Patent ID: 6208302
Filing Date: 2001-03-27
Classification: H01Q

Abstract:
An antenna system for a mobile telephone for operating via a radio channel between said mobile telephone and at least one of a group of stations revolving in non-geosynchronous orbit around the earth, said antenna system comprising a conical antenna having an even number of at least four spiral strands angularly spaced apart by an equi-angular spacing according to a rotation around the axis of a supporting conical body having a large diameter end and an apex or small diameter end, said supporting conical body being adapted to be fixed by its large diameter end to an upper end of a mobile telephone, and switch mode function (SMF) means including phase shifter means for selectively feeding radio frequency signals to or from said strands via one end of said conical body which, in a first mode of operation, are phase shifted between each pair of adjacent strands by said equi-angular spacing and, in a second mode of operation, are phase-shifted by .PI. between each pair of adjacent strands, and control means for automatically controlling the SWF means to effect selection between the first and second modes of operation according to an a priori or a posteriori selection criterion.