AGENDA ITEM 1.21: 15.4-15.7 GHZ RADAR

To consider a primary allocation to the radiolocation service in the band 15.4-15.7 GHz, taking into account the results of ITU-R studies, in accordance with Resolution 614 (WRC-07).1

Radio Astronomy Service

The primary concern is radar in the 15.4-15.7 GHz band could spill into the 15.35-15.40 GHz RAS/EESS band. The RAS band at 15.35-15.40 GHz is used extensively to study the origins of high energy jets driven by black holes in the centers of galaxies, which radiate copiously by the synchrotron process in this band. The nature of these jets and their connection to the evolution of galaxies is an important issue in modern astrophysics. If the radar has a peak power of +30 dBW EIRP then the received signal at 20 km is –67 dBW/m^2, so that the out-of-band emissions of the radar need to be below –89 dBc to meet the limit specified in Recommendation ITU-R RA.769 to avoid the radar causing direct interference in the RAS/EESS band. Airborne transmitters coming closer than 20 km would require even more stringent limits on unwanted emissions into the adjacent passive band.

Recommendation: Radar in the 15.4-15.7 GHz band should have a sufficiently low level of unwanted emissions to avoid interference in the adjacent 15.35-15.40 GHz Radio Astronomy Service/Earth Exploration-Satellite Service band in accordance with the limits specified in Recommendation ITU-R RA.769.

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1 Resolution 614 is to study, as a matter of urgency, the technical characteristics, protection criteria, and other factors to ensure that radiolocation systems can operate compatibly with systems in the aeronautical radionavigation and fixed-satellite services in the band 15.4-15.7 GHz, taking account of the safety nature of the aeronautical radionavigation service; to study, as a matter of urgency, the compatibility between the radiolocation service in the band 15.4-15.7 GHz and RAS in the adjacent band 15.35-15.40 GHz.



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