EISCAT Scientific Association, Kiruna, Sweden
In response to user demands for higher temporal and spatial resolution and better basic radar performance, and in an effort to improve the reliability and economics of the mainland operation, in May 2005 the EISCAT Association in co-operation with several other institutions embarked on a four-year, European Union-supported design study for a new radar facility with greatly enhanced performance to replace the existing VHF and UHF systems.
The performance specifications for the new system, EISCAT_3D, have been established in close collaboration with current and future EISCAT user communities. Phased-array technology will be employed throughout and the powerful multi-static configuration of the EISCAT UHF system will be retained. The design goals include a tenfold improvements in temporal and spatial resolution, instantaneous measurements of full-vector ionospheric drift velocities over the entire altitude range of the radar, fully integrated interferometry capability, real-time raw data access and extensive archiving facilities. For optimum performance in low electron density conditions, and in the middle atmosphere, a frequency in the high VHF band (~240 MHz) will be used.
The first half of the study has focussed on establishing the overall system architecture, studying the feasibility of employing new sampling, beam forming and signal processing techniques, and on establishing how much of the needed technology already exists either in the organisation or as commercial off-the-shelf products. The optical performance of different types of phased arrays has been simulated, both in single-beam mode and in interferometer mode, a direct-sampling receiver design has been shown to meet the performance requirements in simulation, trigger criteria for interferometry have been developed and several commercial data storage options have been identified. A 48-element "Demonstrator" array has been constructed at the Kiruna site. It will be used during the coming winter together with the Tromso VHF transmitter to validate the simulation results in practice before proceeding to a grant application/tender process.
The science case, the performance criteria and the envisaged system architecture will be reviewed and the use of novel techniques and technologies (e.g. the fully digital receivers) highlighted. The Demonstrator sub-project will be covered in-depth. Prospects for the time after the end of the study phase may also be briefly discussed.