You can use this Demonstration to explore the tradeoffs involved in communication link design. You can vary the key system parameters carrier frequency (in MHz), transmitter power (in ), path-loss exponent, receiver antenna temperature (in kelvin), receiver noise figure (in dB), bandwidth (in MHz) and transmitter/receiver antenna sizes (in meters). It is worth noting that the relationship among antenna size, configuration and antenna gain can be complex. However, for the purposes of this Demonstration, a parabolic reflector antenna serves as a proxy for the relationship between the relative size of the antenna and its gain. Consequently, the calculated S/N is not valid if the calculated antenna gain (as displayed) is less than 0 dB, as a gain of 0 dB corresponds to an isotropic antenna. This Demonstration calculates the antenna gains. The S/N is presented as a function of the distance between the transmitter and receiver, which influences S/N values over a selected range of distances.