[BC] Total Power Of An AM Directional Array

[Thomas G. Osenkowsky]

The total power in a DA system would be base current
squared times base operating resistance. There will be
phasing/coupling system and ground losses. The FCC
allows an increase in transmitter power to compensate
for these. Part of the base current will be inclusive of
the ground losses.

Some people mistakenly believe all the base currents should
add up to equal the common point current. This is NOT so!
Also, some measure the base operating impedance with an
OIB and then do the I squared R calculation. The OIB has
an insertion effect which varies with each tower in each array.
This is not an accurate means of determining total radiated
power.

Some DA's exhibit 'gain' or a higher RMS than their counterpart
non-D radiator. These designs, however, usually have degraded
bandwidth (high RSS:RMS ratio) and low operating impedances.
Some patterns have a 'negative tower' which returns power to the
common point. A negative tower is NOT one with a lagging phase
angle.

Yours was not a dumb question, therefore you will not be charged
a dumb question fee.

Tom Osenkowsky, CPBE

> In an AM multiple tower directional array, does the power of 
> all towers as determined by "P equals I squared times R" add 
> up to the authorized power of the station?
> For example, for a one thousand watt station with four towers 
> would the power of each tower add up to one thousand watts?
> Thanks to all who have answered my occasional questions to 
> satisfy my curiosity about radio, even if the questions 
> appear to be dumb ones.
> Tom