A linearity of a voltage change to a tuner insertion amount is verified for at least one of a plurality of tuners. Based on the voltage change linearity, individual voltage change data corresponding to respective insertion amounts are calculated for each of the plurality of tuners through a proportional calculation. A combination of auto-tuners and a combination of respective insertion amounts of the auto-tuners are determined using the individual voltage change data, and an adequacy of the determined combinations is verified through a direct three-dimensional electromagnetic field calculation. The combinations are determined on a condition that, when the individual voltage change data of nominated tuners are added together, respective voltage changes attributed to the nominated tuners are cancelled out to allow an entire voltage distribution to have substantially no change.