1、 Rec. ITU-R F.699-7 1 RECOMMENDATION ITU-R F.699-7*Reference radiation patterns for fixed wireless system antennas for use in coordination studies and interference assessment in the frequency range from 100 MHz to about 70 GHz (Question ITU-R 110/9) (1990-1992-1994-1995-1997-2000-2004-2006) Scope Th
2、is Recommendation provides reference radiation patterns for, and information on, fixed wireless system antennas in the frequency range from 100 MHz to about 70 GHz. This information may be used in coordination studies and interference assessments when particular information concerning the FWS antenn
3、a is not available. The ITU Radiocommunication Assembly, considering a) that, for coordination studies and for the assessment of mutual interference between fixed wireless systems (FWS) and between stations of such systems and earth stations of space radiocommunication services sharing the same freq
4、uency band, it may be necessary to use reference radiation patterns for FWS antennas; b) that, for the above studies, radiation patterns based on the level exceeded by a small percentage of the side-lobe peaks may be appropriate; c) that the side-lobe patterns of antennas of different sizes are stro
5、ngly influenced by the ratio of the antenna diameter to the operating wavelength; d) that reference radiation patterns are required for the case where information concerning the antenna diameter is not available; e) that, at large angles, the likelihood of local ground reflections must be considered
6、; f) that the use of antennas with the best available radiation patterns, noting Report ITU-R. F.2059, will lead to the most efficient use of the radio-frequency spectrum, recommends 1 that, in the absence of particular information concerning the radiation pattern of the FWS antenna involved (see No
7、te 1), the reference radiation pattern as stated below should be used for: 1.1 interference assessment between FWS; 1.2 coordination studies and interference assessment between FWS stations and stations in space radiocommunication services sharing the same frequency band; *This Recommendation should
8、 be brought to the attention of Radiocommunication Study Groups 4, 6, 7, and 8. 2 Rec. ITU-R F.699-7 2 that the following reference radiation pattern should be adopted for frequencies in the range 100 MHz to about 70 GHz; 2.1 for frequencies in the range 1 GHz to about 70 GHz, in cases where the rat
9、io between the antenna diameter and the wavelength is greater than 100, the following equations should be used (see Notes 6 and 7): 23105.2)(=DGGmaxfor 0 m 1)( GG = for m r = log2532)(Gfor r 4810)( =Gfor 48 180 where: G() : gain relative to an isotropic antenna : off-axis angle (degrees) unitssameth
10、einexpressedwavelength:diameter antenna:DG1: gain of the first side-lobe = 2 + 15 log Ddegrees201GGDmaxm= degrees85.156.0=Dr2.2 for frequencies in the range 1 GHz to about 70 GHz, in cases where the ratio between the antenna diameter and the wavelength is less than or equal to 100 the following equa
11、tions should be used (see Notes 6 and 7): 23105.2)(=DGGmaxfor 0 m 1)( GG = for m 100 D= log25log1052)(DG for 100 D 48=DG log1010)( for 48 180Rec. ITU-R F.699-7 3 2.3 for frequencies in the range 100 MHz to less than 1 GHz, in cases where the ratio between the antenna diameter and the wavelength is g
12、reater than 0.63 (Gmaxis greater than 3.7 dBi), the following equations should be used: 23105.2)(=DGGmaxfor 0 m1)( GG = for m 100 D= log25log1052)(DG for 100 D s=DG log52)( for s 180 where: 2.05.144=Ds3 that in cases where only the maximum antenna gain is known, D/ may be estimated from the followin
13、g expression: 7.7log20 maxGDwhere Gmaxis the main lobe antenna gain (dBi); 4 that in cases where only the beamwidths of the antenna are known: 4.1 D/ (expressed in the same unit) may be estimated approximately by the following expression: /70/D where is the beamwidth (3 dB) (degrees); 4.2 given , Gm
14、axmay be estimated approximately by: log205.44)dBi(maxG 5 that administrations submit measured radiation patterns or specifications to allow new and improved reference radiation patterns for use in coordination studies and interference assessment to be developed and proposed (see Appendix 1 of Annex
15、 1); 6 that Annex 1 should be referred to for additional information concerning reference radiation patterns for FWS antennas; 7 that for the detailed calculation of interference levels on interference paths it is necessary to consider the cross-polar response of the victim and interfering system an
16、tennas; 4 Rec. ITU-R F.699-7 7.1 that for the calculation in recommends 7, including the component of signal radiated on the intended polarity by the transmitting antenna and the co-polar response of the victim receive antenna to the component of signal radiated on the unintended polarity by the tra
17、nsmitting antenna, the following equation may be used: +=+10)()(10)()(1010log10)()(rrHttVrrVttHGGGGrrttGG dBi where the following parameters refer to antenna gain (dBi): Gt(t): transmit antenna effective gain in the direction of the victim antenna Gr(r): receive antenna effective gain in the directi
18、on of the interfering antenna GtH(t): horizontally polarized gain component of the transmit antenna GrV(r): vertically polarized gain component of the receive antenna GtV(t): vertically polarized gain component of the transmit antenna GrH(r): horizontally polarized gain component of the receive ante
19、nna. tand rare the angles between the direction of main beam and direction towards victim and transmitting antenna respectively. Further information and numerical examples on using the equation above is given in Annex 2. 8 that the following Notes should be regarded as part of this Recommendation. N
20、OTE 1 It is essential that every effort be made to utilize the actual antenna pattern in coordination studies and interference assessment. NOTE 2 It should be noted that the radiation pattern of an actual antenna may be worse than the reference radiation pattern over a certain range of angles (see N
21、ote 3). Therefore, the reference radiation pattern in this Recommendation should not be interpreted as establishing the maximum limit for radiation patterns of existing or planned FWS antennas. Noting that for certification purpose, administrations may adopt standards, usually based on statistical m
22、easurements of real antennas, that may represent different values for the side-lobe radiation pattern levels. NOTE 3 The reference radiation pattern should be used with caution over the range of angles for which the particular feed system may give rise to relatively high levels of spill-over. NOTE 4
23、 The reference pattern in 2 is only applicable for one polarization (horizontal or vertical). Reference patterns for two polarizations (horizontal and vertical) are under study. NOTE 5 The reference radiation pattern included in this Recommendation is only for antennas which are rotationally symmetr
24、ical. The reference radiation pattern for antennas with asymmetrical apertures and for non-aperture FWS antennas in the frequency range from 100 MHz to 1 GHz requires further study. For such antennas, the above reference patterns may be considered to be provisionally valid. In this case, the D/ valu
25、e computed from Gmaxis an equivalent D/ and not the actual D/. NOTE 6 Mathematical models of average radiation patterns for use in certain coordination studies and interference assessment are given in Recommendation ITU-R F.1245. NOTE 7 Reference radiation patterns of omnidirectional and sectoral an
26、tennas in point-to-multipoint systems are given in Recommendation ITU-R F.1336. Rec. ITU-R F.699-7 5 NOTE 8 Further study is required to ensure that reference radiation patterns continue to develop to take account of advances in antenna design. NOTE 9 While generally applicable, the reference patter
27、n in recommends 2 does not suitably model some practical fixed service antennas and it should be treated with caution over a range of angles from 5 to 70 (see also Notes 2 and 3). Annex 1 Reference radiation patterns for FWS antennas 1 Introduction For the study of frequency sharing between FWS and
28、the FSS or of the possibility of frequency reuse in a FWS network, it is often necessary to use a reference diagram, because the actual radiation pattern of the antennas is not always accurately known or gives too many details. The reference pattern should therefore represent the side-lobe envelope
29、in a simplified fashion. The reference radiation pattern to be selected may, however, vary according to the use for which it is intended. In general, the reference radiation patterns in the main text of this Recommendation shall be used. 2 Uses of reference radiation patterns The two main uses of re
30、ference radiation patterns are the following: 2.1 Preliminary studies within the coordination area In the determination of the coordination area around an earth station, FWS station antennas are assumed to point directly at the earth station. However, in most cases there will be some angular discrim
31、ination. The use of a simple reference radiation diagram makes it possible to eliminate from further consideration FWS stations situated in the coordination area but not likely to produce interference. This diagram, must, of necessity, be conservative to prevent the elimination of critical contribut
32、ing sources of interference. The precise calculation of the interference level of course, requires more accurate information on the antenna diagram. 2.2 Frequency reuse in a fixed wireless network In a fixed wireless network, the same frequency may be used many times, either on sections sufficiently
33、 distant from each other or on sections starting from the same station and lying in different directions, or on the same section using cross-polarization. In the last two cases, the performance of the antenna is of great importance and a fairly precise reference radiation pattern must be used for th
34、e network project; this pattern may be less simple than that considered in 2.1, recognizing that economic efficiencies need to be taken into account, administrations may wish to encourage the use of high performance antenna types in high spectrum use areas. 6 Rec. ITU-R F.699-7 3 Results of measurem
35、ents on the antennas of fixed wireless links Measurements with numerous antennas provide adequate confirmation of the reference radiation patterns in the main text of this Recommendation at least up to a value of D/ of approximately 130. However, the following points must be borne in mind: 3.1 Some
36、antennas of relatively old designs have less satisfactory performance characteristics than more recent models. The existence of such medium performance antennas should be taken into account for frequency sharing. 3.2 The above computation is based on the assumption that the antennas operate in free-
37、space conditions. The performance characteristics of antennas installed in the field may, however, be slightly less satisfactory owing to reflection from neighbouring obstacles or from other antennas installed on the same mast. 4 Radiation patterns of high performance antennas High performance anten
38、nas contribute greatly to the increase of nodal capacity in FWS. For the horn-reflector antennas, which were developed to comply with the requirements of terrestrial FWS in dense networks, the reference diagram above may be regarded as valid only in the horizontal plane. For planes away from the hor
39、izontal significant sensitivity variations are displayed. Figure 1 gives an example for the radiation diagram of a specific but widely-used pyramidal horn reflector antenna. Radiation envelope contours are plotted (in dB below the main beam) in a coordinate system using angles and (the centre of the
40、 spherical coordinate system being the centre of the antenna aperture). The strong departure from the rotational symmetry assumed in the reference radiation patterns in recommends 2 of this Recommendation is due to: the spill-over lobe around = + 90 and 60 80, the weather cover lobe around = 90 and
41、50 90. The spill-over lobe is a consequence of wave diffraction at the upper lip of the aperture caused by direct rays emanating from the pyramidal horn section. This effect is pronounced only for vertical polarization. The weather cover lobe is due to reflection of energy by the tilted plastic weat
42、her cover back onto the parabolic surface which then re-directs most of the energy downward over the lower lip of the aperture. This phenomenon is polarization and frequency insensitive. An offset-reflector type antenna shows sharp directivity especially in the horizontal plane. Figure 2 illustrates
43、 examples of the radiation patterns of the offset-reflector antenna together with an example of the pyramidal horn-reflector antenna read from Fig. 1. Rec. ITU-R F.699-7 7 8 Rec. ITU-R F.699-7 For horn reflector antennas and for offset antennas with a very low illumination on the edge of the reflect
44、or, the following formula may be provisionally used as a reference radiation pattern in the horizontal plane: = log40log3088DG (1) This formula is valid outside the main lobe for up to about 90. However, when the illumination on the edge of the reflector is not very low, the level of side-lobes in c
45、ertain directions may be higher than that given by equation (1). Rec. ITU-R F.699-7 9 Appendix 1 to Annex 1 Measured patterns for use in the further development of this Recommendation 1 Introduction There is a continuing need to review and update the reference radiation patterns contained in this Re
46、commendation. As the frequency bands being used for FWS extend beyond 70 GHz, there is a need to widen the scope of these reference radiation patterns above 70 GHz. To assist with the above, this Appendix contains comparisons of some practical antenna pattern envelopes and radiation patterns with th
47、e corresponding reference patterns derived from this Recommendation and Recommendation ITU-R F.1245. 10 Rec. ITU-R F.699-7 FIGURE 4 Patterns for a sample of production antennas (1.8 m diameter, horizontal polarization, 10.7 GHz) Rec. ITU-R F.699-7 11 12 Rec. ITU-R F.699-7 Rec. ITU-R F.699-7 13 14 Re
48、c. ITU-R F.699-7 Annex 2 Information on the application of recommends 7 1 Introduction Some figures and numerical examples are given with the aim to support the designations used in the equation of recommends 7.1. An alternative equation (see 4) can be used if relative antenna gains data are given. In the case of a mutual gain calculation between co-polar antennas the alternative equation shall be used (see 5). Rec. ITU-R F.699-7 15 2 Situation FIGURE 9 Generic example of mutual situation and orientation of transmitting antenna and victim receiving antenna 3 The numerical example FIGURE 10
