Preliminary measurement and analysis of microwave transmission attenuation in small gas pipeline

The gas pipelines need to be inspected in the case of existence of pipeline's inner problems. Usually, inspection for leakage of gas pipeline has been carried out by wired probes or wired robots equipped with a CCD camera. However, the above inspection approaches are restricted by the cable in the pipe. This study thus focuses on an inspection approach based on microwave communication. However, obtaining the transmission properties (i.e., transmission loss, RSSI (received signal strength indication), maximum transmission distance, etc) in gas pipeline is crucial to determine which frequency is feasible to the further development. In this paper, a communication system for microwave communication in 2.4 and 5.8 GHz band is developed. Then, the transmission loss and RSSI of these microwaves in 2.5 × 100 cm (straight), 5 × 100cm (straight) and 5 × 200cm M-type curved steel gas pipe (with L-junctions) are then measured. The experimental results revealed that the microwave in 2.4 GHz band owns much stronger communication capability in complicated gas pipeline in consideration of few transmission loss, and three approximate linear functions could be modeled on the basis of the measured data.