In Kyoto University, we study microwave power transmission (MPT) and solar power satellite (SPS) MPT system. We have an advanced phased array system to make experiments on beam forming with phased array. The advanced phased array system has 256 antenna elements and 5-bit digital phase shifters. We measured and simulated the radiation patterns of the advanced phased array system and compared the measurement and simulation results. As a result of these comparisons, the measured radiation patterns correspond with the simulated radiation pattern. Hence, the output phases of the system can be controlled with high accuracy in the advanced phased array system.