Some frequencies have been specifically set aside by international agreement for radio astronomy. Of course the reality is not always like that. Some human produced radio noise is very broadband and will disrupt observations at virtually any frequency. Yet even so, the resolution that a modest radio telescope can expect to achieve is much less than what a similarly modest optical telescope could obtain. Expensive Equipment Optical observing can be done with no equipment at all.
Naked eye observing can be both fun and effective.
Radio astronomy requires complex and potentially expensive equipment before anything can be observed at all. In addition to antennas and receivers, observers need to convert the incoming radio information into a form suitable for presentation. This extra complexity can be daunting. Since this doesn't require any special equipment it seems like a good way to get started with amateur radio astronomy. Check out the Observing Meteors by Radio page for more information on the theory and technique involved.