1、 Recommendation ITU-R F.1245-2(03/2012)Mathematical model of average and related radiation patterns for line-of-sight point-to-point fixed wireless system antennas for use in certain coodination studies and interference assessment in the frequency range from 1 GHz to about 70 GHzF SeriesFixed servic
2、eii Rec. ITU-R F.1245-2 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 th
3、e basis of which 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
4、on IPR is described 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
5、 Implementation of 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 pla
6、y-out; film for television 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 an
7、d meteorology SF 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
8、the procedure detailed in Resolution ITU-R 1. Electronic Publication Geneva, 2012 ITU 2012 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without written permission of ITU. Rec. ITU-R F.1245-2 1 RECOMMENDATION ITU-R F.1245-2*Mathematical model of average
9、 and related radiation patterns for line-of-sight point-to-point fixed wireless system antennas for use in certain coordination studies and interference assessment in the frequency range from 1 GHz to about 70 GHz (Question ITU-R 110-2/5) (1997-2000-2012) Scope This Recommendation provides average a
10、nd related reference radiation patterns for line-of-sight point-to-point fixed wireless system (FWS) antennas in the frequency range from 1 GHz to about 70 GHz. The analysis in this Recommendation may be used in certain coordination studies and interference assessments when particular information co
11、ncerning the FWS antenna is not available. The ITU Radiocommunication Assembly, considering a) that the reference radiation pattern of line-of-sight point-to-point fixed wireless system (FWS) antennas stated in Recommendation ITU-R F.699 gives the peak envelope of side-lobe patterns; b) that if the
12、peak envelope radiation pattern is used in the assessment of the aggregate interference consisting of many interference entries, the predicted interference will result in values that are greater than values that would be experienced in practice; c) that, therefore, it is necessary to use the antenna
13、 radiation pattern representing average side-lobe levels in the following cases: to predict the aggregate interference to a geostationary or non-geostationary satellite from numerous radio-relay stations; to predict the aggregate interference to a radio-relay station from many geostationary satellit
14、es; to predict interference to a radio-relay station from one or more non-geostationary satellites under the continuously variable angle which should be averaged; in any other cases where the use of the radiation pattern representing average side-lobe levels is appropriate; d) that a simple mathemat
15、ical formula is preferable to the radiation pattern representing average side-lobe levels; e) that a mathematical model is also required for generalized radiation patterns of antennas for statistical interference analyses involving a few interference entries such as from geostationary satellites int
16、o systems in the fixed service, *This Recommendation should be brought to the attention of Radiocommunication Study Groups 4 and 7. 2 Rec. ITU-R F.1245-2 recommends 1 that, in the absence of particular information concerning the radiation pattern of the line-of-sight FWS antenna involved, the mathem
17、atical model of the average radiation pattern as stated below should be used for the applications referred to in considering c); 2 that the following mathematical model of the average radiation pattern should be adopted for frequencies in the range 1-40 GHz and provisionally in the range 40 GHz to a
18、bout 70 GHz; 2.1 in cases where the ratio between the antenna diameter and the wavelength is greater than 100 (D/ 100), the following equation should be used (see Notes 1 and 7): G() = Gmax 2.5 1032Dfor 0 3 dB or when the radio-relay station is outside the main beam of the antenna of the other servi
19、ce. The angle 3 dBat which the co-polarized gain is 3 dB below the maximum gain Gmax, can be calculated by replacing G() with dB3maxG in the expression for G() for 0 m: DdB64.343NOTE 8 Administrations and other members of ITU-R are encouraged to provide information comparing the average side-lobe le
20、vels and the generalized radiation patterns given in this Recommendation with those obtained by radiation pattern measurements on real antennas. This information may assist in the further development of this Recommendation. NOTE 9 Administrations and other members of ITU-R are encouraged to examine
21、the feasibility of expanding the application of the model in Annex 1. 4 Rec. ITU-R F.1245-2 Annex 1 Mathematical model of generalized radiation patterns of point-to-point fixed-service antennas for use in statistical interference assessment No change. Annex 2 Derivation of Geff () in Note 7 regardin
22、g polarization advantage between linear-polarized and circular-polarized systems 1 Introduction Radio-relay antennas generally employ linear polarization. Therefore, when the interference from a system employing single circular polarization comes into the radio-relay antennas, it is important to eva
23、luate the circular to linear polarization loss, or polarization advantage between linear-polarized and circular-polarized systems. In the ideal case, the circular to linear polarization loss will be 3 dB. Practical systems will achieve somewhat less polarization discrimination than in the ideal situ
24、ation. This Annex discusses the derivation of a circular to linear polarization loss in practical cases. 2 Equation for polarization loss for non-ideal antennas The polarization loss for non-ideal antennas is generally given by the following: ( )( )()()+=1122cos11421log102222awawawprrrrrrLwhere: Lp:
25、 polarization loss rw: voltage axial ratio of the radio wave ra: voltage axial ratio of the antenna : angle between the tilt angle of the antenna polarization ellipse and the tilt angle of the incident wave polarization ellipse, both referred to horizontal at the Earths surface. For the purposes of
26、this analysis, it is assumed that = 0, which is the most conservative case. For a circularly polarized antenna, the voltage axial ratio is usually specified in decibels. These terms are related by the relationship: () ()wrR log20dB = . For a linearly polarized antenna, the decibel axial ratio is equ
27、ivalent in magnitude to the antenna cross-polarization isolation as in the following relationship: ()arXPI log20)dB( = . Rec. ITU-R F.1245-2 5 Figure 1 below shows a plot of polarization loss, Lp, versus cross-polarization isolation (XPI) for three values of circular polarization axial ratio, R. Thi
28、s plot is independent of frequency. FIGURE 1 Polarization loss vs. XPI for various values of R F.1245-0110 15 20 25 30 35 40Linearly polarized antenna XPI (dB)0.511.522.5Lp(dB)R = 1 dBR = 1.5 dBR = 2 dBThe appropriate value of Lpwill depend on the characteristics of circularly and linearly polarized
29、 antennas through the frequency range from 1 to 70 GHz. 3 Examples of the XPI data Examples of the XPI data of fixed service antennas from two administrations are shown in Tables 1 and 2. Table 1 contains a summary of information from one administrations licensing database for a range of frequency b
30、ands from around 1 GHz up to 40 GHz; and Table 2 shows another XPI data based on different antenna types used in another administration for frequency bands from about 6 GHz up to 22 GHz. 6 Rec. ITU-R F.1245-2 TABLE 1 Example of the XPI data in one administration Band (GHz) Number of antenna records
31、5thpercentile XPI (dB) 10thpercentile XPI (dB) Median XPI (dB) 0.953-1.525 484 12 20 30 1.7-2.7 698 20 20 303.4-5.0 280 15 20 30 5.85-7.125 532 20 28 30TABLE 1 (end) Band (GHz) Number of antenna records 5thpercentile XPI (dB) 10thpercentile XPI (dB) Median XPI (dB) 7.125-7.725 403 24 28 30 7.725-8.5
32、 213 30 30 3010.5-10.68 151 28 30 30 10.7-11.7 202 20 25 3012.7-13.25 209 25 25 30 14.5-15.35 172 28 30 3017.7-19.7 181 27 30 30 21.2-23.6 164 25 28 3024.25-25.25 8 30 30 32 24.35-28.35 4 30 30 3228.6-40.0 30 23 26 30 TABLE 2 Example of the XPI data in another administration Band (GHz) Number of ant
33、enna types Number of deployed antennas 10thpercentile XPI (dB) Average XPI (dB) 5.925-7.75 11 600 25 29 10.7-15.23 27 5 700 32 3517.85-23.2 13 2 806 26 28 According to this data, an assumption of a minimum XPI of 20 dB would seem to be appropriate at the frequencies up to 40 GHz. Although antenna pe
34、rformance data above 40 GHz is not available, the trend is towards equal or better cross-polarization performance as frequency increases. Therefore, pending the availability of more specific data for linearly polarized antennas in higher bands and consistent with recommends 2, it can tentatively be
35、concluded that a minimum XPI of 20 dB may also be used between 40 GHz and 70 GHz. Rec. ITU-R F.1245-2 7 4 Conclusion Taking into account Tables 1 and 2, an XPI of 20 dB of radio-relay antenna is appropriate. Taking into account Fig. 1, for an XPI of 20 dB and a tentative interfering antenna maximum
36、circular polarization axial ratio (R) of 1.5 dB, which is applicable around the boresight direction of space stations antenna not practicing frequency reuse by orthogonal polarization operated at around 2 to 30 GHz frequency bands, the polarization loss would be 1.7 dB. This value would be applicable only within the antenna 3 dB beamwidth of radio-relay antenna and around the boresight direction of space stations antenna and should be applicable between 1 and 70 GHz.
