Measuring the radiation bands of overhead power lines glass insulators

In this paper the characteristics radiation of overhead power lines glass insulators is investigated. Two feeding possibilities are used to analyze the radiation effects. The first feeding point is placed on the cap of the insulator and the second one is connected to the pin. The reflection coefficient (S₁₁) for two insulators covering the band of 30 MHz to 1 GHz was measured. The measurements were performed on insulators with different conservation states: one has a metal frame in good condition and the other one has both cap and pin parts rusted. The measured results show bands with good impedance matching (30 MHz to 200 MHz). The cleaned insulator reached S₁₁ = -18.7 dB at 127 MHz while -10.87 dB at 121.2 MHz was obtained for the rusty insulator. These spectral bands can be used in the analysis of insulator´s conservation state and its interference characteristics.