Compact Antennas with Reduced Mutual Coupling for Wireless Sensor Networks

Printed sinusoidal monopoles are a type of meander line antennas, with smooth curve structure and enhanced performance, suitable for building compact multi-element antennas (MEAs). The antennas described here were designed at 2-3 GHz to meet the size and bandwidth constraints of multimedia sensor networks. Their performance was characterized in terms of electrical size, bandwidth, and broadband radiation efficiency. We also studied compact printed arrays built with sinusoidal monopoles; we designed a two-element MEA and tested its behavior for interelement spacing ranging from 0.25 λ 0 to 0.10 λ 0 . Array response was characterized in terms of VSWR bandwidth, 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 λ 0 /10 spacing. 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.

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