Patent ID: 6025816
Filing Date: 2000-02-15
Classification: H01Q

Abstract:
An antenna operable in two disparate frequency bands, comprising:(a) a first quadrifilar helix including four conductive elements arranged helically to define a cylinder of substantially constant radius, said first quadrifilar helix being formed of two bifilar helices arranged orthogonally and excited in phase quadrature; and(b) a quadrature feed network connected to said first quadrifilar helix, wherein one end of a coupling element thereof is connected to a first end of each said conductive element, said quadrature feed network further comprising:(1) a first feedpoint connected to a first pair of said conductive elements, said coupling element being balanced and said first quadrifilar helix having circular polarization, wherein said antenna is operable in a first frequency band; and(2) a second feedpoint connected to a second pair of said conductive elements, said coupling element being unbalanced and said first quadrifilar helix having linear polarization, wherein said antenna is operable in a second frequency band.