Ultra-wideband Multimode Microwave Detection on Insulating Mandrel of HV Polymeric Insulator

In order to improve the accuracy and efficiency of the delivery inspection on polymeric insulators, a novel ultra-wideband multimode microwave (UWB-MMM) detection method is proposed. This technique makes use of the multimode transferring theory, where the transmission signal level difference can be employed to detect internal defects in an insulating mandrel. A typical millimeter-ordered defect is investigated by simulation and experiment, and 30~50 dB and 60~80 dB coupled multimode signal differences have been observed over 0~8 GHz and 0~6 GHz, respectively.