A Direct Radiating Array Antenna (DRAA) concept has been introduced to international satellite communications in order to achieve multiple shaped beams which are electrically reconfigurable. The subject of this paper is to describe the new design method for a reconfigurable DRAA. The design procedure consists of three steps, 1) derivation of the initial array layout using Fourier transform method (FTM) , 2) array shape rearrangement, 3) optimization of the final array excitation with the modified constraint least mean square (MCLMS) algorithm. At the first step, it is necessary to derive the initial array layout for the desired shaped beam with respect to array shape, number of antenna elements, and excitation distribution. For this purpose, a new closed form solution of FTM using N-polygonal desired coverage is used. At the second step, the array shape is rearranged to fit the beam forming network (BFN) configuration which can reduce insertion loss and influence on frequency variation sensitivity. At the third step, the array excitation is optimized using MCLMS which is exploited to satisfy the power sum constraints caused by the restriction of the BFN configuration. The design method provides useful insight regarding the layout design of a DRAA with well-shaped coverages, the low insertion loss of the BFN and the high sidelobe isolation characteristic. The design of the reconfigurable DRAA with the specified multiple shaped (beams is demonstrated and compared with the experimental model.

This paper concerns the study on the Ku band multi-beam direct radiating array antenna technology, which provides frequency reuse and reconfigurable multi-beam capabilities in satellite communication system. The study consists of two dimensional pattern synthesis, beam forming network analysis and design, and fabrication and measurement of an experimental model. The measurement results have shown that the experimental model with 64 array elements including 14 dummy elements has a low loss of less than 2 dB in average and high sidelobe and polarization isolation of more than 27 dB and 29 dB, respectively, over 1 GHz bandwidth in the Ku band. As a result of careful evaluation, it has been confirmed that the design method established here is valid and useful for multi-beam direct radiating array antenna design.