1、 Rec. ITU-R S.731-1 1 RECOMMENDATION ITU-R S.731-1 Reference earth-station cross-polarized radiation pattern for use in frequency coordination and interference assessment in the frequency range from 2 to about 30 GHz (1992-2005) The ITU Radiocommunication Assembly, considering a) that, for coordinat
2、ion studies and for the assessment of mutual interference between radiocommunication-satellite systems and between earth stations of such systems and stations of other services sharing the same frequency band, it may be useful to use a cross-polarized radiation pattern for the earth-station antenna;
3、 b) that, for the determination of coordination distance and for the assessment of interference between earth and terrestrial stations, a cross-polarized radiation pattern based on the level exceeded by a small percentage of the side-lobe peaks may be appropriate; c) that, a reference earth-station
4、co-polarized radiation pattern for use in frequency coordination and interference assessment is contained in Recommendation ITU-R S.465; d) that some measurements have been made of the cross-polarized off-axis gain performance of earth stations and radiation patterns have been developed which are qu
5、antitively similar; e) that a single cross-polarized off-axis reference pattern can be used which includes those contained in Annex 1; f) that the use of antennas with the best achievable radiation patterns will lead to the most efficient use of the radio-frequency spectrum and the geostationary-sat
6、ellite orbit, recognizing 1 that further measured information on cross-polarization performance is desirable; 2 that the measured off-axis gain performance of earth-station antennas contains the cross-polarization emission from the source antenna; 3 that the cross-polarized radiation patterns are me
7、asured in the main beam of the source antenna, recommends 1 that, in the absence of particular information concerning the cross-polarized radiation pattern of the antenna for the earth station involved, a single reference radiation pattern may be used for: 1.1 frequency coordination studies and inte
8、rference assessment between earth stations in the fixed-satellite services and stations of other services sharing the same frequency band; 1.2 coordination studies and interference assessment between networks in the fixed-satellite service; 2 Rec. ITU-R S.731-1 2 that the following cross-polarized r
9、adiation pattern may be used on an interim basis for angles between the directions considered and the axis of the main beam, for frequencies in the range 2-30 GHz: Gx() = 23 20 log dBi for r 7 Gx() = 20.2 16.7 log dBi for 7 100: G/() = 32 25 log G0dBi for 1 48 = 10 G0dBi for 48 ISO: 0log25)/log(1052
10、)( GDG =+(3) for 2 180: G+() = 10 10 log(D/) G0(4) The patterns shown in Figs. 4 and 6 are calculated for stations with antenna diameters of 1.2 m and 1.8 m operating at a centre frequency of 12.625 GHz. The patterns measured for these types of antennas are shown in Figs. 5, 7 and 8. In each case on
11、e example of the measured co- and cross-polarized pattern is given, but the envelopes shown are averages from measurements on several antennas of the same type. 6 Rec. ITU-R S.731-1 0731-0401020304050606050403020100Cross-polarCo-polarOff-axis angle (degrees)Relativegain(dBi)FIGURE 41.2 m antenna, =
12、12.625 GHz, relative co- and cross-polar calculated patternsf0731-0550 40 30 0 20 30 50605040302010020 10 10 40Co-polarizedCross-polarizedAngle off main beam axis (degrees)Relativegain(dB)FIGURE 51.2 m antenna, = 12.625 GHz, relative co- and cross-polar measured patternsfRec. ITU-R S.731-1 7 0731-06
13、01020304050606050403020100Cross-polarCo-polarOff-axis angle (degrees)Relativegain(dBi)FIGURE 61.8 m antenna, = 12.625 GHz, relative co- and cross-polar calculated patternsf0731-07180 150 120 30 30 60 120605040302010090 60 0 907080150 180Angle off main beam axis (degrees)Relativegain(dB)FIGURE 71.8 m
14、 antenna, = 12.625 GHz, relative co-polar measured patternf8 Rec. ITU-R S.731-1 0731-08180 150 120 30 30 60 120605040302010090 60 0 907080150 180Angle off main beam axis (degrees)Relativegain(dB)FIGURE 81.8 m antenna, = 12.625 GHz, relative cross-polar measured patternf2 Large antennas (D 100) G0= m
15、aximum co-polarized gain of antenna (dBi) G() = 29 25 log G0(dBi) 1= 1 1 = 1.8 1(degrees) 2= 20 3= 33.1 ISO= 252910 14.45 for 0 1: )()(1=+GG (5) for 1 2: ()111)()()()(=+ISOISOGGGG (6) for 2 3: G+() = 32 25 log G0(7) for 3 180: 010)( GG =+(8) Rec. ITU-R S.731-1 9 The patterns shown in the Figures bel
16、ow are calculated for stations with the following antenna diameters and frequencies: 2.4 m and 3.5 m at 12.625 GHz, and 3.7 m at 10.7 GHz. The patterns measured for these types of antennas are shown in Figs. 10, 11, 13, 14, 16 and 17. In each case, one example of the co- and cross-polarized measurem
17、ents is shown, but the envelopes given were derived from the average of several antennas of the same type. The functions given above for D 100 and D 100 can be expressed in terms of absolute gain. The functions given for D 100 can be normalized to a (32 25 log ) co-polar function by letting (52 10 l
18、og ) equal 32. Evaluation of these functions as absolute gain for various values of D/ is as follows: Gx() = 22.70 + 0.29 25 log dBi for D/ = 25 (9) = 22.69 + 0.37 25 log dBi for D/ = 50 (10) = 22.87 + 0.42 25 log dBi for D/ = 75 (11) = 22.15 + 0.47 25 log dBi for D/ = 100 (12) The angles at which t
19、hese gain functions are equal to a co-polar envelope gain of (32 25 log ) are ,7.31 ,2.25 21.4 and 20.8 respectively. Additional functions which have been developed are: Gx() = 20 21 log dBi (13) Gx() = 23.6 20 log dBi (14) Gx() = 22 25 log dBi (15) Equation (15) is based on a requirement that the c
20、ross-polar gain be 10 dB less than the co-polar gain out to 7. These functions are plotted in Fig. 18. From this Figure, a single function which adequately covers all the above functions is: G() = 23 20 log dBi for r 7 = 20.2 16.7 log dBi for 7 26.3 = 32 25 log dBi for 26.3 48 = 10 dBi for 48 180 ri
21、s equal to 1 or 100 /D, whichever is greater. 10 Rec. ITU-R S.731-1 0731-090102030405060605040302010070Cross-polarCo-polarOff-axis angle (degrees)Relativegain(dBi)FIGURE 92.4 m antenna, = 12.625 GHz, relative co- and cross-polar calculated patternsf0731-1030 25 20 5 5 10 20605040302010015 10 0 15 25
22、 30Angle off main beam axis (degrees)Relativegain(dB)FIGURE 102.4 m antenna, = 12.625 GHz, relative co-polar measured patternfRec. ITU-R S.731-1 11 0731-11180 150 120 30 30 60 120605040302010090 60 0 907080150 180Angle off main beam axis (degrees)Relativegain(dB)FIGURE 112.4 m antenna, = 12.625 GHz,
23、 relative cross-polar measured patternf0731-120102030405060605040302010070Cross-polarCo-polarOff-axis angle (degrees)Relativegain(dBi)FIGURE 123.5 m antenna, = 12.625 GHz, relative co- and cross-polar calculated patternsf12 Rec. ITU-R S.731-1 0731-1330 25 20 5 5 10 20605040302010015 10 0 15 25 30Ang
24、le off main beam axis (degrees)Relativegain(dB)FIGURE 133.5 m antenna, = 12.625 GHz, relative co-polar measured patternf0731-14180 150 120 30 30 60 120605040302010090 60 0 907080150 180Angle off main beam axis (degrees)Relativegain(dB)FIGURE 143.5 m antenna, = 12.625 GHz, relative cross-polar measur
25、ed patternfRec. ITU-R S.731-1 13 0731-150 102030405060605040302010070Cross-polarCo-polarOff-axis angle (degrees)Relativegain(dBi)FIGURE 153.7 m antenna, = 10.7 GHz, relative co- and cross-polar calculated patternsf0731-16180 150 120 30 30 60 120605040302010090 60 0 907080150 180Angle off main beam a
26、xis (degrees)Relativegain(dB)FIGURE 163.7 m antenna, = 10.7 GHz, relative co-polar measured patternf14 Rec. ITU-R S.731-1 0731-17180 150 120 30 30 60 120605040302010090 60 0 907080150 180Angle off main beam axis (degrees)Relativegain(dB)FIGURE 173.7 m antenna, = 10.7 GHz, relative cross-polar measur
27、ed patternfRec. ITU-R S.731-1 15 0731-1801020304050602010010203040G9G8G6G5G4G7G1G3G2Off-axis angle (degrees)Antenna sidelobegain,(dBi)GxFIGURE 18Absolute cross-polar side-lobe antenna gain patternG1() = 22.70 + 0.29 25 log for D/ = 25 2() = 22.69 + 0.37 25 log for D/ = 50 G3() = 22.87 + 0.42 25 log for D/ = 75 4() = 22.15 + 0.47 25 log for D/ = 100 G5() = 20.0 21 log 6() = 23.6 20 log G7() = 22.0 25 log 8() = 23.0 20 log for r 7 = 20.2 16.7 log for 7 26.3 = 32.0 25 log for 26.3 48 G9() = 32 25 log
