REALWSN'10 Proceedings of the 4th international conference on Real-world wireless sensor networks
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This paper presents the design, signal processing, and field measurements of SPIDA, a direction-finding antenna for the 2.4 GHz ISM band, intended for both communication and localization in wireless sensor networks. The main design goals for the antenna were small size, low production cost, low power consumption, low signal processing requirements, and low interfacing complexity. The most expensive part of SPIDA is its SMA connector. The RFstage power consumption is the same as for a whip antenna. The angle-of-arrival can be computed from received-power measurements through a simple formula using on the order of ten multiplications. Controlling the direction of the antenna by a microprocessor requires only a pair of digital output pins. When field tested with the TI CC2500 radio chip, the RMS error for the uncalibrated antenna was less than 12° up to 100 m distance, covering nearly the full receiving range of the antenna at 1 mW transmitter output power. A distinguishing feature of the SPIDA antenna is the absence of side lobes, despite using a manufacturing-friendly and cost-conscious sparse ground plane.