[Federal Register Volume 64, Number 143 (Tuesday, July 27, 1999)]
[Proposed Rules]
[Pages 40539-40542]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-19096]


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FEDERAL COMMUNICATIONS COMMISSION

47 CFR Part 73

[MM Docket No. 93-177; FCC 99-126]


Reduction of Regulatory Requirements For AM Broadcasters Using 
Directional Antennas

AGENCY: Federal Communications Commission

ACTION: Notice of proposed rulemaking.

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SUMMARY: In this Notice of Proposed Rule Making, the Commission 
proposes substantial reductions in the proof of performance 
requirements for AM directional antenna systems. These proposals are 
intended to alleviate unnecessary financial burdens imposed on AM 
broadcasters by such requirements without jeopardizing the Commission's 
policy objectives of controlling interference and assuring adequate 
community coverage by AM stations. The Commission previously issued a 
Notice of Inquiry in this proceeding in response to a joint petition 
for rule making by five broadcast consulting engineering firms 
requesting a thorough reexamination of testing and verification 
procedures for AM radio stations that use directional antennas.

DATES: Submit comments on or before September 10, 1999 and reply 
comments on or before September 27, 1999.

ADDRESSES: Parties who choose to file comments concerning this Notice 
of Proposed Rule Making by paper should address their comments to 
Magalie Roman Salas, Office of the Secretary, TW-A306, Federal 
Communications Commission, 445 12th Street, S.W., Washington, D.C. 
20554. Comments also should be submitted on a 3.5 inch diskette using 
WordPerfect 5.1 for Windows or compatible software to Son Nguyen, 
Federal Communications Commission, 445 12th Street, S.W., Room 2-A330, 
Washington, DC 20554.

FOR FURTHER INFORMATION CONTACT: Son Nguyen, Dale Bickel or William 
Ball at (202) 418-2660 or [email protected], [email protected], or 
[email protected].

SUPPLEMENTARY INFORMATION: Comments and other data may be submitted via 
electronic mail to http://www.gcc.gov/e-file/ecfs.html.
    The Commission proposes to amend 47 CFR Part 73 Subpart A as set 
forth below:
    1. Computer Modeling versus Proofs of Performance. Several computer 
models have been developed over the years to calculate operating 
characteristics of particular importance to engineers designing, 
installing and adjusting AM antenna systems. Unlike the mathematical 
formulas for calculating the radiation characteristics of AM 
directional antennas contained in 47 CFR 73.150, 73.152 and 73.160, 
these computer models or ``NEC programs'' deal with ``internal'' array 
parameters such as impedances, currents and voltages at locations 
within the power distribution and radiation system. Several 
commentators suggested that proofs of performance may not be

[[Page 40540]]

necessary for directional arrays adjusted pursuant to NEC programs, 
arguing that such programs make possible the satisfactory adjustment of 
directional arrays without reliance on field strength measurements.
    2. The Commission does not propose to adopt a methodology based on 
NEC programs to determine whether directional arrays conform to 
authorized radiation patterns. The Commission has two fundamental 
concerns. First, based on the present record, the Commission is 
concerned that it could not continue to accomplish its core regulatory 
function of preventing interference among AM broadcast stations if the 
requirement of proofs of performance were eliminated for stations 
adjusted pursuant to NEC programs. Second, the Commission is concerned 
that adopting a methodology based on NEC programs could draw it into 
controversial issues relating to the adequacy of adjustment programs 
and procedures, leading to delays in authorizing new service. The 
Commission generally does not regulate either the design of circuitry 
internal to antenna systems or the methodology employed in the 
adjustment of antenna systems. The Commission seeks comment on these 
matters.
    3. Directional Antenna Proofs of Performance. A proof of 
performance establishes whether the radiation pattern of an AM 
directional array is in compliance with the radiation pattern 
authorized by the station's construction permit or license. A full 
proof of performance requires a large number of measurements of the 
station's signal to establish the shape of the radiation pattern. Each 
full proof generally consists of two sets of measurements--
nondirectional and directional measurements--and a minimum of 30 points 
along each of eight radials is required. Complex arrays require more 
radials and, therefore, more measurement points. A partial proof 
requires a lesser number of measurements to show that the station 
continues to operate as it did during the last full proof.
    4. Full Proofs--Number of Radials. The Commission proposes to 
reduce the minimum number of radials required under 47 CFR 73.151 from 
eight to six for simple directional antenna patterns and to generally 
require no more than 12 radials to define complex patterns. (For AM 
stations operating with different daytime and nighttime directional 
antenna patterns, different radials may be required for each pattern.) 
If the major lobe, minor lobes, and nulls of the pattern cannot all be 
accounted for by the required 12 radials, pattern symmetry may be used 
to account for the remaining minor lobes and nulls. The radials would 
be distributed as follows: (A) One radial in the major lobe, at the 
pattern maximum; (B) At least five additional radials, as needed to 
definitely establish the pattern, generally at the peaks of minor lobes 
and at pattern nulls. This may include radials specified on the 
station's authorization. However, no two radials may be more than 90 
degrees azimuth apart. If two radials would be more than 90 degrees 
apart, then an additional radial must be specified within that arc; and 
(C) Any radials specified on the construction permit or license.
    5. Nondirectional antenna measurements would be taken along the 
radials used for directional measurements. In addition, the Commission 
proposes that those few nondirectional stations required to conduct a 
full proof (due to the proximity of reradiating structures or other 
atypical circumstances) be permitted to employ six evenly-spaced 
radials.
    6. The Commission tentatively concludes that it can reasonably rely 
on fewer radials, in conjunction with the 90 degree maximum arc 
restriction, to establish nondirectional and directional patterns. It 
tentatively concludes that using a smaller number of radials, or 
permitting radials to be spaced more than 90 degrees apart, would not 
provide a sufficient number of points to identify distortion of a 
nondirectional pattern. Furthermore, the Commission believes that the 
above-stated proposals can sharply cut the time and cost of conducting 
a proof of performance. Comment is requested on these matters.
    7. Full Proofs-- Number of Points per Radial, Length of Radials. 
The Commission proposes to reduce the number of points per radial 
required under 47 CFR 73.186(a)(1) to a minimum of 15, as well as to 
shorten the minimum length of the radial from 34 to 15 kilometers 
(``km''). These 15 measurement points would include the very important 
close-in measurement points (points at less than three km from the 
transmitter site) used to determine the inverse distance field. The 
Commission proposes to specify intervals between these points as 
follows: (A) The closest point at a distance 10 times the maximum 
distance between the elements of a directional array, or at a distance 
five times the vertical height of the antenna in the case of a 
nondirectional station; (B) Close-in measurements at 0.2 km intervals, 
out to a distance of three km (unchanged from the present requirements 
of 47 CFR 73.186); (C) Measurements at one km intervals between three 
and five km (three points); (D) Measurements at two km intervals 
between five and 15 km (five points); (E) Additional measurements as 
necessary at greater distances to achieve at least 15 points clear of 
potential reradiating structures; and (F) Measurements at any 
monitoring point locations along the radial (unchanged from the present 
rule).
    8. The Commission tentatively concludes that the proposed reduced 
number of points and shorter radial length represent the minimum which 
would allow verification of the performance of the antenna system. The 
Commission tentatively concludes that the present measurement 
requirements for close-in measurements (within three km of the 
transmitter site) should not be modified. The Commission seeks comment 
on each aspect of this proposal.
    9. For each measurement point, the Commission proposes that the 
applicant provide several pieces of data: the date(s) of the 
measurements; the azimuth of the radial; the distance from the center 
of the array to the measurement point; the pattern being measured (day/
night/critical hours); the time of the measurement; and the measured 
field strength value at that point. The Commission proposes to adopt a 
standardized format for the submission of the data in order to 
facilitate electronic filing and processing. The Commission seeks 
comment regarding the format that should be used for the compilation 
and submission of this data. Comment is also requested as to whether 
the time of each measurement should continue to be required with these 
submissions.
    10. Partial Proofs--Number of Points Required. The Commission 
proposes to reduce from 10 to eight the minimum number of points per 
radial required under 47 CFR 73.154. The proof must include any 
monitoring point locations, and must use radial measurement point 
locations established in the last full proof of performance, as is the 
case under the current rule. The Commission believes that reducing the 
number of points would reduce the financial burden on AM directional 
licensees conducting partial proofs while still providing sufficient 
data to confidently verify directional array performance.
    11. Partial Proofs--When Required. The Commission proposes to 
eliminate the requirement under 47 CFR 73.68 to conduct a partial proof 
of performance following replacement or modification of sampling system 
components mounted on the tower, provided the new components are 
mounted in the exact location of the old components,

[[Page 40541]]

measurements made at the monitoring points before and after 
installation establish that the substitution had no effect, and antenna 
monitor values remain within the tolerances specified in the 
Commission's rules or the station's authorization.
    12. Proofs of Performance--Monitoring Points. Monitoring points are 
specific locations on selected proof radials where licensees regularly 
take field strength measurements to verify that a directional array 
remains within the radiation limits specified in the station's 
authorization. They are established at the time a station's full proof 
of performance is conducted. The Commission does not propose to 
eliminate monitoring point requirements, as suggested by some 
commentators, who argue that seasonal variations in ground conductivity 
affect the signal strengths measured at many monitoring points. The 
Commission tentatively concludes that monitoring point measurements 
remain a fundamental tool in verifying the performance of AM 
directional arrays independent of antenna monitor and antenna sampling 
system readings. The Commission also does not propose to adopt a 
suggestion to delete monitoring point measurements in exchange for 
yearly skeleton proofs taken on formerly monitored radials. The 
Commission seeks comment on these tentative conclusions.
    13. Under 47 CFR 73.158, an informal application to change a 
monitoring point must include the results of a partial proof of 
performance taken on the radial containing the monitoring point to be 
changed. The Commission proposes to eliminate this requirement. 
Instead, the applicant would simply reference the measurements taken 
along that radial in the last full proof of performance submitted to 
the Commission. The staff would assign a radiation limit for the new 
monitoring point using the same procedure as described above. The field 
strength limit would be assigned based on the tolerance available 
between the radiation along the monitoring point radial as determined 
by the proof of performance and the radiation permitted by the 
authorized standard (or augmented) radiation pattern.
    14. The Commission also proposes to eliminate the requirement for 
maps and directions indicating how to reach monitoring points for 
applicants using GPS-determined coordinates to identify monitoring 
point locations. A description of the monitoring point as well as a 
photograph would still be required to verify that the location is free 
of obstructions such as overhead power lines, see 47 CFR 73.151(a)(3) 
and 73.158(a)(4), to identify the precise location of the monitoring 
point with respect to nearby landmarks, and to identify the exact 
placement of measurement equipment. See CFR 73.151(a)(3) and 
73.158(a)(2), (3). In order to achieve sufficient accuracy, a 
differential GPS receiver would be required. The Commission would 
specify monitoring point coordinates submitted in this manner on the 
station's license. Parties interested in locating these monitoring 
points could plot the specified coordinates onto topographical or other 
maps to determine the best route. The Commission asks for comment on 
these proposals.
    15. AM Station Equipment & Measurements--Base Current Ammeters. 
Licensees are currently required under 47 CFR 73.58(b) to install base 
current ammeters or toroidal transformers (current registering devices) 
at the power feed point of each tower, typically at the base of the 
tower. The Commission proposes to delete the requirement for base 
current ammeters or toroidal transformers for those directional 
stations employing approved antenna sampling systems. Stations not 
using approved sampling systems have no reliable alternate on-site 
means of assessing antenna performance and, therefore, the Commission's 
rules would continue to require the installation and use of base 
current ammeters if the Commission has not approved the alternative 
system. The Commission seeks comment on this proposal.
    16. Equipment & Measurements--Antenna Monitors. All AM directional 
stations are required to use an antenna monitor verified for compliance 
with the technical requirements in 47 CFR 73.53 as a means of verifying 
directional array performance. This rule also establishes detailed 
specifications that antenna monitors must meet. The Commission proposes 
to delete most of the antenna monitor construction and operational 
requirements of 47 CFR 73.53, with the exception of a few provisions 
that would be shifted to other existing rule sections. Specifically, 
the present requirement in 47 CFR 73.53(a) that the antenna monitor be 
verified for compliance with the Commission's technical requirements 
would be moved to 47 CFR 73.69, which deals with antenna monitors. 
Antenna monitor requirements for critical arrays would be moved from 47 
CFR 73.53(c) to 73.69. Minimum readout levels in 47 CFR 73.53(b)(4) and 
(b)(5) would be moved to 47 CFR 73.1215. The Commission in recent years 
has eliminated detailed construction and operational requirements for 
other types of broadcast equipment, such as transmitters and metering 
equipment, and tentatively concludes that the instant proposal will 
encourage the development of more dependable, less expensive antenna 
monitors. Comment is requested on this proposal.
    17. Several commentators requested that 47 CFR 73.68 be modified to 
permit licensees to use voltage sampling devices to feed antenna 
monitors in lieu of current sampling devices such as sampling 
transformers and pick-up loops. The Commission asks for comments as to 
the accuracy and reliability of voltage sampling devices, whether they 
are appropriate as sampling devices for assessing array performance, 
and whether the rules should be modified to permit their use.
    18. Equipment & Measurements--Impedance Measurements Across a Range 
of Frequencies. Directional and nondirectional AM stations are 
currently required to take measurements of impedance across a range of 
frequencies under 47 CFR 73.54(c)(1) and (c)(2). The Commission 
proposes to delete this requirement. The Commission tentatively 
concludes that retention of 47 CFR 73.54(c) is not necessary because 
competition will serve as a sufficient incentive to maintain quality 
operations, as has proven to be the case with regard to other broadcast 
stations. The Commission seeks comment on this proposal.
    19. Equipment & Measurements--Common Point Impedance Measurements. 
AM directional stations must take impedance (resistance and reactance) 
measurements at the common radiofrequency input location under 47 CFR 
73.54(b). The reactance at this point is adjusted by the antenna 
matching network to a value of zero ohms. The Commission proposes to 
delete the requirement that the common point reactance be adjusted to 
zero ohms. The Commission seeks comment as to whether a limit should be 
set for the maximum amount of reactance permitted.
    20. Critical Arrays--Antenna Monitors. Critical arrays are 
directional antennas which, because they are unusually sensitive to 
slight variations in internal operating parameters, are predicted to 
exceed their standard radiation pattern at normal operating tolerances 
and, therefore, pose a greater potential for causing objectionable 
interference. Licenses of stations with critical arrays specify tighter 
operating tolerances. To monitor these tighter tolerances, 47 CFR 73.69 
requires stations with critical arrays to install

[[Page 40542]]

special precision monitors. The Commission proposes to discontinue 
specifying the use of expensive, specially designed precision antenna 
monitors for critical arrays. Instead, the Commission proposes to 
simply require that the monitor installed have a digital readout 
graduated in increments no larger than one-half of the critical 
parameter specified in the authorization. The Commission tentatively 
concludes that the rule can be relaxed to permit the use of off-the-
shelf equipment without adverse impact on stations that are protected 
by critical arrays. Comment on this proposal is requested.
    21. Critical Arrays--Designation. The Commission does not propose 
to discontinue the critical array classification system, as suggested 
by several commenters. Some directional antenna systems are inherently 
more unstable than others and more likely to cause objectionable 
interference to other AM stations. Authorizations for such stations are 
conditioned require more stringent monitoring. The Commission 
acknowledges that the staff has generally investigated an array for 
stability only if a petition or objection is filed against the 
application proposing the array. As a result, the staff has not 
identified and designated as critical arrays all unstable arrays. The 
Commission intends to change this practice by discontinuing reliance on 
petitions or objections as the primary method of identifying unstable 
arrays. Instead, the Commission proposes to apply a uniform screening 
process to all applications for directional facilities.
    22. In addition, the Commission has analyzed all licensed AM 
directional antennas utilizing its stability criteria and tentatively 
concluded that the current criteria are too stringent, and that 
modifications are necessary to tag only those arrays that have the 
highest probability of causing ``real world'' interference under normal 
operating tolerances. Accordingly, the Commission proposes to relax its 
stability criteria in two ways. First, tests for array stability would 
be restricted to radiation pattern minima (nulls) and maxima of 
standard patterns in the horizontal plane only instead of testing at 
all azimuths and elevations. The studies would be restricted to the 
horizontal plane radiation pattern because only the horizontal plane 
pattern can be directly observed by means of field measurements. 
Second, the Commission proposes to classify an array as critical only 
if the standard pattern is exceeded at 10 percent or more of the 
possible parameter variation combinations. (The current test requires 
only one instance of excessive radiation.) The Commission believes that 
the proposed 10 percent standard will more realistically predict the 
likelihood of excessive radiation. The Commission seeks comments on 
both proposed relaxations to the current stability test criteria.
    23. Finally, based on the results of studies the Commission has 
performed on the licensed AM directional patterns in the AM engineering 
database, the Commission propose to exclude all two-and three-tower 
arrays from designation as critical arrays. Furthermore, the Commission 
proposes to categorically exclude all daytime arrays, considering that 
objections have never been filed based on daytime interference issues 
related to array instability. Thus, only nighttime and critical-hours 
directional proposals would be screened. Licensees with facilities 
currently classified as critical would be permitted to request staff 
review of their designation based on the revised criteria; however, the 
Commission does not propose to review the directional facilities of any 
station not currently classified as critical. The Commission seeks 
comment on each aspect of this proposal.

List of Subjects in 47 CFR Part 73

    Radio.

Federal Communications Commission.
William F. Caton,
Deputy Secretary.
[FR Doc. 99-19096 Filed 7-26-99; 8:45 am]
BILLING CODE 6712-01-P