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## [TowerTalk] Are higher HF antenna's really better?

 To: [TowerTalk] Are higher HF antenna's really better? n4kg@juno.com (n4kg@juno.com) Thu, 10 Jan 2002 16:52:28 -0600
 On Thu, 10 Jan 2002 "Sain'T Tom" writes: > SNIP > My experience was not unlike the W6 who experimented with high > and low quads back in the 60s or 70s. If I recall correctly, his lower > never exceeded the upper in signal strength. > > Tom K4RV I recall that article also. To me, his observations are highly suspect. ANY antenna higher than 3/4 WL will exhibit a NULL in the vertical pattern and ANY antenna around half that height will fill in that null. It's as simple as that. These nulls can be quite deep. If you have a tall tower, the simple solution is to place another antenna at 35 to 40 ft to fill in the nulls of the higher antenna. Even a dipole at 35 to 40 ft will be better than the biggest Yagi you can support at the waveangle corresponding to the null region of the Yagi. On 20M, a NULL occurs at 30 degrees (+/- 5 degrees wide) for antennas at 70 ft. (600 mile skip distance on 20M) This null is centered at 24 degrees for antennas at 90 ft. (800 mile skip distance on 20M) *assuming flat terrain*. My 80 ft high TH6 is typically 20 dB down at 800 miles from my 40 ft high TH7 on 20M. That's equivalent to reducing your power from 1000 W to 10 W. I hear W1's just fine on the higher antenna but if I am calling someone at that takeoff angle, and someone else is calling with a lower antenna, the guy with the LOW antenna will most likely get through first. Same for EU during mid day or Africa anytime, at least from my location. Terrain also needs to be taken into consideration if it is not flat for several wavelengths from the tower and this may explain some of the unaccounted for differences in observations. Tom N4KG ________________________________________________________________ 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/web/. ________________________________________________________________________ This list is sponsored by the new eHam.net Store. When you buy products like ICE filters, Array Solutions StackMatch, or M-Squared Antennas from the eHam Store for the same price you pay direct, a portion of the sale price goes to support this list. Check it out at http://www.eham.net. ----- 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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