[BC] Conductivity vs Skywave

Richard Fry rfry
Sun May 15 14:23:00 CDT 2005


Peter Haas:
>195 degrees, the average over all U.S. ND-U Class As, gives
> about 400 mV/m/kW at 1 km.  A Franklin gives about
> 510 mV/m/kW at 1 km.

By your numbers (and mine), a Franklin produces 2.1 dB more field strength 
in the horizontal plane than a 195? radiator.  As I posted earlier, this may 
not be enough difference in groundwave field at the receiver/listener level 
to justify the costs needed to install and maintain a Franklin.

BTW, from data I checked the average radiator height for all U.S. ND-U Class 
As is about 188.8?.

>As the horizontal field increases with height, the vertical field
>decreases. Then the vertical field begins to increase again at 180
>degrees.

This depends on the radiator height and elevation angle being considered. 
For example, radiators with heights between 180? and 225? have less 
elevation (vertical) field than a 180? radiator at elevation angles ranging 
from about 15? to 50? (all over a perfect earth).

RF 




More information about the Broadcast mailing list