[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: 47CFR73.45]

[Page 20]
 
                       TITLE 47--TELECOMMUNICATION
 
                    CHAPTER I--FEDERAL COMMUNICATIONS
                         COMMISSION (CONTINUED)
 
PART 73_RADIO BROADCAST SERVICES--Table of Contents
 
                     Subpart A_AM Broadcast Stations
 
Sec. 73.45  AM antenna systems.

    (a) All applicants for new, additional, or different AM station 
facilities and all licensees requesting authority to change the 
transmitting system site of an existing station must specify an antenna 
system, the efficiency of which complies with the requirements for the 
class and power of station. (See Sec. Sec. 73.186 and 73.189.)
    (1) An application for authority to install an AM broadcast antenna 
must specify a definite site and include full details of the antenna 
system design and expected performance.
    (2) All data necessary to show compliance with the terms and 
conditions of the construction permit must be filed with the application 
for the station license to cover the construction. If the station has 
constructed a directional antenna, a directional proof of performance 
must be filed. See Sec. Sec. 73.150 through 73.157.
    (b) The simultaneous use of a common antenna or antenna structure by 
more than one AM station or by a station of any other type or service 
may be authorized provided:
    (1) Engineering data are submitted showing that satisfactory 
operation of each station will be obtained without adversely affecting 
the operation of the other station(s).
    (2) The minimum field strength for each AM station complies with 
Sec. 73.189(b).
    (c) Should any changes be made or otherwise occur which would 
possibly alter the resistance of the antenna system, the licensee must 
commence the determination of the operating power by a method described 
in Sec. 73.51(a)(1) or (d). (If the changes are due to the construction 
of FM or TV transmitting facilities, see Sec. Sec. 73.316, 73.685, and 
73.1692.) Upon completion of any necessary repairs or adjustments, or 
upon completion of authorized construction or modifications, the 
licensee must make a new determination of the antenna resistance using 
the procedures described in Sec. 73.54. Operating power should then be 
determined by a direct method as described in Sec. 73.51. Notification 
of the value of resistance of the antenna system must be filed with the 
FCC in Washington, DC as follows:
    (1) Whenever the measurements show that the antenna or common point 
resistance differs from that shown on the station authorization by more 
than 2%, FCC Form 302 must be filed with the information and measurement 
data specified in Sec. 73.54(d).
    (2) Whenever AM stations use direct reading power meters pursuant to 
Sec. 73.51, a letter notification to the FCC in Washington, DC, 
Attention: Audio Division, Media Bureau, must be filed in accordance 
with Sec. 73.54(e).

[43 FR 53735, Nov. 17, 1978, as amended at 45 FR 28141, Apr. 28, 1980; 
47 FR 8589, Mar. 1, 1982; 50 FR 32416, Aug. 12, 1985; 51 FR 2707; Jan. 
21, 1986; 51 FR 26250, July 22, 1986; 63 FR 33875, June 22, 1998; 67 FR 
13231, Mar. 21, 2002]