§  15.255   Operation within the band 57-71 GHz.

   (a) Operation under the provisions of this section is not permitted for
   the following products:

   (1) Equipment used on satellites.

   (2) Field disturbance sensors, including vehicle radar systems, unless
   the field disturbance sensors are employed for fixed operation, or used
   as short-range devices for interactive motion sensing. For the purposes
   of this section, the reference to fixed operation includes field
   disturbance sensors installed in fixed equipment, even if the sensor
   itself moves within the equipment.

   (b) Operation on aircraft is permitted under the following conditions:

   (1) When the aircraft is on the ground.

   (2) While airborne, only in closed exclusive on-board communication
   networks within the aircraft, with the following exceptions:

   (i) Equipment shall not be used in wireless avionics
   intra-communication (WAIC) applications where external structural
   sensors or external cameras are mounted on the outside of the aircraft
   structure.

   (ii) Equipment shall not be used on aircraft where there is little
   attenuation of RF signals by the body/fuselage of the aircraft. These
   aircraft include, but are not limited to, toy/model aircraft, unmanned
   aircraft, crop-spraying aircraft, aerostats, etc.

   (c) Within the 57-71 GHz band, emission levels shall not exceed the
   following equivalent isotropically radiated power (EIRP):

   (1) Products other than fixed field disturbance sensors and short-range
   devices for interactive motion sensing shall comply with one of the
   following emission limits, as measured during the transmit interval:

   (i) The average power of any emission shall not exceed 40 dBm and the
   peak power of any emission shall not exceed 43 dBm; or

   (ii) For fixed point-to-point transmitters located outdoors, the
   average power of any emission shall not exceed 82 dBm, and shall be
   reduced by 2 dB for every dB that the antenna gain is less than 51 dBi.
   The peak power of any emission shall not exceed 85 dBm, and shall be
   reduced by 2 dB for every dB that the antenna gain is less than 51 dBi.

   (A) The provisions in this paragraph (c) for reducing transmit power
   based on antenna gain shall not require that the power levels be
   reduced below the limits specified in paragraph (c)(1)(i) of this
   section.

   (B) The provisions of § 15.204(c)(2) and (4) that permit the use of
   different antennas of the same type and of equal or less directional
   gain do not apply to intentional radiator systems operating under this
   provision. In lieu thereof, intentional radiator systems shall be
   certified using the specific antenna(s) with which the system will be
   marketed and operated. Compliance testing shall be performed using the
   highest gain and the lowest gain antennas for which certification is
   sought and with the intentional radiator operated at its maximum
   available output power level. The responsible party, as defined in
   § 2.909 of this chapter, shall supply a list of acceptable antennas with
   the application for certification.

   (2) For fixed field disturbance sensors that occupy 500 MHz or less of
   bandwidth and that are contained wholly within the frequency band
   61.0-61.5 GHz, the average power of any emission, measured during the
   transmit interval, shall not exceed 40 dBm, and the peak power of any
   emission shall not exceed 43 dBm. In addition, the average power of any
   emission outside of the 61.0-61.5 GHz band, measured during the
   transmit interval, but still within the 57-71 GHz band, shall not
   exceed 10 dBm, and the peak power of any emission shall not exceed 13
   dBm.

   (3) For fixed field disturbance sensors other than those operating
   under the provisions of paragraph (c)(2) of this section, and
   short-range devices for interactive motion sensing, the peak
   transmitter conducted output power shall not exceed -10 dBm and the
   peak EIRP level shall not exceed 10 dBm.

   (4) The peak power shall be measured with an RF detector that has a
   detection bandwidth that encompasses the 57-71 GHz band and has a video
   bandwidth of at least 10 MHz. The average emission levels shall be
   measured over the actual time period during which transmission occurs.

   (d) Limits on spurious emissions:

   (1) The power density of any emissions outside the 57-71 GHz band shall
   consist solely of spurious emissions.

   (2) Radiated emissions below 40 GHz shall not exceed the general limits
   in § 15.209.

   (3) Between 40 GHz and 200 GHz, the level of these emissions shall not
   exceed 90 pW/cm2 at a distance of 3 meters.

   (4) The levels of the spurious emissions shall not exceed the level of
   the fundamental emission.

   (e) Except as specified paragraph (e)(1) of this section, the peak
   transmitter conducted output power shall not exceed 500 mW. Depending
   on the gain of the antenna, it may be necessary to operate the
   intentional radiator using a lower peak transmitter output power in
   order to comply with the EIRP limits specified in paragraph (b) of this
   section.

   (1) Transmitters with an emission bandwidth of less than 100 MHz must
   limit their peak transmitter conducted output power to the product of
   500 mW times their emission bandwidth divided by 100 MHz. For the
   purposes of this paragraph, emission bandwidth is defined as the
   instantaneous frequency range occupied by a steady state radiated
   signal with modulation, outside which the radiated power spectral
   density never exceeds 6 dB below the maximum radiated power spectral
   density in the band, as measured with a 100 kHz resolution bandwidth
   spectrum analyzer. The center frequency must be stationary during the
   measurement interval, even if not stationary during normal operation
   (e.g., for frequency hopping devices).

   (2) Peak transmitter conducted output power shall be measured with an
   RF detector that has a detection bandwidth that encompasses the 57-71
   GHz band and that has a video bandwidth of at least 10 MHz.

   (3) For purposes of demonstrating compliance with this paragraph,
   corrections to the transmitter conducted output power may be made due
   to the antenna and circuit loss.

   (f) Frequency stability. Fundamental emissions must be contained within
   the frequency bands specified in this section during all conditions of
   operation. Equipment is presumed to operate over the temperature range
   -20 to + 50 degrees Celsius with an input voltage variation of 85% to
   115% of rated input voltage, unless justification is presented to
   demonstrate otherwise.

   (g) Radio frequency devices operating under the provisions of this part
   are subject to the radio frequency radiation exposure requirements
   specified in § § 1.1307(b), 1.1310, 2.1091, and 2.1093 of this chapter,
   as appropriate. Applications for equipment authorization of mobile or
   portable devices operating under this section must contain a statement
   confirming compliance with these requirements. Technical information
   showing the basis for this statement must be submitted to the
   Commission upon request.

   (h) Any transmitter that has received the necessary FCC equipment
   authorization under the rules of this chapter may be mounted in a group
   installation for simultaneous operation with one or more other
   transmitter(s) that have received the necessary FCC equipment
   authorization, without any additional equipment authorization. However,
   no transmitter operating under the provisions of this section may be
   equipped with external phase-locking inputs that permit beam-forming
   arrays to be realized.

   (i) Measurement procedures that have been found to be acceptable to the
   Commission in accordance with § 2.947 of this chapter may be used to
   demonstrate compliance.

   [ 63 FR 42279 , Aug. 7, 1998, as amended at  66 FR 7409 , Jan. 23, 2001;  68 FR 68547 , Dec. 9, 2003;  78 FR 59850 , Sept. 30, 2013;  81 FR 79936 , Nov.
   14, 2016;  83 FR 63 , Jan. 2, 2018;  85 FR 18149 , Apr. 1, 2020]