A fast control method for parasitic antennas based on a noniterative measurement is proposed in this paper. This method uses the channel state information at the receivers and predicts the channel even at the parasitic antennas that have tunable reactances instead of receivers. The channel prediction accuracy is investigated by considering the effect of the noise, and it is found that the channel at the parasitic antennas is well predicted from a few trials without recourse to iterated measurements when the signal to noise ratio is higher than 20 dB. The results of the simulation and measurement show that the interference can be suppressed even when the estimation accuracy is affected by the noise if the number of trials is sufficient. The experimental results demonstrate that the proposed methods achieve a fourfold channel capacity improvement and 10 dB improvement in signal-to-interference-plus-noise ratio (SINR) compared to two antennas without the parasitic antennas.