Small medical teams and disaster mitigation personnel in the field need robust and simple communication means to handle their jobs. Learning from major disaster such as last year Tohoku earthquake, we cannot depend on modern communication means. Modern communication such as mobile phone usually will be malfunction during disaster time due to traffic congestion and direct disaster impacts. In this paper we proposed a simple and robust means. We created the specified low-power radio repeater with solar power system that supports the citizens and grassroots disaster relief team's activities at the municipal level in the event of a disaster. The Specified low-power radio in Japan covered in this study is a simplex telephone FM analog voice band 400 Mhz. The radio equipments have already license under the laws of Japan, so personal use is not necessary to obtain a license. However the original radio specification has a very limited transmit power of only 10 mW. It means that the communication distance is extremely short. However, we had solved this problem by using the repeater. In our experiments, the system was able to cover enough of the municipality. It should be placed in the appropriate location to achieve its objective. In addition, we also found that the use of radio wave propagation simulation software is important in order to grasp the area can communicate and to find the location of the repeater.