5. Conclusions

In this chapter we propose a concept of APM for MIMO receiver to reduce the antenna size and hardware cost with keeping the availability of diversity gain. We discuss the types of antennas which achieve the APM, i.e., generating time-varying antenna pattern. Also, we discuss the benefits of the antennas, in particular, for ESPAR antenna-based structure. The number of virtual antennas or antenna patterns can be increased with the number of multiplexed orthogonal signals used to change the antenna patterns. A model of receiving process is proposed for analysing the capacity of systems using APM. We derive a model of received signals to analyse the system performance. The received signal in matrix form includes an equivalent channel matrix, which is a product of antenna pattern matrix, the channel coefficient vector for each output.

When the number of arrival paths and the number of antenna pattern are sufficiently large, the ergodic capacity approaches to that of 2 � 2 MIMO systems.
