Efforts to revitalize the AM radio industry run the gamut from large to small and include modifications as specific as those surrounding the licensing/modification of AM directional antenna arrays.
New data collection requirements that affect a specific set of AM directional antenna array rules officially went into effect on March 21, 2018, the date that a summary of those rules was published in the Federal Register. It was back in September 2017, as part of the Revitalization of the AM Service rulemaking report and order, that the Federal Communications Commission initially adopted certain rules pertaining to these arrays.
Specifically, the FCC voted to eliminate, clarify or ease several of the rules governing AM stations using directional antenna arrays.
First, the FCC eliminated the requirement that broadcasters must take measurements on non-monitored radials adjacent to monitored radials.
Second, the FCC modified several rules pertaining to AM stations that use Method of Moments (MoM) models of directional array performance. Among the changes: that broadcasters, in some cases, can verify antenna system performance through computer modeling as opposed to sending engineers into the field to take strength measurements; and that in some cases broadcasters do not need to submit additional reference field strength measurements in future license applications. Other changes were made to the MOM rules; see a summary of all the revisions here.