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## [TowerTalk] optimum height

 To: [TowerTalk] optimum height alsopb@gloryroad.net (alsopb) Sat, 28 Jul 2001 18:32:41 +0000
 ```OOps. Thinking of a 67 foot dipole in the math. Of course the wavelenth should be about 140'. (the product of approx 3'/M X 40M much greater than 67' DUH!) 73 de Brian/K3KO n4kg@juno.com wrote: > > A FULL Wavelength on 40M is 140 ft. > A HALF WAVE Dipole is 66 ft allowing ~5% for end effects. > A 47 ft boom is .335 WL. The square root is .58 sq rt WL > (whatever the ***? those units represent). If we accept that > the units should be WL, that corresponds to 81 ft which is > close to optimum. Actually, stacked 2L40's exhibit peak > gain when stacked at 80 and 160 ft. > > Tom N4KG > > On Sat, 28 Jul 2001 16:18:19 +0000 alsopb writes: > > > > As stated originally the boom length in the formula is in > > wavelengths. > > A 47' boom is about .7 wavelength on 40 meters. The formula > > predicts > > a spacing of .84 wavelenth or about 56 feet. > > > > 73 > > > > Tom Rauch wrote: > > > > > > Hi Brian, > > > > > > I don't understand what the following means. Is something wrong? > > > > > > > I queries WX0B about the rule of thumb regarding "optimum" > > stacking > > > > height. > > > > > > > > Here was his response: > > > > *********************************** > > > > For HF antennas over ground, W2PV did the math correctly and the > > > > formula is SQ rt of boom length is the widest stacking distance > > you > > > > should use on a yagi. The results are in boom lengths just as > > you > > > > state. > > > > > > My 40 meter yagi has a 47 foot boom. Optimum stacking distance > > > for gain is ~90 feet, depending on array mean height. > > > > > > Using that formula, I should stack my 40 meter beams sqrt of 47, > > > or 7 feet apart MAXIMUM?? A 1 WL boom antenna would stack > > > at .7WL...which also would be much less than optimum > > > ....although getting closer. > > > > > > Was something stated or conveyed incorrectly above, or is > > > something missing? It clearly is not correct. > > > 73, Tom W8JI > > > W8JI@contesting.com > > > > > > ----- > > FAQ on WWW: http://www.contesting.com/FAQ/towertalk > > Submissions: towertalk@contesting.com > > Administrative requests: towertalk-REQUEST@contesting.com > > Problems: owner-towertalk@contesting.com > > > > ________________________________________________________________ > GET INTERNET ACCESS FROM JUNO! > Juno offers FREE or PREMIUM Internet access for less! > Join Juno today! For your FREE software, visit: > http://dl.www.juno.com/get/tagj. > > ----- > FAQ on WWW: http://www.contesting.com/FAQ/towertalk > Submissions: towertalk@contesting.com > Administrative requests: towertalk-REQUEST@contesting.com > Problems: owner-towertalk@contesting.com ----- FAQ on WWW: http://www.contesting.com/FAQ/towertalk Submissions: towertalk@contesting.com Administrative requests: towertalk-REQUEST@contesting.com Problems: owner-towertalk@contesting.com ```
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