In the previous chapters receiver diversity related to antenna arrays has been discussed to some extent, but the additional flexibility derived from having more than one antenna element leads to many more uses. The interdependence between the antennas and the propagation environment is even more clear in this new connection. The signal correlation between elements is very important for the potential applications, and this correlation depends on the angular spread as seen from each array antenna. In general there will be M transmitting antennas in a transmit array and N receiving antennas in a receive array. Although there will be reciprocity between any two antennas, it will be necessary to distinguish between the transmit and receive situation, since the knowledge of the channel parameters may be different in the two situations. Also in the most general case the angular spread of the same environment will be different seen from the two sides. Another important distinction will be between one-port and multi-port arrays. In the first case the different elements may have different complex weights, but combined into one port, whereas in the second case each element may be connected to a network with several ports.

Inspec keywords: antenna arrays; receiving antennas; correlation methods; transmitting antennas; multipath channels; diversity reception

Other keywords: antenna element; receiving antenna arrays; angular spread; transmitting antenna arrays; antenna propagation environment; signal correlation; multipath environment; channel parameters

Subjects: Radio links and equipment