No. All the multiswitch does is to distribute the Four outputs of an ASTRA sat system to any receiver so receiver 1 may be tuned to the Hi-band and Vertical polarisation, RX 2 to the Low band Horiz polarisation and the rest to any off them or combination.
Its just like TV distribution of course every TV or satellite receiver has to have a suitable tuner.
We if the existing one works at like gutter height then perhaps a hi gain amplified one might well do the trick in the loft. Modern Digital reception is very tolerant of ghosting which may have plagued analogue so if its above a sufficient threshold?.
I somehow doubt a more esoteric aerial will improve matters is in the end is all down to how much metal is up there to develop the required volts in the right place!.
Nowhere else it could go then?.?.