Window antenna for a motor vehicle body

Claim 1

In a window opening of a motor vehicle having a metallic body, the combination therewith of a window pane having adjacent a metal frame member of said body, a mobile radio antenna on said pane for dual band operation at two frequencies of wavelengths L and K, respectively, differing by a factor of 2 and whereby L=2K, said antenna comprising: an L/4 monopole and a K/4 monopole electrically connected in parallel and extending in a U or V pattern away from a common foot portion of the antenna electrically interconnecting the L/4 monopole and K/4 monopole whereby ends of said L/4 monopole and K/4 monopole remote from said foot portion are spaced apart, only a respective one of said monopoles being resonant at each of said frequencies; an l-radial assigned to said L/4 monopole and a k-radial assigned to said K/4 monopole, said radials extending parallel to said metal frame member; means for connecting a core wire of a coaxial feeder cable to said common foot portion; means for connecting a shielding of said coaxial feeder cable to both of said radials, said radials being so spaced from said metal frame member, being of such widths, and having respective lengths l and k optimizing the radiation characteristics and such that an outer surface of said cable is substantially free from surface standing waves, said antenna comprising a further L/4 monopole parallel to the first-mentioned L/4 monopole and forming a U pattern therewith and with said foot portion which electrically interconnects both of said L/4 monopoles, said L/4 monopoles being disposed symmetrically with respect to said K/4 monopole.