Slot-antenna for autonomous sensor systems mounted on overhead power lines

A slot antenna for mounting on overhead power lines is presented. The antenna enables autonomous sensor systems to communicate in the 2.4 GHz band. Using two radiating slots the simulated antenna gain is 7.9 dBi. The usable bandwidth is more than 300 MHz. The general concept of the sensor system is outlined. It contains a DC-isolating bandpass filter with 1.5 dB insertion loss and more than 60 dB attenuation at frequencies below 1.0 GHz. Experiments performed on a deactivated power line confirm that the conductors and the power poles do not influence the radiation characteristic significantly. The transmission follows the Friis transmission equation. Using only 7.5 dBm of transmitted power yields -79.9 dBm at the receiver side at a distance of 1420 m. The immunity to interference of the communication system was tested by exposing it to strong artificially generated partial discharges.