Artikel 21

21.1 § 1 Sites and frequencies for terrestrial stations and earth stations, operating in frequency bands shared with equal rights between terrestrial radiocommunication and space radiocommunication services, shall be selected having regard to the relevant ITU-R Recommendations with respect to geographical separation between earth stations and terrestrial stations.
21.2 § 2 1) As far as practicable, sites for transmitting128)21.2.1 For their own protection receiving stations in the fixed or mobile service operating in frequency bands shared with space radiocommunication services (space-to-Earth) should also avoid directing their antennas towards the geostationary-satellite orbit if their sensitivity is sufficiently high that interference from space station transmissions may be significant. In particular, in the frequency bands 13.4-13.65 GHz and 21.4-22 GHz, it is recommended to maintain a minimum separation angle of 1.5° with respect to the direction of the geostationary-satellite orbit. (WRC-15), 129)21.2.4 For frequency bands above 15 GHz (except 25.25-27.5 GHz), there is no restriction on the angular separation for transmitting stations of the fixed or mobile service. This matter is being studied in ITU-R. stations, in the fixed or mobile service, employing maximum values of equivalent isotropically radiated power (e.i.r.p.) exceeding the values given in Table 21-1 in the frequency bands indicated, should be selected so that the direction of maximum radiation of any antenna will be separated from the geostationary-satellite orbit by at least the angle in degrees shown in the Table, taking into account the effect of atmospheric refraction130)21.2.2 Information on this subject is given in the most recent version of Recommendation ITU-R SF.765. (WRC-23)21.2.3 Not used.: (WRC-12)
1)21.2.4 For frequency bands above 15 GHz (except 25.25-27.5 GHz), there is no restriction on the angular separation for transmitting stations of the fixed or mobile service. This matter is being studied in ITU-R.
21.3 § 3 1) The maximum equivalent isotropically radiated power (e.i.r.p.) of a station in the fixed or mobile service shall not exceed +55 dBW.
21.4 2) Where compliance with No. 21.2 for frequency bands between 1 GHz and 10 GHz is impracticable, the maximum equivalent isotropically radiated power (e.i.r.p.) of a station in the fixed or mobile service shall not exceed:
+47 dBW in any direction within 0.5° of the geostationary-satellite orbit; or
+47 dBW to +55 dBW, on a linear decibel scale (8 dB per degree), in any direction between 0.5° and 1.5° of the geostationary-satellite orbit, taking into account the effect of atmospheric refraction131)21.4.1 Information on this subject is given in the most recent version of Recommendation ITU-R SF.765. (WRC-23).
21.5 3) The power delivered by a transmitter to the antenna of a station in the fixed or mobile services shall not exceed +13 dBW in frequency bands between 1 GHz and 10 GHz, or
+10 dBW in frequency bands above 10 GHz, except as cited in No. 21.5A. (WRC-2000)
21.5A As an exception to the power levels given in No. 21.5, the sharing environment within which the Earth exploration-satellite (passive) and space research (passive) services shall operate in the band 18.6-18.8 GHz is defined by the following limitations on the operation of the fixed service: the power of each RF carrier frequency delivered to the input of each antenna of a station in the fixed service in the band 18.6-18.8 GHz shall not exceed −3 dBW. (WRC-2000)
21.6 4) The limits given in Nos. 21.2, 21.3, 21.4, 21.5 and 21.5A apply, where applicable, to the services and frequency bands indicated in Table 21-2 for reception by space stations where the frequency bands are shared with equal rights with the fixed or mobile services: (WRC-2000)
NOTE: Additional frequency bands above 29.5 GHz may be considered for inclusion in Table 21-2 by a future competent conference.
1)21.6.1 The equality of right to operate when a band of frequencies is allocated in different Regions to different services of the same category is established in No. 4-8. Therefore any limits concerning inter-Regional interference which may appear in ITU-R Recommendations should, as far as practicable, be observed by administrations.
2) For this frequency band only the limits of Nos.21-3 and 21-5 apply.
21.7 5) Transhorizon systems in the 1 700-1 710 MHz, 1 980-2 010 MHz, 2 025-2 110 MHz and 2 200-2 290 MHz bands may exceed the limits given in Nos. 21.3 and 21.5, but the provisions of Nos. 21.2 and 21.4 should be observed. Considering the difficult sharing conditions with other services, administrations are urged to keep the number of transhorizon systems in these bands to a minimum. (WRC-2000)
21.8 § 4 1) The equivalent isotropically radiated power (e.i.r.p.) transmitted in any direction towards the horizon by an earth station shall not exceed the following limits except as provided in No. 21.10 or 21.11:
a) in frequency bands between 1 GHz and 15 GHz +40 dBW in any 4 kHz band for θ ≤ 0° +40 + 3 θ dBW in any 4 kHz band for 0° < θ ≤ 5°; and
b) in frequency bands above 15 GHz +64 dBW in any 1 MHz band for θ ≤ 0° +64 + 3 θ dBW in any 1 MHz band for 0° < θ ≤ 5°,
where θ is the angle of elevation of the horizon viewed from the centre of radiation of the antenna of the earth station and measured in degrees as positive above the horizontal plane and negative below it.
21.9 2) For angles of elevation of the horizon greater than 5° there shall be no restriction as to the equivalent isotropically radiated power (e.i.r.p.) transmitted by an earth station towards the horizon.
21.10 3) As an exception to the limits given in No. 21.8, the equivalent isotropically radiated power (e.i.r.p.) towards the horizon for an earth station in the space research service (deep space) shall not exceed +55 dBW in any 4 kHz band in frequency bands between 1 GHz and 15 GHz, or +79 dBW in any 1 MHz band in frequency bands above 15 GHz.
21.11 4) The limits given in Nos. 21.8 and 21.10, as applicable, may be exceeded by not more than 10 dB. However, when the resulting coordination area extends into the territory of another country, such increase shall be subject to agreement by the administration of that country.
21.12 5) The limits given in No. 21.8 apply, where applicable, to the services and frequency bands indicated in Table 21-3 below for transmission by earth stations where the frequency bands are shared with equal rights with the fixed or mobile service:
1)21.12.1 The equality of right to operate when a band of frequencies is allocated in different Regions to different services of the same category is established in No. 4.8. Therefore any limits concerning inter-Regional interference which may appear in ITU-R Recommendations should, as far as practicable, be observed by administrations.
21.13 6) The equivalent isotropically radiated power (e.i.r.p.) transmitted in any direction by an earth station in the radiodetermination-satellite service in the band 1 610-1 626.5 MHz shall not exceed −3 dBW in any 4 kHz band.
21.13A 7) In the band 13.75-14 GHz, the level of off-axis e.i.r.p. emitted by an earth station of a geostationary fixed-satellite service network with an antenna diameter smaller than 4.5 m shall not exceed the following values:
21.14 § 5 1) Earth station antennas shall not be employed for transmission at elevation angles of less than 3° measured from the horizontal plane to the direction of maximum radiation, except when agreed to by administrations concerned and those whose services may be affected. In case of reception by an earth station, the above value shall be used for coordination purposes if the operating angle of elevation is less than that value.
21.15 2) As an exception to No. 21.14, earth station antennas in the space research service (near Earth) shall not be employed for transmission at elevation angles of less than 5°, and earth station antennas in the space research service (deep space) shall not be employed for transmission at elevation angles of less than 10°, both angles being those measured from the horizontal plane to the direction of maximum radiation. In the case of reception by an earth station, the above values shall be used for coordination purposes if the operating angle of elevation is less than those values.
21.16 § 6 1) The power flux-density at the Earth’s surface produced by emissions from a space station, including emissions from a reflecting satellite, for all conditions and for all methods of modulation, shall not exceed the limit given in Table 21-4. The limit relates to the power flux-density which would be obtained under assumed free-space propagation conditions and applies to emissions by a space station of the service indicated where the frequency bands are shared with equal rights with the fixed or mobile service, unless otherwise stated.
1) The references to services are those services which have allocations in Article 5.
2)21.16.1 The equality of right to operate when a frequency band is allocated in different Regions to different services of the same category is established in No. 4.8. Therefore, any limits concerning inter-Regional interference which may appear in ITU R Recommendations should, as far as practicable, be observed by administrations.
3)21.16.2 In addition to the limits given in Table 21-4, in the band 18.6-18.8 GHz the sharing environment within which the Earth exploration-satellite (passive) and space research (passive) services shall operate is defined by the following limitations on the operation of the fixed-satellite service: the power flux-density across the 200 MHz band 18.6 18.8 GHz produced at the surface of the Earth by emissions from a space station under assumed free-space propagation conditions shall not exceed −95 dB(W/m2), except for less than 5% of time, when the limit may be exceeded by up to 3 dB. The provisions of No. 21.17 do not apply in this band. (WRC-2000)
4)21.16.3 These power flux-density values are derived on the basis of protecting the fixed service using line-of-sight techniques. Where a fixed service using tropospheric scatter operates in the bands listed in the first column and there is insufficient frequency separation, there must be sufficient angular separation between the direction to the space station and the direction of maximum radiation of the antenna of the receiving station of the fixed service using tropospheric scatter, in order to ensure that the interference power at the receiver input of the fixed-service station does not exceed −168 dBW in any 4 kHz band.
5)21.16.3A Resolution 903 (Rev.WRC-19) shall apply. (WRC-19)
6)21.16.4 The values given in this table entry shall apply to emissions of space stations of non-geostationary satellites in systems operating with 99 or fewer satellites. Further study concerning the applicability of these values is necessary in order to apply them to systems operating with 100 or more satellites. (WRC-2000)
7)21.16.5 These values are applicable where this band is shared with equal rights with meteorological aids service.
8)21.16.6 The function X is defined as a function of the number, N, of satellites in the non-geostationary satellite constellation in the fixed-satellite service and Nv, as follows:
where:
– Nv132)Where Nvis determined as follows: Nv= Max(Nv(j = 0,1,2...)) with Nv(j) = Max(Nv(j(t)), Nv(j(t − 1))), where Nv(j(t)) represents all visible satellites (with elevation ≥ 0 degrees) at each time-step (t) on any point on the surface of the Earth (j). is the maximum number of visible space stations – considering a minimum elevation angle equal to 0 degrees – from any location on the surface of the Earth and within the service area of the non-GSO system. Nv does not depend on latitude; it encompasses the maximum number of visible satellites across all latitudes within the service area of the relevant non-GSO system.
In the frequency band 18.8-19.3 GHz, these limits apply to emissions of any space station in a non-geostationary-satellite system
– in the fixed-satellite service for which complete coordination or notification information, as appropriate, has been received by the Radiocommunication Bureau since 17 November 1995 and which was not operational by that date, and
– in the inter-satellite service. (WRC-23)
9)21.16.6A These limits apply to emissions of a space station in the meteorological-satellite service and of a geostationary satellite in the fixed-satellite and inter-satellite services. They also apply to emissions of any space station in a non-geostationary-satellite system in the fixed-satellite service in the band 18.8-19.3 GHz for which complete coordination or notification information has been received by the Radiocommunication Bureau by 17 November 1995, or which was in operation by that date. (WRC-23)
10)21.16.6B These limits also apply to fixed-satellite service space stations using highly-inclined orbits having an apogee altitude greater than 18 000 km and an orbital inclination between 35° and 145° in the band 17.7-19.7 GHz to which Resolution 147 (WRC-07) applies. (WRC-07)
11)21.16.6C These limits apply to all space stations that use highly-inclined orbits having an apogee altitude greater than 18 000 km and an orbital inclination between 35° and 145° in the band 17.7-19.7 GHz in the fixed-satellite service and that are not covered by Resolution 147 (WRC-07), and for which complete coordination or notification information, as appropriate, was received by the Radiocommunication Bureau after 16 November 2007, and in the inter-satellite service. (WRC-23)
12)21.16.7 These power flux-density limits are subject to review by ITU-R and shall apply until they are revised by a competent world radiocommunication conference.
13)21.16.8 The pfd values given for EESS (active) are mean pfd values defined as follows:
where:
P: RF peak power at the input of the antenna of the SAR satellite (dBW)
τ: SAR pulse length (μs)
PRF: SAR pulse repetition frequency (kHz)
δ: elevation angle of the EESS SAR satellite above ground, in the vertical plane (perpendicular to the satellite orbit) (°)
Bc: SAR emission bandwidth (MHz)
Gt (δ): transmit antenna gain of the SAR satellite in the vertical plane (perpendicular to the satellite orbit) for the elevation angle ö considered (dBi)
d (δ): distance between the SAR satellite and the ground for the elevation angle δ considered (m). (WRC-15)
14)21.16.9 These values are also based on sharing with the Earth exploration-satellite (active) and space research services. (WRC-15)
15)21.16.10 During the launch and near-Earth operational phase of deep-space facilities, non-geostationary satellite systems in the space research service shall not exceed a power flux-density value of:
in any 1 MHz band, where δ is the angle of arrival above the horizontal plane. (WRC-2000)
21.16.11 (SUP – WRC-03)
21.16.12 (SUP – WRC-03)
21.16.13 (SUP – WRC-03)
16)21.16.14 When addressing the sharing conditions between the fixed service and the fixed-satellite service in the bands 37.5-40 GHz and 40.5-42.5 GHz, the power flux-density at the Earth’s surface from any FSS satellite should be no greater than the level(s) required to meet the FSS link availability and performance objectives of the subject applications, taking into account the technical and operational requirements of the overall design of the satellite network. In any case, the levels shall not exceed the applicable power flux-density limits in Table 21-4. (WRC-03)
17)21.16.15 The value of Y is defined as Y = 0 for max(NN, NS) ≤ 2; Y = 5 log(max(NN, NS)) for max(NN, NS) >2, where NN is the maximum number of space stations in a system simultaneously transmitting on a co-frequency basis in the fixed-satellite service in the Northern Hemisphere, and NS is the maximum number of space stations in the same system simultaneously transmitting on a co-frequency basis in the fixed-satellite service in the Southern Hemisphere. In determining NN and NS, two space stations simultaneously transmitting during periods of short-duration handover shall be considered as one satellite. (WRC-03)
18)21.16.16 The applicability of these limits may need to be reviewed by a future competent conference if the number of co-frequency non-geostationary systems brought into use and simultaneously operating in the same hemisphere is greater than five. (WRC-03)
19)21.16.17 These limits apply to non-geostationary fixed-satellite service space stations employing an orbit with an inclination angle between 35° and 145° and apogee altitude greater than 18 000 km. (WRC-03)
20)21.16.18 These limits apply to non-geostationary fixed-satellite service space stations that are not covered by No. 21.16.17. (WRC-03)
21)21.16.19 The methodology included in Annex 2 to Resolution 679 (WRC-23) shall be applied to calculate the pfd produced at the surface of the Earth by emissions from a non-geostationary-satellite space station transmitting in the frequency band 27.5-30.0 GHz. (WRC-23)
21.17 2) The limits given in Table 21-4 may be exceeded on the territory of any country whose administration has so agreed.
21.18 § 7 Administrations operating or planning to operate radionavigation-satellite service systems or networks in the 1 164-1 215 MHz frequency band, for which complete coordination or notification information, as appropriate, was received by the Bureau after 2 June 2000, shall, in accordance with resolves 2 of Resolution 609 (WRC-03)132)Note by the Secretariat: This Resolution was revised by WRC-07., take all necessary steps to ensure that the actual aggregate interference into aeronautical radionavigation service systems caused by such radionavigation-satellite service systems or networks operating co-frequency in these frequency bands does not exceed the equivalent power flux-density level shown in resolves 1 of Resolution 609 (WRC-03)133)Note by the Secretariat: This Resolution was revised by WRC-07.. (WRC-03)