A planar antenna design is developed for integration with a temperature sensor to monitor frozen goods condition during transportation. Antenna geometries as well as radiation patterns are configured to address the distinctive propagation environment, which is the cargo space filled with stacks of thermal insulated boxes. The sensor, a Bluetooth module, periodically relays temperature data to a dedicated reader or the driver's smart phone. With these data, quality of service can be ensured for cold chain logistics. The sensor antenna, which is mounted on the surface of the insulated box, has a sideways pattern that is aimed to propagate along the gap between boxes and avoid attenuation from perishable goods within. Numerical simulations of this distinctive propagation environment are conducted to determine the required antenna polarization. To demonstrate advantages of the proposed temperature monitoring system, several field tests have been devised. Received signal strength indicators are measured for stacked containers in both closed and open truck environments to validate the superior performance of the developed sensor. Stable connections to sensors on boxes filled with frozen goods can be made successfully in delivery trucks.
- cold chain logistic
- planar inverted-F (PIFA) antenna
- received signal strength indicator (RSSI)