Goto Section: 73.53 | 73.57 | Table of Contents
Revised as of September 1, 2021
Goto Year:2020 |
§ 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
(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 § 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
(d) AM stations using direct reading power meters in accordance with
§ 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]
Goto Section: 73.53 | 73.57
Goto Year: 2020 |
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