An antenna solution for MIMO channels: the multimode antenna

A novel way of exploiting diversity by employing the higher order modes of a biconical antenna is introduced. Essentially, the biconical antenna offers characteristics similar to an antenna array through multiple modes using just a single antenna element. An analytical expression for the correlation between different modes in a realistic environment is presented. It is found that the correlation is low enough to yield a diversity gain. Furthermore, the channel capacity of a multi-input multi-output (MIMO) system using a multimode antenna, i.e. an antenna employing multiple modes, is found to be comparable to that of an array. Since only one antenna element is needed, the multimode antenna offers several advantages over traditional arrays and is an interesting antenna solution for future high capacity MIMO systems.