Prototype of 32-element Horn Antenna Array for Imaging Reflector Antenna of 21-GHz Band Broadcasting Satellite

A 21-GHz band satellite broadcasting system is being studied as a means of delivering 8K (Super Hi-Vision), 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, 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 improve the accuracy of the antenna's arrangement, we combined the 32 horn antennas into one unit. To evaluate the characteristics of this unit type feed array, we fabricated and tested a 32-element horn antenna array.