Given the size of your project, here are some guidelines re. the design of an MATV system. Not the final word on the subject but helpful (IMO).
http://www.dipolnet.com/document-print-BIB05.html
Serving this number of users justifies the use of commercial grade components. Blonder-Tongue, Pico Macom and other names come to mind. The Holland Agile Digital Signal Processor comes to mind...
http://www.techtoolsupply.com/Produc...Code=HPH-860AD One per real RF channel would be used to shift the antenna derived signal to a different RF channel, with the output level stabilized and at a level that could drive the distribution network.
I agree with TG, you will want to get this right the first time. With 50 users, your phone
will ring at 3:06 AM if there is a problem. You will be a small scale cable provider.