1、 Report ITU-R SA.2177(10/2010)Selection of frequency bandsin the 1-120 GHz range fordeep-space researchSA SeriesSpace applications and meteorologyii Rep. ITU-R SA.2177 Foreword The role of the Radiocommunication Sector is to ensure the rational, equitable, efficient and economical use of the radio-f
2、requency spectrum by all radiocommunication services, including satellite services, and carry out studies without limit of frequency range on the basis of which Recommendations are adopted. The regulatory and policy functions of the Radiocommunication Sector are performed by World and Regional Radio
3、communication Conferences and Radiocommunication Assemblies supported by Study Groups. Policy on Intellectual Property Right (IPR) ITU-R policy 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
4、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 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 Reports (Al
5、so available online at http:/www.itu.int/publ/R-REP/en) Series Title BO Satellite delivery BR Recording for production, archival and play-out; film for television BS Broadcasting service (sound) BT Broadcasting service (television) F Fixed service M Mobile, radiodetermination, amateur and related sa
6、tellite services P Radiowave propagation RA Radio astronomy RS Remote sensing systems S Fixed-satellite service SA Space applications and meteorology SF Frequency sharing and coordination between fixed-satellite and fixed service systems SM Spectrum management Note: This ITU-R Report was approved in
7、 English by the Study Group under the procedure detailed 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. Rep. ITU-R SA.2177 1 REPORT ITU-R SA.2177 Selec
8、tion of frequency bands in the 1-120 GHz range for deep-space research (2010) TABLE OF CONTENTS Page 1 Introduction 3 2 Selection of frequency bands in the 1-40 GHz range . 3 2.1 Equipment characteristics that concern link performance analysis 3 2.1.1 Antenna sizes and gains . 3 2.1.2 Transmitter po
9、wer 4 2.1.3 Receiving equipment noise temperature 4 2.2 Propagation considerations . 4 2.3 Results of performance analysis . 4 2.4 Preferred frequency bands in the 1-40 GHz range . 10 2.5 Requirement for several allocations that are widely spaced in the spectrum . 11 3 Selection of frequency bands i
10、n the 40-120 GHz range . 12 3.1 Advantages of higher frequencies 12 3.1.1 Increased link performance 13 3.1.2 Wider bandwidth 13 3.1.3 More accurate measurement of phase and group-delay . 13 3.1.4 Shielding from terrestrial interference . 13 3.2 Basis for frequency selection 13 3.3 Frequency-depende
11、nt characteristics of interplanetary propagation 13 3.3.1 Interplanetary attenuation 14 3.3.2 Interplanetary sky noise temperature . 14 3.3.3 Sky noise temperature at earth stations 15 3.3.4 Velocity of interplanetary propagation 15 3.3.5 Interplanetary scintillation . 15 2 Rep. ITU-R SA.2177 Page 3
12、.4 Frequency-dependent characteristics of propagation through an atmosphere 15 3.4.1 Atmospheric attenuation 15 3.4.2 Atmospheric scintillation . 17 3.5 Frequency-dependent equipment factors 17 3.6 Example of link performance analysis . 18 3.7 Preferred frequency bands in the 40-120 GHz range . 19 4
13、 Conclusions 19 Rep. ITU-R SA.2177 3 1 Introduction Telecommunication link performance, equipment characteristics and mission requirements determine the frequency bands that are preferred for deep-space research. This Report presents an analysis that leads to the selection of preferred frequency ban
14、ds in the 1-120 GHz range. For information on general mission requirements and equipment considerations, see Recommendation ITU-R SA.1014; for information on required bandwidths, see Recommendation ITU-R SA.1015. The objective of identifying preferred frequency bands is to provide the technical basi
15、s for band allocations from which the designer can select operating frequencies best suited to mission requirements. Sections 2 and 3 of this Report give the technical basis for the selection of frequency bands in the 1-40 GHz and 40-120 GHz ranges. 2 Selection of frequency bands in the 1-40 GHz ran
16、ge For each telecommunication function, i.e. maintenance and science telemetry, telecommand, tracking and radio science, there is a frequency band, or set of frequency bands, which will provide best performance. Best performance may be expressed in terms of lowest bit error rate, highest measurement
17、 accuracy, maximum data rate, highest link reliability, or some combination of these parameters. The best performance that is obtainable at a particular time with a particular system depends upon the characteristics of radio-wave propagation. A convenient index of best performance is the ratio of re
18、ceived signal power to noise power spectral density (Pr/N0). The frequency band which provides the highest value of Pr/N0ratio for a particular system and propagation conditions is defined as a preferred frequency band. From the resulting data, frequency ranges that provide optimum performance for t
19、he assumed conditions may be identified. 2.1 Equipment characteristics that concern link performance analysis 2.1.1 Antenna sizes and gains Earth stations for deep-space research typically employ large steerable parabolic antennas which are expensive and infrequently constructed. A mission designer
20、is generally not free to consider a range of earth station antenna diameters when selecting frequencies. For this reason, the analysis considers the earth station antenna to have a fixed diameter. The gain and beamwidth of this antenna are a function of frequency. For space stations, the designer ma
21、y consider a variety of antenna types and sizes. The analysis accounts for this freedom by considering two cases: a parabolic reflector antenna with a fixed diameter and whose beamwidth and gain are a function of frequency, and an antenna whose beamwidth (gain) does not vary with frequency. The fixe
22、d diameter case may be applied over the frequency band to be considered if the diameter is small enough (beamwidth at highest frequency is wide enough) so that the antenna pointing accuracy does not limit the minimum beamwidth. The fixed beamwidth (fixed gain) case arises when antenna pointing accur
23、acy determines the minimum beamwidth, or when the antenna must give very wide coverage to permit communication without regard to space station attitude. An omnidirectional antenna is an example of the fixed beamwidth case. Link analysis in this Report assumes that a fixed diameter antenna for a spac
24、e station is 60% efficient and has a gain which increases directly as the frequency squared. For the fixed beamwidth (fixed gain) case the gain is assumed to be 0 dBi and independent of frequency. 4 Rep. ITU-R SA.2177 The earth station antenna gain used in the analysis is taken from Recommendation I
25、TU-R SA.1014. 2.1.2 Transmitter power For space station transmitters, the RF output power depends on the amount of primary power that can be provided by the spacecraft and is further limited by transmitter efficiency. For earth stations these limitations are much less significant. For link performan
26、ce analysis in this Report, transmitter power is considered to be independent of frequency. 2.1.3 Receiving equipment noise temperature The space station receiving system noise temperature is dominated by the input preamplifier and associated pre-selection filter. Antenna feedline losses are relativ
27、ely unimportant in their noise contribution. The space station noise temperature used in this Report is representative of current technology utilizing uncooled solid state devices. At earth stations there is no important size, weight, or complexity limitation and the most sensitive possible receiver
28、 is needed. Cryogenically cooled MASER preamplifiers are commonly used. Link analysis in this Report assumes that the earth station noise temperatures are as shown in Recommendation ITU-R SA.1014. 2.2 Propagation considerations Analysis of link performance requires assumptions about propagation cond
29、itions. A critical assumption is the rain rate and resulting attenuation. For low noise receiving systems typical of deep-space research, particularly the earth station receivers, even a small increase in attenuation caused by rain results in a significant reduction in Pr/N0. This is because the inc
30、rease in sky noise is several times as large as the receiver noise temperature and therefore dominates the overall system noise temperature. The analysis for this Report assumes a rain rate of 10 mm/h (the amount exceeded 0.1% of the time at an earth station near Madrid, Spain). Although this rate r
31、esults in only 0.7 dB of attenuation compared to the clear air case at 8.4 GHz with 30 elevation angle, it causes a 5 dB degradation in the space-to-Earth Pr /N0. As a result of the sensitivity of system performance (Pr/N0) to small changes in attenuation along the propagation path, the performance
32、curves shown later are strongly influenced by the assumed rain rate. 2.3 Results of performance analysis The variation of Pr/N0shown in Figs 1 to 4 was determined by the method of Report ITU-R SA.2183 for the following assumed set of equipment characteristics and operating conditions: Communication
33、distance: 8 108km Diameter of earth station antenna: 70 m Power of earth station transmitter: 20 kW Diameter of space station antenna: 3.7 m (Case 1: fixed diameter) Fixed gain of space station antenna: 0 dB (Case 2: fixed gain) Power of space station transmitter: 25 W The important features of the
34、performance curves are the location of maxima and the effects of elevation angle and weather. The absolute values of Pr/N0depend upon the assumed link parameters. Different assumptions about communication distance, antenna characteristics and transmitter power would alter the absolute values but wou
35、ld not change the shape of the curves. Rep. ITU-R SA.2177 5 The figures show curves for clear and rainy weather and for earth station antenna elevation angles of 15, 30 and 75 above the horizon. Figures 1a), 2a), 3a) and 4a) assume the use of perfect antennas and noiseless receivers. These curves il
36、lustrate performance as limited only by natural propagation phenomena. Figures 1b), 2b), 3b) and 4b) reflect the limitations imposed by typical equipment of earth and deep-space stations. Comparison of the (a) and (b) curves in each figure shows the potential for better link performance that could r
37、esult from improvement of equipment technology. FIGURE 1a) Ideal space-to-Earth link performance as limited only by natural propagation phenomena (space station antenna = 3.7 m, earth station antenna = 70 m) 1530751530ElevationAngle:754045505560657075800 10203040Pr/No,dBHzFrequency, GHz_ Clear atmos
38、phere, 7.5 gm/m3 water vapour_ _Atmosphere plus rain (0.1%), 10 mm/h6 Rep. ITU-R SA.2177 FIGURE 1b) Achievable space-to-Earth link performance as limited by natural propagation phenomena and equipment characteristics (space station antenna = 3.7 m, earth station antenna = 70 m) FIGURE 2a) Ideal spac
39、e-to-Earth link performance as limited only by natural propagation phenomena (space station antenna = 0 dB (fixed gain), earth station antenna = 70 m) 1530751530ElevationAngle:753035404550556065700 10203040Pr/No,dBHzFrequency, GHz_ Clear atmosphere, 7.5 gm/m3 water vapour_ _Atmosphere plus rain (0.1
40、%), 10 mm/h1530751530ElevationAngle:75-25-20-15-10-505101520250 10203040Pr/No,dBHzFrequency, GHz_ Clear atmosphere, 7.5 gm/m3 water vapour_ _Atmosphere plus rain (0.1%), 10 mm/h_ Atmosphere, 7.5 g/m3 water vapour - - - Atmosphere plus rain (0.1%), 10 mm/h_ Atmosphere, 7.5 g/m3 water vapour - - - Atm
41、osphere plus rain (0.1%), 10 mm/hRep. ITU-R SA.2177 7 FIGURE 2b) Achievable space-to-Earth link performance as limited by natural propagation phenomena and equipment characteristics (space station antenna = 0 dB (fixed gain), earth station antenna = 70 m) FIGURE 3a) Ideal Earth-to-space link perform
42、ance as limited only by natural propagation phenomena (earth station antenna = 70 m, space station antenna = 3.7 m) 1530751530ElevationAngle:75-30-25-20-15-10-50510152010203040Pr/No,dBHzFrequency, GHz_ Clear atmosphere, 7.5 gm/m3 water vapour_ _Atmosphere plus rain (0.1%), 10 mm/h1530751530Elevation
43、Angle:75808590951001051101151200 10203040Pr/No,dBHzFrequency, GHz_ Clear atmosphere, 7.5 gm/m3 water vapour_ _Atmosphere plus rain (0.1%), 10 mm/h_ Atmosphere, 7.5 g/m3 water vapour - - - Atmosphere plus rain (0.1%), 10 mm/h_ Atmosphere, 7.5 g/m3 water vapour - - - Atmosphere plus rain (0.1%), 10 mm
44、/h8 Rep. ITU-R SA.2177 FIGURE 3b) Achievable Earth-to-space link performance as limited by natural propagation phenomena and equipment characteristics (earth station antenna = 70 m, space station antenna = 3.7 m) FIGURE 4a) Ideal Earth-to-space link performance as limited only by natural propagation
45、 phenomena (earth station antenna = 70 m, space station antenna = 0 dB (fixed gain) 1530751530ElevationAngle:755055606570758085900 10203040Pr/No,dBHzFrequency, GHz_ Clear atmosphere, 7.5 gm/m3 water vapour_ _Atmosphere plus rain (0.1%), 10 mm/h1530751530ElevationAngle:75253035404550550 10203040Pr/No
46、,dBHzFrequency, GHz_ Clear atmosphere, 7.5 gm/m3 water vapour_ _Atmosphere plus rain (0.1%), 10 mm/h_ Atmosphere, 7.5 g/m3 water vapour - - - Atmosphere plus rain (0.1%), 10 mm/h_ Atmosphere, 7.5 g/m3 water vapour - - - Atmosphere plus rain (0.1%), 10 mm/hRep. ITU-R SA.2177 9 FIGURE 4b) Achievable E
47、arth-to-space link performance as limited by natural propagation phenomena and equipment characteristics (earth station antenna = 70 m, space station antenna = 0 dB (fixed gain) Tables 1 and 2 show optimum frequency bands for an indicated antenna configuration and weather condition. The criterion fo
48、r selecting a frequency band was performance (Pr/N0) within approximately 1 dB of the maximum available. TABLE 1 Preferred frequency bands: space-to-Earth Antenna configuration Weather Range of preferred frequencies Ideal equipment(1)Current equipment(2)Fixed diameter transmit, fixed diameter receiv
49、e Clear 11.5-19 GHz 28.5-40 GHz 12-20 GHz 26-39.5 GHz Rain 3 000-6 500 MHz 3 500-9 000 MHz Fixed gain transmit, fixed diameter receive Clear 1 000-9 500 MHz 1 000-6 500 MHz Rain 1 000-3 500 MHz 1 000-4 000 MHz (1)Based on analysis that considers only natural propagation phenomena. (2)Based on analysis that includes the effect on equipment characteristics. 1530751530ElevationAngle:75-10-50510152025303510203040Pr/No,dBHzFrequency, GHz_ Clear atmosphere, 7.5 gm/m3 water vapour_ _Atmosphere plus rain
