[BC] Radaitors - Was: KKGM

[PeterH5322@aol.com]

>The reason is found in the vertical plane. Above 180 deg the high angle
>lobe begins to form, and above 225 deg the low angle lobe begins to
>diminish. I recall seeing numbers to 240 somewhere, but anything above
>225 is beyond the point of diminishing returns.

It would take an NEC-2 simulation, but 225 is generally taken to be that 
height ... for a non-sectional ... where the horizontal field is maximum, 
at about 440 mV/m/kW at 1 km.

But, the vertical lobe is already fully formed, and is substantial, such 
than for 5 kW or more, 225 is not a good idea, due to the fringe ground 
wave being canceled by the reflected skywave.

Also, more than 225, non-sectional, and the horizontal lobe is moving 
away from zero degrees elevation ... hence the observed reduction in 
horizontal field for non-sectional radiators taller than 225.

Incredibly, 240 ... implemented as a 120 over 120 sectional ... is where 
the vertical field is quite small, all with a very significant horizontal 
field, at about 420-430 mV/m/kW at 1 km.


180 over 180 (Franklin), 180 over 120 (WHO) and 120 over 120 (WOAI) have 
been tried, and were successful.

If one is thinking of building a 225 non-sectional, one might consider a 
120 over 120 sectional instead.

225, non-sectional, makes sense for 5 kW or under (1 kW or under being 
best for this height), whereas 120 over 120 (240 total, sectional) is 
good out to 50 kW or even more.