Near-field channel measurements for UWB RFID with on-chip antenna

In this paper we present channel measurements of an ultra-wideband radio frequency identification tag (UWB RFID) with on-chip antenna (OCA). The manufactured prototype with a size of 1×1.3 mm2 transmits a carrier-based UWB signal, with adjustable pulse duration and carrier frequency. The signal bandwidth is more than 1 GHz, on a carrier frequency up to 12.5 GHz. A measurement setup has been developed to emulate a relevant office scenario at very short distances, up to 30 cm. The known bit sequence, sent by the manufactured tag, allows us to estimate the near-field channel characteristics, and path loss exponent. We propose a simple near-field UWB path loss model based on our measurements.