Demands for increased channel capacity in future communication satellite systems coupled with basic limitations in terms of satellite power and frequency spectrum will lead to requirements for advanced multiple‐beam antenna systems with frequency re‐use capability. This paper describes the results of a study of multiple‐beam antenna systems suitable for an advanced European business services satellite. Initially, background work is described which serves to define the overall system, analyse the link performance and specify the antenna requirements. A generalized parametric study of the capabilities of a model antenna is discussed to set the bounds of feasibility, as it was appreciated that some specification targets might prove impossible to attain. In parallel, a comparative survey of a wide range of antenna types is presented to determine the most promising configurations. Based on these two outputs, candidate antenna configurations are analysed in detail to predict accurately the capability of the more promising antenna types to meet the range of performance objectives. Finally, detailed electrical design studies are performed for specific example missions.

Adaptive TDMA is a member of the 'Shared Resource' branch of the Fade Countermeasures family. It attempts to maximize the throughput of a satellite channel by varying the data-rate used by a number of transmitters according to the signal-to-noise ratio at the receivers. The highest possible transmission rate is used on un-faded links so that the traffic is passed in the shortest possible bursts. This leaves the maximum fraction of the TDMA frame free for faded links to use a lower transmission rate giving rise to longer bursts. This process is transparent to the end-user equipment, which operates at a fixed data-rate.A new model of rainfall distribution in both area and time, based on data collected by a weather radar in Northern Italy, has been generated to analyse the performance of A-TDMA. Taking account of all the signalling overhead and dynamic effects needed to reconfigure the system under rapidly varying rain distribution, capacity enhancement factors of 7 to 14 compared to the conventional design approach were calculated.

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