Short-distance and near-ground signal measurements in a car park of wireless sensor network system at 433 MHz

The short-range and near ground measurements of signal attenuation in the UHF band are performed to study radio wave propagation in a car park for a wireless sensor network application. The measurement setup is based on the radio wave propagation along the row of a parking lot (full of cars) by varying heights of server antenna. In the application, a small antenna and a compact antenna are employed at the server antenna and the sensor antenna respectively, by radiating horizontal polarization. The test points are located under cars and above ground. The transmitter is radiated at 433 MHz with 120 cm, 180 cm and 240 cm of antenna height. The propagation models, such as the two-ray model and the free-space model, are compared with measurement results. These results can be used to approximate the signal level in practical planning of wireless sensor network systems in car parks.