 For example, in satellite dishes, the microwave downlink signal received by the dish is converted to a much lower IF at the dish, to allow a relatively inexpensive coaxial cable to carry the signal to the receiver inside the building.Bringing the signal in at the original microwave frequency would require an expensive waveguide.A second reason, in receivers that can be tuned to different frequencies, is to convert the various different frequencies of the stations to a common frequency for processing.