First you need to motivate a license to ICASA or relevant national broadcast control body, this generally means paying a research company to provide stats motivating the need for a radio station for a niche in the market which is both unexploited and large enough to warrant a license.
Size of bandwidth you can get depends on no. of peeps you gon be broadcasting to. However this costs money...
The way UCT RAdio started was as a pirate station for 7 years, without the knowledge or support of the institution of UCT itself, finally sum1 at ICAS or the IBA as it was then known, cottoned on to the fact that the RAMS listenership figures were refelcting a station not registered with them.
That brought kak, for the brave souls who started UCT Radio station, IBA took them to court and initially UCT Senate sed "FUK U ur on your own!".
A student outcry changed UCT's mind cos the Station had a lot of student support. A deal was worked out to allow UCT Radio to apply for a dual Community/Student license and keep running cos the niche made itself heard.
That was back in the early 80's and uptill I left every three years UCT radio went thru the hell off license re-application, even though we fulfilled requirements and grew listenership and adherred to mission statement, it never got any easier.
So really if you want to start a Community radio station, you need shitloads of cash, and i do mean shitloads. Think a**ets and liquid capital in excess of a million rand, no lies, good broadcast equipment is fukkin expensive.