> I am not sure but I think WHO on 1040 kh in DesMoines,
Iowa still uses a
> Franklin Antenna. The top 1/2 wave is isolated from the
bottom 1/2 wave and is fed
> through a phase shift tuned ckt on the tower. This
information can be found
> in Capt. Paul Lee, USN handbook, "The Amateur Radio
Vertical Antenna Handbook."
> page 46. The vertical pattern for this antenna shows a
very low angle.
Jim,
Remember the goal of a AM BCB station is totally different
than a skywave station. They generally intend to confine
everything they can to groundwave. The exception is clear
channel, but even then they don't want first hop ever
landing in the fringe groundwave area.
The 5/8th was abandoned because the high angle lobe commonly
landed in the fringe groundwave area, and it had a null at
the most common useful skywave angle. This gave rise to
severe fading right where they most wanted to extend the
signal. Two half waves would be clean, but probably not the
thing for amateur since it would waste power on groundwave
that would be more useful in the sky.
73 Tom
_______________________________________________
Topband mailing list
Topband@contesting.com
http://lists.contesting.com/mailman/listinfo/topband
|