Sec. 25.203  Choice of sites and frequencies.

    (a) Sites and frequencies for earth stations, operating in frequency 
bands shared with equal rights between terrestrial and space services, 
shall be selected, to the extent practicable, in areas where the 
surrounding terrain and existing frequency usage are such as to minimize 
the possibility of harmful interference between the sharing services.
    (b) An applicant for an earth station authorization in a frequency 
band shared with equal rights with terrestrial microwave services shall 
compute the great circle coordination distance contour(s) for the 
proposed station in accordance with the procedures set forth in Sec. 
25.251. The applicant shall submit with the application a map or maps 
drawn to appropriate scale and in a form suitable for reproduction 
indicating the location of the proposed station and these contours. 
These maps, together with the pertinent data on which the computation of 
these contours is based, including all relevant transmitting and/or 
receiving parameters of the proposed station that is necessary in 
assessing the likelihood of interference, an appropriately scaled plot 
of the elevation of the local horizon as a function of azimuth, and the 
electrical characteristics of the earth station antenna(s), shall be 
submitted by the applicant in a single exhibit to the application. The 
coordination distance contour plot(s), horizon elevation plot, and 
antenna horizon gain plot(s)

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required by this section may also be submitted in tabular numerical 
format at 5[deg] azimuthal increments instead of graphical format. At a 
minimum, this exhibit shall include the information listed in paragraph 
(c)(2) of this section. An earth station applicant shall also include in 
the application relevant technical details (both theoretical 
calculations and/or actual measurements) of any special techniques, such 
as the use of artificial site shielding, or operating procedures or 
restrictions at the proposed earth station which are to be employed to 
reduce the likelihood of interference, or of any particular 
characteristics of the earth station site which could have an effect on 
the calculation of the coordination distance.
    (c) Prior to the filing of its application, an earth station 
applicant shall coordinate the proposed frequency usage with existing 
terrestrial users and with applicants for terrestrial station 
authorizations with previously filed applications in accordance with the 
following procedure:
    (1) An applicant for an earth station authorization shall perform an 
interference analysis in accordance with the procedures set forth in 
Sec. 25.251 for each terrestrial station, for which a license or 
construction permit has been granted or for which an application has 
been accepted for filing, which is or is to be operated in a shared 
frequency band to be used by the proposed earth station and which is 
located within the great circle coordination distance contour(s) of the 
proposed earth station.
    (2) The earth station applicant shall provide each such terrestrial 
station licensee, permittee, and prior filed applicant with the 
technical details of the proposed earth station and the relevant 
interference analyses that were made. At a minimum, the earth station 
applicant shall provide the terrestrial user with the following 
technical information:
    (i) The geographical coordinates of the proposed earth station 
antenna(s),
    (ii) Proposed operating frequency band(s) and emission(s),
    (iii) Antenna center height above ground and ground elevation above 
mean sea level,
    (iv) Antenna gain pattern(s) in the plane of the main beam,
    (v) Longitude range of geostationary satellite orbit (GSO) 
satellites at which antenna may be pointed, for proposed earth station 
antenna(s) accessing GSO satellites,
    (vi) Horizon elevation plot,
    (vii) Antenna horizon gain plot(s) determined in accordance with 
Sec. 25.251 for satellite longitude range specified in paragraph 
(c)(2)(v) of this section, taking into account the provisions of Sec. 
25.251 for earth stations operating with non-geostationary satellites,
    (viii) Minimum elevation angle,
    (ix) Maximum equivalent isotropically radiated power (e.i.r.p.) 
density in the main beam in any 4 kHz band, (dBW/4 kHz) for frequency 
bands below 15 GHz or in any 1 MHz band (dBW/MHz) for frequency band 
above 15 GHz,
    (x) Maximum available RF transmit power density in any 1 MHz band 
and in any 4 kHz band at the input terminals of the antenna(s),
    (xi) Maximum permissible RF interference power level as determined 
in accordance with Sec. 25.251 for all applicable percentages of time, 
and
    (xii) A plot of great circle coordination distance contour(s) and 
rain scatter coordination distance contour(s) as determined by Sec. 
25.251.
    (3) The coordination procedures specified in Sec. 101.103 of this 
chapter and Sec. 25.251 shall be applicable except that the information 
to be provided shall be that set forth in paragraph (c)(2) of this 
section, and that the 30-day period allowed for response to a request 
for coordination may be increased to a maximum of 45 days by mutual 
consent of the parties.
    (4) Where technical problems are resolved by an agreement or 
operating arrangement between the parties that would require special 
procedures be taken to reduce the likelihood of harmful interference 
(such as the use of artificial site shielding) or would result in 
lessened quality or capacity of either system, the details thereof shall 
be contained in the application.
    (5) The Commission may, in the course of examining any application, 
require the submission of additional showings, complete with pertinent 
data and calculations in accordance with

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