> In a message dated 3/19/2005 12:36:34 P.M. Central
Standard Time,
> k6rix@earthlink.net writes:
>
> I need an education here...
>
> When the FCC gives the "Electrical Height" (in degrees)
of a broadcast
> tower as 175.7 degrees, what does that mean?
>
> In this situation, I'm specifically talking about the
(former) KFI tower in
> Los Angeles. It has been my understanding that this 750'
tower is about a
> 5/8 wave length at 640khz. The "degrees" leads me to
believe that it is
> just under a 1/2 wave (180 degrees).
An additional note..
BC stations very quickly learned that 5/8th wave verticals
were undesirable. They offered very little if any gain at
all over a 1/2 wl or shorter, and they were subject to
severe fading in areas near the limit of groundwave. Because
of the fading issues and limited (if any) gain, 5/8th waves
were abandoned in favor of verticals 1/2 wl or shorter. As a
matter of fact a ~ .525 WL tall vertical is or was
sometimes called a "non-fading vertical".
Just over 1/4 wl is normal, but the big stations sometimes
crept up around 1/2 wl.
The electrical height in degrees should equal the physical
tower height expressed as a function of wavelength rather
than feet. It is not the effective electrical height that
would be SHORTER if the tower was tapered to a point or
longer if the tower had top loading.
73 Tom
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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