Sec.  90.1321   Power and antenna limits.

   (a) Base and fixed stations are limited to 25 watts/25 MHz equivalent
   isotropically radiated power (EIRP). In any event, the peak EIRP power
   density shall not exceed 1 Watt in any one-megahertz slice of spectrum.

   (b) In addition to the provisions in paragraph (a) of this section,
   transmitters operating in the 3650–3700 MHz band that emit multiple
   directional beams, simultaneously or sequentially, for the purpose of
   directing signals to individual receivers or to groups of receivers provided
   the emissions comply with the following:

   (1) Different information must be transmitted to each receiver.

   (2) If the transmitter employs an antenna system that emits multiple
   directional beams but does not emit multiple directional beams
   simultaneously, the total output power conducted to the array or arrays that
   comprise the device, i.e., the sum of the power supplied to all antennas,
   antenna elements, staves, etc. and summed across all carriers or frequency
   channels, shall not exceed the limit specified in paragraph (a) of this
   section, as applicable. The directional antenna gain shall be computed as
   follows:

   (i) The directional gain, in dBi, shall be calculated as the sum of 10 log
   (number of array elements or staves) plus the directional gain, in dBi, of
   the individual element or stave having the highest gain.

   (ii) A lower value for the directional gain than that calculated in
   paragraph (b)(2)(i) of this section will be accepted if sufficient evidence
   is presented, e.g., due to shading of the array or coherence loss in the
   beam-forming.

   (3) If a transmitter employs an antenna that operates simultaneously on
   multiple directional beams using the same or different frequency channels
   and if transmitted beams overlap, the power shall be reduced to ensure that
   the aggregate power from the overlapping beams does not exceed the limit
   specified in paragraph (b)(2) of this section. In addition, the aggregate
   power transmitted simultaneously on all beams shall not exceed the limit
   specified in paragraph (b)(2) of this section by more than 8 dB.

   (4) Transmitters that emit a single directional beam shall operate under the
   provisions of paragraph (b)(2) of this section.

   (c) Mobile and portable stations are limited to 1 watt/25 MHz EIRP. In any
   event, the peak EIRP density shall not exceed 40 milliwatts in any
   one-megahertz slice of spectrum.