Composite antenna for receiving signals transmitted simultaneously via satellite and by terrestrial stations, in particular for receiving digital audio broadcasting radio signals

Claim 1

A composite antenna comprising, in combination: a skirt-helix assembly having first and second radiating elements operating independently to separately receive respective first and second signals of like frequency; said first radiating element comprising a quarter-wavelength skirt antenna adapted to be disposed over an artificial ground and comprising a vertically disposed cylindrical tube having a closure surface closing an upper end of said tube, and a feed point means on a wall of said tube for sampling said first signal received by said skirt antenna, said skirt antenna having a radiation pattern which is essentially omnidirectional with a low elevation angle suitable for receiving signals from terrestrially situated transmitting antennas; said second radiating element comprising a helical antenna disposed vertically and coaxially above said skirt antenna and insulated therefrom with said closure surface constituting a reflective plane means for modifying a typical radiation pattern of said helical antenna, by lowering a receive lobe of said radiation pattern to an elevation angle suitable for receiving signals from a satellite, so as to provide a hybrid radiation pattern which is partially axial and partially radial, said helical antenna also having a feed line means for sampling said second signal received by said helical antenna, said feed line means having an outer conductor being in electrical contact with said closure surface of said skirt antenna and an inner conductor being insulated from said outer conductor, passing through said closure surface to an inside of said skirt antenna, and electrically attached to said helical antenna; and coupling means for receiving said first and second signals of like frequency from said feed point means and said feed line means, respectively, and for combining and feeding said like frequency signals from an output of said coupling means on a common line.