Rec. ITU-R S.580-61
RECOMMENDATION ITU-R S.580-6
Radiation diagrams for u as design objectives for antennas
of earth stations operating with geostationary satellites
(Question ITU-R 42/4)
(1982-1986-1990-1992-1993-1994-2003) The ITU Radiocommunication Asmbly,
considering
a) that efficient utilization of the radio spectrum is a primary factor in the management of the geostationary-satellite orbit (GSO);
b) that the side-lobe characteristic of earth-station antennas is one of the main factors in determining the minimum spacing between satellites and therefore the extent to which the radio spectrum can be efficiently employed;
c) that the radiation diagram of antennas directly affects both the p. outside the main radiation axis and the power received by the side lobes;
d) that the construction of antennas with improved side-lobe characteristics may be envisaged using current design techniques but that their practical applications may involve increa in cost; e) that the Radiocommunication Study Groups are studying the potential advantages of using antennas with improved side-lobe characteristics for a better utilization of the GSO,
托福听力评分标准recommends
1that new antennas of an earth station operating with a geostationary satellite should have a design objective such that the gain, G, of at least 90% of the side-lobe peaks does not exceed:
–
=
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G
29ϕ
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25
(G being the gain relative to an isotropic antenna and ϕ being the off-axis angle in the direction of the GSO referred to the main-lobe axis).
This requirement should be met for ϕ between 1° or (100 λ/D) whichever is the greater and 20° for any off-axis direction which is within 3° of the GSO;
2for an off-axis angle, ϕ, greater than the limits specified above, Recommendation ITU-R S.465 should be ud as a reference (e Note 5);
2 Rec. ITU-R S.580-6
0580-01
GSO
Satellite
报考会计师的条件longitude
FIGURE 1
发明家英文Example of a zone around the GSO to which the design objective for earth-station antennas applies
3 that the following Notes should be considered part of this Recommendation.connsus
NOTE 1 – This Recommendation primarily address the GSO sharing criteria. However, it must be emphasized that the application of this Recommendation should not prejudice the antenna characteristics concerned with frequency coordination between the FSS and terrestrial rvices (e Recommendation ITU-R S.465).
NOTE 2 – When asymmetric beam or asymmetric aperture antennas are ud, the side-lobe radiation in the direction of the GSO can be reduced if the minor axis of the beam (major axis of the antenna aperture) is oriented so that it is parallel to the GSO arc. In this ca, the alignment of the antenna aperture axes relative to the GSO arc would facilitate the compliance with recommends 1 in the affected zone around the GSO arc as indicated in Fig. 1:
– for the aperture minor axis plane, Recommendation ITU-R S.465 should be complied with
for any off-axis angle ϕ beyond 1° or (100 λ/D e ), whichever is the greater but not exceeding 3°, where D e is provisionally defined as the circular equivalent diameter using the aperture area of the asymmetric aperture antenna as given below:
脱产班是什么意思π=/4A D e
Rec. ITU-R S.580-6 3 where A is the aperture area of the asymmetrical antenna;
– for the aperture major axis plane, recommends 1 should be complied with for any off-axis
healthyangle ϕ beyond 1° or (100 λ/D e ), whichever is the greater but not exceeding 2°, where D e is provisionally defined above.
NOTE 3 – This Recommendation applies to antennas with D /λ greater than or equal to 50. Further studies are required to determine a design objective for circular aperture antennas having a D /λ less than 50, and also to confirm the definition of D e for the asymmetric aperture antennas.
NOTE 4 – The method of statistical processing of side-lobe peaks is dealt with in Recommendation ITU-R S.732.
NOTE 5 – In tho cas where there is discontinuity between this design objective Recommendation and the reference radiation patterns of Recommendation ITU-R S.465, the gain, G , of at least 90% of the side-lobe peak is defined as follows:
芭比公主之梦幻仙境truetype°≤ϕ<°=3.2620for dBi 5.3–G
NOTE 6 – For the analysis of an antenna pattern for angles ϕ not specified in this Recommendation, additional mathematical expressions from Appendix 7 of the Radio Regulations may be ud as a reference to reprent the radiation pattern limits for ϕ less than 1° or (100 λ/D ), whichever is the greater. Further study is required to define the most adequate expressions for this purpo.
NOTE 7 – Small earth-station antennas with improved main beam and side-lobe characteristics are being developed. It is indicated that the efficient u of the GSO may necessitate reflecting the improved characteristics in the ITU Radiocommunication Asmbly texts and Recommendations. NOTE 8 – The performance objectives in § 1 have been met by off-t-fed type antennas operating in the 10-14 GHz with D /λ ≥ 35 and by off-t-fed type receive only antennas operating in the 10.7-11.7 GHz band with D /λ ≥ 22.
NOTE 9 – Theoretical calculations supported by preliminary test results of the side-lobe radiation pat
tern, in the diagonal plane, for square microstrip array antennas with D /λ ≅ 26 meet the current design objective of § 1. The tests were performed on an active array in the 14 GHz band. Further studies are required to confirm that this design objective can be applied to square microstrip phad array antennas.
