Dual-polarisation and dual-pattern planar antenna for diversity in body-centric communications

A novel dual-polarisation/dual-pattern stripline-fed annular-ring slot antenna for body-centric communication systems working in the IEEE 802.11a frequency band at 5.725-5.825-GHz is presented. A stripline feeding technique has been implemented in order to reduce the back radiation level and make the antenna suitable for wearable communication systems. The planar antenna has been designed to provide capabilities for implementation of a polarisation/pattern diversity scheme in body-centric communications. Two prototypes have been fabricated and characterised. The design criteria are described and measurements of return loss, isolation between ports, principal plane radiation patterns and radiation efficiency are shown. A measurement campaign has also been carried out to evaluate the diversity scheme performance.