**PUBLIC NOTICE**![](media/image1.png){width="0.7388888888888889in"
height="0.7458333333333333in"}

**FEDERAL COMMUNICATIONS COMMISSION** News Media Information: (202)
418-0500

**445 12th STREET, S.W.** Fax-On-Demand: (202) 418-2830

# WASHINGTON, D.C. 20554 Internet: [http://www.fcc.gov](http://www.fcc.gov/)

# ftp.fcc.gov

DA 07-2143

May 23, 2007

**Comment Sought on PROPOSED RULES PERMITTING ANTENNA MODELING to verify
am directional antenna performance**

MM Docket No. 93-177

**Comment Date: July 23, 2007**

**Reply Comment Date: August 22, 2007**

In late 2006 and early 2007, an *ad hoc* technical group of radio
broadcasters, equipment manufacturers, and broadcast consulting
engineers, acting collectively as the AM Directional Antenna Performance
Verification Coalition ("Coalition"), convened to assess previous
comments and to refresh the record in the Commission's directional
antenna proceeding.[^1] On May 4, 2007, the Coalition submitted
recommendations to the Commission. The Coalition requests rule changes
to permit applicants to use moment method computer modeling[^2] to
demonstrate that AM directional antennas perform as authorized. The
proposed rules also would permit use of moment method modeling to assess
the effects of tower construction in proximity to AM antennas. The
Coalition's recommendations and draft rules are available electronically
from the Commission\'s website at:
<http://gullfoss2.fcc.gov/prod/ecfs/comsrch_v2.cgi> under MM Docket No.
93-177, or from the Commission's duplicating contractor, Best Copy and
Printing, Inc., 445 12^th^ Street, SW, Room CY-B402, Washington, DC,
20554, 800-378-3160. The Media Bureau seeks comment on the Coalition's
conclusions and recommendations.

Currently, an AM station using a directional antenna array must rely on
field strength measurements performed at a distance from the antenna to
verify its performance.[^3] Moment method programs, in contrast, use
certain internal antenna parameters, such as current and phase, to
predict the resulting antenna pattern accurately. The *Further Notice*
sought comment on the use of moment method modeling as a more efficient
substitute for traditional field strength proofs, which are
time-consuming and expensive. In response to the *Further Notice*, a
predecessor *ad hoc* technical group developed an initial set of
criteria to define those directional antenna systems that could be
modeled reliably.[^4] The criteria included antenna array physical
characteristics and antenna sampling system requirements. This *ad hoc*
technical group also concluded that the Commission should not permit
moment method modeling if an AM array is located near towers, power
lines, or other structures that might scatter or reradiate the AM field,
and thereby distort the pattern shape. Although the restrictions
concerning nearby reradiators were so conservative as to prohibit many
AM arrays from performing moment method proofs, commenters stated that
the criteria would nevertheless allow the Commission and the industry to
gain some initial experience with this new methodology with minimal
risk.[^5]

In the ensuing period, moment method programs have gained wider
acceptance among broadcast engineers and among Commission staff. Twenty
broadcast group owners and ten broadcast consulting firms support the
rules proposed by the Coalition. The proposed rules would permit most
directional AM stations to perform moment method proofs, substantially
reducing the time required for a directional antenna proof of
performance by both licensee and Commission staff. In a related
application, the draft rules also would permit use of moment method
modeling to assess the effect of nearby reradiators on AM patterns. This
proposal reflects current industry practice, and is appropriately
considered in connection with this proposal to adopt moment method
modeling.

Interested parties may submit comments on or before July 23, 2007, and
reply comments on or before August 22, 2007. Comments and replies should
specifically reference this Public Notice. Comments and reply comments
must be filed electronically at <http://www.fcc.gov/cgb/ecfs>.

***Ex parte* status:** This is a "permit-but-disclose" rulemaking
proceeding.[^6] "Permit-but-disclose" *ex parte* procedures permit
interested parties to make *ex parte* presentations to the Commissioners
and Commission employees and require that these presentations be
disclosed in the record of the relevant proceeding. Persons making a
written *ex parte* presentation to the Commissioners or Commission
employees must file the written presentation with the Commission, as set
forth below, no later than the next business day after the presentation.
*See* 47 C.F.R. § 1.1206(b)(1). Persons making oral *ex parte*
presentations must file a summary of the presentation, as set forth
below, and deliver copies to the Commissioners or Commission employees
involved with the presentation no later than the next business day after
the presentation. *See* 47 C.F.R. § 1.1206(b)(2). All *ex parte* filings
must be clearly labeled as such and must reference this Public Notice,
as well as any other applicable docket or file numbers.

An original and one copy of all *ex parte* memoranda must be filed with
the Commission's Secretary, Marlene Dortch, Federal Communications
Commission, c/o Natek, Inc., 236 Massachusetts Avenue, NE, Suite 110,
Washington, DC, 20002, in accordance with 47 C.F.R. § 1.1206(b)(1). In
addition, one copy of each *ex parte* memorandum should be delivered to
each of the following locations: (1) the Commission's duplicating
contractor, Best Copy and Printing, Inc., 445 12^th^ Street, SW, Room
CY-B402, Washington, DC, 20554. Copies of the reports and any
subsequently filed documents in this matter may be obtained
electronically at <http://www.fcc.gov/e-file/ecfs.html>, and on paper
from the contractor during normal business hours in the Commission's
Reference Information Center located at 445 12^th^ Street, SW, Room
CY-A257, Washington, DC, 20554.

For additional information, contact Ann Gallagher or Susan N. Crawford
at the Audio Division, Media Bureau at (202) 418-2700.

By: Chief, Media Bureau

**-FCC-**

[^1]: *See An Inquiry Into the Commission's Policies and Rules Regarding
    AM Radio Service Directional Antenna Performance Verification,*
    Further Notice of Proposed Rule Making, 16 FCC Rcd 5635 (2001) (MM
    Docket No. 93-177) (*"Further Notice"*).

[^2]: Computer programs to predict antenna performance are generically
    referred to as "moment method" or "NEC" programs. NEC programs are
    based on the Numerical Electromagnetics Code moment method of
    analysis developed at Lawrence Livermore Laboratory, Livermore,
    California.

[^3]: *See* 47 C.F.R. § 73.186. A proof of performance requires field
    strength measurements made on a minimum of six radials, to a
    distance of approximately 15 kilometers from the antenna.

[^4]: *See* *generally* Joint Comments of Broadcasters, Broadcast
    Engineering Consultants, and Equipment Manufacturers (filed July 9,
    2001).

[^5]: *Ibid.* at 7.

[^6]: *Further Notice,* 16 FCC Rcd at 5650.