IARU Recommendations

22:18 Fernando Luiz de Souza 0 Comments






Dear Colleagues,

I should have sent out this notice much earlier, but please note the recommendation below which has been agreed at the Region 3 Directors meeting in Tokyo, August 2013.

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At the Region 3 Directors meeting held in August 26th and 27th, 2013, the following two recommendations were adopted regarding usage of two meter band for the amateur satellite service.
1. It is recommended that the band 144-146 MHz (“two-meter” band) be used exclusively for down link on all future satellites.
2. It is recommended that the 144.000-144.035 MHz section be additionally allocated for satellite down link .

Background information
1. Usage of the band 144-146 MHz for down link only
The band 144-146 MHz (“two-meter” band) is, according to the Radio Regulations, allocated to the amateur and the amateur-satellite services world-wide on a primary basis with exceptions in several footnotes. But by agreement of all three IARU Regions, currently only a sub-section, namely 145.80–146 MHz of the allocation, is used on an exclusive basis for the amateur-satellite service.
Although the band 145.80 – 146 MHz is presently used for both uplink and downlink portions, the Cavtat Conference of IARU Region 1 in 2008 agrees to recommend its use for downlink-only to reduce interference signals from non-amateur signals (illegal’s like taxis) being relayed if it is used for uplinks.
The usage of the band 145.8 - 146 MHz reduces path losses by about 9dB compared with usage of the band 435 - 438 MHz.
Most amateur satellites do not employ attitude control due to their size and financial constraints, therefore the use of simple omni-directional antenna would be popular. In this situation 9 dB pass loss advantage is essential.
On the other hand, some societies in Region 3 have mentioned that to avoid interference signals from non-amateur signals (illegal’s like taxis) the band 145.8 – 146 MHz has not been used for downlinks in most amateur-satellite services. But comparing effects of interference caused by illegal signals on uplinks and downlinks, to avoid uplink interference is important because many amateur satellites would be affected if there is interference on uplink.
Taking into account these factors mentioned above, it is recommended that the band 145.8 - 146 MHz should be used for downlink only in Region 3.

2. Additional allocation of 144.000-144.035 MHz section for satellite down link only
The IARU Satellite Advisory Group has been discussing the additional allocation of the 144.000-144.035 MHz section for satellite down link only taking into account the shortage of spectrum of 2m band for the amateur satellite service .
In 2008 it appeared that very little EME was then taking place at the very bottom of the 144 MHz band, due to interference from computer oscillators. This section is already aligned worldwide and therefore it was considered that this could be suitable part of the band to be used.
More recent research and discussions suggested that this situation remains the same today. Further research has concluded that the bottom 35% of the 2 metre band is almost completely unused.
It was noted that Region 1 had also discussed this matter and their opinion was on similar lines.
This subject was also discussed at the Region 2 conference in September this year and approved.
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73 de Ken Yamamoto, JA1CJP
Secretary, IARU Region 3
secretary<at>iaru-r3.org

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