It is all about which part of the dish is illuminated by the LNB.
A normal LNB with round illumination sees just a 80 cm (circle diameter) of this dish. This is a "multifocus" dish; it is as though some overlapping 80cm dishes are glued together next to each other. Hence the advantage of the byrider LNBs receiving equally well, as I wrote.
The width of a multifocus dish is not the important measure; the hight is the 'equivalent' measure that is of importance (as to be compared with normal dish's height).
Nice toroidal dish: google "SMW OA1600" !
greetz,
A33
Added: the width of a multifocus dish, of course, is important for the range of the arc that can be received. The wider the dish, the greater the part of the Clarke Belt that can be received by it.
Edit: Sorry, I wrote SMA. Should be SMW. Now corrected.