Conventional circuit designs have considered only visibility distance and transmission power. However, these are part of circuit design variables. There are a variety of other variables such as modulation method, carrier wave length, type of wavefront. Communication circuits should be designed appropriately depending on the installation environment. This study has performed an evaluation of the propagation characteristics of combinations of each modulation method and carrier waves, and considered indexes for communication circuit designs that suit the installation environment. As a result, the result has been obtained that modulation method needs to be selected depending on the CNR, and the wave length and wavefront of carrier waves depending on the propagation distance.