extraction of coupling coefficients

hi frnds iam desinging a combline bandpass filter......i want to know the spacing between the resonators and the location of tapped feed line.....
for extracting coupling coefficients between a pair of resonators using EM simulation how should be the resonators be placed( like they should be placed as they are in the actual filter or in some other way)...
my question is
1) since my combline filter is having resonators short circuit to ground at the end .for extracting K whether they should be placed like that only as the resonators in actual filter design... if it is so ,for extracting K feedline should be given to first resonator on one end and other end is shortcircuited to ground and output is given to second resonator same as like first resonator ......my doubt is whether there is coupling between these two feedlines or not if it is placed like this...........