RE: Sunday Globe Magazine article on Jerry Williams

[dan.strassberg@att.net]

So? Presumably, it reduced radiation toward CBF to 
something in the neighborhood of what WLW radiated with 
50 kW ND. If the parasitic tower had such an effect, the 
signal in the opposite direction pretty much had to be 
roughly equivalent to twice the actual antenna-input 
power. Since the second tower was presumably 
considerably shorter than the Blaw-Knox tower, maybe the 
height was chosen to produce a minimum in the vertical-
radiation pattern over the range of critical angles for 
the path from Cincinnati to Montreal.

On the other hand, I wonder whether enough was known at 
the time about the vertical-radiation characteristics of 
medium-wave antennas to design such a setup. Probably 10 
years later, KFAB compelled KRLA to use such techniques 
(towers of different heights) to minimize its skywave 
toward Omaha. The attempt did not wor

Still, designers _do_ sometimes use the height of AM 
towers to achieve design objectives. I theorize that 
three of the four towers in WBBR's night array are 
significantly shorter than half wave (101 degrees) to 
boost the nighttime signal here in Boston. Because of 
the use of short towers, WBBR (then WNEW) had to get a 
waiver of the requirement for rms field intensity for 
Class I stations.

Since all of WBBR's towers are self-supporting, it seems 
unlikely that some reason, such as inadequate room for 
guy anchors for tall towers, was involved in the use of 
the 101-degree towers. And the reason wasn't economics 
either; the State of New Jersey took the old site in S 
Kearney and paid--handsomely--for the move. Taller 
towers would have increased the signal strength in the 
New York market but would have reduced it here. Back 
when WNEW moved to the Secaucus site (late 60s?), I 
think that skywave service was still a design objective 
for clear-channel AMs.
--
dan.strassberg@att.net
617-558-4205
eFax 707-215-6367

> <<On Tue, 18 Jun 2002 19:34:25 +0000, dan.strassberg@att.net said:
> 
> > had to do, though, was to directionalize to protect 
> > first-adjacent CBF in Montreal. Imagine, 500 kW 
> > directional!
> 
> According to what I've read, the additional antenna which was added
> for this purpose was solely parasitic.
> 
> -GAWollman
>