The EISCAT Scientific Association (EISCAT) conducts research on the lower, middle and upper atmosphere, and ionosphere using the incoherent scatter radar technique. At present, EISCAT operates three incoherent scatter radar systems in Northern Fenno-Scandinavia and on Svalbard. EISCAT is funded and operated by research institutes and research councils of Norway, Sweden, Finland, Japan, China and the United Kingdom. EISCAT has now started the construction of EISCAT_3D, a new radar system which will be the next generation incoherent scatter radar capable of providing 3D monitoring of the atmosphere and ionosphere.
The full EISCAT_3D system will consist of five phased-array antenna fields located in the northernmost areas of Finland, Norway and Sweden, each with 9919 crossed dipole antenna elements. One of these sites (at Skibotn, Norway) will transmit radio waves at 233 MHz, and all five sites will have sensitive receivers to measure the returned radio signals. Digital control of the transmission and low-level digitisation of the received signal will permit instantaneous electronic steering of the transmitted beam and measurements using multiple simultaneous beams. The active antenna array in Skibotn will be surrounded by smaller outlying arrays which will facilitate aperture synthesis imaging to acquire sub-beam transverse spatial resolution. Each antenna array will be of a size of about 70 m from side to side, and the receive-only sites will be located at a distance of 90 km to 250 km from the core site in order to be able to maximise the coverage by the system. In the first stage of implementation, EISCAT_3D Stage 1 (E3DS1), three sites, the active array at Skibotn, Norway and receive-only arrays at Kaiseniemi, Sweden, and Karesuvanto, Finland, will be built. The Antenna Unit procurement covers the antenna system at the three sites. Due to potential funding constraints, a part of the procurement will be handled as options that may be ordered later, but before the final regular deliveries are done