Experimental evaluation of the Hybrid Smart Antenna system with directional array elements

The hybrid smart antenna algorithm (HSAA) relies on elimination of the array elements with the smallest received signal powers in the beamforming process in order to improve the computational efficiency, and reduce the hardware cost. Earlier computer simulations (Liberti and Rappaport, 1999) suggested that it is possible to further suppress the sidelobes by employing directive array elements. In this paper we present the results of experimental verification of this observation. Specifically, an 8-element array consisting of 30deg half power beamwidth (HPBW) Yagi-Uda antennas is used with the HSAA. Although the directivity of the array elements is heavily affected by the mutual coupling effects, a significant decrease in the sidelobe levels is observed thus confirming the simulation results. This experimental effort further confirmed other advantages of the HSAA approach. It is shown that the exact direction of arrival (DOA) is determined by selecting only 2 elements out of the 8 possible with the Yagi-Uda elements while the array of omni-directional dipole elements required at least 5 out of 8 elements. The experimental procedure is described and comparison with simulation results is presented.