On a radio data network: See http://www.rand.org/publications/RM/RM3762/ In this Memorandum we consider something we have earlier referred to as "poor-boy" microwave. The "poor-boy" designation resulted from an imposed constraint on the design of an ensemble of microwave communications equipments--namely, that the designer should have to pay for the system out of his own pocket! Even so, a look at price tags for anything to do with any large electronic or communications system would appear to render the term "poor-boy" inappropriate. "Mini-cost," a contraction of "minimum-cost," now seems more fitting. Mini-cost microwave, therefore, is a minimum-cost, line-of-sight microwave communications system designed to transmit digital information in as inexpensive a manner as possible. It is one way of building the links for the proposed Distributed Adaptive Message Block communications system with which this series of Memoranda is concerned. The distributed system itself is designed around digital modulation, using redundant paths selected on an instant-by-instant basis. The communications links for such a system can be built in a different manner than their equivalents in today's systems, taking advantage of the system's less rigid distortion level and tandem reliability requirements. The fundamental objective for the system's links is that they permit formation of new routes cheaply (a necessary survivability criterion), yet allow transmission on the order of millions of bits per second (see ODC-I, -VII[1]); system reliability and a low raw error rate are secondary. And, since future networks conveying military traffic must be designed with the expectation of heavy damage, powerful digital error detection and error removal methods have been built into the system.