# 47 CFR 73.184 - Groundwave field strength graphs.

*p*and phase angle

*b*. On graph paper with coordinates similar to those of Graph 21, plot the measured values of field strength as ordinates versus the corresponding distances from the antenna in kilometers as abscissae. The data should be plotted only for distances greater than one wavelength (or, when this is greater, five times the vertical height of the antenna in the case of a nondirectional antenna or 10 times the spacing between the elements of a directional antenna) and for distances less than 80f

^{1/3}MHz kilometers (

*i.e.*, 80 kilometers at 1 MHz). Then, using a light box, place the plotted graph over Graph 21 and shift the plotted graph vertically and horizontally (making sure that the vertical lines on both sheets are parallel) until the best fit with the data is obtained with one of the curves on Graph 21. When the two sheets are properly lined up, the value of the field strength corresponding to the intersection of the inverse distance line of Graph 21 with the 1 kilometer abscissa on the data sheet is the inverse distance field strength at 1 kilometer, and the values of the numerical distance at 1 kilometer,

*p*

*1*, and of

*b*are also determined. Knowing the values of

*b*and

*p*

*1*(the numerical distance at one kilometer), we may substitute in the following approximate values of the ground conductivity and dielectric constant.

*1*= Number of wavelengths in 1 kilometer,

*MHz*=frequency expressed in megahertz,

*p*

*1*, (R/λ)

*1*, and cos

*b*in equation (1). Equation (2) may then be solved for δ and equation (3) for ε. At distances greater than 80/f

*1/3*MHz kilometers the curves of Graph 21 do not give the correct relative values of field strength since the curvature of the earth weakens the field more rapidly than these plane earth curves would indicate. Thus, no attempt should be made to fit experimental data to these curves at the larger distances.

*p,*at 1 kilometer, and the value of

*b*. Then superimpose the log-log graph paper over Graph 21, shifting it vertically until both inverse distance lines coincide and shifting it horizontally until the numerical distance at 1 kilometer on Graph 21 coincides with 1 kilometer on the log-log graph paper. The curve of Graph 21 corresponding to the calculated value of

*b*is then traced on the log-log graph paper giving the field strength versus distance in kilometers.

(a) Graphs 1 to 20 show, for each of 20 frequencies, the computed values of groundwave field strength as a function of groundwave conductivity and distance from the source of radiation. The groundwave field strength is considered to be that part of the vertical component of the electric field which has not been reflected from the ionosphere nor from the troposphere. These 20 families of curves are plotted on log-log graph paper and each is to be used for the range of frequencies shown thereon. Computations are based on a dielectric constant of the ground (referred to air as unity) equal to 15 for land and 80 for sea water and for the ground conductivities (expressed in mS/m) given on the curves. The curves show the variation of the groundwave field strength with distance to be expected for transmission from a vertical antenna at the surface of a uniformly conducting spherical earth with the groundwave constants shown on the curves. The curves are for an antenna power of such efficiency and current distribution that the inverse distance (unattenuated) field is 100 mV/m at 1 kilometer. The curves are valid for distances that are large compared to the dimensions of the antenna for other than short vertical antennas.

(b) The inverse distance field (100 mV/m divided by the distance in kilometers) corresponds to the groundwave field intensity to be expected from an antenna with the same radiation efficiency when it is located over a perfectly conducting earth. To determine the value of the groundwave field intensity corresponding to a value of inverse distance field other than 100 mV/m at 1 kilometer, multiply the field strength as given on these graphs by the desired value of inverse distance field at 1 kilometer divided by 100; for example, to determine the groundwave field strength for a station with an inverse distance field of 2700 mV/m at 1 kilometer, simply multiply the values given on the charts by 27. The value of the inverse distance field to be used for a particular antenna depends upon the power input to the antenna, the nature of the ground in the neighborhood of the antenna, and the geometry of the antenna. For methods of calculating the interrelations between these variables and the inverse distance field, see “The Propagation of Radio Waves Over the Surface of the Earth and in the Upper Atmosphere,” Part II, by Mr. K.A. Norton, Proc. I.R.E., Vol. 25, September 1937, pp. 1203-1237.

The computed values of field strength versus distance used to plot Graphs 1 to 20 are available in tabular form. For information on obtaining copies of these tabulations call or write the Consumer Affairs Office, Federal Communications Commission, Washington, DC 20554, (202) 632-7000.

(c) Provided the value of the dielectric constant is near 15, the ground conductivity curves of Graphs 1 to 20 may be compared with actual field strength measurement data to determine the appropriate values of the ground conductivity and the inverse distance field strength at 1 kilometer. This is accomplished by plotting the measured field strengths on transparent log-log graph paper similar to that used for Graphs 1 to 20 and superimposing the plotted graph over the Graph corresponding to the frequency of the station measured. The plotted graph is then shifted vertically until the plotted measurement data is best aligned with one of the conductivity curves on the Graph; the intersection of the inverse distance line on the Graph with the 1 kilometer abscissa on the plotted graph determines the inverse distance field strength at 1 kilometer. For other values of dielectric constant, the following procedure may be used to determine the dielectric constant of the ground, the ground conductivity and the inverse distance field strength at 1 kilometer. Graph 21 gives the relative values of groundwave field strength over a plane earth as a function of the numerical distance p and phase angle b. On graph paper with coordinates similar to those of Graph 21, plot the measured values of field strength as ordinates versus the corresponding distances from the antenna in kilometers as abscissae. The data should be plotted only for distances greater than one wavelength (or, when this is greater, five times the vertical height of the antenna in the case of a nondirectional antenna or 10 times the spacing between the elements of a directional antenna) and for distances less than 80f 1/3 MHz kilometers (i.e., 80 kilometers at 1 MHz). Then, using a light box, place the plotted graph over Graph 21 and shift the plotted graph vertically and horizontally (making sure that the vertical lines on both sheets are parallel) until the best fit with the data is obtained with one of the curves on Graph 21. When the two sheets are properly lined up, the value of the field strength corresponding to the intersection of the inverse distance line of Graph 21 with the 1 kilometer abscissa on the data sheet is the inverse distance field strength at 1 kilometer, and the values of the numerical distance at 1 kilometer, p 1, and of b are also determined. Knowing the values of b and p 1 (the numerical distance at one kilometer), we may substitute in the following approximate values of the ground conductivity and dielectric constant.

First solve for χ by substituting the known values of p 1, (R/λ)1, and cos b in equation (1). Equation (2) may then be solved for δ and equation (3) for ε. At distances greater than 80/f 1/3 MHz kilometers the curves of Graph 21 do not give the correct relative values of field strength since the curvature of the earth weakens the field more rapidly than these plane earth curves would indicate. Thus, no attempt should be made to fit experimental data to these curves at the larger distances.

For other values of dielectric constant, use can be made of the computer program which was employed by the FCC in generating the curves in Graphs 1 to 20. For information on obtaining a printout of this program, call or write the Consumer Affairs Office, Federal Communications Commission, Washington, DC 200554, (202) 632-7000.

(d) At sufficiently short distances (less than 55 kilometers at AM broadcast frequencies), such that the curvature of the earth does not introduce an additional attenuation of the waves, the curves of Graph 21 may be used to determine the groundwave field strength of transmitting and receiving antennas at the surface of the earth for any radiated power, frequency, or set of ground constants. First, trace the straight inverse distance line corresponding to the power radiated on transparent log-log graph paper similar to that of Graph 21, labelling the ordinates of the chart in terms of field strength, and the abscissae in terms of distance. Next, using the formulas given on Graph 21, calculate the value of the numerical distance, p, at 1 kilometer, and the value of b. Then superimpose the log-log graph paper over Graph 21, shifting it vertically until both inverse distance lines coincide and shifting it horizontally until the numerical distance at 1 kilometer on Graph 21 coincides with 1 kilometer on the log-log graph paper. The curve of Graph 21 corresponding to the calculated value of b is then traced on the log-log graph paper giving the field strength versus distance in kilometers.

(e) This paragraph consists of the following Graphs 1 to 20 and 21.

The referenced graphs are not published in the CFR, nor will they be included in the Commission's automated rules system. For information on obtaining copies of the graphs call or write the Consumer Affairs Office, Federal Communications Commission, Washington, DC 20554, Telephone: (202) 632-7000.

**Title 47 published on 2015-10-01**

The following are **ALL** rules, proposed rules, and notices (chronologically) published in the Federal Register relating to *47 CFR Part 73* **after** this date.

GPO FDSys XML | Text type regulations.gov FR Doc. 2015-29483 RIN GN Docket No. 12-268 DA 15-1238 FEDERAL COMMUNICATIONS COMMISSION Final action; requirements and procedures. November 30, 2015. 47 CFR Part 73 In this document, the Media Bureau adopts the following a final catalog of expenses; a procedure whereby reimbursement payments will be disbursed via the agency's internal vendor payment system; a procedural requirement that the Reimbursement Form, with supporting cost documentation, must be submitted each time an entity makes a request for reimbursement from the Fund; and a decision that cost documentation, as well as the name, address, and other identifying information pertaining to vendors, will not be made publicly available.

GPO FDSys XML | Text type regulations.gov FR Doc. 2015-29239 RIN GN Docket No. 12-268 ET Docket Nos. 13-26 and 14-14 FCC 15-141 FEDERAL COMMUNICATIONS COMMISSION Final rule. Effective December 17, 2015, except for the amendments to §§ 27.1310 and 73.3700(b)(1)(iv)(B), which contain new or modified information collection requirements subject to the Paperwork Reduction Act of 1995, Public Law 104-13, that are not effective until approved by the Office of Management and Budget (OMB). The Commission will publish a document in the Federal Register announcing the effective date once OMB approves. 47 CFR Parts 27 and 73 This document resolves the remaining technical issues affecting the operation of new 600 MHz wireless licensees and broadcast television stations in areas where they operate on the same or adjacent channels in geographic proximity. Specifically, the Commission adopted the methodology and the regulatory framework for the protection of both wireless services and broadcasting in the post-auction environment that it proposed in October 2014. The Commission affirms its decision regarding the methodology to be used during the incentive auction to predict inter-service interference between broadcasting and wireless services. The Commission also affirmed its decision declining to adopt a cap on the aggregate amount of new interference a broadcast television station may receive from other television stations in the repacking process.

GPO FDSys XML | Text type regulations.gov FR Doc. 2015-28344 RIN GN Docket No. 15-236 FCC 15-137 FEDERAL COMMUNICATIONS COMMISSION Proposed rule. Submit comments on or before December 21, 2015, and replies on or before January 20, 2016. The NPRM contains potential information collection requirements subject to the PRA, Public Law 104-13. OMB, the general public, and other Federal agencies are invited to comment on the potential new and modified information collection requirements contained in this NPRM. If the information collection requirements are adopted, the Commission will submit the appropriate documents to OMB for review under Section 3507(d) of the PRA. OMB, the general public, and other Federal agencies will again be invited to comment on the new and modified information collection requirements adopted by the Commission. 47 CFR Parts 1, 25, 73, and 74 In this document, the Federal Communications Commission (Commission) proposes to extend its foreign ownership rules and procedures that apply to common carrier licensees to broadcast licensees, with certain modifications to tailor them to the broadcast context. The Commission also seeks comment on whether and how to revise the methodology a licensee should use to assess its compliance with the 25 percent foreign ownership benchmark in section 310(b)(4) of the Communications Act of 1934, as amended, in order to reduce regulatory burdens on applicants and licensees. Finally, the Commission makes several proposals to clarify and update existing foreign ownership policies and procedures for broadcast, common carrier and aeronautical licensees.

GPO FDSys XML | Text type regulations.gov FR Doc. 2015-27738 RIN GN Docket No. 12-268 MB Docket No. 15-137 FCC 15-67 FEDERAL COMMUNICATIONS COMMISSION Final rule. Effective December 2, 2015, except for §§ 1.2204(c)(4) and 73.3700(b)(1), which contain new or modified information collection requirements that require approval by OMB under the PRA and will become effective after the Commission publishes a notice in the Federal Register announcing such approval and the relevant effective date. 47 CFR Parts 1 and 73 In this document, the Commission refines the rules it adopted in the Incentive Auction Report and Order and the preceding Channel Sharing Report and Order to provide greater flexibility and certainty regarding channel sharing agreements (“CSAs”). Among other things, we modify our rules to allow broadcasters that relinquish rights in the incentive auction in order to channel share to enter into CSAs after the auction and, whether they enter into CSAs before or after the auction, to determine the length of their agreements.

GPO FDSys XML | Text type regulations.gov FR Doc. 2015-27632 RIN GN Docket No. 12-268 and MB Docket No. 15-137 FCC 15-139 FEDERAL COMMUNICATIONS COMMISSION Final rule. Effective December 2, 2015. 47 CFR Part 73 In this Second Order on Reconsideration, the Federal Communications Commission (Commission) provides more flexibility to broadcasters interested in the channel sharing option in the broadcast incentive auction by clarifying that back-up channel sharing agreements (“CSAs”) are permitted under its rules and providing more time for successful bidders to transition to shared facilities after the auction. The Commission also provides guidance regarding how the CSA exception to the prohibited communications rule applies with respect to back-up CSAs.

GPO FDSys XML | Text type regulations.gov FR Doc. 2015-27621 RIN WT Docket No. 12-269 GN Docket No. 12-268 AU Docket No. 14-252 DA 15-1183 FEDERAL COMMUNICATIONS COMMISSION Final rule; requirements and procedures. Reverse Auction (Auction 1001) applications must be filed prior to 6 p.m. Eastern Time (ET) on December 18, 2015; Forward Auction (Auction 1002) applications must be filed prior to 6 p.m. ET on January 28, 2016. 47 CFR Parts 1, 20, 27, and 73 This document announces the final application procedures for the broadcast television spectrum incentive auction (Auction 1000), including the forward and reverse auctions (Auctions 1001 and 1002 respectively). This document also summarizes detailed information, instructions, and deadlines for filing applications, as well as certain post-auction procedures established by the Commission's prior orders.

GPO FDSys XML | Text type regulations.gov FR Doc. 2015-26093 RIN MB Docket No. 14-226 FCC 15-118 FEDERAL COMMUNICATIONS COMMISSION Final rule. This rule contains information collection requirements that have not been approved by OMB. The Commission will publish a document in the Federal Register announcing the effective date. 47 CFR Part 73 In this document, the Federal Communications Commission (“Commission”) amends the portion of its rules known as the “Contest Rule” to permit broadcast licensees to comply with their obligation to disclose material contest terms either by broadcasting those terms or by making them available in writing on a publicly accessible Internet Web site. In particular, the Commission amends the Contest Rule to allow licensees to satisfy their disclosure obligation by posting material contest terms on the station's Web site, the licensee's Web site, or, if neither the individual station nor the licensee has its own Web site, any Internet Web site that is readily accessible to the public. The Commission also adopts requirements that define the disclosure obligation in cases where a licensee has chosen to meet its obligation through an Internet Web site.

GPO FDSys XML | Text type regulations.gov FR Doc. 2015-26872 RIN GN Docket No. 12-268 Report No. 3028 FEDERAL COMMUNICATIONS COMMISSION Petition for reconsideration. Oppositions to the Petitions must be filed on or before November 9, 2015. Replies to an opposition must be filed on or before November 17, 2015. 47 CFR Parts 15 and 73 Petitions for Reconsideration (Petitions) have been filed in the Commission's Rulemaking Proceeding by Ari Q. Fitzgerald, on behalf of GE Healthcare; Ronald J. Bruno on behalf of The VideoHouse, Inc.; Benjamin Perez on behalf of Abacus Television; Lawrence Rogow on behalf of WMTM, LLC; and Larry E. Morton on behalf of KMYA, LLC.