To learn about the specific mode or transmission that interests you check on the net.There are hundreds of sites describing how to build everything from antenna to receiver.
ACARS Aircraft Communication Addressing and Reporting System MHz 131.550 Primary Channel worldwide 130.025 Secondary channel for USA and Canada 131.125 Additional channel for USA 136.800 Additional channel for USA 131.725 Primary channel in Europe 131.525 European secondary 131.450 Primary channel for Japan