Abstract: The invention concerns a system for transmission of spatial diversity radio signals via a geostationary main communication satellite and one or more auxiliary satellites "colocated" in the same orbit. The distance between an auxiliary satellite and the main satellite is in the range from 200 km to 400 km. The system includes conventional bidirectional transmission links between terrestrial mobile terminals and the main satellite and between the latter and a terrestrial station. Additionally, unidirectional transmission links are provided between the auxiliary satellites and the main satellite. Applications include a mobile communication service with portable terminals via a geostationary satellite.

Abstract: The invention concerns a beam forming network for radiofrequency antennas and applying to the input signals a two-dimensional hexagonal discrete Fourier transform in order to control radiating elements for generating multiple beams. The number of inputs and outputs is equal to N.sub.t with N.sub.t =R.times.N.sup.2, R and N being integers. A first circuit layer comprises a row of N.sup.2 cells each having R inputs and R outputs, each cell receiving a signal present at one of said N.sub.t inputs and applying to the signals present at its R inputs a one-dimensional R.times.R discrete Fourier transform, and a second circuit layer comprises R independent sets of cells each having N inputs and N outputs, each set including a first row and a second row of N cells, each cell applying to the signals present at its N inputs a one-dimensional R.times.R discrete Fourier transform.The invention also concerns a hardware structure for a network of this kind.