Abstract: The invention concerns a quadrifilar helix antenna that has four orthogonal conductive elements helically wound around a common axis. Each of the conductive elements can have between 3 to 7 turns about the common axis at a pitch of between 45 to 65 degrees. Further, each turn has a diameter of about 0.13 wavelengths to 0.27 wavelengths. A feed coupler excites each of the orthogonal conductive elements in phase quadrature at a feed point located at a first end of the antenna adjacent to a ground plane. The resulting antenna can have an axial length of about 2.3 wavelengths to 6.9 wavelengths. Unlike conventional quadrifillar helix antennas, an opposing end of each of the conductive elements distal from the feed point forms an open circuit. The antenna configured as described can have a peak gain on horizon when the common axis is oriented vertically.

Abstract: A multi-frequency band antenna may include a base and a first antenna array including a plurality of spaced apart monopole antenna elements extending outwardly from the base a first distance for operating at a first frequency. Further, the multi-frequency band antenna may also include a second antenna array including a plurality of spaced apart antenna elements arranged outside the first antenna array and extending outwardly from the base a second distance less than the first distance. The second antenna array may be for operating at a second frequency lower than the first frequency.

Abstract: The invention concerns a quadrifilar helix antenna that has four orthogonal conductive elements helically wound around a common axis. Each of the conductive elements can have between 3 to 7 turns about the common axis at a pitch of between 45 to 65 degrees. Further, each turn has a diameter of about 0.13 wavelengths to 0.27 wavelengths. A feed coupler excites each of the orthogonal conductive elements in phase quadrature at a feed point located at a first end of the antenna adjacent to a ground plane. The resulting antenna can have an axial length of about 2.3 wavelengths to 6.9 wavelengths. Unlike conventional quadrifillar helix antennas, an opposing end of each of the conductive elements distal from the feed point forms an open circuit. The antenna configured as described can have a peak gain on horizon when the common axis is oriented vertically.

Abstract: A multi-frequency band antenna may include a base and a first antenna array including a plurality of spaced apart monopole antenna elements extending outwardly from the base a first distance for operating at a first frequency. Further, the multi-frequency band antenna may also include a second antenna array including a plurality of spaced apart antenna elements arranged outside the first antenna array and extending outwardly from the base a second distance less than the first distance. The second antenna array may be for operating at a second frequency lower than the first frequency.