Trapezoidal monopole antenna and array for UWB-MIMO applications

Ultra-wideband (UWB) antenna arrays are important for UWB communications, positioning, and radar. Antenna efficiency as well as omnidirectionality of the antenna pattern are important for these applications. This paper introduces and investigates a new printed array consisting of trapezoidal monopole antennas. The antenna elements have good impedance matching and omni-directional radiation pattern in the frequency range of interest, namely 2.2 GHz -7.5 GHz. Since a uniform linear array (ULA) of these elements shows severe pattern distortions at higher frequencies, we propose an interleaved uniform rectangular array (iURA). The iURA achieves a lower mutual coupling and thus improved omni-directionality of the radiation pattern. Furthermore, by comparing the ambiguity functions of a virtual iURA with that of a virtual ULA, it is found that, even though without considering the mutual coupling, the iURA has a better angular resolution performance than the ULA. We conclude that the iURA is more suitable than the ULA for UWB-MIMO applications.