  The Square Kilometre Array (SKA) will be operating at the time when several
new large optical, X-ray and Gamma-ray facilities are expected to be working.
To make SKA both competitive and complementary to these large facilities,
thorough design studies are needed, focused in particular on imaging
performance of the array. One of the crucial aspects of such studies is the
choice of the array configuration, which affects substantially the resolution,
rms noise, sidelobe level and dynamic range achievable with the SKA. We present
here a quantitative assessment of the effect of the array configuration on
imaging performance of the SKA, introducing the spatial dynamic range (SDR) and
a measure of incompleteness of the Fourier domain coverage ($\Delta u/u$) as
prime figures of merit.
