Page:United States Statutes at Large Volume 63 Part 2.djvu/296

 UWSTAT.] AMULTILATERAL-TELECOMAIIUNICATIONS-OCT. 2, 1947 (Chapter 1, art. 1 R) (6-66) 60 Power of a Transmitter: a) When not otherwise specified, one shall use only the definition of "peak power of a radio trans- mitter" as follows: 61 Peak Power of a Radio Transmitter: The mean power supplied to the antenna during one radio frequency cycle at the highest crest of the modulation envelope, taken under conditions of normal operation. 62 b) In cases where the first definition does not suffice, in view of the classification of the emis- sion, to characterise fully its practical proper- ties, the following definition of "mean power of a radio transmitter" may be employed in addi- tion. 63 Mean Power of a Radio Transmitter:The power sup- plied to the antenna during normal operation, averaged over a time sufficiently long compared to the period corresponding to the lowest frequency encountered in actual modulation." ) 64 c) When the words "peak power" or "mean power" are not used in the context, the figure for "peak power" is to be followed by the letter "p" and that for "mean power" by the letter "m". 65 Gain of an Antenna: The gain of an antenna'2 in a given direction is the ratio, expressed in decibels, of the square of the field intensity radiated in this direction by the given antenna to the square of the field intensity radiated in its median plane by a perfect half-wave antenna isolated in space, where the fields are measured at a distance sufficiently great. It is assumed that the real antenna and the perfect half wave antenna are supplied with equal power. 63.1 ) In general a time of 1/10 second, during which the mean power is a maximum, will be selected. 65.1 ° When not specified otherwise, the figure expressing the gain of an antnna refers to the gain in the direction of the main beam. 1593

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