Active arrays for satellite communications

This presentation deals with the optimal synthesis of non periodic, isophoric arrays capable of generating high gain spot beams for satellite communications. After discussing the advantages and potentialities of such a kind of antennas, as well as the difficulty of their optimal design, a three step synthesis strategy and the algorithms for its implementation are presented and briefly discussed. Then the case of a sub-regional coverage is addressed, showing how very high performances can be actually achieved with a strongly reduced number of feeds, by exploiting an innovative architecture adopting both amplitude and feed-size tapering. Finally, the case of full Earth coverage, requiring relatively high scanning capabilities, is addressed. The impact of this requirement on the inter-feed distance, on the number of required entry points and on the achievable performances is analyzed, both theoretically and numerically, assessing in a quantitative way the price that must unavoidably be paid for achieving a global coverage.