miso@sushi.com wrote:

I can't say I've ever seen a big J-pole...

Very, very common for AM broadcast and shortwave.

It's much safer for lightning strike protection.
The element is DC grounded.

Typically an AM broadcast band array will be
several shunt fed verticals in a phased array,
like the CB twins on an 18 wheeler (only the CB
antennas aren't jpoles). That way they can change
the feed phase and adjust the directional
characteristics of the array to comply with FCC
or whatever governing body there is in their country.

The KFI article mentions a "top hat", a capacitive
bunch of metal which allows the vertical element to
appear longer than it is (longer in RF wavelength).
Hams do that all the time. They mount their yagi beams
on top of their tower. Then when they want to work
160m or other low freq's, they load the tower as the
driven element, and allow the yagi to serve as
a cap hat, making the element appear longer to
the transmitter.

I still say the tower top looks like a plus symbol

I'm not talking about the air conditioners on top.
I'm talking about the shape of the structure. It's
three sided. Like a typical shed/garage/hanger is
4 sided, this thing is three sided. It's floor plan is
a triangle that's a bunch of stories high.


Lumpy

In Your Ears for 40 Something Years
 www.LumpyMusic.com