Realization of a compact antenna with reconfigurable pattern for multiple antenna systems

A pattern reconfigurable antenna for a multiple-input multiple-output (MIMO) antenna system is presented in this paper. For this antenna a feeding structure, consisting of back-to-back balun, that supports realization of different radiation patterns is proposed. Thanks to novel application of this feeding structure any wanted switchable directivity patterns can be realized. Presented antenna generates two switchable patterns, which are optimized for automotive case. As a proof of concept a prototype of this antenna has been fabricated and measured. In this case p-i-n diodes are used as switching elements. The maximal gain achieved is about 6.5 dBi. The measurement results correspond well with the simulation results in terms of S-parameter and radiation.