WP5: Interferometry

February 12, 2010
Studies of very fine scale plasma phenomena require the routine employment of interferometric techniques in order to resolve features whose spatial scales are less than the scales of the scattering volumes defined by range gating and the transmitter beam geometry, or the intersection geometry of transmit and receive beams. This Work Package was responsible for studying the requirements needed to realise an interferometric imaging capability for the EISCAT_3D radar system, so that observations enabling the resolution of sub-beamwidth scale scattering structures could be made as a standard part of the radar operations.

The main conclusions from this Work Package can be summarised as follows:

  • The core antenna will be composed of about 20 or more modules (sets of 343 antenna elements) accompanied by a few outlying modules, the latter to comply with the resolution requirements. This is an optimum and flexible antenna layout from which favourable configurations can be quickly implemented to obtain the resolution and bandwidth of the required image; several simulated configurations have been suggested.
  • The phase accuracy of the timing system has been specified to fulfill the desired image resolution.
  • A novel way to calibrate the imaging system has been proposed using the phases obtained from measurements of the usual incoherent scattering signals.
  • The inversion algorithm based on the Maximum Entropy Method (MEM) has been implemented and tested on simulated and real data, the latter obtained with the imaging-capable radar of Jicamarca.
  • Methods to represent visually a function of five independent variables – with various degrees of completeness and compression – have been investigated and tested with simulated data and real world data (from Jicamarca).
    The work in this Work Package was performed by the University of Tromsø.