§  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.