> antenna as a flattop radiator, fed by a vertical wire. Most
likely they didn't realize it was their "feeder" doing all the work
and the flattop radiation was being cancelled out !
By 1921, they knew the importance of the flat-top as a non-radiating loading
device to increase radiation efficiency. The theory of the Marconi "T" and
its variants was pretty well understood by J. Fleming during the time of
Marconi's transatlantic tests. Fleming was responsible for the design of
Marconi's Poldhu transmitting station ca. 1900-1901. I've seen several
early references to the use of top-loading with single wire "Ts" and the
more prominent multi-wire flat-tops. These typically employed 4-6 wires.
In reading through some materials from R.H.G. Matthews, owner of 9ZN in
Chicago, early spark stations generally employed one device to determine
antenna radiation efficiency : An R.F. ammeter placed in series with the
vertical portion of the antenna offered the clue. The multiwire "T" evolved
as a result of the ammeter. As more wires were added to the flat-top, the
ammeter displayed more current. Horizontal wires would be added to the
point of reaching diminishing returns as measured on the ammeter.
Paul, W9AC
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