New directional measurement techniques proposed

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New directional measurement techniques proposed

Jul 1, 2007 12:00 PM, By Harry Martin

The FCC has requested comments on a proposal to let some, but not necessarily all, AM directional applicants use moment method computer modeling to demonstrate that their directional antennas perform as authorized. The proposal was advanced by a coalition of broadcasters, manufacturers and consulting engineers in May, following several months of meetings and deliberations. The idea is to reduce the burden on AM applicants and the commission's processing staff by eliminating the need to conduct and analyze field strength measurements of directional arrays to verify proper performance.

Historically, the commission has required directional AM applicants to undertake elaborate, labor-intensive measurements to confirm that their arrays are within licensed parameters. Those measurements are then sent to the commission, where staff members review them as well.

But moment method computer programs (also referred to as Numerical Electromagnetic Code or NEC programs) permit the accurate calculation of actual performance based on certain internal antenna parameters, such as current and phase. The coalition also created draft rules that would permit the use of moment method modeling to assess the effect of nearby reradiators on the pattern.

The coalition's proposal, which is supported by 20 group owners and 10 consulting firms, was submitted to the commission in connection with its long-running inquiry in AM directional antennas (MM Docket 93-177). While not all AM applicants would be eligible to use the proposed modeling approach, it appears that the approach would still save considerable time and effort throughout the industry.

Meanwhile, the commission has amended its rules to clarify the circumstances and time frames in which a directional AM station must act when it runs into antenna system problems. Two rules � Sections 73.62 and 73.1350 � have historically provided conflicting directions. Under the new versions, Section 73.62 requires an AM licensee to identify and address directional antenna problems within 27 hours when operating parameters exceed �15 percent sample current ratio or �3� phase tolerances required by the rules, or when any monitoring point field strength exceeds 125 percent of the licensed limit, or when the operation at variance results in interference complaints. And Section 73.1350, which requires a scant three-minute response time, will now kick in when the operation at variance poses a threat to life or property or is likely to significantly disrupt the operation of other stations. Variant operations not covered by Section 73.62 or the three-minute provision of 73.1350 must be addressed within three hours.

90-day lighting inspection rule waived

The FCC has waived the rule requiring that towers subject to lighting requirements be inspected at least every three months to confirm that their lighting systems are operating properly. The waivers apply to tower companies using lighting systems developed by Flash Technology (the Eagle Monitoring System) and Hark Tower Systems. Both systems include alarm notifications set to alarm response centers, automatic 24-hour polling of all tower sites using the systems, and capability for manual contact and diagnostic review of any tower in the system. These systems are backed up through network operations call (NOC) centers.

In granting the waivers the FCC noted that it is working on a rulemaking that would grant exemptions to the 90-day inspection rule for towers employing NOC-based technologies. In the meantime waivers will be granted to others using this technology.

Martin is a past president of the Federal Communications Bar Association and a member of Fletcher, Heald & Hildreth, Arlington, VA.


Aug. 1 is the deadline for radio stations in California, North Carolina and South Carolina to file their biennial ownership reports.

Also on or before Aug. 1, North Carolina and South Carolina stations with more than 10 full-time employees must file an interim EEO report with the FCC using Form 397.

Aug. 1 is the deadline for radio stations in the following states with five or more full-time employees to place their annual EEO reports in their public files and post them on their websites: California, Illinois, North Carolina, South Carolina and Wisconsin.