Chak is correct, but there’s one further scenario.
In situations where the satellite dish is providing Pay-TV services (e.g. Foxtel), even to one Owner, the dish is usually the property of the Service Provider, and Executive Committees (on behalf of the OC) often enter into Service Agreements with these Providers that indemnify the OC by amongst other things stipulating that any damage caused to Common Property during the installation/removal of satellite dishes and all on-going maintenance and repairs of them are the responsibility of that Provider.
However as Chak has said, IF the satellite dish has been installed under any other arrangement, such as to receive overseas-based TV programs, then your OC would first be required to properly resolve (at a General Meeting) to permit such installations, which constitute an alteration / addition to the Common Property, under the conditions contained in a Special By-Law approved by >75% of Owners present personally or by proxy at that Meeting.
If the preceding paragraph is the situation, you need to write to the Secretary of your EC and inform them that the satellite dish installation is illegal under the Provisions of the NSW Strata Schemes Management Act (Ch3, Pt2, Cl 65A & B).