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.
http://rfry.org/Software%20Download/Ground%20Systems%20-%20Brown,%20Lewis%20and%20Epstein%201937.pdf 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<[email protected]> 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 > _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
