Improvement of MIMO channel capacity using tunable transmit-array antenna

In this paper, we proposed improvement method of MIMO channel capacity using transmit array with tunable reactance for the environment suffering from the key-hole effect. The tunable transmit-array is placed at the aperture of the enclosed room to increase the number of the paths. From the numerical result, it is found that the 50 %, channel capacity of the arbitrarily optimized termination condition of the transmit-array elements is improved by 6 bits/s/Hz compared to that without transmit-array. Moreover, the 10 %, channel capacity with the arbitrarily optimized termination condition is improved by 10 bits/s/Hz compared to that without transmit-array. It is found that the larger the aperture of the transmit-array becomes the higher the channel capacity becomes. These results have demonstrated the validity of the improvement of MIMO channel capacity using transmit-array with tunable reactances.