally arranging the first balun and the second balun in relation to the circle.