AM stations making the IBOC transition must scrutinize their antenna systems and transmitters to determine if they are capable of accommodating the technical criteria the IBOC signal demands. In many cases modifications to the coupling system must be implemented, especially in directional antenna arrays.
Many will recall this scenario when AM stereo was introduced. The first published presentations addressing AM antenna bandwidth date to July, 1949. Whether your station is directional or non-directional, AM stereo or IBOC, the antenna system is an important factor in coverage and audio fidelity.
There is no need to wait for IBOC to determine if you can improve your coverage.
The first step in AM improvement is to examine your coverage area. Is your signal reaching the intended audience? Is it adequately serving rated market areas?
Perhaps your directional transmitter site was chosen long ago, when nulls fell over pasture or unpopulated regions, or a non-directional tower was placed on the outskirts of town. Today there may be condos or shopping malls in the nulls; or perhaps the population has shifted away from your tower site.
Is it possible to relocate your transmitter site to realize a signal improvement or profit from valuable real estate? Is there another station you could purchase and turn dark, allowing you to increase power or improve coverage? Have you considered diplexing with another station?
All of these are possibilities to explore. An experienced consulting engineer can examine your allocation and determine if such improvements are possible.
Some directional antenna systems have been improved greatly by dropping one or more towers and meeting FCC limits with fewer sticks. Other antenna systems may require considerable reworking to meet IBOC requirements or coverage improvements. Directional antenna systems must be analyzed for pattern and impedance bandwidth. Any improvements made to your transmission system will result in better coverage, increased listenership and revenue. In some cases, it may be possible to reduce tower height and extinguish tower lighting requirements.
There is no reason to wait for IBOC to begin your examination. Your business may profit greatly from it.