Optimum wireless power transmission through reinforced concrete structure

Wireless embedded sensors are ideally suitable for monitoring concrete structures because of their small size and ability to measure various quantities inside concrete. Wireless power transmission for such sensors embedded in plain/reinforced concrete slab is studied here. The return loss and transmission loss of dipole and patch antennas are studied at typical RFID frequencies. Also, the antennas´ performance is investigated for free-space, dry concrete, saturated concrete and reinforced concrete. Our results lead to the determination of the optimum operating frequency as well as the suitable antenna type for wireless powering. Finally, a matched rectification circuit is designed, and typical battery charging times are calculated.