HF backscatter radar at the magnetic equator : System details and preliminary results

Abstract

A phase coherent, pulsed, monostatic and moderately high power HF Doppler radar, operating at 18 and 9 MHz has been installed at the magnetic equatorial station, Trivandrum (8.5°N, 77°E; dip 0.5°N), India. It is a powerful tool to study the plasma instability processes responsible for the generation of equatorial electrojet (EEJ) and equatorial spread-F (ESF) irregularities. A novelty in the radar system is the usage of the same phased array antenna at the two harmonically related frequencies of 18 and 9 MHz. The radar employs Doppler beam swinging (DBS) technique with beam orientations of vertical and ±30° off zenith in the E-W plane, providing the unique capability of obtaining both zonal and vertical drifts of the ionospheric irregularities. The radar is also capable of providing zonal wind information in the region of 80-95 km. The new radar has opened up the possibilities of investigating different aspects of EEJ, like the E-W spectral asymmetry, diurnal pattern of the electric field and the effect of small scale plasma turbulence on the large scale EEJ altitude structure. In this paper the detailed system description, data processing scheme and some preliminary results obtained using the radar at 18 MHz are presented.