On Sun, 29 Jul 2007 21:24:56 -0500, K4SAV wrote:
>They then shortened the antenna to something
>close to 1/2 wavelength, 808 feet, which gives all low angle radiation
>with no high angle lobes.
In the old days (when those big clear channel stations were licensed) they
all were 5/8 wave towers. My AM broadcast engineer friends who run 50kW
stations in Chicago told me that they all were getting much closer to a half
wave length, for exactly the reason you noted. The website below will allow
you to look at the technical parameters for any AM, FM, of TV broadcast
license.
http://www.fcc.gov/mb/audio/
To use it, select AM, FM, or TV, then use the various search windows to zero
in on the information you're interested in. For example, WGN's tower is 195
electrical degrees. WSM's is 190 degrees. WLS is 189 degrees. And so on. I
suspect they might be using 190-195 degrees to make it easier to load.
73,
Jim Brown K9YC
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