During the last decade, atmospheric research that focuses on understanding the roles clouds and cloud micro-physics plays in radiative processes, has highlighted the use millimeter radar in cloud observing systems. With the deployment of unattended Ka band cloud radars for use as cloud profilers at numerous remote field sites, in programs such as ARM, their use as a tool for long term studies has become more routine. While conventional radars operating in the Ka and W band have been used predominately because of their ë4 sensitivity advantage, other frequencies offer similar impressive cloud observations capability but at reduced cost. Future observing systems that will look at long term climatic change in the Arctic, in programs such as SEARCH, will rely on unprecedented data bases of cloud observations. In this paper we summarize some of the key tradeoffs for several radars operating a S, X, Ka and W band used to observe clouds.