Key:tower:insulated

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  A radio mast insulated against ground used as mast radiator for medium wave
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  A radio tower insulated against ground used as tower radiator for medium wave

Radio towers used for transmitting on low frequencies are sometimes insulated against ground as they can act directly as antenna. Sometimes towers carrying wire antennas are also insulated against ground in order to improve their effiency. Radio towers insulated against ground can be guyed masts with lattice structure, guyed tubular masts or free-standing lattice towers.

See man_made=mast and man_made=tower for mapping and tagging.