Effective radiated power Warning: You are not logged in. Your IP address will be publicly visible if you make any edits. If you log in or create an account, your edits will be attributed to your username, along with other benefits.Anti-spam check. Do not fill this in! === United States regulatory usage === ERP for FM radio in the United States is always relative to a theoretical [[Dipole antenna#Dipole as a reference standard|reference half-wave dipole]] antenna. (That is, when calculating ERP, the most direct approach is to work with antenna gain in dBd). To deal with antenna polarization, the [[Federal Communications Commission]] (FCC) lists ERP in both the horizontal and vertical [[measurement]]s for FM and TV. Horizontal is the standard for both, but if the vertical ERP is larger it will be used instead. The maximum ERP for US FM broadcasting is usually 100,000 watts (FM Zone II) or 50,000 watts (in the generally more densely populated Zones I and I-A), though exact restrictions vary depending on the class of license and the antenna [[height above average terrain]] (HAAT).<ref>47 [[Code of Federal Regulations|CFR]] 73.211</ref> Some stations have been [[grandfather clause|grandfathered]] in or, very infrequently, been given a [[waiver]], and can exceed normal restrictions. Summary: Please note that all contributions to Christianpedia may be edited, altered, or removed by other contributors. If you do not want your writing to be edited mercilessly, then do not submit it here. You are also promising us that you wrote this yourself, or copied it from a public domain or similar free resource (see Christianpedia:Copyrights for details). Do not submit copyrighted work without permission! Cancel Editing help (opens in new window) Discuss this page