The EISCAT High Power HF Radar Capability

Summary form only given. The EISCAT HF facility or ionospheric heater near Tromsø, Norway, has recently been upgraded with the capability to function as a radar. One of the antenna arrays has been converted for receiving use, covering the frequency range 5.5-8 MHz. The transmitters now have direct digital synthesizers and are controlled by the same hardware and software systems used by the other EISCAT radars. With the new two-channel HF receiver the facility is capable of operating simultaneously as a heater and a HF radar. Various types of experiments are being performed or planned, such as probing of the mesosphere and ionosphere using the artificial periodic irregularity (API) technique where the facility is used both as heater and as a radar. Mesospheric sounding while actively modulating polar mesospheric summer echoes (PMSE) will be performed, as well as sounding the magnetosphere for possible coherent echoes associated with aurora.