The 120 comes from the watershed 1937 Brown Lewis and Eppstein study now
found in the IEEE journals. There were distinct characteristics to 120
times 0.4 wl (actually 115) that improved results even vs. 60.
That a deficient radial system on one side has any significant reduction in
that direction alone VS THE OTHER DIRECTIONS is a fairly well debunked
idea. That the missing radials reduce radiation in all directions, due to
diminished efficiency, is not disputed.
73, Guy.
On Fri, Feb 10, 2012 at 2:54 PM, Herb Schoenbohm <herbs@vitelcom.net> wrote:
>
>
> On 2/10/2012 1:11 PM, Milt -- N5IA wrote:
> > If that is the case, WHY do the pro broadcasters install all 120 radials
> at
> > full length; even bare wire buried a couple of inches underground?
>
> Answer:
>
> Because the FCC requires it as part of your AM application. Some
> stations that were required to protect a distant station on the same
> channel but away from the area they wanted to cover, even applied for a
> waivers with a deliberately poor ground system in the protected
> direction ...but the FCC said no way Jose. Another consulting engineer
> when modeling a slant wire shunt fed and running test FSM noticed some
> cancellation in the opposite direction of the slant wire shunt fed
> tower. This appeared a sensible solution to enhanced protection without
> the addition of another tower and expensive pahser, not to mention the
> cost of additional real estate. Again the boys at 1919 M Street said
> no. (The Portals today)
>
> With the price of copper skyrocketing the amount of theft in some parts
> of the country is unbelievable. AM stations are immediate targets as
> thieves just pull up the systems with a winch or just hook it to the
> bumper and drive off into seclusion and roll it up in the back of a
> truck. Some station owners in PR have opted to plow in barbed wire as a
> lower cost alternative to bare copper. So far none of the barbed wire
> buried ground systems have not been touched.
>
>
> Herb Schoenbohm, KV4FZ
> _______________________________________________
> UR RST IS ... ... ..9 QSB QSB - hw? BK
>
_______________________________________________
UR RST IS ... ... ..9 QSB QSB - hw? BK
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