A software package is developed for communication design engineers that allows for quick and accurate evaluations of established and proposed link designs. The package is designed to be used with geostationary satellites. The computer program is written in Microsoft Basic and uses an Apple Macintosh personal computer. The software package is particularly useful in the design of K and Ku Band satellite systems. The adverse effect of rain is significant for this frequency range. The program determines the rain attenuation loss and the increase in the system noise temperature due to rain. The rain induced cross-polarization discrimination is also calculated for systems that operate with frequency reuse. The program also provides a link design for a rain attenuated downlink based upon a specified carrier-to-noise ratio. The software package also calculates basic link budget equations, derives adjacent satellite system interference, and performs baseband analog analysis. The software program finally determines the communication system availability. A link design for three commercial satellites is shown using the computer program. The communications design software package is a very useful tool for it provides rapid response that will save the designer valuable time in the design process.