Coupling and Correlation Reduction in Compact Arrays for WSN Nodes via Pre-fractal Defected Ground Plane

We studied compact printed arrays built with sinusoidal monopoles. The antennas were designed at 2-3 GHz according to the size and bandwidth constraints of broadband sensor networks. Their performance was characterized in terms of VSWR bandwidth, broadband radiation efficiency, mutual coupling and broadband envelope correlation. Results show that densely-packed compact arrays feature controllable element detuning, whereas envelope correlation stays below 0.5 even for lambda 0/10 spacing. Finally, if coupling and correlation suppression is needed, we describe a simple yet effective technique that offers multi-decibel gains. It is based on disturbance of the ground currents by insertion of a defect.