Switched Parasitic Dipole Antenna Array for High-Data-Rate Body-Worn Wireless Applications

A switched parasitic dipole antenna array is introduced for 2.45-GHz body-worn wireless applications. The array consists of a driven folded dipole and four parasitic dipoles whose excitation currents are controlled using p-i-n diode switches. Radiation beam can be steered in the azimuth plane using selective switching of the parasitic dipoles. An experimental prototype array was fabricated and tested to demonstrate performance both in free-space and next to the human body. Measured S11(dB) data clearly demonstrate that the array meets the 2.45-GHz ISM band bandwidth requirements when operated on or near the body. Simulation results of the array against an anatomical human body model show that the array beam can be scanned within an angular region of 65° with 6.9-8 dBi of peak gain. Significant improvement in radiation efficiency and considerably lower specific absorption rate (SAR) are achieved with this array. Measured radiated field strength test shows that the array performance is 2-5 dB superior to a single folded dipole for body-worn applications.