Sections 1.30002, 1.30003, 1.30004, 73.875, 73.1675 and 73.1690, Disturbance of AM Broadcast Station Antenna Patterns

On August 14, 2013, the Commission adopted the Third Report and Order and Second Order on Reconsideration in the matter of An Inquiry Into the Commission's Policies and Rules Regarding AM Radio Service Directional Antenna Performance Verification, MM Docket No. 93-177, FCC 13-115. In the Third Report and Order in this proceeding, the Commission harmonized and streamlined the Commission's rules regarding tower construction near AM stations. In AM radio, the tower itself functions as the antenna. Consequently, a nearby tower may become an unintended part of the AM antenna system, reradiating the AM signal and distorting the authorized AM radiation pattern. Our old rules contained several sections concerning tower construction near AM antennas that were intended to protect AM stations from the effects of such tower construction, specifically, Sections 73.1692, 22.371, and 27.63. These old rule sections imposed differing requirements on the broadcast and wireless entities, although the issue is the same regardless of the types of antennas mounted on a tower. Other rule parts, such as Part 90 and Part 24, entirely lacked provisions for protecting AM stations from possible effects of nearby tower construction. In the Third Report and Order the Commission adopted a uniform set of rules applicable to all services, thus establishing a single protection scheme regarding tower construction near AM tower arrays. The Third Report and Order also designates "moment method" computer modeling as the principal means of determining whether a nearby tower affects an AM radiation pattern. This serves to replace time-consuming direct measurement procedures with a more efficient computer modeling methodology that is reflective of current industry practice.

The latest form for Sections 1.30002, 1.30003, 1.30004, 73.875, 73.1675 and 73.1690, Disturbance of AM Broadcast Station Antenna Patterns expires 2022-09-30 and can be found here.