Topband: Radials help
w2xj at nyc.rr.com
Fri Feb 10 15:31:38 PST 2012
Here is a link to that paper. It is easy see what field a radiator of X
height will produce with varying number of radials from 2 to 113. From
the graphs 15 radials and a 45 deg tower gets reasonably close to the
ideal. It also shows a 45 deg tower with 113 radials is almost as good
as a 90 deg.
On 2/10/12 4:03 PM, Guy Olinger K2AV wrote:
> 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 at 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
>>> full length; even bare wire buried a couple of inches underground?
>> 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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