Patent ID: 6480173
Filing Date: 2002-11-12
Classification: H01Q

Abstract:
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 180Â° 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 180Â° 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.