Medium Frequency Re-Radiation from an Unstrung Steel Power Line Tower

Computations of AM broadcast re-radiation from a power line tower without phase conductor wires or overhead ground wires are compared with measurements. The tower is a 500 kV type located near Toronto. Computations of re-radiation using a detailed tower model including ground effects due to the footings, compared with measurements done in the near field of the tower, show good agreement in terms of frequency response and variation with distance from the tower. Two simplified computational models are compared with the detailed one in the far field and found to be accurate enough to be of practical use. Methods are given for deriving the models, predicting re-radiation from any tower within certain specifications, and extrapolating near-field measurements to far-field values.