Details have been released by Ofcom of the UK positions for WRC-15 which takes place in Geneva, November 2-27, 2015.
Ofcom’s statement references the document containing the European Common Proposals for agenda items for the next conference, WRC-19. One proposal is EUR-A25-2 – Primary allocation of the band 50-54 MHz to the Amateur Service in Region 1. The inclusion of this proposal is very welcome since it would facilitate further worldwide harmonization.
Although the proposal only references the Amateur Service such an allocation would be of great benefit to the Amateur Satellite Service.
A 50 MHz Amateur Satellite allocation would offer:
• low Doppler shift
• good link budget requirements
• relieve pressure on the only existing VHF amateur satellite allocation on 145 MHz.
A 50 MHz signal from a satellite in an 800 km orbit would have a Doppler shift of +/-1.1 kHz during a 15 minute pass compared with +/-3.27 kHz at 145 MHz greatly easing tuning requirements.
The free space path loss at 50 MHz would be 9.2 dB lower than on 145 MHz. A low path loss is particularly important for small satellites with a limited power budget such as CubeSats or PocketQubes. These satellites may be just 10x10x10 cm or smaller and the limited surface area restricts the amount of solar power than can be generated. Typical transmitter output powers range between 100 mW and 400 mW. This power might be shared by a beacon and up to 5 SSB stations in the transponder passband, giving maybe 50 mw per station. Because of their size these satellites have to use simple omni-directional antennas such as a dipole or monopole
Satellite antennas for this band will need to be kept to a manageable size, this will help drive experimentation and innovation in antenna design for these frequencies. Where the band is used as a satellite uplink there is no need to utilize a full size antenna.
The low path loss of this band could facilitate the development of compact rapid deployment satellite ground stations utilizing omni-directional antennas for emergency communication scenarios.
The existing satellite segment at 145.8-146.0 MHz is already congested with satellite downlinks. Most frequencies are already in use by four or more satellites. An additional VHF allocation would relieve the pressure.
ITU Footnote 5.282
This footnote currently covers the Amateur Satellite Service UHF and Microwave allocations between 435 MHz and 6 GHz.
It would be desirable if the footnote could be expanded to include operation in 50-51 MHz.