The Peculiar Case of the Concentric Circular Hexagonal-Star Array: Design and Features

This paper proposes a peculiar concentric circular antenna array (CCAA) design with ability to incorporate in band full duplex (IBFD) access. The CCAA is deployed as a hexagonal star array (HSA) geometry. The design introduces virtual antenna formations, each consisting of at least two cancelling elements placed on axially opposite sides of a CCAA centre. The geometry of the HSA provides phase shifts which cancel out the self-signals at this centre, thus enabling it to function as an IBFD receiving point. While CCAA provides excellent beam-forming abilities, the IBFD centre provides the potential for acquiring a continuous instantaneous stream of channel state information (CSI). The CSI enhances the CCAA performance. The proposed HSA consists of two CAA rings of rectangular monopole patches resonating at 2.44GHz. The design was simulated using the Dassault electromagnetic field simulation (CST) simulator. The combination of the CCAA beam-forming abilities and the IBFD nulling were effectively demonstrated. The array diversity and multiplexing gains were also demonstrated, i.e., the array exhibits a multi input multi output with IBFD (MIMO-IBFD) performance. The measured self-interference cancellation (SIC) figure was -30.8dB, achieved at only the front-end antenna interface without integrating the SIC in other system blocks, which is a practical one stage figure.