SHARE, principles of operation
SHARE Principles of Operation

Like all radars, SHARE determines the position and motion of distant objects by bouncing beams of radio waves off them. In this case, the distant objects are ripples in the density of electrons in the ionosphere and the ripples are carried along with the background plasma flow. The time delay between a transmitted and received radio pulse tells us how far away the ripples are from the radar. The frequency difference between the pulses tells us how fast the irregularities (and hence the plasma) are moving away from or towards the radar (the Doppler effect).

The SHARE radar operates in a manner similar to air surveillance radars. A narrow beam of high-frequency (HF; 8-20MHz) radio waves is formed which is then swept through 16 pointing directions to scan 4 million square kilometres of the polar ionosphere every 2 minutes.

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