In article ,
"David Eduardo" wrote:

"Telamon" wrote in message
...
In article ,
"David Eduardo" wrote:

"Telamon" wrote in message
news:telamon_spamshield-

Guess where you went wrong. Give it a shot.

Most single tower AMs have more broadband ATUs than directionals. It is a
lot easier to tune a directional system with high-Q circuits in the
phasor,
so throught the 60's, most directional systems had such narrow band,
high-Q
circuits.

You don't think there might be a problem with tower itself?

What kind of problem do you have in mind? The FCC, for the most part
requires 1/4 wave for all but class A stations, that are supposed to be 1/2
wave. There are exceptions, granted due to the lack of enough land or FAA
regulations and zoning issues.

I would say bandwidth. Large aspect ratio antenna elements have a narrow
band of resonance. It seems to me that there are some companies out
there that have tower kits that run 3 to 4 wires on spreaders so the
electrical diameter of the tower is increased. This will allow the tower
to have lower VSWR over the +/-15KHz required.

Next up I would look at the transmission line to tower coupling. Many AM
broadcast towers are series coupled with the tower isolated from ground.
The tower would tune a little more broadly if it was grounded and shunt
coupled. I believe this is the preferred method in central and south
America.

--
Telamon
Ventura, California