Concentric Circular Arrays for Stratospheric High-Altitude Platforms Wireless Sensor Networks

In this paper, a concentric circular array (CCA) is designed to provide feasible link between High-Altitude Platform (HAP)—which acts as a sink station—to sensor nodes placed on ground to form a Wireless Sensor Network. The proposed array design technique provides two types of coverage cells namely; wider coverage cell of 30 km radius and another smaller cell of 8 km radius. The link feasibility is examined for practical sensor models at two different frequencies (2.4 GHz and 868 MHz) and two corresponding bit rates (250 and 38.4 kbps) and shows the possibility of communications between the HAP and sensors at all scenarios. The CCA is optimized to improve the power gain inside the cell and reduce the out-of-cell sidelobe radiation using a modified Dolph-Chebyshev CCA. The comparison with conventional antenna models that give the same coverage radii shows that the link performance in terms of bit energy to noise power spectral density ratio can be improved by 11.37 dB for cells of 8 km radius and by 16.8 dB in the case of 30 km radius cells which make the link at 2.4 GHz to be feasible and realizable compared to using conventional antenna techniques.