A multiport antenna for indoor PCS smart receiver

Space division multiple access (SDMA) is emerging as a promising multiple access technique to provide a considerable increase in capacity and quality of many wireless systems. To implement SDMA optimally, a smart antenna system, composed of a multiport antenna with substantial port-to-port isolation and a digital signal processor with an adaptive algorithm, is required. This paper describes the design of a compact multiport antenna that can be integrated with a transmitter or receiver to yield a smart antenna system for the indoor PCS base station. The electrical performances of the antenna are presented. The multiport antenna has a novel structure with twelve elemental antennas. By applying both polarization and pattern diversity schemes to the same antenna, antenna elements can be located in close proximity, within a radius of half wavelength at the design frequency, to allow a significant reduction in antenna size while maintaining the low mutual coupling. The experimental results indicate that the multiport antenna features a good isolation between elements and a practical input impedance for each elemental antenna over a wide bandwidth.