WA4SZEwrote
I have installed a FAA approved NDB beacon here at our private
airport located in Manchester,TN .... Is a shunt feed tower lossy???
poor radiator??? comments???
_____________

Other things equal, a shunt fed MW vertical monopole can produce
essentially the same radiation pattern shape and gain as when series fed.

The link below leads to an analysis of what might be expected for either
case for the system you described.

Assumptions made in the analysis:

1) The four top-hat radials added 10 feet to the electrical height of the
tower

2) The ground radials described have a net r-f resistance of 25 ohms at the
operating frequency.

The analysis shows that for 50 watts of available power, this system could
generate an inverse-distance groundwave field strength of better than 700
µV/m at a radius of about 15 miles.

Of course, earth losses along the groundwave path will reduce that value,
but even with 6 dB of additional loss the field should still be better than
350 µV/m, and higher than that for higher elevations above the earth at that
distance (as would be true for airborne receive systems).

The performance you are describing indicates that the antenna is not
radiating much of the available power, which may point to problems with the
feed system.

http://i62.photobucket.com/albums/h8...alRadiator.gif

RF