[Code of Federal Regulations]
[Title 47, Volume 4]
[Revised as of October 1, 2004]
From the U.S. Government Printing Office via GPO Access
[CITE: 47CFR73.54]

[Page 24]
 
                       TITLE 47--TELECOMMUNICATION
 
                    CHAPTER I--FEDERAL COMMUNICATIONS
                         COMMISSION (CONTINUED)
 
PART 73_RADIO BROADCAST SERVICES--Table of Contents
 
                     Subpart A_AM Broadcast Stations
 
Sec. 73.54  Antenna resistance and reactance measurements.

    (a) The resistance of an omnidirectional series fed antenna is 
measured at either the base of the antenna without intervening coupling 
or tuning networks, or at the point the transmission line connects to 
the output terminals of the transmitter. The resistance of a shunt 
excited antenna may be measured at the point the radio frequency energy 
is transferred to the feed wire circuit or at the output terminals of 
the transmitter.
    (b) The resistance and reactance of a directional antenna shall be 
measured at the point of common radiofrequency input to the directional 
antenna system after the antenna has been finally adjusted for the 
required radiation pattern.
    (c) A letter of notification must be filed with the FCC in 
Washington, DC, Attention: Audio Division, Media Bureau, when 
determining power by the direct method pursuant to Sec. 73.51. The 
letter must specify the antenna or common point resistance at the 
operating frequency. The following information must also be kept on file 
at the station:
    (1) A full description of the method used to make measurements.
    (2) A schematic diagram showing clearly all components of coupling 
circuits, the point of resistance measurement, the location of the 
antenna ammeter, connections to and characteristics of all tower 
lighting isolation circuits, static drains, and any other fixtures 
connected to and supported by the antenna, including other antennas and 
associated networks. Any network or circuit component used to dissipate 
radio frequency power shall be specifically identified, and the 
impedances of all components which control the level of power 
dissipation, and the effective input resistance of the network must be 
indicated.
    (d) AM stations using direct reading power meters in accordance with 
Sec. 73.51, can either submit the information required by paragraph (c) 
of this section or submit a statement indicating that such a meter is 
being used. Subsequent station licenses will indicate the use of a 
direct reading power meter in lieu of the antenna resistance value in 
such a situation.

[66 FR 20755, Apr. 25, 2001,as amended at 67 FR 13231, Mar. 21, 2002]