1、 Recommendation ITU-R S.1855(01/2010)Alternative reference radiation pattern for earth station antennas used with satellites in the geostationay-satellite orbit for use in coordination and/or interference assessment in the frequency range from 2 to 31 GHzS SeriesFixed-satellite serviceii Rec. ITU-R
2、S.1855 Foreword The role of the Radiocommunication Sector is to ensure the rational, equitable, efficient and economical use of the radio-frequency spectrum by all radiocommunication services, including satellite services, and carry out studies without limit of frequency range on the basis of which
3、Recommendations are adopted. The regulatory and policy functions of the Radiocommunication Sector are performed by World and Regional Radiocommunication Conferences and Radiocommunication Assemblies supported by Study Groups. Policy on Intellectual Property Right (IPR) ITU-R policy on IPR is describ
4、ed in the Common Patent Policy for ITU-T/ITU-R/ISO/IEC referenced in Annex 1 of Resolution ITU-R 1. Forms to be used for the submission of patent statements and licensing declarations by patent holders are available from http:/www.itu.int/ITU-R/go/patents/en where the Guidelines for Implementation o
5、f the Common Patent Policy for ITU-T/ITU-R/ISO/IEC and the ITU-R patent information database can also be found. Series of ITU-R Recommendations (Also available online at http:/www.itu.int/publ/R-REC/en) Series Title BO Satellite delivery BR Recording for production, archival and play-out; film for t
6、elevision BS Broadcasting service (sound) BT Broadcasting service (television) F Fixed service M Mobile, radiodetermination, amateur and related satellite services P Radiowave propagation RA Radio astronomy RS Remote sensing systems S Fixed-satellite service SA Space applications and meteorology SF
7、Frequency sharing and coordination between fixed-satellite and fixed service systems SM Spectrum management SNG Satellite news gathering TF Time signals and frequency standards emissions V Vocabulary and related subjects Note: This ITU-R Recommendation was approved in English under the procedure det
8、ailed in Resolution ITU-R 1. Electronic Publication Geneva, 2010 ITU 2010 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without written permission of ITU. Rec. ITU-R S.1855 1 RECOMMENDATION ITU-R S.1855 Alternative*reference radiation pattern for earth
9、station antennas used with satellites in the geostationary-satellite orbit for use in coordination and/or interference assessment in the frequency range from 2 to 31 GHz (2010) Scope This Recommendation provides alternative reference radiation patterns to the ones given in Recommendation ITU-R S.465
10、 which may be used for both circular and non-circular earth station antennas used with satellites in the geostationary-satellite orbit (GSO) and which, in the absence of particular information concerning the radiation pattern, may be used for coordination and/or interference assessment between earth
11、 stations in the fixed-satellite service (FSS) and stations of other services sharing the same frequency band as well as coordination and/or interference assessment between systems in the FSS. The ITU Radiocommunication Assembly, considering a) that, for coordination and for the assessment of mutual
12、 interference between radiocommunication-satellite systems and between earth stations of such systems and stations of other services sharing the same frequency band, it is convenient to use a commonly agreed upon radiation pattern that is met by most antennas for the earth station antenna; b) that,
13、for the determination of coordination distance and for the assessment of interference between earth and terrestrial stations, a radiation pattern based on the level met by all but a small percentage of the side-lobe peaks may be appropriate; c) that, for coordination and for the assessment of interf
14、erence between earth stations and space stations, a radiation pattern for the region near the main beam based on the envelope of the peak gain of the side lobes in this region may be appropriate; d) that, at angles relative to the axis of the main beam where effects peculiar to the particular feed s
15、ystem used do not contribute appreciably to the gain in the side lobes, the radiation patterns for numerous existing earth station antennas show only moderate scatter about a simple generalized radiation pattern, at least within the frequency range from 2 to 31 GHz; e) that, for antennas of the Cass
16、egrain type over the range of angles relative to the axis of the main beam where contributions to the side-lobe gain occur primarily as a result of spill-over, the patterns of a number of existing antennas also show reasonable agreement; f) that, at large off-boresight axis angles, the likelihood of
17、 local ground reflections needs to be considered; g) that the use of antennas with the best achievable radiation patterns will contribute to a more efficient use of the radio-frequency spectrum and the geostationary-satellite orbit (GSO); *This Recommendation provides an alternative reference radiat
18、ion pattern to be considered in those cases where use of this reference pattern results in improved sharing conditions, as compared to Recommendation ITU-R S.465 which also addresses reference earth station radiation pattern for use in coordination and/or interference assessment. See also noting c).
19、 2 Rec. ITU-R S.1855 h) that in the case of smaller antennas (diameter-to-wavelength (D/) ratio less than 46.8), some relaxation in the radiation pattern for far side lobes and back lobes relative to the radiation pattern envelope of Recommendation ITU-R S.465 may be necessary, recognizing a) that f
20、or the radiation pattern envelope of any non-rotationally symmetric antenna aperture shape, the minimum off-axis angle at which an antenna reference pattern applies may vary depending upon the angle of rotation about the antenna main-lobe axis, noting a) that by the principle of reciprocity, for the
21、 same or a nearby frequency band, the antenna pattern envelope for receiving antennas should be similar to that for transmitting antennas; b) that increased utilization of the orbital arc has resulted in the increased use of small antennas having the larger physical dimension aligned with the GSO ar
22、c as seen from the earth station location (defined in this Recommendation as DGSO) therefore improving the off-axis characteristics in the GSO plane; c) that in the case of small antennas, where the far side lobes and back lobes do not meet the radiation pattern of Recommendation ITU-R S.465 but do
23、meet the radiation pattern of this Recommendation, there is little impact to spectrum and orbit efficiency, however use of such antennas could make coordination more difficult with other services sharing the same frequency band, and thus such use should be confined to frequency bands that do not sha
24、re primary allocations with other services or to situations where either there has been no previous coordination or where sharing conditions with other services have not yet been developed, recommends 1 that, in the absence of particular information concerning the radiation pattern of the antennas u
25、sed with satellites in the geostationary orbit, the reference radiation patterns depicted in recommends 2 and subject to the Notes in recommends 3 may be used for: 1.1 coordination and/or interference assessment between earth stations in the fixed-satellite service (FSS) and any station in other ser
26、vices sharing the same frequency band; 1.2 coordination and/or interference assessment between systems in the FSS; 2 that the following reference radiation patterns may be used for antennas used with satellites in the GSO for angles between the direction of interest and the axis of the main beam tow
27、ards the GSO: 2.1 for earth station antennas with a diameter-to-wavelength1(D/) ratio greater than or equal to 46.8 (see Note 1): G() = 29 + 3 sin2 () 25 log () dBi for min 7 G() = 7.9 + ()() 2.22.9sin32dBi for 7 9.2 G() = 32 25 log () dBi for 9.2 48 G() = 10 dBifor 48 180 1In the case of a circular
28、 antenna aperture, D is the antenna diameter. The ratio D/, in recommends 2.1 and 2.2 is referred to as the diameter-to-wavelength ratio for the sake of simplicity (see Note 1). Rec. ITU-R S.1855 3 min = 6.085.15Dor 06.1118Ddegrees, whichever is greater where: : the off-axis angle between the direct
29、ion of interest and the boresight axis (degrees) min : the minimum off-axis angle at which the envelope gain of 29 + 3 sin2() 25 log () applies (degrees) G() : the antenna gain relative to an isotropic antenna (dBi) D : the dimension (m) of the antenna aperture in the plane of interest as shown in F
30、ig. 1 : wavelength (m) : the angle (degrees) between the plane containing the boresight and the dimension DGSO, and the plane of interest, where the plane of interest passes through the boresight and the direction of interest (see Fig. 1)2; FIGURE 1 Parameters related to the antenna aperture 1855-01
31、: the angle (degrees) betweenthe plane containing the boresightand the dimension , andthe plane of interest, where thepasses throughthe boresight and the direction of interestDplane of interestGSO Direction of interestD: Dimension in the direction of interestDimension ( ) DGSOalignedwith GSO arc as
32、seen from the earth station(see Annex 1 for meaning)NOTE 1 The ellipse and the dimensions and depict the physical aperture, whereas theangle and the direction of interest are used for specifying the reference radiation pattern.DDGSO2In the case of a circular antenna aperture, the factor 3 sin2() is
33、set to zero for all angles of for cases where the performance is the same for all angles (). 4 Rec. ITU-R S.1855 2.2 for earth station antennas with a diameter-to-wavelength (D/) ratio less than 46.8 and greater than or equal to 15 (see Notes 1, 2 and 3): G() = 29 + 3 sin2() 25 log () dBi for min 7
34、G() = 7.9 + ()() 2.22.9sin32dBi for 7 9.2 G() = 32 25 log () dBi for 9.2 30.2 G() = 5 dBi for 30.2 70 G() = 0 dBi for 70 180 , min, and G() are as defined in recommends 2.1; 3 that the following Notes should be considered as part of this Recommendation. NOTE 1 In the case of non-circular antenna ape
35、rtures, the equivalent diameter should be used for the purpose of determining D/ in order to apply recommends 2.1 or 2.2. NOTE 2 The radiation pattern of recommends 2.2 represents a maximum envelope, especially with respect to the back lobes. Measurements have demonstrated that some antennas with D/
36、 46.8 can meet the more stringent radiation pattern envelope in recommends 2.1. NOTE 3 For the purpose of this Recommendation, it is assumed that the minimum (D/) ratio in any direction of interest is not less than 15. NOTE 4 This Recommendation only applies where the off-axis angle between the dire
37、ction of interest and the boresight axis is greater than or equal to min. NOTE 5 Measurements of antenna radiation patterns need only be made in two planes, the first containing the boresight and DGSO, and the second containing the boresight and being orthogonal to the first for off-axis angles grea
38、ter than or equal to minto demonstrate compliance with the reference radiation pattern in recommends 2. The reference radiation patterns in recommends 2 allow the determination of gain in all other directions for off-axis angles greater than or equal to minfor the purpose of applying this Recommenda
39、tion. NOTE 6 The calculation of the minimum angle minused in recommends 2 requires the determination of the cross-sectional dimension D of the antenna aperture. In the case of a circular or elliptical antenna, Annex 1 should be consulted for details on the calculation of D at an angle of rotation ,
40、in a counter-clockwise direction, around the boresight axis. NOTE 7 For the coordination of earth station receiving antennas, where the formula for minin recommends 2 results in a value greater than 2.5 in the direction of interest, a value of 2.5 should be used for min. Annex 1 For application in c
41、oordination using data filed in accordance with the format of Appendix 4 of the Radio Regulations (RR) the dimensions of an equivalent area antenna aperture can be determined for any circular or elliptical aperture. In order to facilitate the use of this reference earth station antenna pattern in th
42、e Bureaus Antenna Pattern Library, two parameters, DGSOand Deq, are necessary in order to properly characterize the reference antenna pattern using the equations in recommends 2. The parameter DGSOis a data element of RR Appendix 4 in general that needs to be Rec. ITU-R S.1855 5 provided for all cas
43、es where there is relaxation of the radiation envelope in accordance with recommends 2, for directions not aligned with the GSO arc. In the event that the antenna is the case of a circular aperture where the performance is the same for all angles () as in the direction of interest where = 0 and = 18
44、0 and there is no relaxation of the radiation envelope for directions not aligned with the GSO arc, no value for DGSOis specified. The equivalent diameter (Deq) can be calculated using the following expression: =maxeqGD (1) where: Gmax: antenna gain in the direction of the antenna boresight expresse
45、d as a ratio : wavelength (m) : antenna aperture efficiency expressed as a fraction. Knowing Deqand DGSO,the cross-sectional dimension D (see Fig. 1) of an antenna described by an equivalent area ellipse can be specified at an angle of rotation in a counter-clockwise direction from the GSO plane. The expression for D is: cos1sin222+=KKDDGSO(2) where the parameter 2=eqGSODDK The value of D, in the direction of interest at a rotation angle , may be used directly in the calculation of the minimum angle minin recommends 2.
