what structure to develop a low IL chip filter!

I find the spec of chip filter in big company is very rigorous.But I find chip filter on IEEE paper is usually poor.For example,by LTCC technology，on IEEE paper, the insertion loss is usually up to about 3 db,but by some companys' introduction,the value of their productions is usually about 1db。How can they do this? some new structures?some new materials?

Are the size of the filters the same? Are the bandwidth the same? Bigger size usually means less loss and wider bandwidth also suggests lower loss.

for example: the size of 2mm×1.2mm×1mm with a IL of 0.6dB,the material is LTCC,the εr is about 20.