Ground Plane Considerations for Printed Monopole Antennas Integrated into Wireless Sensor Devices

This work presents the results of a parametric study on small integrated antennas for wireless sensor network (WSN) devices operating in the 2-3 GHz range. The performance of small antennas depends heavily on their electrical size, which is controlled by the size of the ground (GND) Plane, since the GND plane is an integral part of the overall radiator. Therefore, we cannot design small antennas for tiny sensor nodes without considering the GND plane effect. We examined the performance of Fractal and Euclidean antenna configurations located on device-sized ground planes. The electrical performance of the tested schemes was characterized in terms of VSWR bandwidth and broadband total radiation efficiency. A suitable figure-of- merit (FOM) is also suggested for a fair comparison. This FOM is an attempt to gather all fundamental antenna parameters in a single scalar quantity. The results show that (a) every element couples to the GND plane in its own unique way, (b) a large ground plane does not produce optimal antenna performance. Although the results shown are for specific element sizes, the parametric analysis aids the designer to estimate the effect of the ground plane for various sizes of sensor nodes.