Horn Antenna Array for Imaging Reflector Antenna Engineering Model in 21-GHz Band

A 21-GHz band satellite broadcasting system is being studied as a means of delivering Ultra High Definition TV, 3DTV, and other advanced forms of broadcasting. We assumed the use of two 300-MHz class wideband channels in the 21.4 to 22.0-GHz band and devised an array-fed imaging reflector antenna (array-fed IRA) to supply enough power for a transponder with such a wide band. The array-fed IRA is an effective means of exploiting limited resources because of its ability to control radiation patterns; the 21-GHz band suffers from severe fading due to rain. To confirm the feasibility of the array-fed IRA system in the space environment, we designed an engineering model of an array-fed IRA for a 21-GHz band broadcasting satellite. The engineering model has a feed array that consists of 32 horn antennas. To estimate the fundamental characteristics of the feed array, we fabricated and tested a partial prototype which had seven horn antennas, before we built the 32-horn feed array.